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Sample records for hybrid tandem mass

  1. Hybrid silica monolith for microextraction by packed sorbent to determine drugs from plasma samples by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    de Souza, Israel D; Domingues, Diego S; Queiroz, Maria E C

    2015-08-01

    The present study (1) reports on the synthesis of two hybrid silica monoliths functionalized with aminopropyl or cyanopropyl groups by the sol-gel process; (2) evaluates these monoliths as selective stationary phase for microextraction by packed sorbent (MEPS) to determine drugs in plasma samples via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the multiple reactions monitoring (MRM) mode; and (3) discusses important factors related to the optimization of MEPS efficiency as well as the carryover effect. The prepared hybrid silica monoliths consisted of a uniform, porous, and continuous silica monolithic network. The structure of the aminopropyl hybrid silica monolith was more compact than the structure of the cyanopropyl hybrid silica monolith. The Fourier-transform infrared spectroscopy (FTIR) spectra of the hybrid silica monoliths displayed readily identifiable peaks, characteristic of the cyanopropyl and aminopropyl groups. Compared with the aminopropyl hybrid silica phase, the cyanopropyl hybrid silica phase exhibited higher binding capacity for most of the target drugs. The developed method afforded adequate linearity at concentrations ranging from the lower limit of quantification (0.05-1.00 ng mL(-1)) to the upper limit of quantification (40-10,500 ng mL(-1)); the coefficients of determination (r(2)) were higher than 0.9955. The precision of the method presented coefficients of variation (CV) lower than 14%; the relative standard error (RSE) of the accuracy ranged from -12% to 14%. The developed method allowed for simultaneous analysis of five antipsychotics (olanzapine, quetiapine, clozapine, haloperidol, and chlorpromazine) in combination with seven antidepressants (mirtazapine, paroxetine, citalopram, sertraline, imipramine, clomipramine, fluoxetine), two anticonvulsants (carbamazepine and lamotrigine), and two anxiolytics (diazepam and clonazepam) in plasma samples from schizophrenic patients, which should be valuable for therapeutic drug

  2. Analysis of 44 drugs of abuse and metabolites in wastewater and river water using a hybrid quadrupole time-of-flight tandem mass spectrometry

    Science.gov (United States)

    Andres-Costa, M. Jesus; Andreu, Vicente; Picó, Yolanda

    2016-04-01

    The presence of drugs of abuse in the aquatic environment has been recognized as an important issue for the ecosystem due their possible negative effect on it (Richardson, 2011). Incomplete removal of these substances during wastewater treatment could be one of the causes of their release in the environment (Zuccato and Castiglioni, 2009). Pollution by illicit drug residues at very low concentrations is generalized in populated areas, with potential risks for human health and the environment (Zuccato, 2008; Castiglioni et al 2007).The aim of this study was to screen and quantify 44 drugs of abuse and metabolites of wastewater samples using a hybrid quadrupole time-of-flight tandem mass spectrometry and furthermore carry out a post-target screening to identify additional compounds present in the water samples. Wastewater samples were collected from the influent and effluent of three wastewater treatment plants (WWTPs) in Valencia and river water samples form Turia River Basin. Illicit drugs were extracted by solid-phase extraction (SPE). The chromatography was performed with an Agilent 1260 Infinity ultra high performance liquid chromatography (UHPLC). The UHPLC system was coupled to a hybrid quadrupole time-of-flight ABSciex Triple TOFTM 5600. All analytes were analyzed in positive mode. Acquiring full scan MS data was employed for quantification of drugs of abuse, and automatic data dependent information product ion spectra (IDA-MS/MS) was checked for identifying emerging illicit drugs and other compounds in water samples. The use of a database containing 1212 compounds achieved high confidence results for a wide number of contaminants. In the present study, the presence of compounds that belong to amphetamines group (amphetamine, methamphetamine, ephedrine, MDMA, MDA and MDEA), tryptamines (bufotenine), pirrolidinophenone group (α-PVP and 4'-MePHP), arylcyclohexylamines (ketamine), cocainics (cocaine, benzoylecgonine, cocaethylene and ecgonine methyl ester) and

  3. Protein Sequencing with Tandem Mass Spectrometry

    Science.gov (United States)

    Ziady, Assem G.; Kinter, Michael

    The recent introduction of electrospray ionization techniques that are suitable for peptides and whole proteins has allowed for the design of mass spectrometric protocols that provide accurate sequence information for proteins. The advantages gained by these approaches over traditional Edman Degradation sequencing include faster analysis and femtomole, sometimes attomole, sensitivity. The ability to efficiently identify proteins has allowed investigators to conduct studies on their differential expression or modification in response to various treatments or disease states. In this chapter, we discuss the use of electrospray tandem mass spectrometry, a technique whereby protein-derived peptides are subjected to fragmentation in the gas phase, revealing sequence information for the protein. This powerful technique has been instrumental for the study of proteins and markers associated with various disorders, including heart disease, cancer, and cystic fibrosis. We use the study of protein expression in cystic fibrosis as an example.

  4. Optimized verification method for detection of an albumin-sulfur mustard adduct at Cys(34) using a hybrid quadrupole time-of-flight tandem mass spectrometer after direct plasma proteolysis.

    Science.gov (United States)

    John, Harald; Siegert, Markus; Gandor, Felix; Gawlik, Michael; Kranawetvogl, Andreas; Karaghiosoff, Konstantin; Thiermann, Horst

    2016-02-26

    The vesicant sulfur mustard (SM) is a banned chemical warfare agent that is controlled by the Organisation for the Prohibition of Chemical Weapons (OPCW). Bioanalytical procedures are mandatory for proving an alleged use and incorporation of SM into the body. We herein present the development and application of a novel optimized procedure suitable for qualitative verification analysis of plasma targeting the SM-adduct of human serum albumin (HSA) alkylated at the cysteine(34) residue. Diluted human plasma is directly mixed with pronase in an ultrafiltration device (10kDa cut-off) for proteolysis (4h, 37°C). Following ultrafiltration the filtrate is diluted and analyzed by microbore liquid chromatography-electrospray ionization high resolution tandem-mass spectrometry (μLC-ESI HR MS/MS) targeting the alkylated dipeptide hydroxyethylthioethyl-CysPro (HETE-CP). A hybrid quadrupole time-of-flight mass spectrometer provided high mass spectrometric resolution in the MS/MS mode enabling highest selectivity and sensitivity (lower limit of detection corresponding to 9.8nM SM in plasma). Kinetics of HETE-CP formation from heparin-, citrate-, and EDTA-plasma as well as serum are presented and the influence of different EDTA and pronase concentrations was characterized. The novel procedure was applied to plasma samples provided by the OPCW as well as to patientś plasma derived from real cases of SM-poisoning. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  5. Dispersive micro-solid-phase extraction using mesoporous hybrid materials for simultaneous determination of semivolatile compounds from plant tea by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry.

    Science.gov (United States)

    Cao, Wan; Hu, Shuai-Shuai; Ye, Li-Hong; Cao, Jun

    2014-10-08

    This report described the use of mesoporous hybrid materials (MHM) in a dispersive micro-solid-phase extraction procedure to extract semivolatile compounds from plant tea that were then analyzed by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Dihydrotanshinone I, tanshinone I, cryptotanshinone, and tanshinone IIA were selected as the model compounds, and the extraction parameters, including mesoporous concentration, extraction time, sample agitation and desorption solvents, were optimized. The interaction with the analytes and the large surface area of the MHM facilitated the adsorption of analytes. The method showed good linearity, with correlation coefficients >0.9980 in the range 0.25-100 ng/mL, and low limits of detection (0.012-0.046 pg). Finally, the recovery values were 91-103% for Danshen tea, 89-102% for Danshen, and 88-96% for tanshinone capsules. The results showed that the proposed method was suitable for the extraction and determination of tanshinones in complex samples.

  6. Self-passivating hybrid (organic/inorganic) tandem solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Jin; Cartwright, Alexander N. [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Institute for Lasers, Photonics and Biophotonics, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Kim, Won Jin [Institute for Lasers, Photonics and Biophotonics, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Prasad, Paras N. [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Department of Chemistry, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Institute for Lasers, Photonics and Biophotonics, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States)

    2009-05-15

    A tandem photovoltaic device structure, consisting of a PbSe nanocrystal film and a P3HT/PCBM bulk heterojunction film, was fabricated. The PbSe film (top layer) serves as a photocurrent generator as well as a UV protector for the underlying polymer cell. The P3HT/PCBM photovoltaic cell (bottom layer) provides the necessary electric field to the top photoconducting layer to extract the photogenerated charge from that layer. The charge extraction from the PbSe layer is demonstrated by using light-biased spectral response measurements. In addition, device lifetime measurements were performed under AM 1.5 and UV-enhanced illumination on the tandem cell and on a control P3HT/PCBM device. These measurements demonstrated that the hybrid tandem cell is significantly more durable due to the preferential UV absorption in the upper inorganic PbSe nanocrystal film. (author)

  7. Sequencing of Oligourea Foldamers by Tandem Mass Spectrometry

    National Research Council Canada - National Science Library

    Bathany, Katell; Owens, Neil W; Guichard, Gilles; Schmitter, Jean-Marie

    2013-01-01

    This study is focused on sequence analysis of peptidomimetic helical oligoureas by means of tandem mass spectrometry, to build a basis for de novo sequencing for future high-throughput combinatorial...

  8. Liquid chromatographic-tandem mass spectrometric assay for ...

    African Journals Online (AJOL)

    Liquid chromatographic-tandem mass spectrometric assay for simultaneous quantitation of tofacitinib, cabozantinib and afatinib in human plasma and urine. Adnan A. Kadi, Ali S. Abdelhameed, Hany W. Darwish, Mohamed W. Attwa, Ahmed H. Bakheit ...

  9. Ultra Performance Liquid Chromatography Tandem Mass ...

    African Journals Online (AJOL)

    NICOLAAS

    Acquity UPLC columns contain hybrid X-Terra sorbent, which utilizes a bridged ethyl siloxane/silica hybrid (BEH) structure, ensures column stability under high pressure and a wide. pH range (1–12).25. In all the documented references, no validated UPLC-MS/MS method has been reported for the determination of NTB ...

  10. Interpretation of tandem mass spectra of posttranslationally modified peptides

    DEFF Research Database (Denmark)

    Bunkenborg, J.; Matthiesen, R.

    2013-01-01

    Tandem mass spectrometry provides a sensitive means of analyzing the amino acid sequence of peptides and modified peptides by providing accurate mass measurements of precursor and fragment ions. Modern mass spectrometry instrumentation is capable of rapidly generating many thousands of tandem mas...... spectra and protein database search engines have been developed to match the experimental data to peptide candidates. In most studies there is a schism between discarding perfectly valid data and including nonsensical peptide identifications-this is currently a major bottleneck in data...

  11. Interpretation of tandem mass spectra of posttranslationally modified peptides.

    Science.gov (United States)

    Bunkenborg, Jakob; Matthiesen, Rune

    2013-01-01

    Tandem mass spectrometry provides a sensitive means of analyzing the amino acid sequence of peptides and modified peptides by providing accurate mass measurements of precursor and fragment ions. Modern mass spectrometry instrumentation is capable of rapidly generating many thousands of tandem mass spectra and protein database search engines have been developed to match the experimental data to peptide candidates. In most studies there is a schism between discarding perfectly valid data and including nonsensical peptide identifications-this is currently a major bottleneck in data-analysis and it calls for an understanding of tandem mass spectrometry data. Manual evaluation of the data and perhaps experimental cross-checking of the MS data can save many months of experimental work trying to do biological follow-ups based on erroneous identifications. Especially for posttranslationally modified peptides there is a need for manual validation of the data because search algorithms seldom have been optimized for the identification of modified peptides and because there are many pitfalls for the unwary. This chapter describes some of the issues that should be considered when interpreting and validating tandem mass spectra and gives some useful tables to aid this process.

  12. Interpretation of Tandem Mass Spectrometry (MSMS) Spectra for Peptide Analysis

    DEFF Research Database (Denmark)

    Hjernø, Karin; Højrup, Peter

    2015-01-01

    The aim of this chapter is to give a short introduction to peptide analysis by mass spectrometry (MS) and interpretation of fragment mass spectra. Through examples and guidelines we demonstrate how to understand and validate search results and how to perform de novo sequencing based on the often ...... very complex fragmentation pattern obtained by tandem mass spectrometry (also referred to as MSMS). The focus is on simple rules for interpretation of MSMS spectra of tryptic as well as non-tryptic peptides....

  13. Screening of drugs and toxic compounds with liquid chromatography-linear ion trap tandem mass spectrometry.

    Science.gov (United States)

    Sauvage, François-Ludovic; Saint-Marcoux, Franck; Duretz, Bénédicte; Deporte, Didier; Lachatre, Gérard; Marquet, Pierre

    2006-09-01

    In clinical and forensic toxicology, general unknown screening is used to detect and identify exogenous compounds. In this study, we aimed to develop a comprehensive general unknown screening method based on liquid chromatography coupled with a hybrid triple-quadrupole linear ion trap mass spectrometer. After solid-phase extraction, separation was performed using gradient reversed-phase chromatography. The mass spectrometer was operated in the information-dependent acquisition mode, switching between a survey scan acquired in the Enhanced Mass Spectrometry mode with dynamic subtraction of background noise and a dependent scan obtained in the enhanced product ion scan mode. The complete cycle time was 1.36 s. A library of 1000 enhanced product ion-tandem mass spectrometry spectra in positive mode and 250 in negative mode, generated using 3 alternated collision tensions during each scan, was created by injecting pure solutions of drugs and toxic compounds. Comparison with HPLC-diode array detection and gas chromatography-mass spectrometry for the analysis of 36 clinical samples showed that linear ion trap tandem mass spectrometry could identify most of the compounds (94% of the total). Some compounds were detected only by 1 of the other 2 techniques. Specific clinical cases highlighted the advantages and limitations of the method. A unique combination of new operating modes provided by hybrid triple-quadrupole linear ion trap mass spectrometers and new software features allowed development of a comprehensive and efficient method for the general unknown screening of drugs and toxic compounds in blood or urine.

  14. Analysis of posttranslational modifications of proteins by tandem mass spectrometry

    DEFF Research Database (Denmark)

    Larsen, Martin Røssel; Trelle, Morten B; Thingholm, Tine E

    2006-01-01

    -temporal distribution in cells and tissues. Most PTMs can be detected by protein and peptide analysis by mass spectrometry (MS), either as a mass increment or a mass deficit relative to the nascent unmodified protein. Tandem mass spectrometry (MS/MS) provides a series of analytical features that are highly useful...... for the characterization of modified proteins via amino acid sequencing and specific detection of posttranslationally modified amino acid residues. Large-scale, quantitative analysis of proteins by MS/MS is beginning to reveal novel patterns and functions of PTMs in cellular signaling networks and biomolecular structures....

  15. A novel organic-inorganic hybrid tandem solar cell with inverted structure

    Science.gov (United States)

    Bahrami, A.; Faez, R.

    2017-04-01

    A novel organic-inorganic hybrid tandem solar cell with inverted structure is proposed. This efficient double-junction hybrid tandem solar cell consists of a single-junction hydrogenated amorphous silicon (a-Si:H) subcell with n-i-p structure as front cell and a P3HT:PCBM organic subcell with inverted structure as back cell. In order to optimize the hybrid tandem cell, we have performed a simulation based on transfer matrix method. We have compared the characteristics of this novel structure with a conventional structure. As a result, a power conversion efficiency (PCE) of 6.1 and 24% improvement compared to the conventional hybrid tandem cell was achieved. We also discuss the high potential of this novel structure for realizing high-stability organic-inorganic hybrid photovoltaic devices.

  16. Comparison and Evaluation of Clustering Algorithms for Tandem Mass Spectra.

    Science.gov (United States)

    Rieder, Vera; Schork, Karin U; Kerschke, Laura; Blank-Landeshammer, Bernhard; Sickmann, Albert; Rahnenführer, Jörg

    2017-11-03

    In proteomics, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is established for identifying peptides and proteins. Duplicated spectra, that is, multiple spectra of the same peptide, occur both in single MS/MS runs and in large spectral libraries. Clustering tandem mass spectra is used to find consensus spectra, with manifold applications. First, it speeds up database searches, as performed for instance by Mascot. Second, it helps to identify novel peptides across species. Third, it is used for quality control to detect wrongly annotated spectra. We compare different clustering algorithms based on the cosine distance between spectra. CAST, MS-Cluster, and PRIDE Cluster are popular algorithms to cluster tandem mass spectra. We add well-known algorithms for large data sets, hierarchical clustering, DBSCAN, and connected components of a graph, as well as the new method N-Cluster. All algorithms are evaluated on real data with varied parameter settings. Cluster results are compared with each other and with peptide annotations based on validation measures such as purity. Quality control, regarding the detection of wrongly (un)annotated spectra, is discussed for exemplary resulting clusters. N-Cluster proves to be highly competitive. All clustering results benefit from the so-called DISMS2 filter that integrates additional information, for example, on precursor mass.

  17. Estimating the Efficiency of Phosphopeptide Identification by Tandem Mass Spectrometry

    Science.gov (United States)

    Hsu, Chuan-Chih; Xue, Liang; Arrington, Justine V.; Wang, Pengcheng; Paez Paez, Juan Sebastian; Zhou, Yuan; Zhu, Jian-Kang; Tao, W. Andy

    2017-06-01

    Mass spectrometry has played a significant role in the identification of unknown phosphoproteins and sites of phosphorylation in biological samples. Analyses of protein phosphorylation, particularly large scale phosphoproteomic experiments, have recently been enhanced by efficient enrichment, fast and accurate instrumentation, and better software, but challenges remain because of the low stoichiometry of phosphorylation and poor phosphopeptide ionization efficiency and fragmentation due to neutral loss. Phosphoproteomics has become an important dimension in systems biology studies, and it is essential to have efficient analytical tools to cover a broad range of signaling events. To evaluate current mass spectrometric performance, we present here a novel method to estimate the efficiency of phosphopeptide identification by tandem mass spectrometry. Phosphopeptides were directly isolated from whole plant cell extracts, dephosphorylated, and then incubated with one of three purified kinases—casein kinase II, mitogen-activated protein kinase 6, and SNF-related protein kinase 2.6—along with 16O4- and 18O4-ATP separately for in vitro kinase reactions. Phosphopeptides were enriched and analyzed by LC-MS. The phosphopeptide identification rate was estimated by comparing phosphopeptides identified by tandem mass spectrometry with phosphopeptide pairs generated by stable isotope labeled kinase reactions. Overall, we found that current high speed and high accuracy mass spectrometers can only identify 20%-40% of total phosphopeptides primarily due to relatively poor fragmentation, additional modifications, and low abundance, highlighting the urgent need for continuous efforts to improve phosphopeptide identification efficiency. [Figure not available: see fulltext.

  18. Tandem mass spectrometry data quality assessment by self-convolution

    Directory of Open Access Journals (Sweden)

    Tham Wai

    2007-09-01

    Full Text Available Abstract Background Many algorithms have been developed for deciphering the tandem mass spectrometry (MS data sets. They can be essentially clustered into two classes. The first performs searches on theoretical mass spectrum database, while the second based itself on de novo sequencing from raw mass spectrometry data. It was noted that the quality of mass spectra affects significantly the protein identification processes in both instances. This prompted the authors to explore ways to measure the quality of MS data sets before subjecting them to the protein identification algorithms, thus allowing for more meaningful searches and increased confidence level of proteins identified. Results The proposed method measures the qualities of MS data sets based on the symmetric property of b- and y-ion peaks present in a MS spectrum. Self-convolution on MS data and its time-reversal copy was employed. Due to the symmetric nature of b-ions and y-ions peaks, the self-convolution result of a good spectrum would produce a highest mid point intensity peak. To reduce processing time, self-convolution was achieved using Fast Fourier Transform and its inverse transform, followed by the removal of the "DC" (Direct Current component and the normalisation of the data set. The quality score was defined as the ratio of the intensity at the mid point to the remaining peaks of the convolution result. The method was validated using both theoretical mass spectra, with various permutations, and several real MS data sets. The results were encouraging, revealing a high percentage of positive prediction rates for spectra with good quality scores. Conclusion We have demonstrated in this work a method for determining the quality of tandem MS data set. By pre-determining the quality of tandem MS data before subjecting them to protein identification algorithms, spurious protein predictions due to poor tandem MS data are avoided, giving scientists greater confidence in the

  19. Hybrid tandem solar cells with depleted-heterojunction quantum dot and polymer bulk heterojunction subcells

    KAUST Repository

    Kim, Taesoo

    2015-10-01

    We investigate hybrid tandem solar cells that rely on the combination of solution-processed depleted-heterojunction colloidal quantum dot (CQD) and bulk heterojunction polymer:fullerene subcells. The hybrid tandem solar cell is monolithically integrated and electrically connected in series with a suitable p-n recombination layer that includes metal oxides and a conjugated polyelectrolyte. We discuss the monolithic integration of the subcells, taking into account solvent interactions with underlayers and associated constraints on the tandem architecture, and show that an adequate device configuration consists of a low bandgap CQD bottom cell and a high bandgap polymer:fullerene top cell. Once we optimize the recombination layer and individual subcells, the hybrid tandem device reaches a VOC of 1.3V, approaching the sum of the individual subcell voltages. An impressive fill factor of 70% is achieved, further confirming that the subcells are efficiently connected via an appropriate recombination layer. © 2015.

  20. Cloud parallel processing of tandem mass spectrometry based proteomics data.

    Science.gov (United States)

    Mohammed, Yassene; Mostovenko, Ekaterina; Henneman, Alex A; Marissen, Rob J; Deelder, André M; Palmblad, Magnus

    2012-10-05

    Data analysis in mass spectrometry based proteomics struggles to keep pace with the advances in instrumentation and the increasing rate of data acquisition. Analyzing this data involves multiple steps requiring diverse software, using different algorithms and data formats. Speed and performance of the mass spectral search engines are continuously improving, although not necessarily as needed to face the challenges of acquired big data. Improving and parallelizing the search algorithms is one possibility; data decomposition presents another, simpler strategy for introducing parallelism. We describe a general method for parallelizing identification of tandem mass spectra using data decomposition that keeps the search engine intact and wraps the parallelization around it. We introduce two algorithms for decomposing mzXML files and recomposing resulting pepXML files. This makes the approach applicable to different search engines, including those relying on sequence databases and those searching spectral libraries. We use cloud computing to deliver the computational power and scientific workflow engines to interface and automate the different processing steps. We show how to leverage these technologies to achieve faster data analysis in proteomics and present three scientific workflows for parallel database as well as spectral library search using our data decomposition programs, X!Tandem and SpectraST.

  1. Instruction manual for ORNL tandem high abundance sensitivity mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.H.; McKown, H.S.; Chrisite, W.H.; Walker, R.L.; Carter, J.A.

    1976-06-01

    This manual describes the physical characteristics of the tandem mass spectrometer built by Oak Ridge National Laboratory for the International Atomic Energy Agency. Specific requirements met include ability to run small samples, high abundance sensitivity, good precision and accuracy, and adequate sample throughput. The instrument is capable of running uranium samples as small as 10/sup -12/ g and has an abundance sensitivity in excess of 10/sup 6/. Precision and accuracy are enhanced by a special sweep control circuit. Sample throughput is 6 to 12 samples per day. Operating instructions are also given.

  2. Analysis of oxysterols by electrospray tandem mass spectrometry.

    Science.gov (United States)

    Griffiths, William J; Wang, Yuqin; Alvelius, Gunvor; Liu, Suya; Bodin, Karl; Sjövall, Jan

    2006-03-01

    Oxysterols are oxygenated derivatives of cholesterol. They are intermediates in cholesterol excretion pathways and may also be regarded as transport forms of cholesterol. The introduction of additional hydroxyl groups to the cholesterol skeleton facilitates the flux of oxysterols across the blood brain barrier, and oxysterols have been implicated in mediating a number of cholesterol-induced metabolic effects. Oxysterols are difficult to analyze by atmospheric pressure ionization mass spectrometry on account of the absence of basic or acidic functional groups in their structures. In this communication, we report a method for the derivatization and analysis of oxysterols by electrospray mass spectrometry. Oxysterols with a 3beta-hydroxy-Delta5 structure were converted by cholesterol oxidase to 3-oxo-Delta4 steroids and then derivatized with the Girard P reagent to give Girard P hydrazones, which were subsequently analyzed by tandem mass spectrometry. The improvement in sensitivity for the analysis of 25-hydroxycholesterol upon oxidation and derivatization was over 1000.

  3. Sequencing of Oligourea Foldamers by Tandem Mass Spectrometry

    Science.gov (United States)

    Bathany, Katell; Owens, Neil W.; Guichard, Gilles; Schmitter, Jean-Marie

    2013-03-01

    This study is focused on sequence analysis of peptidomimetic helical oligoureas by means of tandem mass spectrometry, to build a basis for de novo sequencing for future high-throughput combinatorial library screening of oligourea foldamers. After the evaluation of MS/MS spectra obtained for model compounds with either MALDI or ESI sources, we found that the MALDI-TOF-TOF instrument gave more satisfactory results. MS/MS spectra of oligoureas generated by decay of singly charged precursor ions show major ion series corresponding to fragmentation across both CO-NH and N'H-CO urea bonds. Oligourea backbones fragment to produce a pattern of a, x, b, and y type fragment ions. De novo decoding of spectral information is facilitated by the occurrence of low mass reporter ions, representative of constitutive monomers, in an analogous manner to the use of immonium ions for peptide sequencing.

  4. Hybrid tandem quantum dot/organic photovoltaic cells with complementary near infrared absorption

    Science.gov (United States)

    Kim, Taesoo; Palmiano, Elenita; Liang, Ru-Ze; Hu, Hanlin; Murali, Banavoth; Kirmani, Ahmad R.; Firdaus, Yuliar; Gao, Yangqin; Sheikh, Arif; Yuan, Mingjian; Mohammed, Omar F.; Hoogland, Sjoerd; Beaujuge, Pierre M.; Sargent, Edward H.; Amassian, Aram

    2017-05-01

    Monolithically integrated hybrid tandem solar cells that effectively combine solution-processed colloidal quantum dot (CQD) and organic bulk heterojunction subcells to achieve tandem performance that surpasses the individual subcell efficiencies have not been demonstrated to date. In this work, we demonstrate hybrid tandem cells with a low bandgap PbS CQD subcell harvesting the visible and near-infrared photons and a polymer:fullerene—poly (diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C60-butyric acid methyl ester (PC61BM)—top cell absorbing effectively the red and near-infrared photons of the solar spectrum in a complementary fashion. The two subcells are connected in series via an interconnecting layer (ICL) composed of a metal oxide layer, a conjugated polyelectrolyte, and an ultrathin layer of Au. The ultrathin layer of Au forms nano-islands in the ICL, reducing the series resistance, increasing the shunt resistance, and enhancing the device fill-factor. The hybrid tandems reach a power conversion efficiency (PCE) of 7.9%, significantly higher than the PCE of the corresponding individual single cells, representing one of the highest efficiencies reported to date for hybrid tandem solar cells based on CQD and polymer subcells.

  5. Hybrid tandem quantum dot/organic photovoltaic cells with complementary near infrared absorption

    KAUST Repository

    Kim, Taesoo

    2017-06-01

    Monolithically integrated hybrid tandem solar cells that effectively combine solution-processed colloidal quantum dot (CQD) and organic bulk heterojunction subcells to achieve tandem performance that surpasses the individual subcell efficiencies have not been demonstrated to date. In this work, we demonstrate hybrid tandem cells with a low bandgap PbS CQD subcell harvesting the visible and near-infrared photons and a polymer:fullerene—poly (diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C60-butyric acid methyl ester (PC61BM)—top cell absorbing effectively the red and near-infrared photons of the solar spectrum in a complementary fashion. The two subcells are connected in series via an interconnecting layer (ICL) composed of a metal oxide layer, a conjugated polyelectrolyte, and an ultrathin layer of Au. The ultrathin layer of Au forms nano-islands in the ICL, reducing the series resistance, increasing the shunt resistance, and enhancing the device fill-factor. The hybrid tandems reach a power conversion efficiency (PCE) of 7.9%, significantly higher than the PCE of the corresponding individual single cells, representing one of the highest efficiencies reported to date for hybrid tandem solar cells based on CQD and polymer subcells.

  6. Assay for Glycosaminoglycans by Tandem Mass Spectrometry and its Applications

    Science.gov (United States)

    Tomatsu, Shunji; Shimada, Tsutomu; Mason, Robert W; Kelly, Joan; LaMarr, William A; Yasuda, Eriko; Shibata, Yuniko; Futatsumori, Hideyuki; Montaño, Adriana M; Yamaguchi, Seiji; Suzuki, Yasuyuki; Orii, Tadao

    2014-01-01

    Glycosaminoglycans (GAGs) are distributed in the whole body and play a variety of important physiological roles associated with inflammation, growth, coagulation, fibrinolysis, lipolysis, and cell-matrix biology. Accumulation of undegraded GAGs in lysosomes gives rise to a distinct clinical syndrome, mucopolysaccharidoses. Measurement of each specific GAG in a variety of specimens is urgently required to understand GAG interaction with other molecules, physiological status of patients, and prognosis and pathogenesis of the disease. We established a highly sensitive and accurate tandem mass spectrometry (LC-MS/MS) method for measurements of disaccharides derived from four specific GAGs [dermatan sulfate (DS), heparan sulfate (HS), keratan sulfate (KS), and chondroitin sulfate (CS)]. Disaccharides were produced by specific enzyme digestion of each GAG, and quantified by negative ion mode of multiple reaction monitoring. Subclasses of HS and GAGs with identical molecular weights can be separated using a Hypercarbcolumn (2.0 mm×50 mm, 5 μm) with an aectonitrile gradient in ammonium acetate (pH 11.0). We also developed a GAG assay by RapidFire with tandem mass spectrometry (RF-MS/MS). The RF system consists of an integrated solid phase extraction robot that binds and de-salts samples from assay plates and directly injects them into a MS/MS detector, reducing sample processing time to ten seconds. RF-MS/MS consequently yields much faster throughput than conventional LC-MS/MS-based methods. However, the RF system does not have a chromatographic step, and therefore, cannot distinguish GAGs that have identical molecular weights. Both methods can be applied to analysis of dried blood spots, blood, and urine specimens. In this article, we compare the assay methods for GAGs and describe their potential applications. PMID:25068074

  7. TANDEM

    Data.gov (United States)

    Federal Laboratory Consortium — The Tandem Van de Graaff facility provides researchers with beams of more than 40 different types of ions - atoms that have been stripped of their electrons. One of...

  8. Fast atom bombardment tandem mass spectrometry of carotenoids

    Energy Technology Data Exchange (ETDEWEB)

    van Breeman, R.B. [Univ. of Illinois, Chicago, IL (United States); Schmitz, H.H.; Schwartz, S.J. [North Carolina State Univ., Raleigh, NC (United States)

    1995-02-01

    Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

  9. Simulation of Two Dimensional Electrophoresis and Tandem Mass Spectrometry for Teaching Proteomics

    Science.gov (United States)

    Fisher, Amanda; Sekera, Emily; Payne, Jill; Craig, Paul

    2012-01-01

    In proteomics, complex mixtures of proteins are separated (usually by chromatography or electrophoresis) and identified by mass spectrometry. We have created 2DE Tandem MS, a computer program designed for use in the biochemistry, proteomics, or bioinformatics classroom. It contains two simulations--2D electrophoresis and tandem mass spectrometry.…

  10. Interim report on the tandem mirror hybrid design study

    Energy Technology Data Exchange (ETDEWEB)

    Moir, R.W. (ed.)

    1979-08-01

    The initial phase of a 2-year design study of a tandem mirror fusion reactor is presented. The following chapters are included: (1) mechanical design of the plant; (2) plasma physics; (3) blanket design; (4) magnet design; (5) injector design; (6) direct convertor design; (7) balance of plant design; (8) fission burner reactor; (9) environment and safety; and (10) economic analysis. (MOW)

  11. Screening of carnitine and biotin deficiencies on tandem mass spectrometry.

    Science.gov (United States)

    Hagiwara, Shin-Ichiro; Kubota, Mitsuru; Nambu, Ryusuke; Kagimoto, Seiichi

    2017-04-01

    It is important to assess pediatric patients for nutritional deficiency when they are receiving specific interventions, such as enteral feeding. We focused on measurement of C0 and 3-hydroxyisovalerylcarnitine (C5-OH) with tandem mass spectrometry (MS/MS), which is performed as part of the newborn mass screening. The purpose of this study was to investigate the usefulness of MS/MS for screening carnitine and biotin deficiencies. Forty-two children (24 boys, 18 girls) were enrolled between December 2013 and December 2015. Blood tests, including measurement of serum free carnitine via the enzyme cycling method, and acylcarnitine analysis on MS/MS of dried blood spot (DBS), were performed for the evaluation of nutrition status. Median patient age was 2 years (range, 2 months-14 years). Mean serum free carnitine was 41.8 ± 19.2 μmol/L. In six of the 42 patients, serum free carnitine was 1.00 nmol/L. Therapy-resistant eczema was improved by treatment with additional biotin and a non-hydrolyzed formula. C0 and C5-OH, measured on MS/MS of DBS, were useful for screening carnitine and biotin deficiencies. © 2016 Japan Pediatric Society.

  12. Large pore dermal microdialysis and liquid chromatography-tandem mass spectroscopy shotgun proteomic analysis

    DEFF Research Database (Denmark)

    Petersen, Lars J; Sørensen, Mette A; Codrea, Marius C

    2013-01-01

    phases of the study; trauma due to implantation of the dialysis device, a post implantation steady-state period, and after induction of vasodilatation and plasma extravasation. For shotgun proteomics, the proteins were extracted and digested with trypsin. Peptides were separated by capillary and nanoflow...... HPLC systems, followed by tandem mass spectrometry (MS/MS) on a Quadrupole-TOF hybrid instrument. The MS/MS spectra were merged and mapped to a human target protein database to achieve peptide identification and protein inference. ResultsResults showed variation in protein amounts and profiles for each...... of the different sampling phases. The total protein concentration was 1.7, 0.6, and 1.3mg/mL during the three phases, respectively. A total of 158 different proteins were identified. Immunoglobulins and the major classes of plasma proteins, including proteases, coagulation factors, apolipoproteins, albumins...

  13. Hybrid inorganic–organic tandem solar cells for broad absorption of the solar spectrum

    NARCIS (Netherlands)

    Speirs, M. J.; Groeneveld, B. G. H. M.; Protesescu, L.; Piliego, Claudia; Kovalenko, M. V.; Loi, M. A.

    2014-01-01

    We report the first hybrid tandem solar cell with solution processable active layers using colloidal PbS quantum dots (QDs) as the front subcell in combination with a polymer-fullerene rear subcell. Al/WO3 is introduced as an interlayer, yielding an open circuit voltage (V-OC) equal to about 92% of

  14. Gas-phase fragmentation study of a novel series of synthetic 2-oxo-2H-benzopyrano[2,3-d]pyrimidine derivatives using electrospray ionization tandem mass spectroscopy measured with a quadrupole orthogonal time-of-flight hybrid instrument.

    Science.gov (United States)

    Turki, Hamida; Genestie, Benoit; Gharbi, Rachid El; Boussiry, Sameh El; Banoub, Joseph

    2009-01-01

    The fragmentation patterns of a series of six novel synthesized benzopyranopyrimidine derivatives 1-6, possessing the same 2-oxo-2H-benzopyrano[2,3-d]pyrimidine backbone structure, were investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) techniques using a quadrupole orthogonal time-of-flight (QqToF)-hybrid instrument. The series of six pure benzopyranopyrimidine compounds contained three constitutional isobaric isomers (compounds 4-6). A simple methodology, based on the use of ESI (positive ion mode) and increasing the declustering potential in the atmospheric pressure/vacuum interface resulting in collision-induced dissociation (CID), was used to enhance the formation of the product ions. In general, the novel synthetic benzopyranopyrimidine derivatives 1-6 afforded exact accurate masses for the protonated molecules. This led to the confirmation of both molecular masses and chemical structures of the studied compounds. The breakdown routes of the protonated molecules were rationalized by conducting low-energy CID-MS/MS analyses. It was shown that the MS/MS fragmentation routes for the protonated molecules 1 and 2 were similar, and that the MS/MS fragmentations of the constitutional isobaric protonated molecules 5 and 6 were identical. It was also shown that the gas-phase CID fragmentations of 5 and 6 were different from that of their constitutional isomer 4. Finally, the ESI-MS and CID-MS/MS analyses of the protonated molecules that were obtained from the monodeuterated benzopyranopyrimidine derivatives 1-6 confirmed the values obtained for the exact masses, the precise structural assignments of all product ions and all the pathways described in the proposed CID fragmentations. Copyright (c) 2008 John Wiley & Sons, Ltd.

  15. Fluconazole bioequivalence study: quantification by tandem mass spectrometry.

    Science.gov (United States)

    Moraes, L A; Lerner, F E; Moraes, M E; Moraes, M O; Corso, G; De Nucci, G

    1999-04-01

    To develop a new method for quantifying fluoconazole in human plasma and to compare the bioavailability of two fluconazole capsule formulations, an open, randomized, two-period crossover study with a one-week washout interval was conducted in 24 healthy volunteers. Plasma samples were obtained up to 168 hours after drug administration and the serum fluconazole concentrations were analyzed using electrospray tandem mass spectrometry coupled to liquid chromatography using multiple reaction monitoring mode. The pharmacokinetic parameters obtained for fluconazole after the administration of each formulation included the Area under the curve (AUC)(0-168h), AUC(0-infinity), Cmax, Cmax/AUC(0-168h), Tmax, elimination rate constant (Ke), and half-life (T1/2). Within- and between-run imprecision was less than 2.3% and 8.2%, respectively. Inaccuracy within and between runs was -1.5% and -9.7%, respectively. The pharmacokinetic parameters for bioequivalence showed a normal distribution, and the variance of AUC(0-168h), AUC(0-infinity), and Cmax were homoscedastic. The geometric mean for the Fluconal/Zoltec (Fluconal; Libbs Farmacêutica Ltda, São Paulo, Brazil; Zoltec; Laboratórios Pfizer Ltda., São Paulo, Brazil) individual percent ratio was 94.9% for AUC(0-168h), 94.7% for AUC(0-infinity), 80.1% for Cmax, 102.6% for Ke, 97.5% for T1/2, and 0.93 for Tmax (arithmetic mean of individual differences). We have developed a method in which liquid chromatography is coupled with electrospray tandem mass spectrometry to improve the pharmacokinetic analysis of fluconazole. Because the 90% CI AUC is within the interval proposed for the Food and Drug Administration, we concluded that Fluconal is bioequivalent to Zoltec in terms of absorption. The CV was 27.5% for the Cmax parameter, indicating that fluconazole's absorption rate is highly variable. The European Union Regulatory Agency accepts an interval of 70-143%, and because the 90% CI for Cmax is within the interval proposed for

  16. A high-throughput de novo sequencing approach for shotgun proteomics using high-resolution tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Banfield Jillian F

    2010-03-01

    Full Text Available Abstract Background High-resolution tandem mass spectra can now be readily acquired with hybrid instruments, such as LTQ-Orbitrap and LTQ-FT, in high-throughput shotgun proteomics workflows. The improved spectral quality enables more accurate de novo sequencing for identification of post-translational modifications and amino acid polymorphisms. Results In this study, a new de novo sequencing algorithm, called Vonode, has been developed specifically for analysis of such high-resolution tandem mass spectra. To fully exploit the high mass accuracy of these spectra, a unique scoring system is proposed to evaluate sequence tags based primarily on mass accuracy information of fragment ions. Consensus sequence tags were inferred for 11,422 spectra with an average peptide length of 5.5 residues from a total of 40,297 input spectra acquired in a 24-hour proteomics measurement of Rhodopseudomonas palustris. The accuracy of inferred consensus sequence tags was 84%. According to our comparison, the performance of Vonode was shown to be superior to the PepNovo v2.0 algorithm, in terms of the number of de novo sequenced spectra and the sequencing accuracy. Conclusions Here, we improved de novo sequencing performance by developing a new algorithm specifically for high-resolution tandem mass spectral data. The Vonode algorithm is freely available for download at http://compbio.ornl.gov/Vonode.

  17. Hybrid/Tandem Laser-Arc Welding of Thick Low Carbon Martensitic Stainless Steel Plates =

    Science.gov (United States)

    Mirakhorli, Fatemeh

    High efficiency and long-term life of hydraulic turbines and their assemblies are of utmost importance for the hydropower industry. Usually, hydroelectric turbine components are made of thick-walled low carbon martensitic stainless steels. The assembly of large hydroelectric turbine components has been a great challenge. The use of conventional welding processes involves typical large groove design and multi-pass welding to fill the groove which exposes the weld to a high heat input creating relatively large fusion zone and heat affected zone. The newly-developed hybrid/tandem laser-arc welding technique is believed to offer a highly competitive solution to improve the overall hydro-turbine performance by combining the high energy density and fast welding speed of the laser welding technology with the good gap bridging and feeding ability of the gas metal arc welding process to increase the productivity and reduce the consumable material. The main objective of this research work is to understand different challenges appearing during hybrid laser-arc welding (HLAW) of thick gauge assemblies of low carbon 13%Cr- 4%Ni martensitic stainless steel and find a practical solution by adapting and optimizing this relatively new welding process in order to reduce the number of welding passes necessary to fill the groove gap. The joint integrity was evaluated in terms of microstructure, defects and mechanical properties in both as-welded and post-welded conditions. A special focus was given to the hybrid and tandem laser-arc welding technique for the root pass. Based on the thickness of the low carbon martensitic stainless steel plates, this work is mainly focused on the following two tasks: • Single pass hybrid laser-arc welding of 10-mm thick low carbon martensitic stainless steel. • Multi-pass hybrid/tandem laser-arc welding of 25-mm thick martensitic stainless steel.

  18. Preparation and tandem mass spectrometric analyses of deuterium-labeled cysteine-containing leukotrienes.

    Science.gov (United States)

    Raftery, M J; Thorne, G C; Orkiszewski, R S; Gaskell, S J

    1990-08-01

    Leukotrienes (LT) C4, E4 and N-acetyl-E4, their respective monomethyl esters and 14,15-2H2 analogs have been synthesized. The collisionally activated decompositions of the [M + H]+ and [M - H]- ions formed by fast atom bombardment (FAB) have been studied by tandem mass spectrometry using a hybrid sector/quadrupole instrument. Structurally informative product ion spectra were obtained for each analyte; the fragmentation pathways proposed are consistent with the parallel data obtained for labeled and derivatized species. Fragmentation of [M + H]+ ions occurs prominently via cleavage of the thioether linkage with charge retention on the cysteine-containing (predominant for LTC4) or lipid-derived (predominant for LTE4) moieties. More pronounced differences were observed between the fragmentations of [M - H]- ions derived from LTC4 and LTE4; the preference for charge retention, however, parallels that observed for the fragmentation of [M + H]+ ions. Selected ion monitoring during continuous-flow FAB mass spectrometric analysis of authentic LTC4 indicated a low-picogram detection limit.

  19. MAZIE: a mass and charge inference engine to enhance database searching of tandem mass spectra.

    Science.gov (United States)

    Victor, Ken G; Murgai, Meera; Lyons, Charles E; Templeton, Thaddeus A B; Moshnikov, Sergey A; Templeton, Dennis J

    2010-01-01

    Peptide sequence identification using tandem mass spectroscopy remains a major challenge for complex proteomic studies. Peptide matching algorithms require the accurate determination of both the mass and charge of the precursor ion and accommodate uncertainties in these properties by using a wide precursor mass tolerance and by testing, for each spectrum, several possible candidate charges. Using a data acquisition strategy that includes obtaining narrow mass-range MS(1) "zoom" scans, we describe here a post-acquisition algorithm dubbed mass and charge (Z) inference engine (MAZIE), which accurately determines the charge and monoisotopic mass of precursor ions on a low-resolution Thermo LTQ-XL mass spectrometer. This is achieved by examining the isotopic distribution obtained in the preceding MS(1) zoom spectrum and comparing to theoretical distributions for candidate charge states from +1 to +4. MAZIE then writes modified data files with the corrected monoisotopic mass and charge. We have validated MAZIE results by comparing the sequence search results obtained with the MAZIE-generated data files to results using the unmodified data files. Using two different search algorithms and a false discovery rate filter, we found that MAZIE-interpreted data resulted in 80% (using SEQUEST) and 30% (using OMSSA) more high-confidence sequence identifications. Analyses of these results indicate that the accurate determination of the precursor ion mass greatly facilitates the ability to differentiate between true and false positive matches, while the determination of the precursor ion charge reduces the overall search time but does not significantly reduce the ambiguity of interpreting the search results. MAZIE is distributed as an open-source PERL script. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  20. Towards maximizing the haze effect of electrodes for high efficiency hybrid tandem solar cell

    Science.gov (United States)

    Vincent, Premkumar; Song, Dong-Seok; Kwon, Hyeok Bin; Kim, Do-Kyung; Jung, Ji-Hoon; Kwon, Jin-Hyuk; Choe, Eunji; Kim, Young-Rae; Kim, Hyeok; Bae, Jin-Hyuk

    2018-02-01

    In this study, we executed optical simulations to compute the optimum power conversion efficiency (PCE) of a-Si:H/organic photovoltaic (OPV) hybrid tandem solar cell. The maximum ideal short circuit current density (Jsc,max) of the tandem solar cell is initially obtained by optimizing the thickness of the active layer of the OPV subcell for varying thickness of the a-Si:H bottom subcell. To investigate the effect of Haze parameter on the ideal short-circuit current density (Jsc,ideal) of the solar cells, we have varied the haze ratio for the TCO electrode of the a-Si:H subcell in the tandem structure. The haze ratio was obtained for various root mean square (RMS) roughness of the TCO of the front cell. The effect of haze ratio on the Jsc,ideal on the tandem structured solar cell was studied, and the highest Jsc,ideal was obtained at a haze of 55.5% when the thickness of the OPV subcell was 150 nm and that of the a-Si:H subcell was 500 nm.

  1. Hybrid dielectric light trapping designs for thin-film CdZnTe/Si tandem cells.

    Science.gov (United States)

    Chung, H; Zhou, C; Tee, X T; Jung, K-Y; Bermel, P

    2016-07-11

    Tandem solar cells consisting of high bandgap cadmium telluride alloys atop crystalline silicon have potential for high efficiencies exceeding the Shockley-Queisser limit. However, experimental results have fallen well below this goal significantly because of non-ideal current matching and light trapping. In this work, we simulate cadmium zinc telluride (CZT) and crystalline silicon (c-Si) tandems as an exemplary system to show the role that a hybrid light trapping and bandgap engineering approach can play in improving performance and lowering materials costs for tandem solar cells incorporating crystalline silicon. This work consists of two steps. First, we optimize absorption in the crystalline silicon layer with front pyramidal texturing and asymmetric dielectric back gratings, which results in 121% absorption enhancement from a planar structure. Then, using this pre-optimized light trapping scheme, we model the dispersion of the CdxZn1-xTe alloys, and then adjust the bandgap to realize the best current matching for a range of CZT thicknesses. Using experimental parameters, the corresponding maximum efficiency is predicted to be 16.08 % for a total tandem cell thickness of only 2.2 μm.

  2. Feasibility study of a fission supressed blanket for a tandem-mirror hybrid reactor

    Energy Technology Data Exchange (ETDEWEB)

    Moir, R.W.; Lee, J.D.; Barr, W.L.

    1981-10-05

    A study of fission suppressed blankets for the tandem mirror not only showed such blankets to be feasible but also to be safer than fissioning blankets. Such hybrids could produce enough fissile material to support up to 17 light water reactors of the same nuclear power rating. Beryllium was compared to /sup 7/Li for neutron multiplication; both were considered feasible but the blanket with Li produced 20% less fissile fuel per unit of nuclear power in the reactor. The beryllium resource, while possibly being too small for extensive pure fusion application, would be adequate (with carefully planned industrial expansion) for the hybrid because of the large support ratio, and hence few hybrids required. Radiation damage and coatings for beryllium remain issues to be resolved by further study and experimentation.

  3. High-Speed Tandem Mass Spectrometric in Situ Imaging by Nanospray Desorption Electrospray Ionization Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lanekoff, Ingela T.; Burnum-Johnson, Kristin E.; Thomas, Mathew; Short, Joshua TL; Carson, James P.; Cha, Jeeyeon; Dey, Sudhansu K.; Yang, Pengxiang; Prieto Conaway, Maria C.; Laskin, Julia

    2013-10-15

    Nanospray desorption electrospray ionization (nano-DESI) combined with tandem mass spectrometry (MS/MS), high-resolution mass analysis (m/m=17,500 at m/z 200), and rapid spectral acquisition enabled simultaneous imaging and identification of more than 300 molecules from 92 selected m/z windows (± 1 Da) with a spatial resolution of better than 150 um. Uterine sections of implantation sites on day 6 of pregnancy were analyzed in the ambient environment without any sample pre-treatment. MS/MS imaging was performed by scanning the sample under the nano-DESI probe at 10 um/s while acquiring higher-energy collision-induced dissociation (HCD) spectra for a targeted inclusion list of 92 m/z values at a rate of ~6.3 spectra/s. Molecular ions and their corresponding fragments, separated using high-resolution mass analysis, were assigned based on accurate mass measurement. Using this approach, we were able to identify and image both abundant and low-abundance isobaric species within each m/z window. MS/MS analysis enabled efficient separation and identification of isobaric sodium and potassium adducts of phospholipids. Furthermore, we identified several metabolites associated with early pregnancy and obtained the first 2D images of these molecules.

  4. Multiplexed Post-Experimental Monoisotopic Mass Refinement ( m PE-MMR) to Increase Sensitivity and Accuracy in Peptide Identifications from Tandem Mass Spectra of Cofragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Madar, Inamul Hasan [Laboratory; Ko, Seung-Ik [Laboratory; Kim, Hokeun [Laboratory; Mun, Dong-Gi [Laboratory; Kim, Sangtae [Biological; Smith, Richard D. [Biological; Lee, Sang-Won [Laboratory

    2016-12-22

    Mass spectrometry (MS)-based proteomics, which uses high-resolution hybrid mass spectrometers such as the quadrupole-orbitrap mass spectrometer, can yield tens of thousands of tandem mass (MS/MS) spectra of high resolution during a routine bottom-up experiment. Despite being a fundamental and key step in MS-based proteomics, the accurate determination and assignment of precursor monoisotopic masses to the MS/MS spectra remains difficult. The difficulties stem from imperfect isotopic envelopes of precursor ions, inaccurate charge states for precursor ions, and cofragmentation. We describe a composite method of utilizing MS data to assign accurate monoisotopic masses to MS/MS spectra, including those subject to cofragmentation. The method, “multiplexed post-experiment monoisotopic mass refinement” (mPE-MMR), consists of the following: multiplexing of precursor masses to assign multiple monoisotopic masses of cofragmented peptides to the corresponding multiplexed MS/MS spectra, multiplexing of charge states to assign correct charges to the precursor ions of MS/ MS spectra with no charge information, and mass correction for inaccurate monoisotopic peak picking. When combined with MS-GF+, a database search algorithm based on fragment mass difference, mPE-MMR effectively increases both sensitivity and accuracy in peptide identification from complex high-throughput proteomics data compared to conventional methods.

  5. High explosives vapor detection by atmospheric sampling glow discharge ionization/tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    McLuckey, S.A.; Goeringer, D.E.; Asano, K.G. [Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.

    1996-02-01

    The combination of atmospheric sampling glow discharge ionization with tandem mass spectrometry for the detection of traces of high explosives is described. Particular emphasis is placed on use of the quadrupole ion trap as the type of tandem mass spectrometer. Atmospheric sampling glow discharge provides a simple, rugged, and efficient means for anion formation while the quadrupole ion trap provides for efficient tandem mass spectrometry. Mass selective ion accumulation and non-specific ion activation methods can be used to overcome deleterious effects arising from ion/ion interactions. Such interactions constitute the major potential technical barrier to the use of the ion trap for real-time monitoring of targeted compounds in uncontrolled and highly variable matrices. Tailored waveforms can be used to effect both mass selective ion accumulation and ion activation. Concatenated tailored waveforms allow for both functions in a single experiment thereby providing the capability for monitoring several targeted species simultaneously. The combination of atmospheric sampling glow discharge ionization with a state-of-the-art analytical quadrupole ion trap is a highly sensitive and specific detector for traces of high explosives. The combination is also small and inexpensive relative to virtually any other form of tandem mass spectrometry. The science and technology underlying the glow discharge/ion trap combination is sufficiently mature to form the basis for an engineering effort to make the detector portable. 85 refs.

  6. Metabolism of halogenated compounds in the white rot fungus Bjerkandera adusta studied by membrane inlet mass spectrometry and tandem mass spectrometry

    DEFF Research Database (Denmark)

    Beck, Hans Christian; Lauritsen, F.R.; Patrick, J.S.

    1996-01-01

    Membrane inlet mass spectrometry has been used for the characterization of halogenated organic compounds produced by the fungus Bjerkandera adusta. Using this technique, electron impact-, chemical ionization-, electron capture negative chemical ionization-mass spectra and tandem mass spectra were...

  7. Quantification of levetiracetam in plasma of neonates by ultra performance liquid chromatography-tandem mass spectrometry

    NARCIS (Netherlands)

    Blonk, Maren I.; van der Nagel, Bart C.; Smit, Liesbeth S.; Mathot, Ron A. A.

    2010-01-01

    A sensitive and specific method using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the determination of levetiracetam (LEV) in plasma of neonates. A plasma aliquot of 50 microl was deproteinized by addition of 500 microl methanol which contained 5

  8. Liquid chromatographic-tandem mass spectrometric determination of selected sulphonamides in milk

    NARCIS (Netherlands)

    Rhijn, van J.A.; Lasaroms, J.J.P.; Berendsen, B.J.A.; Brinkman, U.A.Th.

    2002-01-01

    Liquid chromatography–tandem mass spectrometry is used for the quantitative analysis of selected sulphonamides in milk. Ultrafiltration is the only sample pre-treatment technique which is required. Consequently, sample throughput is much higher than with conventional procedures, and analyte

  9. Determination of Bedaquiline in Human Serum Using Liquid Chromatography-Tandem Mass Spectrometry

    NARCIS (Netherlands)

    Alffenaar, Jan-Willem C.; Bolhuis, Mathieu; van Hateren, Kai; Sturkenboom, Marieke; Akkerman, Onno; de Lange, Wiel; Greijdanus, Ben; van der Werf, Tjip; Touw, Daan

    Bedaquiline, a diarylquinoline for the treatment of multidrug-resistant tuberculosis (TB), relies on exposure-dependent killing. As data on drug exposure in specific populations are scarce, pharmacokinetic studies may be of interest. No simple and robust validated liquid chromatography-tandem mass

  10. Quantification and validation of ertapenem using a liquid chromatography-tandem mass spectrometry method

    NARCIS (Netherlands)

    van Rijn, S.P.; Wessels, A.M.A.; Greijdanus, B.; Touw, D.J.; Alffenaar, J.W.C.

    Ertapenem, a carbapenem, relies on time-dependent killing. Therapeutic drug monitoring (TDM) should be considered, when ertapenem is used in specific populations, to achieve optimal bactericidal activity and optimize drug-dosing regimens. No validated liquid chromatography-tandem mass spectrometry

  11. Liquid chromatography-tandem mass spectrometry - Application in the clinical laboratory

    OpenAIRE

    Vogeser, Michael

    2003-01-01

    This review provides a concise survey of liquid chromatography tandem mass spectrometry (LCTMS) as an emerging technology in clinical chemistry. The combination of two mass spectrometers with an interposed collision cell characterizes LCTMS as an analytical technology on its own and not just as a more specific detector for HPLC compared with conventional techniques. In LCTMS, liquid chromatography is rather used for sample preparation but not for complete resolution of compounds of interest. ...

  12. Quantitative analysis of phytosterols in edible oils using APCI liquid chromatography-tandem mass spectrometry

    OpenAIRE

    Mo, Shunyan; Dong, Linlin; Hurst, W. Jeffrey; van Breemen, Richard B.

    2013-01-01

    Previous methods for the quantitative analysis of phytosterols have usually used GC-MS and require elaborate sample preparation including chemical derivatization. Other common methods such as HPLC with absorbance detection do not provide information regarding the identity of the analytes. To address the need for an assay that utilizes mass selectivity while avoiding derivatization, a quantitative method based on LC-tandem mass spectrometry (LC-MS-MS) was developed and validated for the measur...

  13. Adult testosterone and calculated free testosterone reference ranges by tandem mass spectrometry.

    Science.gov (United States)

    Neale, S M; Hocking, R; Biswas, M; Turkes, A; Rees, D; Rees, D A; Evans, C

    2013-03-01

    Testosterone is measured for the investigation of female hyperandrogenism and male hypogonadism. Liquid chromatography-tandem mass spectrometry (tandem MS) is becoming the method of choice but comprehensive reference ranges are lacking. Testosterone was measured by tandem MS on 90 healthy women, 67 young healthy men and pregnant women (59 first trimester and 60 second trimester). The male, male calculated free, first trimester and second trimester testosterone reference ranges (derived using the antilog of mean ± 1.96 SD of log transformed data) were 10.6-31.9, 0.23-0.63, 0.6-4.9 and 0.9-4.9 nmol/L, respectively. The female testosterone upper reference range limit, derived non-parametrically from the 97.5th centile, was testosterone reference ranges to support clinical services.

  14. High Energy Collisions on Tandem Time-of-Flight Mass Spectrometers

    Science.gov (United States)

    Cotter, Robert J.

    2013-05-01

    Long before the introduction of matrix-assisted laser desorption/ionization (MALDI), electrospray ionization (ESI), Orbitraps, and any of the other tools that are now used ubiquitously for proteomics and metabolomics, the highest performance mass spectrometers were sector instruments, providing high resolution mass measurements by combining an electrostatic energy analyzer (E) with a high field magnet (B). In its heyday, the four sector mass spectrometer (or EBEB) was the crown jewel, providing the highest performance tandem mass spectrometry using single, high energy collisions to induce fragmentation. During a time in which quadrupole and tandem triple quadrupole instruments were also enjoying increased usage and popularity, there were, nonetheless, some clear advantages for sectors over their low collision energy counterparts. Time-of-flight (TOF) mass spectrometers are high voltage, high vacuum instruments that have much in common with sectors and have inspired the development of tandem instruments exploiting single high energy collisions. In this retrospective, we recount our own journey to produce high performance TOFs and tandem TOFs, describing the basic theory, problems, and the advantages for such instruments. An experiment testing impulse collision theory (ICT) underscores the similarities with sector mass spectrometers where this concept was first developed. Applications provide examples of more extensive fragmentation, side chain cleavages, and charge-remote fragmentation, also characteristic of high energy sector mass spectrometers. Moreover, the so-called curved-field reflectron has enabled the design of instruments that are simpler, collect and focus all of the ions, and may provide the future technology for the clinic, for tissue imaging, and the characterization of microorganisms.

  15. Isocratic Solid Phase Extraction-Liquid Chromatography (SPE-LC) Interfaced to High-Performance Tandem Mass Spectrometry for Rapid Protein Identification

    DEFF Research Database (Denmark)

    Hørning, Ole B; Kjeldsen, Frank; Theodorsen, Søren

    2008-01-01

    Reversed-phase liquid chromatography interfaced to electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) allows analysis of very complex peptide mixtures at great sensitivity, but it can be very time-consuming, typically using 60 min, or more, per sample analysis. We recently introduced...... the isocratic solid phase extraction-liquid chromatography (SPE-LC) technology for rapid separation ( approximately 8 min) of simple peptide samples. We now extend these studies to demonstrate the potential of SPE-LC separation in combination with a hybrid linear ion trap-Orbitrap tandem mass spectrometer...... for efficient analysis of peptide samples in proteomics research. The system performance of SPE-LC-MS/MS was evaluated in terms of sensitivity and efficiency for the analysis of tryptic peptide digests obtained from samples consisting of up to 12 standard proteins. The practical utility of the analytical setup...

  16. ELISA reagent coverage evaluation by affinity purification tandem mass spectrometry.

    Science.gov (United States)

    Henry, Scott M; Sutlief, Elissa; Salas-Solano, Oscar; Valliere-Douglass, John

    2017-10-01

    Host cell proteins (HCPs) must be adequately removed from recombinant therapeutics by downstream processing to ensure patient safety, product quality, and regulatory compliance. HCP process clearance is typically monitored by enzyme-linked immunosorbent assay (ELISA) using a polyclonal reagent. Recently, mass spectrometry (MS) has been used to identify specific HCP process impurities and monitor their clearance. Despite this capability, ELISA remains the preferred analytical approach due to its simplicity and throughput. There are, however, inherent difficulties reconciling the protein-centric results of MS characterization with ELISA, or providing assurance that ELISA has acceptable coverage against all process-specific HCP impurities that could pose safety or efficacy risks. Here, we describe efficient determination of ELISA reagent coverage by proteomic analysis following affinity purification with a polyclonal anti-HCP reagent (AP-MS). The resulting HCP identifications can be compared with the actual downstream process impurities for a given process to enable a highly focused assessment of ELISA reagent suitability. We illustrate the utility of this approach by performing coverage evaluation of an anti-HCP polyclonal against both an HCP immunogen and the downstream HCP impurities identified in a therapeutic monoclonal antibody after Protein A purification. The overall goal is to strategically implement affinity-based mass spectrometry as part of a holistic framework for evaluating HCP process clearance, ELISA reagent coverage, and process clearance risks. We envision coverage analysis by AP-MS will further enable a framework for HCP impurity analysis driven by characterization of actual product-specific process impurities, complimenting analytical methods centered on consideration of the total host cell proteome.

  17. Tandem Mass Spectrum Sequencing: An Alternative to Database Search Engines in Shotgun Proteomics.

    Science.gov (United States)

    Muth, Thilo; Rapp, Erdmann; Berven, Frode S; Barsnes, Harald; Vaudel, Marc

    2016-01-01

    Protein identification via database searches has become the gold standard in mass spectrometry based shotgun proteomics. However, as the quality of tandem mass spectra improves, direct mass spectrum sequencing gains interest as a database-independent alternative. In this chapter, the general principle of this so-called de novo sequencing is introduced along with pitfalls and challenges of the technique. The main tools available are presented with a focus on user friendly open source software which can be directly applied in everyday proteomic workflows.

  18. Fast multi-blind modification search through tandem mass spectrometry.

    Science.gov (United States)

    Na, Seungjin; Bandeira, Nuno; Paek, Eunok

    2012-04-01

    With great biological interest in post-translational modifications (PTMs), various approaches have been introduced to identify PTMs using MS/MS. Recent developments for PTM identification have focused on an unrestrictive approach that searches MS/MS spectra for all known and possibly even unknown types of PTMs at once. However, the resulting expanded search space requires much longer search time and also increases the number of false positives (incorrect identifications) and false negatives (missed true identifications), thus creating a bottleneck in high throughput analysis. Here we introduce MODa, a novel "multi-blind" spectral alignment algorithm that allows for fast unrestrictive PTM searches with no limitation on the number of modifications per peptide while featuring over an order of magnitude speedup in relation to existing approaches. We demonstrate the sensitivity of MODa on human shotgun proteomics data where it reveals multiple mutations, a wide range of modifications (including glycosylation), and evidence for several putative novel modifications. Based on the reported findings, we argue that the efficiency and sensitivity of MODa make it the first unrestrictive search tool with the potential to fully replace conventional restrictive identification of proteomics mass spectrometry data.

  19. Fast Multi-blind Modification Search through Tandem Mass Spectrometry*

    Science.gov (United States)

    Na, Seungjin; Bandeira, Nuno; Paek, Eunok

    2012-01-01

    With great biological interest in post-translational modifications (PTMs), various approaches have been introduced to identify PTMs using MS/MS. Recent developments for PTM identification have focused on an unrestrictive approach that searches MS/MS spectra for all known and possibly even unknown types of PTMs at once. However, the resulting expanded search space requires much longer search time and also increases the number of false positives (incorrect identifications) and false negatives (missed true identifications), thus creating a bottleneck in high throughput analysis. Here we introduce MODa, a novel “multi-blind” spectral alignment algorithm that allows for fast unrestrictive PTM searches with no limitation on the number of modifications per peptide while featuring over an order of magnitude speedup in relation to existing approaches. We demonstrate the sensitivity of MODa on human shotgun proteomics data where it reveals multiple mutations, a wide range of modifications (including glycosylation), and evidence for several putative novel modifications. Based on the reported findings, we argue that the efficiency and sensitivity of MODa make it the first unrestrictive search tool with the potential to fully replace conventional restrictive identification of proteomics mass spectrometry data. PMID:22186716

  20. Quantitation of soybean allergens using tandem mass spectrometry.

    Science.gov (United States)

    Houston, Norma L; Lee, Dong-Gi; Stevenson, Severin E; Ladics, Gregory S; Bannon, Gary A; McClain, Scott; Privalle, Laura; Stagg, Nicola; Herouet-Guicheney, Corinne; MacIntosh, Susan C; Thelen, Jay J

    2011-02-04

    Soybean (Glycine max) seed contain some proteins that are allergenic to humans and animals. However, the concentration of these allergens and their expression variability among germplasms is presently unknown. To address this problem, 10 allergens were quantified from 20 nongenetically modified commercial soybean varieties using parallel, label-free mass spectrometry approaches. Relative quantitation was performed by spectral counting and absolute quantitation was performed using multiple reaction monitoring (MRM) with synthetic, isotope-labeled peptides as internal standards. During relative quantitation analysis, 10 target allergens were identified, and five of these allergens showed expression levels higher than technical variation observed for bovine serum albumin (BSA) internal standard (∼11%), suggesting expression differences among the varieties. To confirm this observation, absolute quantitation of these allergens from each variety was performed using MRM. Eight of the 10 allergens were quantified for their concentration in seed and ranged from approximately 0.5 to 5.7 μg/mg of soy protein. MRM analysis reduced technical variance of BSA internal standards to approximately 7%, and confirmed differential expression for four allergens across the 20 varieties. This is the first quantitative assessment of all major soybean allergens. The results show the total quantity of allergens measured among the 20 soy varieties was mostly similar.

  1. Biological Matrix Effects in Quantitative Tandem Mass Spectrometry-Based Analytical Methods: Advancing Biomonitoring

    Science.gov (United States)

    Panuwet, Parinya; Hunter, Ronald E.; D’Souza, Priya E.; Chen, Xianyu; Radford, Samantha A.; Cohen, Jordan R.; Marder, M. Elizabeth; Kartavenka, Kostya; Ryan, P. Barry; Barr, Dana Boyd

    2015-01-01

    The ability to quantify levels of target analytes in biological samples accurately and precisely, in biomonitoring, involves the use of highly sensitive and selective instrumentation such as tandem mass spectrometers and a thorough understanding of highly variable matrix effects. Typically, matrix effects are caused by co-eluting matrix components that alter the ionization of target analytes as well as the chromatographic response of target analytes, leading to reduced or increased sensitivity of the analysis. Thus, before the desired accuracy and precision standards of laboratory data are achieved, these effects must be characterized and controlled. Here we present our review and observations of matrix effects encountered during the validation and implementation of tandem mass spectrometry-based analytical methods. We also provide systematic, comprehensive laboratory strategies needed to control challenges posed by matrix effects in order to ensure delivery of the most accurate data for biomonitoring studies assessing exposure to environmental toxicants. PMID:25562585

  2. FAST DETECTION OF ACETYLSALICYLIC ACID BY LIQUID CHROMATOGRAPHY TANDEM MASS SPECTROMETRY(LC-MSMS)

    OpenAIRE

    Abusoglu, Sedat; Unlu, Ali; Sivrikaya, Abdullah

    2018-01-01

    ObjectivesAcetylsalicylic acid (ASA) is themost widely used as an analgesic, anti-inflammatory and antipyretic drug, andalso used to inhibit cyclooxygenase dependent platelet aggregation.   The aimof this study was to develop a simple, fast and accurate tandem mass method fordetermination and quantification of ASA.  MethodsChromatographic seperation was performedusing an Shimadzu LC-20-AD (Kyoto, Japan) coupledwith a ABSCIEX API 3200 triple quadrupole massspectromete...

  3. Measurement of teicoplanin by liquid chromatography-tandem mass spectrometry:development of a novel method

    OpenAIRE

    Fung, Francis H Y; Tang, Jonathan C Y; Hopkins, John P P; Dutton, John; Bailey, Lisa M; Davison, Andrew S

    2012-01-01

    Teicoplanin is an antibiotic used for the treatment of endocarditis, osteomyelitis, septic arthritis and methicillin-resistant Staphylococcus aureus. Teicoplanin is emerging as a suitable alternative antibiotic to vancomycin, where their trough serum levels are monitored by immunoassay routinely. This is the first report detailing the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring teicoplanin in patients' serum.

  4. Ultrahigh pressure liquid chromatography-(tandem) mass spectrometry in human sports drug testing: possibilities and limitations.

    Science.gov (United States)

    Thevis, Mario; Thomas, Andreas; Pop, Valentin; Schänzer, Wilhelm

    2013-05-31

    Doping control analytical laboratories for human sports predominantly employ nowadays chromatographic-mass spectrometric test methods for routine, high throughput screening and confirmation assays concerning low and high molecular mass analytes. Liquid chromatography-(tandem) mass spectrometry [(LC-MS(/MS)] and particularly ultrahigh pressure liquid chromatography (UHPLC)-MS/MS instruments have become devices of choice due to their indispensable capabilities that compensate for limitations inherent to other commonly used strategies such as immunological and gas chromatography-(tandem) mass spectrometry [(GC-MS(/MS)]-based detection methods. UHPLC-MS/MS-based assays at low mass spectrometric resolution have been established allowing for fast and sensitive targeted analyses focusing on pre-selected target analytes with diagnostic precursor-product ion pairs. Combining UHPLC to high resolution/high accuracy MS(/MS) further expanded the targeted approach (i.e., plotting extracted ion chromatograms of protonated or deprotonated molecules as well as product ions measured with accurate masses) toward non-targeted analyses enabling also retrospective data mining. In this review, recent applications of UHPLC-MS/MS in sports drug testing procedures published between 2008 and 2012 are presented and advantages as well as limitations in a short- and long-term perspective are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Classification of Tandem Mass Spectra for Identification of N- and O-linked Glycopeptides

    Science.gov (United States)

    Toghi Eshghi, Shadi; Yang, Weiming; Hu, Yingwei; Shah, Punit; Sun, Shisheng; Li, Xingde; Zhang, Hui

    2016-11-01

    Analysis of intact glycopeptides by mass spectrometry is essential to determining the microheterogeneity of protein glycosylation. Higher-energy collisional dissociation (HCD) fragmentation of glycopeptides generates mono- or disaccharide ions called oxonium ions that carry information about the structure of the fragmented glycans. Here, we investigated the link between glycan structures and the intensity of oxonium ions in the spectra of glycopeptides and utilized this information to improve the identification of glycopeptides in biological samples. Tandem spectra of glycopeptides from fetuin, glycophorin A, ovalbumin and gp120 tryptic digests were used to build a spectral database of N- and O-linked glycopeptides. Logistic regression was applied to this database to develop model to distinguish between the spectra of N- and O-linked glycopeptides. Remarkably, the developed model was found to reliably distinguish between the N- and O-linked glycopeptides using the spectral features of the oxonium ions using verification spectral set. Finally, the performance of the developed predictive model was evaluated in HILIC enriched glycopeptides extracted from human serum. The results showed that pre-classification of tandem spectra based on their glycosylation type improved the identification of N-linked glycopeptides. The developed model facilitates interpretation of tandem mass spectrometry data for assignment of glycopeptides.

  6. Quantitative Caffeine Analysis Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Michael J [ORNL; Deibel, Michael A. [Earlham College; Tomkins, Bruce A [ORNL; Van Berkel, Gary J [ORNL

    2005-01-01

    Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 {mu}m/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and thin-layer chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 {mu}L) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three diet soft drinks (Diet Coke, Diet Cherry Coke, Diet Pepsi) and three diet sport drinks (Diet Turbo Tea, Speed Stack Grape, Speed Stack Fruit Punch) was measured. The HPLC/UV and mass spectrometry determinations were in general agreement, and these values were consistent with the quoted values for two of the three diet colas. In the case of Diet Cherry Coke and the diet sports drinks, the determined caffeine amounts using both methods were consistently higher (by 8% or more) than the literature values.

  7. Doping control analysis of anabolic steroids in equine urine by gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Wong, April S Y; Leung, Gary N W; Leung, David K K; Wan, Terence S M

    2017-09-01

    Anabolic steroids are banned substances in equine sports. Gas chromatography-mass spectrometry (GC-MS) has been the traditional technique for doping control analysis of anabolic steroids in biological samples. Although liquid chromatography-mass spectrometry (LC/MS) has become an important technique in doping control, the detection of saturated hydroxysteroids by LC-MS remains a problem due to their low ionization efficiency under electrospray. The recent development in fast-scanning gas-chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) has provided a better alternative with a significant reduction in chemical noise by means of selective reaction monitoring. Herein, we present a sensitive and selective method for the screening of over 50 anabolic steroids in equine urine using gas chromatography-tandem mass spectrometry (GC-MS/MS). Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. Arsenic speciation by liquid chromatography coupled with ionspray tandem mass spectrometry

    DEFF Research Database (Denmark)

    Corr, J. J.; Larsen, Erik Huusfeldt

    1996-01-01

    fragmentation patterns showing molecular dissociation through an expected common product ion were obtained for the four arsenosugars, Molecular mode detection was utilized for qualitative verification of speciation analysis by high-performance liquid chromatography coupled to inductively coupled plasma mass......Ionspray mass spectrometry, a well established organic analysis technique, has been coupled to high-performance liquid chromatography for speciation of organic arsenic compounds, The ionspray source and differentially pumped interface of the mass spectrometer were operated in dual modes...... for elemental and molecular analysis, Tandem mass spectrometry was employed to increase selectivity, Dual mode detection was applied to demonstrate the utility of the technique for analysis of nine organoarsenic standards, including four dimethylarsinylriboside derivatives (arsenosugars), Structural...

  9. Modeling low cost hybrid tandem photovoltaics with the potential for efficiencies exceeding 20%

    KAUST Repository

    Beiley, Zach M.

    2012-01-01

    It is estimated that for photovoltaics to reach grid parity around the planet, they must be made with costs under $0.50 per W p and must also achieve power conversion efficiencies above 20% in order to keep installation costs down. In this work we explore a novel solar cell architecture, a hybrid tandem photovoltaic (HTPV), and show that it is capable of meeting these targets. HTPV is composed of an inexpensive and low temperature processed solar cell, such as an organic or dye-sensitized solar cell, that can be printed on top of one of a variety of more traditional inorganic solar cells. Our modeling shows that an organic solar cell may be added on top of a commercial CIGS cell to improve its efficiency from 15.1% to 21.4%, thereby reducing the cost of the modules by ∼15% to 20% and the cost of installation by up to 30%. This suggests that HTPV is a promising option for producing solar power that matches the cost of existing grid energy. © 2012 The Royal Society of Chemistry.

  10. Measurement of teicoplanin by liquid chromatography-tandem mass spectrometry: development of a novel method.

    Science.gov (United States)

    Fung, Francis H Y; Tang, Jonathan C Y; Hopkins, John P P; Dutton, John J; Bailey, Lisa M; Davison, Andrew S

    2012-09-01

    Teicoplanin is an antibiotic used for the treatment of endocarditis, osteomyelitis, septic arthritis and methicillin-resistant Staphylococcus aureus. Teicoplanin is emerging as a suitable alternative antibiotic to vancomycin, where their trough serum levels are monitored by immunoassay routinely. This is the first report detailing the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring teicoplanin in patients' serum. An Acquity™ UPLC (ultra-pressure liquid chromatography) tandem mass spectrometer was used to measure teicoplanin concentrations in samples from patients, quality assurance schemes and quality control preparations. Ristocetin was successfully implemented as a suitable internal standard. Ion suppression, linearity, stability, matrix effects, recovery, imprecision, lower limits of quantification and detection, interference and method comparison against immunoassay were all assessed. Teicoplanin and ristocetin had elution times of 1.39 and 1.24 min, respectively. Ion suppression was shown to be negligible, and linear calibration curves (0-200 μg/mL) were consistently reproduced to have r(2) values >0.99. Postextraction stability was achieved up to 20 h, while matrix effects were minimal coupled with sample recovery of >93%. The lower limit of quantification was 1 μg/mL, and 0.2 μg/mL was the lower limit of detection. Interference with other antibiotics was dependent on the combination of drugs present in patients' serum. A method comparison between immunoassay and LC-MS/MS suggested a negative bias for tandem mass spectrometry. This novel method of teicoplanin determination by LC-MS/MS is proven to be a robust protocol that is consistent and reproducible. Clinicians searching for alternatives in therapeutic drug monitoring may have an additional option that is potentially more accurate and specific.

  11. Phosphopeptide detection and sequencing by matrix-assisted laser desorption/ionization quadrupole time-of-flight tandem mass spectrometry

    DEFF Research Database (Denmark)

    Bennett, Keiryn L; Stensballe, Allan; Podtelejnikov, Alexandre V

    2002-01-01

    A prototype matrix-assisted laser desorption/ionization quadrupole time-of-flight (MALDI-TOF) tandem mass spectrometer was used to sequence a series of phosphotyrosine-, phosphothreonine- and phosphoserine-containing peptides. The high mass resolution and mass accuracy of the instrument allowed...... ion at m/z 216.04 was observed in these MALDI low-energy CID tandem mass spectra. Elimination of phosphate groups was evident from the triphosphorylated peptide but not from the monophosphorylated species. The main fragmentation pathway for the synthetic phosphothreonine-containing peptide...... the localization of one, three or four phosphorylated amino acid residues in phosphopeptides up to 3.1 kDa. Tandem mass spectra of two different phosphotyrosine peptides permitted amino acid sequence determination and localization of one and three phosphorylation sites, respectively. The phosphotyrosine immonium...

  12. Analysis of xyloglucans by ambient chloride attachment ionization tandem mass spectrometry.

    Science.gov (United States)

    Vinueza, Nelson R; Gallardo, Vanessa A; Klimek, John F; Carpita, Nicholas C; Kenttämaa, Hilkka I

    2013-10-15

    Xyloglucan oligomers obtained upon enzyme digestion from Hymenaea courbaril, Arabidopsis Columbia-0 and mur3 were ionized and analyzed by using chloride anion attachment electrospray ionization (ESI) and tandem mass spectrometry. MW determination and structural elucidation of several xyloglucan oligomers was performed directly from the mixture solutions without sample pretreatment or derivatization. Sodium cation attachment was used to determine the number of xyloglucans present in the mixtures and their MWs. However, tandem mass spectrometry results showed that structure elucidation based on the sodium adducts is ambiguous. Chloride anion also forms stable adducts with these xyloglucans upon ESI. These adducts can be readily identified due to the chlorine isotope pattern. The mass spectral profile of xyloglucans obtained for the mixtures matches the HPAEC results, thus validating this methodology for the determination of the xyloglucan composition and the MW of each xyloglucan. Upon collisional activation in MS(2) experiments, the chloride anion adducts readily lose HCl, which helps verify the molecular weight of each xyloglucan. Isolating the resulting anion (deprotonated oligomer) and subjecting it to further collision-activated dissociation experiments (MS(n); n=3-4) yields useful structural information that allows the differentiation between isomeric anions and hence determination of the sequence of the xyloglucan oligomers. The deprotonated oligomers fragment by a stepwise loss of sugar units from the reducing end. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  13. Authentication of Fish Products by Large-Scale Comparison of Tandem Mass Spectra

    DEFF Research Database (Denmark)

    Wulff, Tune; Nielsen, Michael Engelbrecht; Deelder, André M.

    2013-01-01

    workflow including protein extraction, digestion, and data analysis. First, a set of reference spectral libraries was generated using unprocessed muscle tissue from 22 different fish species. Query tandem mass spectrometry data sets from “unknown” fresh muscle tissue samples were then searched against...... the reference libraries. The number of matching spectra could unambiguously identify the origin of all fresh samples. A number of processed samples were also analyzed to further test the robustness and applicability of the method. The results clearly show that the method is also able to correctly identify...... heavily processed samples....

  14. Identification and Quantification of Dimethylamylamine in Geranium by Liquid Chromatography Tandem Mass Spectrometry

    OpenAIRE

    Li, J. S.; Chen, M.; Z.C. Li

    2012-01-01

    A sensitive and reliable method of liquid chromatography–electrospray ionization/tandem mass spectrometry (LC-ESI/MS/ MS) was developed and validated for determining 1,3-dimethylamylamine (1,3-DMAA) and 1,4-dimethylamylamine (1,4-DMAA) in geranium plants (Pelargonium graveolens). The sample was extracted with 0.5 M HCl and purified by liquid-liquid partition with hexane. The parameters for reverse-phase (C18) LC and positive ESI/MS/MS were optimized. The matrix effect, specificity, linearity,...

  15. Analyse des cannabinoïdes par spectrométrie de masse en mode tandem

    OpenAIRE

    Fabritius Marie Staub Christian et Giroud Christian

    2011-01-01

    Depuis quelques années la spectrométrie de masse en tandem (MS/MS) ne cesse de gagner du terrain comme méthode d’analyse en toxicologie forensique notamment pour le dosage des cannabinoïdes. Couplée à la chromatographie liquide (LC) ou gazeuse (GC) elle permet l’identification fiable et le dosage rapide du THC de son précurseur acide et de ses principaux métabolites y compris les glucuronides. Au cours de ces dix dernières années un nombre significatif de publications sont parues sur ce sujet...

  16. Liquid chromatography tandem-mass spectrometry (LC-MS/MS)--technique and applications in endocrinology.

    Science.gov (United States)

    Vogeser, M; Parhofer, K G

    2007-10-01

    In recent years, liquid chromatography tandem mass spectrometry (LC-MS/MS) has emerged as an innovative analytical technology applicable to a wide number of analyses in the endocrinology laboratory. Compared to the "traditional" technique of gas chromatography-mass spectrometry (GC-MS), LC-MS/MS is easier to use and is applicable for a substantially larger number of relevant analytes. With the development of LC-MS/MS, the widespread application of the proven principle of isotope dilution mass spectrometry is now feasible not only in research but also for routine applications. The aim of this review is to explain the basic technical principles of LC-MS/MS, to describe the general characteristics of analytical LC-MS/MS applications and to comprehensively discuss the application of this technology in the field of endocrinology.

  17. Atmospheric pressure ionization-tandem mass spectrometry of the phenicol drug family.

    Science.gov (United States)

    Alechaga, Élida; Moyano, Encarnación; Galceran, M Teresa

    2013-11-01

    In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H](+) dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M-H](-), while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high-resolution mass spectrometry in a quadrupole-Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N-(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS(3) and MS(4) spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high-performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. Copyright © 2013 John Wiley & Sons, Ltd.

  18. Quantitative and confirmative performance of liquid chromatography coupled to high-resolution mass spectrometry compared to tandem mass spectrometry.

    Science.gov (United States)

    Kaufmann, Anton; Butcher, Patrick; Maden, Kathryn; Walker, Stephan; Widmer, Miryam

    2011-04-15

    The quantitative and confirmative performance of two different mass spectrometry (MS) techniques (high-resolution MS and tandem MS) was critically compared. Evaluated was a new extraction and clean-up protocol which was developed to cover more than 100 different veterinary drugs at trace levels in a number of animal tissues and honey matrices. Both detection techniques, high-resolution mass spectrometry (HRMS) (single-stage Orbitrap instrument operated at 50 000 full width at half maximum) and tandem mass spectrometry (MS/MS) (quadrupole technology) were used to validate the method according to the EU Commission Decision 2002/657/EEC. Equal or even a slightly better quantitative performance was observed for the HRMS-based approach. Sensitivity is higher for unit mass resolution MS/MS if only a subset of the 100 compounds has to be monitored. Confirmation of suspected positive findings can be done by evaluating the intensity ratio between different MS/MS transitions, or by accurate mass based product ion traces (no precursor selection applied). MS/MS relies on compound-specific optimized transitions; hence the second, confirmatory transition generally shows relatively high ion abundance (fragmentation efficacy). This is often not the case in single-stage HRMS, since a generic (not compound-optimized) collision energy is applied. Hence, confirmation of analytes present at low levels is superior when performed by MS/MS. Slightly better precision, but poorer accuracy (fortified matrix extracts versus pure standard solution) of ion ratios were observed when comparing data obtained by HRMS versus MS/MS. Copyright © 2011 John Wiley & Sons, Ltd.

  19. Quantitative analysis of racecadotril metabolite in human plasma using a liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Xu, Yu; Huang, Jinchang; Liu, Fei; Gao, Shu; Guo, Qingxiang

    2007-06-01

    Orally administered racecadotril is rapidly hydrolyzed to the more potent enkephalinase inhibitor thiorphan in vivo. A sensitive and specific liquid chromatography/tandem mass spectrometry method was developed and validated to quantify thiorphan in human plasma using lisinopril as the internal standard. After a simple protein precipitation with methanol, the post-treatment samples were analyzed on a CN column interfaced with a triple-quadruple tandem mass spectrometer using negative electrospray ionization. The method was validated to demonstrate the specificity, lower limit of quantification, accuracy, and precision of measurements. The assay was linear over the concentration range 9.38-600 ng/mL using a 5 microL aliquot of plasma. The correlation coefficients for the calibration curves ranged from 0.9985 to 0.9995. The intra- and inter-day precisions over the entire concentration were not more than 6.33%. Methanol and water (35:65, v/v) is used as the isocratic mobile phase, with 0.1% of formic acid in water. The method was successfully applied for pharmacokinetic study after a single oral administration of 200 mg racecadotril to 20 healthy volunteers.

  20. Detection of Inborn Errors of Metabolism using Tandem Mass Spectrometry among High-risk Omani Patients

    Directory of Open Access Journals (Sweden)

    Sulaiman Al Riyami

    2012-11-01

    Full Text Available Objectives: This is a report on the types and patterns of inborn errors of metabolism (IEMs of amino acids, organic acids and fatty acids oxidation detected by Tandem Mass Spectrometry for a period of 10 years (1998-2008 at Sultan Qaboos University Hospital (SQUH, the major centre for diagnosis and management of IEM in Oman.Methods: Tandem mass spectrometry (MS/MS was used in the initial screening and diagnosis of IEMs in high risk neonatal and pediatric populations.Results: Out of 1100 patients investigated, 119 were detected positive for IEM by MS/MS spectrometry. Twenty six different metabolic diseases were detected. Patients were categorized into three major groups: a 54 with amino acids and urea cycle disorders, b 35 with organic acid disorders, and c 30 with fatty acid oxidation disorders. The commonest conditions encountered were maple syrup urine disease (MSUD, phenylketonuria (PKU, propionic and isovaleric acidurias, as well as HMG-CoA lyase deficiency and glutaric aciduria type II (GA-II. Most of these IEMs were over representedin babies born to consanguineous parents, which is consistent with the recessive autosomal inheritance.Conclusion: This study shows that various types of IEMs, reported elsewhere, were also prevalent in Oman, but the pattern of prevalence and distribution is different. The situation, therefore, warrants the development of a nationwide screening and prevention program.

  1. Improved liquid chromatography-tandem mass spectrometry method for the analysis of eptifibatide in human plasma.

    Science.gov (United States)

    Zhou, Zhi-Ling; Yu, Xi-Yong; Yang, Min; Mai, Li-Ping; Lin, Qiu-Xiong; Deng, Chun-Yu; Shan, Zhi-Xin; Kuang, Su-Juan; Zhu, Ping; Huang, Xiao-Zhong; Li, Xiao-Hong; Chen, Tie-Feng; Lin, Shu-Guang

    2010-08-01

    A rapid, selective and highly sensitive high performance liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated for the determination and pharmacokinetic investigation of eptifibatide in human plasma. Eptifibatide and the internal standard (IS), EPM-05, were extracted from plasma samples using solid phase extraction. Chromatographic separation was performed on a C(18) column at a flow rate of 0.5 mL/min. Detection of eptifibatide and the IS was achieved by tandem mass spectrometry with an electrospray ionization (ESI) interface in positive ion mode. Traditional multiple reaction monitoring (MRM) using the transition of m/z 832.6-->m/z 646.4 and m/z 931.6-->m/z 159.4 was performed to quantify eptifibatide and the IS, respectively. The calibration curves were linear over the range of 1-1000 ng/mL with the lower limit of quantitation validated at 1 ng/mL. The intra- and inter-day precisions were within 13.3%, while the accuracy was within +/-7.6% of nominal values. The validated LC-MS/MS method was successfully applied for the evaluation of pharmacokinetic parameters of eptifibatide after intravenous (i.v.) administration of a 45 microg/kg bolus of eptifibatide to 8 healthy volunteers. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Determination of parabens in serum by liquid chromatography-tandem mass spectrometry: Correlation with lipstick use.

    Science.gov (United States)

    Tahan, Gabriella Padovani; Santos, Nayara de Kássia Souza; Albuquerque, Ana Carolina; Martins, Isarita

    2016-08-01

    Parabens are the most widely used preservative and are considered to be relatively safe compounds. However, studies have demonstrated that they may have estrogenic activity, and there is ongoing debate regarding the safety and potential cancer risk of using products containing these compounds. In the present work, liquid chromatography-tandem mass spectrometry was applied to determine methylparaben and propylparaben concentrations in serum, and the results were correlated with lipstick application. Samples were analyzed using liquid-liquid extraction, followed by liquid chromatography-tandem mass spectrometry. The validation results demonstrated the linearity of the method over a range of 1-20 ng/mL, in addition to the method's precision and accuracy. A statistically significant difference was demonstrated between serum parabens in women who used lipstick containing these substances compared with those not using this cosmetic (p = 0.0005 and 0.0016, respectively), and a strong association was observed between serum parabens and lipstick use (Spearman correlation = 0.7202). Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Determination of bromate in drinking water by ultraperformance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Alsohaimi, Ibrahim Hotan; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan; Abdalla, Mohammad Abulhassan; Busquets, Rosa; Alomary, Ahmad Khodran

    2012-10-01

    Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 μg/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Strategies for dereplication of natural compounds using high-resolution tandem mass spectrometry.

    Science.gov (United States)

    Kind, Tobias; Fiehn, Oliver

    2017-09-01

    Complete structural elucidation of natural products is commonly performed by nuclear magnetic resonance spectroscopy (NMR), but annotating compounds to most likely structures using high-resolution tandem mass spectrometry is a faster and feasible first step. The CASMI contest 2016 (Critical Assessment of Small Molecule Identification) provided spectra of eighteen compounds for the best manual structure identification in the natural products category. High resolution precursor and tandem mass spectra (MS/MS) were available to characterize the compounds. We used the Seven Golden Rules, Sirius2 and MS-FINDER software for determination of molecular formulas, and then we queried the formulas in different natural product databases including DNP, UNPD, ChemSpider and REAXYS to obtain molecular structures. We used different in-silico fragmentation tools including CFM-ID, CSI:FingerID and MS-FINDER to rank these compounds. Additional neutral losses and product ion peaks were manually investigated. This manual and time consuming approach allowed for the correct dereplication of thirteen of the eighteen natural products.

  5. Steroid hormone levels in pregnancy and 1 year postpartum using isotope dilution tandem mass spectrometry

    Science.gov (United States)

    Soldin, Offie P.; Guo, Tiedong; Weiderpass, Elisabete; Tractenberg, Rochelle E.; Hilakivi-Clarke, Leena; Soldin, Steven J.

    2013-01-01

    Objective To establish normal, trimester-specific reference intervals for serum 17β-estradiol, progesterone (P), 17α-hydroxyprogesterone, cortisol, 11-deoxycortisol, androstenedione, DHEA, and DHEAS, measured simultaneously using isotope dilution tandem mass spectrometry. Design Sequential cohort study. Patient(s) Healthy women undergoing a normal pregnancy (age, 25–38 years; mean, 30 years) attending a prenatal well clinic at gestation weeks 12, 22, and 32 and approximately 1 year postpartum. Main Outcome Measure(s) Trimester-specific reference intervals of endogenous steroid hormones analyzed using an isotope dilution tandem mass spectrometer equipped with an atmospheric pressure photoionization source with deuterium-labeled internal standards. Result(s) Serum estradiol, P, 17α-hydroxyprogesterone, and 11-deoxycortisol increased throughout pregnancy; cortisol increased up to the second trimester and then remained steady, while androstenedione increased by 80 percent by gestation week 12, then remained constant. Serum DHEA-S decreased by 50% by the third trimester. Conclusion(s) Trimester-specific reference intervals are reported for eight serum steroids. The ratios of individual serum hormone concentrations during pregnancy relative to their 1-year postpartum concentrations illustrate the expected normal trends of changes in hormone concentrations during pregnancy. PMID:16169406

  6. Reactivity and analytical performance of oxygen as cell gas in inductively coupled plasma tandem mass spectrometry

    Science.gov (United States)

    Virgilio, Alex; Amais, Renata S.; Amaral, Clarice D. B.; Fialho, Lucimar L.; Schiavo, Daniela; Nóbrega, Joaquim A.

    2016-12-01

    The reactivity and analytical performance of O2 as cell gas in inductively coupled plasma tandem mass spectrometry was investigated. Selected analytes in a wide mass range were divided in three groups according to their reactivity: G1 represents elements with high oxygen affinity (Ce, La, P, Sc, Ti, and Y), G2 contains elements that may partially react with oxygen (As, Ba, Mo, Si, Sr, and V), and G3 comprises elements expected to be less reactive towards oxygen (Al, Bi, Cu, Mg, Pb, and Pd). On-mass and mass-shift modes were evaluated by monitoring atomic and metal oxide ions, respectively. Analytical signal profiles, oxide percentages, sensitivities and limits of detection for oxygen flow rates varying from 0.1 to 1.0 mL min- 1 were also studied. Group 1 elements plus As and V presented better sensitivities and LODs when measuring oxides, which were the major species for all flow rates evaluated. Molybdenum and Si oxides presented intermediate behavior and MoO fraction was up to 47% and limit of detection was the same as that obtained in on-mass mode. For others G2 and G3 elements, on-mass mode presented higher sensitivity and better LODs, with estimated oxide contents lower than 10%. In most cases, increasing oxygen flow rates led to lower sensitivities and worse LODs.

  7. PECAN: library-free peptide detection for data-independent acquisition tandem mass spectrometry data

    Energy Technology Data Exchange (ETDEWEB)

    Ting, Ying S.; Egertson, Jarrett D.; Bollinger, James G.; Searle, Brian C.; Payne, Samuel H.; Noble, William Stafford; MacCoss, Michael J.

    2017-08-07

    Data-independent acquisition (DIA) is an emerging mass spectrometry (MS)-based technique for unbiased and reproducible measurement of protein mixtures. DIA tandem mass spectrometry spectra are often highly multiplexed, containing product ions from multiple cofragmenting precursors. Detecting peptides directly from DIA data is therefore challenging; most DIA data analyses require spectral libraries. Here we present PECECAN (http://pecan.maccosslab.org), a library-free, peptide-centric tool that robustly and accurately detects peptides directly from DIA data. PECECAN reports evidence of detection based on product ion scoring, which enables detection of low-abundance analytes with poor precursor ion signal. We demonstrate the chromatographic peak picking accuracy and peptide detection capability of PECECAN, and we further validate its detection with data-dependent acquisition and targeted analyses. Lastly, we used PECECAN to build a plasma proteome library from DIA data and to query known sequence variants.

  8. A novel method to determine valnemulin in feedingstuffs for several animal species by liquid chromatography-electrospray tandem mass spectrometry.

    Science.gov (United States)

    Gallo, Pasquale; Di Marco Pisciottano, Ilaria; Urbani, Valeria; Bianco, Raffaele; Picarelli, Emanuela

    2016-11-01

    A new method specific for the determination and unambiguous confirmation of the antibiotic valnemulin in feed for all animal species is described. Simple clean-up based on solvent extraction and liquid partition is carried out prior to determination by liquid chromatography coupled to electrospray tandem mass spectrometry on a hybrid QTRAP 4000 system, in multiple reaction monitoring mode. Valnemulin is licensed in the European Union as a veterinary drug for use in feed for pigs and rabbits, but unavoidable carryover in feed for non-target species should be monitored. The method is rapid and reliable, and was validated in-house at 10, 100 and 750 ng g-1, evaluating the analytical performances according to Commission Regulation (EC) No. 882/2004. Good mean recoveries from 79.7% to 92.6%, and within-laboratory reproducibility RSDs, ranging from 6.2% to 12.1%, were measured; the limit of quantification at 10.0 ng g-1 also allows for sensitive evaluation of undesirable carryover in feed for non-target species. The results of monitoring 24 compound feeds for several animal species are also reported.

  9. Evaluation of strong cation exchange versus isoelectric focusing of peptides for multidimensional liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Slebos, Robbert J C; Brock, Jonathan W C; Winters, Nancy F; Stuart, Sarah R; Martinez, Misti A; Li, Ming; Chambers, Mathew C; Zimmerman, Lisa J; Ham, Amy J; Tabb, David L; Liebler, Daniel C

    2008-12-01

    Shotgun proteome analysis platforms based on multidimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS) provide a powerful means to discover biomarker candidates in tissue specimens. Analysis platforms must balance sensitivity for peptide detection, reproducibility of detected peptide inventories and analytical throughput for protein amounts commonly present in tissue biospecimens (cation exchange (SCX) and isoelectric focusing (IEF) separations of peptides prior to LC-MS/MS analysis on a LTQ-Orbitrap hybrid instrument. IEF separations provided superior reproducibility and resolution for peptide fractionation from samples corresponding to both large (100 microg) and small (10 microg) protein inputs. SCX generated more peptide and protein identifications than did IEF with small (10 microg) samples, whereas the two platforms yielded similar numbers of identifications with large (100 microg) samples. In nine replicate analyses of tryptic peptides from 50 microg colon adenocarcinoma protein, overlap in protein detection by the two platforms was 77% of all proteins detected by both methods combined. IEF more quickly approached maximal detection, with 90% of IEF-detectable medium abundance proteins (those detected with a total of 3-4 peptides) detected within three replicate analyses. In contrast, the SCX platform required six replicates to detect 90% of SCX-detectable medium abundance proteins. High reproducibility and efficient resolution of IEF peptide separations make the IEF platform superior to the SCX platform for biomarker discovery via shotgun proteomic analyses of tissue specimens.

  10. Structure determination of adipokinetic hormones using fast atom bombardment tandem mass spectrometry; An unknown adipokinetic hormone (AKH-III) from Locusta migratoria

    Energy Technology Data Exchange (ETDEWEB)

    Heerma, W.; Versluis, C.; Lankhof, H. (Utrecht University (Netherlands). Faculty of Chemistry, Department of Analytical Molecular Spectrometry); Oudejans, R.C.H.M.; Kooiman, F.P.; Beenakkers, A.M.T. (Utrecht University (Netherlands). Department of Experimental Zoology)

    1991-08-01

    Fast atom bombardment mass spectrometry combined with various tandem mass spectrometric techniques and accurate mass measurement were used to elucidate the structure of an unknown biologically active peptide isolated from Locusa migratoria. (author). 23 refs.; 6 figs.; 2 schemes.

  11. Advanced Laser Architecture for Two-Step Laser Tandem Mass Spectrometer

    Science.gov (United States)

    Fahey, Molly E.; Li, Steven X.; Yu, Anthony W.; Getty, Stephanie A.

    2016-01-01

    Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. These missions require advanced instrument techniques to fully and unambiguously characterize the composition of surface and dust materials. Laser desorptionionization mass spectrometry (LDMS) is an emerging instrument technology for in situ mass analysis of non-volatile sample composition. A recent Goddard LDMS advancement is the two-step laser tandem mass spectrometer (L2MS) instrument to address the need for future flight instrumentation to deconvolve complex organic signatures. The L2MS prototype uses a resonance enhanced multi-photon laser ionization mechanism to selectively detect aromatic species from a more complex sample. By neglecting the aliphatic and inorganic mineral signatures in the two-step mass spectrum, the L2MS approach can provide both mass assignments and clues to structural information for an in situ investigation of non-volatile sample composition. In this paper we will describe our development effort on a new laser architecture that is based on the previously flown Lunar Orbiter Laser Altimeter (LOLA) laser transmitter for the L2MS instrument. The laser provides two discrete midinfrared wavelengths (2.8 m and 3.4 m) using monolithic optical parametric oscillators and ultraviolet (UV) wavelength (266 nm) on a single laser bench with a straightforward development path toward flight readiness.

  12. Improving quantitative precision and throughput by reducing calibrator use in liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rule, Geoffrey S., E-mail: geoffrey.s.rule@aruplab.com [ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108 (United States); Rockwood, Alan L. [ARUP Institute for Clinical and Experimental Pathology, 500 Chipeta Way, Salt Lake City, UT 84108 (United States); Department of Pathology, University of Utah School of Medicine, 2100 Jones Medical Research Bldg., Salt Lake City, UT 84132 (United States)

    2016-05-05

    To improve efficiency in our mass spectrometry laboratories we have made efforts to reduce the number of calibration standards utilized for quantitation over time. We often analyze three or more batches of 96 samples per day, on a single instrument, for a number of assays. With a conventional calibration scheme at six concentration levels this amounts to more than 5000 calibration points per year. Modern LC-tandem mass spectrometric instrumentation is extremely rugged however, and isotopically labelled internal standards are widely available. This made us consider whether alternative calibration strategies could be utilized to reduce the number of calibration standards analyzed while still retaining high precision and accurate quantitation. Here we demonstrate how, by utilizing a single calibration point in each sample batch, and using the resulting response factor (RF) to update an existing, historical response factor (HRF), we are able to obtain improved precision over a conventional multipoint calibration approach, as judged by quality control samples. The laboratory component of this study was conducted with an existing LC tandem mass spectrometric method for three androgen analytes in our production laboratory. Using examples from both simulated and laboratory data we illustrate several aspects of our single point alternative calibration strategy and compare it with a conventional, multipoint calibration approach. We conclude that both the cost and burden of preparing multiple calibration standards with every batch of samples can be reduced while at the same time maintaining, or even improving, analytical quality. - Highlights: • Use of a weighted single point calibration approach improves quantitative precision. • A weighted response factor approach incorporates historical calibration information. • Several scenarios are discussed with regard to their influence on quantitation.

  13. Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer

    Science.gov (United States)

    Stolzenberg, H.; Becker, St.; Bollen, G.; Kern, F.; Kluge, H.-J.; Otto, Th.; Savard, G.; Schweikhard, L.; Audi, G.; Moore, R. B.

    1990-12-01

    A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for 118-137Cs. A resolving power of over 106 and an accuracy of 1.4×10-7 have been achieved, corresponding to about 20 keV.

  14. Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Stolzenberg, H.; Becker, S.; Bollen, G.; Kern, F.; Kluge, H.; Otto, T.; Savard, G.; Schweikhard, L. (Institut fuer Physik, Universitaet Mainz, D-6500 Mainz (Federal Republic of Germany)); Audi, G. (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Laboratoire Rene Bernas, Batiment 108, F-91405 Orsay (France)); Moore, R.B. (Foster Radiation Laboratory, McGill University, Montreal (Canada)); The ISOLDE Collaboration

    1990-12-17

    A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for {sup 118}Cs--{sup 137}Cs. A resolving power of over 10{sup 6} and an accuracy of 1.4{times}10{sup {minus}7} have been achieved, corresponding to about 20 keV.

  15. Mining Large Scale Tandem Mass Spectrometry Data for Protein Modifications Using Spectral Libraries.

    Science.gov (United States)

    Horlacher, Oliver; Lisacek, Frederique; Müller, Markus

    2016-03-04

    Experimental improvements in post-translational modification (PTM) detection by tandem mass spectrometry (MS/MS) has allowed the identification of vast numbers of PTMs. Open modification searches (OMSs) of MS/MS data, which do not require prior knowledge of the modifications present in the sample, further increased the diversity of detected PTMs. Despite much effort, there is still a lack of functional annotation of PTMs. One possibility to narrow the annotation gap is to mine MS/MS data deposited in public repositories and to correlate the PTM presence with biological meta-information attached to the data. Since the data volume can be quite substantial and contain tens of millions of MS/MS spectra, the data mining tools must be able to cope with big data. Here, we present two tools, Liberator and MzMod, which are built using the MzJava class library and the Apache Spark large scale computing framework. Liberator builds large MS/MS spectrum libraries, and MzMod searches them in an OMS mode. We applied these tools to a recently published set of 25 million spectra from 30 human tissues and present tissue specific PTMs. We also compared the results to the ones obtained with the OMS tool MODa and the search engine X!Tandem.

  16. Xylose Migration During Tandem Mass Spectrometry of N-Linked Glycans

    Science.gov (United States)

    Hecht, Elizabeth S.; Loziuk, Philip L.; Muddiman, David C.

    2017-04-01

    Understanding the rearrangement of gas-phase ions via tandem mass spectrometry is critical to improving manual and automated interpretation of complex datasets. N-glycan analysis may be carried out under collision induced (CID) or higher energy collision dissociation (HCD), which favors cleavage at the glycosidic bond. However, fucose migration has been observed in tandem MS, leading to the formation of new bonds over four saccharide units away. In the following work, we report the second instance of saccharide migration ever to occur for N-glycans. Using horseradish peroxidase as a standard, the beta-1,2 xylose was observed to migrate from a hexose to a glucosamine residue on the (Xyl)Man3GlcNac2 glycan. This investigation was followed up in a complex N-linked glycan mixture derived from stem differentiating xylem tissue, and the rearranged product ion was observed for 75% of the glycans. Rearrangement was not favored in isomeric glycans with a core or antennae fucose and unobserved in glycans predicted to have a permanent core-fucose modification. As the first empirical observation of this rearrangement, this work warrants dissemination so it may be searched in de novo sequencing glycan workflows.

  17. Atmospheric-Pressure Chemical Ionization Tandem Mass Spectrometry (APGC/MS/MS) an Alternative to High-Resolution Mass Spectrometry (HRGC/HRMS) for the Determination of Dioxins

    NARCIS (Netherlands)

    Bavel, Van Bert; Geng, Dawei; Cherta, Laura; Nácher-Mestre, Jaime; Portolés, Tania; Ábalos, Manuela; Sauló, Jordi; Abad, Esteban; Dunstan, Jody; Jones, Rhys; Kotz, Alexander; Winterhalter, Helmut; Malisch, Rainer; Traag, Wim; Hagberg, Jessika; Ericson Jogsten, Ingrid; Beltran, Joaquim; Hernández, Félix

    2015-01-01

    The use of a new atmospheric-pressure chemical ionization source for gas chromatography (APGC) coupled with a tandem quadrupole mass spectrometry (MS/MS) system, as an alternative to high-resolution mass spectrometry (HRMS), for the determination of PCDDs/PCDFs is described. The potential of

  18. A novel tandem quadrupole mass spectrometer allowing gaseous collisional activation and surface induced dissociation.

    Science.gov (United States)

    Mohammed, S; Chalmers, M J; Gielbert, J; Ferro, M; Gora, L; Smith, D C; Gaskell, S J

    2001-12-01

    A novel tandem quadrupole mass spectrometer is described that enables gaseous collision-induced dissociation (CID) and surface-induced dissociation (SID) experiments. The instrument consists of a commercially available triple quadrupole mass spectrometer connected to an SID region and an additional, orthogonal quadrupole mass analyser. The performance of the instrument was evaluated using leucine-enkephalin, allowing a comparison between CID and SID, and with previous reports of other SID instruments. The reproducibility of SID data was assessed by replicate determinations of the collision energy required for 50% dissociation of leucine-enkephalin; excellent precision was observed (standard deviation of 0.6 eV) though, unexpectedly, the reproducibility of the equivalent figure for CID was superior. Several peptides were analysed using SID in conjunction with liquid secondary-ion mass spectrometry or electrospray; a comparison of the fragmentation of singly protonated peptide ions and the further dissociation of y-type fragments was consistent with the equivalence of the latter fragments to protonated peptides. Few product ions attributable to high-energy cleavages of amino acid side-chains were observed. The SID properties were investigated of a series of peptides differing only in the derivatization of a cysteine residue; similar decomposition efficiencies were observed for all except the cysteic acid analogue, which demonstrated significantly more facile fragmentation. Copyright 2001 John Wiley & Sons, Ltd.

  19. ISOLTRAP: a tandem Penning trap system for accurate on-line mass determination of short-lived isotopes

    Science.gov (United States)

    Bollen, G.; Becker, S.; Kluge, H.-J.; König, M.; Moore, R. B.; Otto, T.; Raimbault-Hartmann, H.; Savard, G.; Schweikhard, L.; Stolzenberg, H.; Isolde Collaboration

    1996-02-01

    The tandem Penning trap mass spectrometer ISOLTRAP has been set up at the on-line mass separator ISOLDE at CERN/Geneva for accurate mass measurements of short-lived nuclei with T {1}/{2} ≥ 1 s. The mass measurement is performed via the determination of the cyclotron frequency of an ion in a magnetic field. The design of the spectrometer matches the particular requirements for on-line mass measurements on short-lived isotopes. With the ISOLTRAP spectrometer masses of more than 70 radioactive nuclei have so far been determined with resolving powers exceeding one million and an accuracy of typically 10 -7.

  20. ISOLTRAP: a tandem Penning trap system for accurate on-line mass determination of short-lived isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Bollen, G. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Becker, S. [Mainz Univ. (Germany). Inst. fuer Physik; Kluge, H.J. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Koenig, M. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Moore, R.B. [McGill Univ., Montreal, PQ (Canada). Foster Radiation Lab.; Otto, T. [Mainz Univ. (Germany). Inst. fuer Physik; Raimbault-Hartmann, H. [Mainz Univ. (Germany). Inst. fuer Physik; Savard, G. [Mainz Univ. (Germany). Inst. fuer Physik; Schweikhard, L. [Mainz Univ. (Germany). Inst. fuer Physik; Stolzenberg, H. [Mainz Univ. (Germany). Inst. fuer Physik; ISOLDE Collaboration

    1996-01-11

    The tandem Penning trap mass spectrometer ISOLTRAP has been set up at the on-line mass separator ISOLDE at CERN/Geneva for accurate mass measurements of short-lived nuclei with T{sub 1/2} {>=}1 s. The mass measurement is performed via the determination of the cyclotron frequency of an ion in a magnetic field. The design of the spectrometer matches the particular requirements for on-line mass measurements on short-lived isotopes. With the ISOLTRAP spectrometer masses of more than 70 radioactive nuclei have so far been determined with resolving powers exceeding one million and an accuracy of typically 10{sup -7}. (orig.).

  1. Determination of prostaglandin analogs in cosmetic products by high performance liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Wittenberg, James B; Zhou, Wanlong; Wang, Perry G; Krynitsky, Alexander J

    2014-09-12

    A method was developed and validated for the determination of 16 prostaglandin analogs in cosmetic products. The QuEChERS (Quick, Easy, Cheap, Efficient, Rugged, Safe) liquid-liquid extraction method, typically used for pesticide residue analysis, was utilized as the sample preparation technique. The prostaglandin analogs were chromatographically separated and quantified using high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). Thirty-one cosmetic products were surveyed, and 13 products were determined to contain a prostaglandin analog with amounts ranging from 27.4 to 297μg/g. The calculated concentrations for the cosmetic products were in a similar range when compared to the concentrations of three different prostaglandin analog-containing prescription products. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Discovery of neuropeptides in the nematode Ascaris suum by database mining and tandem mass spectrometry.

    Science.gov (United States)

    Jarecki, Jessica L; Frey, Brian L; Smith, Lloyd M; Stretton, Antony O

    2011-07-01

    Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was used to discover peptides in extracts of the large parasitic nematode Ascaris suum. This required the assembly of a new database of known and predicted peptides. In addition to those already sequenced, peptides were either previously predicted to be processed from precursor proteins identified in an A. suum library of expressed sequence tags (ESTs) or newly predicted from a library of A. suum genome survey sequences (GSSs). The predicted MS/MS fragmentation patterns of this collection of real and putative peptides were compared with the actual fragmentation patterns found in the MS/MS spectra of peptides fractionated by MS; this enabled individual peptides to be sequenced. Many previously identified peptides were found, and 21 novel peptides were discovered. Thus, this approach is very useful, despite the fact that the available GSS database is still preliminary, having only 1× coverage.

  3. Tandem Mass Spectrometry Detection of Quorum Sensing Activity in Multidrug Resistant Clinical Isolate Acinetobacter baumannii

    Directory of Open Access Journals (Sweden)

    Kok-Gan Chan

    2014-01-01

    Full Text Available Many Proteobacteria communicate via production followed by response of quorum sensing molecules, namely, N-acyl homoserine lactones (AHLs. These molecules consist of a lactone moiety with N-acyl side chain with various chain lengths and degrees of saturation at C-3 position. AHL-dependent QS is often associated with regulation of diverse bacterial phenotypes including the expression of virulence factors. With the use of biosensor and high resolution liquid chromatography tandem mass spectrometry, the AHL production of clinical isolate A. baumannii 4KT was studied. Production of short chain AHL, namely, N-hexanoyl-homoserine lactone (C6-HSL and N-octanoyl-homoserine lactone (C8-HSL, was detected.

  4. A dedicated AMS setup for medium mass isotopes at the Cologne FN tandem accelerator

    Science.gov (United States)

    Schiffer, M.; Altenkirch, R.; Feuerstein, C.; Müller-Gatermann, C.; Hackenberg, G.; Herb, S.; Bhandari, P.; Heinze, S.; Stolz, A.; Dewald, A.

    2017-09-01

    AMS measurements of medium mass isotopes, e.g. of 53Mn and 60Fe, are gaining interest in various fields of operation, especially geoscience. Therefore a dedicated AMS setup has been built at the Cologne 10 MV FN tandem accelerator. This setup is designed to obtain a sufficient suppression of the stable isobars at energies around 100 MeV. In this contribution we report on the actual status of the new setup and the first in-beam tests of its individual components. The isobar suppression is done with (dE/dx) techniques using combinations of energy degrader foils with an electrostatic analyzer (ESA) and a time of flight (ToF) system, as well as a (dE/dx),E gas ionization detector. Furthermore, the upgraded ion source and its negative ion yield measurement for MnO- are presented.

  5. Analysis of bromate in drinking water using liquid chromatography-tandem mass spectrometry without sample pretreatment.

    Science.gov (United States)

    Kosaka, Koji; Asami, Mari; Takei, Kanako; Akiba, Michihiro

    2011-01-01

    An analytical method for determining bromate in drinking water was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The (18)O-enriched bromate was used as an internal standard. The limit of quantification (LOQ) of bromate was 0.2 µg/L. The peak of bromate was separated from those of coexisting ions (i.e., chloride, nitrate and sulfate). The relative and absolute recoveries of bromate in two drinking water samples and in a synthesized ion solution (100 mg/L chloride, 10 mg N/L nitrate, and 100 mg/L sulfate) were 99-105 and 94-105%, respectively. Bromate concentrations in 11 drinking water samples determined by LC-MS/MS were water without sample pretreatment.

  6. Determination of Metabolic Viability and Cell Mass Using a Tandem Resazurin/Sulforhodamine B Assay.

    Science.gov (United States)

    Silva, Filomena S G; Starostina, Irina G; Ivanova, Vilena V; Rizvanov, Albert A; Oliveira, Paulo J; Pereira, Susana P

    2016-05-04

    The identification of rapid, reliable, and highly reproducible biological assays that can be standardized and routinely used in preclinical tests constitutes a promising approach to reducing drug discovery costs and time. This unit details a tandem, rapid, and reliable cell viability method for preliminary screening of chemical compounds. This assay measures metabolic activity and cell mass in the same cell sample using a dual resazurin/sulforhodamine B assay, eliminating the variation associated with cell seeding and excessive manipulations in assays that test different cell samples across plates. The procedure also reduces the amount of cells, test compound, and reagents required, as well as the time expended in conventional tests, thus resulting in a more confident prediction of toxic thresholds for the tested compounds. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

  7. Glucose and glycerol concentrations and their tracer enrichment measurements using liquid chromatography tandem mass spectrometry

    DEFF Research Database (Denmark)

    Bornø, Andreas; Foged, Lene; van Hall, Gerrit

    2014-01-01

    in connection to in vivo metabolic studies investigating glucose turnover and lipolytic rate. Moreover, in order to keep up with this new fast analysis, simple derivatization procedures have been developed. Prior to analysis, glucose and glycerol were derivatized using benzoyl chloride in order to form......The present study describes a new liquid chromatography tandem mass spectrometry method for high-throughput quantification of glucose and glycerol in human plasma using stable isotopically labeled internal standards and is suitable for simultaneous measurements of glucose and glycerol enrichments...... benzoylated derivatives via new simplified fast procedures. For glucose, two internal standards were evaluated, [U-(13) C(6)]glucose and [U-(13) C(6), D(7)]glucose, and for glycerol, [U-(13) C(3), D(8)]glycerol was used. The method was validated by means of calibration curves, quality control samples...

  8. Rapid confirmatory analysis of avermectin residues in milk by liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Nurullah Ozdemir

    2016-01-01

    Full Text Available Our study developed a quick method for confirmatory analysis of avermectins (abamectin B1a, doramectin, ivermectin B1a, eprinomectin B1a, and moxidectin in bovine milk according to the European Commission Decision 2002/657/EC requirements. Avermectins were liquid–liquid extracted with acetonitrile, followed by an evaporation step, and then analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry in the negative ion mode. An in-house method validation was performed and the data reported on specificity, linearity, recovery, limit of detection, limit of quantitation, decision limit, and detection capability. The advantage of this method is that low levels of avermectins are detectable and quantitatively confirmed at a rapid rate in milk.

  9. Determination of dapsone in meat and milk by liquid chromatography tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hadjigeorgiou, M. [State General Laboratory of Cyprus, Veterinary Drug Residues Lab, Kimonos 44, 1451 Nicosia (Cyprus)], E-mail: mhadjigeorgiou@sgl.moh.gov.cy; Papachrysostomou, Ch.; Theodorou, Z.; Kanari, P.; Constantinou, S. [State General Laboratory of Cyprus, Veterinary Drug Residues Lab, Kimonos 44, 1451 Nicosia (Cyprus)

    2009-04-01

    Within the EU the use of dapsone (4,4-diaminodiphenylsulfone) is prohibited in food-producing animals and consequently it's included in the Annex IV of the Directive 90/2377/EC. A quantitative confirmatory method has been developed and validated according to the criteria defined in the Commission Decision 2002/657/EC, for the determination of dapsone in meat and milk. Samples, after homogenization in alkaline conditions and organic solvent extraction, were purified on silica gel solid phase extraction cartridges. The eluate was evaporated and redissolved in mobile phase and was analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS) in positive electrospray ionisation (ESI) using deuterium labelled Sulphadimidine-d7 as internal standard. The calculated value for, decision limit, CC{alpha} is 0.12 {mu}g kg{sup -1}, and the detection capability; CC{beta} value is 0.16 {mu}g kg{sup -1}.

  10. [Determination of pesticides in Chinese dumplings using liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Okamoto, You; Takatori, Satoshi; Kitagawa, Yoko; Okihashi, Masahiro; Fukui, Naoki; Murata, Hiroshi; Sumimoto, Tatsuo; Tanaka, Yukio; Obana, Hirotaka

    2009-02-01

    A rapid and easy multiresidue method for determination of pesticide residues in Chinese dumplings using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Pesticide residues were extracted with ethyl acetate in the presence of anhydrous magnesium sulfate in a disposable tube using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids. The acetonitrile layer was purified with a double-layered cartridge column (graphite carbon black/primary secondary amine silica gel). After removal of the solvent, the extract was resolved in methanol/water and analyzed with LC-MS/MS. Recovery tests of 99 pesticide residues from Chinese dumpling were performed at 20 and 100 ng/g, and 72 pesticides exhibited acceptable recoveries (70-120%) with low relative standard deviations (pesticide residues in the Chinese dumplings.

  11. Fast methods for screening of trichothecenes in fungal cultures using gas chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, Kristian Fog; Thrane, Ulf

    2001-01-01

    The paper presents a fast method for trichothecene profiling and chemotaxonomic studies in species of Fusarium, Stachybotrys, Trichoderma and Memnoniella. Micro scale extracted crude Fusarium extracts were derivatised using pentafluoropropionic anhydride and analysed by gas chromatography...... with simultaneous full scan and tandem mass spectrometric detection. It was possible to monitor for up to four compounds simultaneous, making detection of acetyl T-2 toxin, T-2 toxin, HT-2 toxin, T-2 triol, T-2 tetraol, neosolaniol, iso-neosolaniol, scirpentriol, 4,15- diacetoxyscirpenol, 15-acetoxyscirpenol, 4......-acetoxyscirpentriol, nivalenol, fusarenon-X, deoxynivalenol, 15-acetyl- deoxynivalenol and 3-acetyl-deoxynivalenol possible during a 23-min GC run. A slightly modified method could detect trichothecenes produced by Stachybotrys, Memnoniella and Trichoderma, by hydrolysing crude extracts prior to derivatisation...

  12. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

    Directory of Open Access Journals (Sweden)

    Maximiliano Martínez-Cifuentes

    2016-07-01

    Full Text Available A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS, using Collision-Induced Dissociation (CID to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP, local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA and gas phase basicity (GB, were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD. The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules.

  13. Identification of microorganisms grown in blood culture flasks using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Berendsen, Erwin M; Levin, Evgeni; Braakman, René; der Riet-van Oeveren, Debora van; Sedee, Norbert Ja; Paauw, Armand

    2017-10-01

    Bloodstream infections are a common cause of disease and a fast and accurate identification of the causative agent or agents of bloodstream infections would aid the start of adequate treatment. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) shotgun proteomics method was developed for the identification of bacterial species directly from blood cultures that were simulated by inoculating blood culture bottles with single or multiple clinically relevant microorganisms. Using LC-MS/MS, the single species were correctly identified in 100% of the blood cultures, whereas for polymicrobial infections, 78% of both species were correctly identified in blood cultures. The LC-MS/MS method allows for the identification of the causative agent of positive blood cultures.

  14. Tandem Mass Spectrometry for Structural Identification of Sesquiterpene Alkaloids from the Stems of Dendrobium nobile Using LC-QToF.

    Science.gov (United States)

    Wang, Yan-Hong; Avula, Bharathi; Abe, Naohito; Wei, Feng; Wang, Mei; Ma, Shuang-Cheng; Ali, Zulfiqar; Elsohly, Mahmoud A; Khan, Ikhlas A

    2016-05-01

    Dendrobium nobile is one of the fundamental herbs in traditional Chinese medicine. Sesquiterpene alkaloids are the main active components in this plant. Due to weak ultraviolet absorption and low content in D. nobile, these sesquiterpene alkaloids have not been extensively studied using chromatographic methods. Herein, tandem mass spectrometry combined with liquid chromatography separation provides a tool for the identification and characterization of the alkaloids from D. nobile. A total of nine sesquiterpene alkaloids were characterized by ultrahigh-performance liquid chromatography tandem mass spectrometry. These alkaloids can be classified into two subgroups that are represented by dendrobine and nobilonine. Tandem mass spectrometric studies revealed the fragmentation pathways of these two subgroup alkaloids that were used for the identification and characterization of other alkaloids in D. nobile. Characterization of these alkaloids using accurate mass and diagnostic fragments provided a reliable methodology for the analysis of D. nobile by ultrahigh-performance liquid chromatography tandem mass spectrometry. The limit of detection was defined as the signal-to-noise ratio equal to 3 : 1. Limits of detection of dendrobine and nobilonine were less than 30 ng/mL. The developed method was applied for the analysis of various Dendrobium species and related dietary supplements. Alkaloids were identified from D. nobile, but not detected from commercial samples including 13 other Dendrobium species and the 7 dietary supplements. Georg Thieme Verlag KG Stuttgart · New York.

  15. Quantitative profiling of endogenous retinoic acid in vivo and in vitro by tandem mass spectrometry.

    Science.gov (United States)

    Kane, Maureen A; Folias, Alexandra E; Wang, Chao; Napoli, Joseph L

    2008-03-01

    We report an improved tandem mass spectrometric assay for retinoic acid (RA) applicable to in vitro and in vivo biological samples. This liquid chromatography tandem mass spectrometric (LC/MS/MS) assay for direct RA quantification is the most sensitive to date, with a 62.5 attomol lower limit of detection and a linear range spanning greater than 4 orders of magnitude (from 250 attomol to 10 pmol). This assay resolves all-trans-RA (atRA) from its endogenous geometric isomers, is applicable to samples of limited size (10-20 mg of tissue), and functions with complex biological matrixes. Coefficients of variation are as follows: instrumental, quantification of endogenous RA and RA production (from retinol) in primary cultured astrocytes. Quantification of endogenous atRA and its geometric isomers in 129SV mouse serum and tissues (liver, kidney, adipose, muscle, spleen, testis, and brain) reveals in vivo utility of the assay. The ability to discriminate spatial concentrations of RA in vivo is illustrated with C57BL/6 mouse brain loci (hippocampus, cortex, olfactory bulb, thalamus, cerebellum, and striatum), as well as with Lewis rat proximal/distal mammary gland regions during various morphological stages: virgin, early pregnancy (e7), late pregnancy (e20), lactating (day 4), involuting day 1, and involuting day 11. This assay provides the sensitivity necessary for direct, endogenous RA quantification necessary to elucidate RA function, e.g., in neurogenesis, morphogenesis, and the contribution of altered RA homeostasis to diseases, such as Alzheimer's disease, type 2 diabetes, obesity, and cancer.

  16. Determination of eptifibatide concentration in human plasma utilizing the liquid chromatography-tandem mass spectrometry method.

    Science.gov (United States)

    Liu, Jia; Duan, Xiaotao; Chen, Xiaoyan; Zhong, Dafang

    2009-02-15

    A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine the concentration of eptifibatide in human plasma. Following protein precipitation, the analyte was separated on a reversed-phase C(18) column. Acetonitrile:5mM ammonium acetate:acetic acid (30:70:0.1, v/v/v) was used at a flow-rate of 0.5mL/min with the isocratic mobile phase. An API 4000 tandem mass spectrometer equipped with a Turbo IonSpray ionization source was used as the detector and was operated in the positive ion mode. "Truncated" multiple reaction monitoring using the transition of m/z 832.6-->m/z 832.6 and m/z 931.3-->m/z 931.3 was performed to quantify eptifibatide and the internal standard (EPM-05), respectively. The method had a lower limit of quantification of 4.61ng/mL for eptifibatide. The calibration curve was demonstrated to be linear over the concentration range of 4.61-2770ng/mL. The intra- and inter-day precisions were less than 10.5% for each QC level, and the inter-day relative errors were 2.0%, 5.6%, and 2.8% for 9.22, 184, and 2490ng/mL, respectively. The validated method was successfully applied to the quantification of eptifibatide concentration in human plasma after intravenous (i.v.) administration of a 270-microg/kg bolus of eptifibatide and i.v. administration of eptifibatide at a constant rate of infusion of 2microg/(kgmin) for 18h in order to evaluate the pharmacokinetics.

  17. Rapid quantification of ionophores in feeds by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Huang, Min; Rumbeiha, Wilson K; Braselton, W Emmett; Johnson, Margaret

    2011-09-01

    Ionophores are widely used in veterinary medicine as coccidiostats and for improving nutrient utilization in livestock production. Because of widespread use, ionophores sometimes cause poisoning in livestock. Quantifying concentration of these compounds in feeds for diagnostic purposes is needed. A method with a single step of solvent extraction was developed for rapid simultaneous quantification of monensin, lasalocid, salinomycin, and narasin in feeds by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The ionophores were extracted using methanol:water (90:10). With the high specificity and high sensitivity of tandem mass spectrometry, the extract was introduced for measurement without further processing. The effect of particle size of feeds on extraction efficiency was also investigated. It was found that feeds passing through a 1-mm filter or sieve show better quantitative extraction. Nigericin was used as internal standard for the measurement. The method was validated by fortification of the selected ionophore compounds in horse feed at different concentrations. The typical recovery rate was 69-122%. Meanwhile, various interlaboratory proficiency test samples of different matrices were also quantified as part of the procedure for method validation. A good agreement was found between results and the suggested values. The method is very sensitive, with detection limits between 0.018 µg/g and 0.056 µg/g for the compounds tested. Results showed that the lower limit of quantification was 0.2 µg/g for the ionophore compounds, which is much lower than the contents of the ionophores in medicated feeds, which is generally approximately 10-100 µg/g feed.

  18. Exploiting the multiplexing capabilities of tandem mass tags for high-throughput estimation of cellular protein abundances by mass spectrometry.

    Science.gov (United States)

    Ahrné, Erik; Martinez-Segura, Amalia; Syed, Afzal Pasha; Vina-Vilaseca, Arnau; Gruber, Andreas J; Marguerat, Samuel; Schmidt, Alexander

    2015-09-01

    The generation of dynamic models of biological processes critically depends on the determination of precise cellular concentrations of biomolecules. Measurements of system-wide absolute protein levels are particularly valuable information in systems biology. Recently, mass spectrometry based proteomics approaches have been developed to estimate protein concentrations on a proteome-wide scale. However, for very complex proteomes, fractionation steps are required, increasing samples number and instrument analysis time. As a result, the number of full proteomes that can be routinely analyzed is limited. Here we combined absolute quantification strategies with the multiplexing capabilities of isobaric tandem mass tags to determine cellular protein abundances in a high throughput and proteome-wide scale even for highly complex biological systems, such as a whole human cell line. We generated two independent data sets to demonstrate the power of the approach regarding sample throughput, dynamic range, quantitative precision and accuracy as well as proteome coverage in comparison to existing mass spectrometry based strategies. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Fast screening of lovastatin in red yeast rice products by flow injection tandem mass spectrometry.

    Science.gov (United States)

    Song, Fenhong; El-Demerdash, Aref; Lee, Shwn-Ji Susie H; Smith, Robert E

    2012-01-05

    Drug adulteration in dietary supplement materials is a world-wide problem and poses a regulatory challenge. Red yeast rice is a product used by consumers to lower blood levels of cholesterol. While most current methods to analyze red yeast rice are based on HPLC separation with a photo-diode array detector and/or a mass spectrometry detector, which takes 20-40min analysis time per sample, we developed a method to do fast screening of the active compound lovastatin by direct infusion into a mass spectrometer. This method takes under 1min per analysis on the instrument. By using multiple reaction monitoring with five product ions, all the ion ratios of the analyte in the samples are compared with those from the standards for qualitative analysis. The results from this method were compared to the result from the liquid chromatography tandem mass spectrometry, which uses retention time and one ion ratio as the confirmation criteria. No false positives or false negatives were found among the 12 samples tested. The method also seems to be effective in measuring the lovastatin in red yeast rice semi-quantitatively. This kind of method could be adapted to the screening of other dietary supplement products. Published by Elsevier B.V.

  20. Quantitative bioanalysis of peptides by liquid chromatography coupled to (tandem) mass spectrometry.

    Science.gov (United States)

    van den Broek, Irene; Sparidans, Rolf W; Schellens, Jan H M; Beijnen, Jos H

    2008-09-01

    With the growing interest for peptides and proteins in different kinds of fields, e.g. pharmacy, clinical diagnostics or food industry, the quantification of these compounds is becoming more and more important. Quantitative analysis of these analytes in biological matrices, however, remains a challenging task, due to the complexity of both the matrix and the analytical characteristics of these large bio-molecules. Liquid chromatography coupled to (tandem) mass spectrometry (LC-MS or LC-MS/MS) is the preferred analytical technique for peptide analysis as it allows very selective and sensitive measurements. This article summarizes the numerous published LC-MS applications for the quantification of peptides in biological matrices and discusses all different issues herewith concerned. This includes chromatographic aspects as the selection and effects of mobile and stationary phase, flow rate and temperature, as well as mass spectrometric characteristics such as ionization and detection modes, collision-induced dissociation of peptides and factors influencing the mass spectrometric response. For both techniques the main properties of all described methods have been listed, creating a comprehensive overview with the peptide analytes divided into different classes. Likewise, all other issues concerned with quantitative bioanalysis have been evaluated in detail, including extensive consideration of several different applied sample pre-treatment techniques and reflection of subjects as the choice for an internal standard and assay validation. Furthermore, several issues which are of particular interest for the quantitative bioanalysis of peptide compounds like peptide adsorption and degradation have been regarded.

  1. Peptides derivatized with bicyclic quaternary ammonium ionization tags. Sequencing via tandem mass spectrometry.

    Science.gov (United States)

    Setner, Bartosz; Rudowska, Magdalena; Klem, Ewelina; Cebrat, Marek; Szewczuk, Zbigniew

    2014-10-01

    Improving the sensitivity of detection and fragmentation of peptides to provide reliable sequencing of peptides is an important goal of mass spectrometric analysis. Peptides derivatized by bicyclic quaternary ammonium ionization tags: 1-azabicyclo[2.2.2]octane (ABCO) or 1,4-diazabicyclo[2.2.2]octane (DABCO), are characterized by an increased detection sensitivity in electrospray ionization mass spectrometry (ESI-MS) and longer retention times on the reverse-phase (RP) chromatography columns. The improvement of the detection limit was observed even for peptides dissolved in 10 mM NaCl. Collision-induced dissociation tandem mass spectrometry of quaternary ammonium salts derivatives of peptides showed dominant a- and b-type ions, allowing facile sequencing of peptides. The bicyclic ionization tags are stable in collision-induced dissociation experiments, and the resulted fragmentation pattern is not significantly influenced by either acidic or basic amino acid residues in the peptide sequence. Obtained results indicate the general usefulness of the bicyclic quaternary ammonium ionization tags for ESI-MS/MS sequencing of peptides. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dron, J.; El Haddad, I.; Temime-Roussel, B.; Wortham, H.; Marchand, N. [Univ Aix Marseille, CNRS, Lab Chim Provence, Equipe Instrumentat and React Atmospher, UMR 6264, F-13331 Marseille 3 (France); Jaffrezo, J.L. [Univ Grenoble 1, CNRS, UMR 5183, Lab Glaciol and Geophys Environm, F-38402 St Martin Dheres (France)

    2010-07-01

    The functional group composition of various organic aerosols (OA) is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCIMS/MS). The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-R' respectively) and precursor ion (nitro groups, R-NO{sub 2}) scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA) produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular) to 13.5% (o-xylene photooxidation) of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France) during a strong winter pollution event. The three functional groups under study account for a total functionalization rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60%. Finally, examples of functional

  3. Functional group composition of ambient and source organic aerosols determined by tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    J. Dron

    2010-08-01

    Full Text Available The functional group composition of various organic aerosols (OA is investigated using a recently developed analytical approach based on atmospheric pressure chemical ionisation-tandem mass spectrometry (APCI-MS/MS. The determinations of three functional groups contents are performed quantitatively by neutral loss (carboxylic and carbonyl groups, R-COOH and R-CO-R´ respectively and precursor ion (nitro groups, R-NO2 scanning modes of a tandem mass spectrometer. Major organic aerosol sources are studied: vehicular emission and wood combustion for primary aerosol sources; and a secondary organic aerosol (SOA produced through photooxidation of o-xylene. The results reveal significant differences in the functional group contents of these source aerosols. The laboratory generated SOA is dominated by carbonyls while carboxylics are preponderate in the wood combustion particles. On the other hand, vehicular emissions are characterised by a strong nitro content. The total amount of the three functional groups accounts for 1.7% (vehicular to 13.5% (o-xylene photooxidation of the organic carbon. Diagnostic functional group ratios are then used to tentatively discriminate sources of particles collected in an urban background environment located in an Alpine valley (Chamonix, France during a strong winter pollution event. The three functional groups under study account for a total functionalisation rate of 2.2 to 3.8% of the organic carbon in this ambient aerosol, which is also dominated by carboxylic moieties. In this particular case study of a deep alpine valley during winter, we show that the nitro- and carbonyl-to-carboxylic diagnostic ratios can be a useful tool to discriminate sources. In these conditions, the total OA concentrations are highly dominated by wood combustion OA. This result is confirmed by an organic markers source apportionment approach which assess a wood burning organic carbon contribution of about 60

  4. Potential of short-column liquid chromatographia with tandem mass spectrometric detection for the rapid study of pesticide degradation

    NARCIS (Netherlands)

    Hogenboom, A.C.; Steen, R.J.C.A.; Niessen, W.M.A.; Brinkman, U.A.T.

    1998-01-01

    The applicability of solid-phase extraction-LC using two short columns (SPE-LC) and/or single-short-column liquid chromatography (SSC) combined on- line with tandem mass spectrometry (MS) was demonstrated for the rapid study of pesticide degradation. A fast analytical procedure was developed to

  5. Single short-column liquid chromatography with atmospheric pressure chemical ionization - (tandem) mass spectrometric detection for trace environmental analysis.

    NARCIS (Netherlands)

    Hogenboom, A.C.; Vreuls, J.J.; Rontree, J.A.; van Baar, B.L.M.; Niessen, W.M.A.; Brinkman, U.A.T.; Slobodník, J.

    1996-01-01

    Single short, i.e. ca 2-cm long, high-pressure-packed columns coupled with mass spectrometric (MS) or tandem MS detection enable rapid trace-level determination and identification of environmental pollutants in water samples. In this study an atmospheric pressure chemical ionization (APCI) interface

  6. Clinical validation of cutoff target ranges in newborn screening of metabolic disorders by tandem mass spectrometry : A worldwide collaborative project

    NARCIS (Netherlands)

    McHugh, David M. S.; Cameron, Cynthia A.; Abdenur, Jose E.; Abdulrahman, Mahera; Adair, Ona; Al Nuaimi, Shahira Ahmed; Ahlman, Henrik; Allen, Jennifer J.; Antonozzi, Italo; Archer, Shaina; Au, Sylvia; Auray-Blais, Christiane; Baker, Mei; Bamforth, Fiona; Beckmann, Kinga; Pino, Gessi Bentz; Berberich, Stanton L.; Binard, Robert; Boemer, Francois; Bonham, Jim; Breen, Nancy N.; Bryant, Sandra C.; Caggana, Michele; Caldwell, S. Graham; Camilot, Marta; Campbell, Carlene; Carducci, Claudia; Cariappa, Rohit; Carlisle, Clover; Caruso, Ubaldo; Cassanello, Michela; Miren Castilla, Ane; Castineiras Ramos, Daisy E.; Chakraborty, Pranesh; Chandrasekar, Ram; Ramos, Alfredo Chardon; Cheillan, David; Chien, Yin-Hsiu; Childs, Thomas A.; Chrastina, Petr; Sica, Yuri Cleverthon; Cocho de Juan, Jose Angel; Elena Colandre, Maria; Cornejo Espinoza, Veronica; Corso, Gaetano; Currier, Robert; Cyr, Denis; Czuczy, Noemi; D'Apolito, Oceania; Davis, Tim; de Sain-Van der Velden, Monique G.; Delgado Pecellin, Carmen; Di Gangi, Iole Maria; Di Stefano, Cristina Maria; Dotsikas, Yannis; Downing, Melanie; Downs, Stephen M.; Dy, Bonifacio; Dymerski, Mark; Rueda, Inmaculada; Elvers, Bert; Eaton, Roger; Eckerd, Barbara M.; El Mougy, Fatma; Eroh, Sarah; Espada, Mercedes; Evans, Catherine; Fawbush, Sandy; Fijolek, Kristel F.; Fisher, Lawrence; Franzson, Leifur; Frazier, Dianne M.; Garcia, Luciana R. C.; Garcia-Valdecasas Bermejo, Maria Sierra; Gavrilov, Dimitar; Gerace, Rosemarie; Giordano, Giuseppe; Irazabal, Yolanda Gonzalez; Greed, Lawrence C.; Grier, Robert; Grycki, Elyse; Gu, Xuefan; Gulamali-Majid, Fizza; Hagar, Arthur F.; Han, Lianshu; Hannon, W. Harry; Haslip, Christa; Hassan, Fayza Abdelhamid; He, Miao; Hietala, Amy; Himstedt, Leslie; Hoffman, Gary L.; Hoffman, William; Hoggatt, Philis; Hopkins, Patrick V.; Hougaard, David M.; Hughes, Kerie; Hunt, Patricia R.; Hwu, Wuh-Liang; Hynes, June; Ibarra-Gonzalez, Isabel; Ingham, Cindy A.; Ivanova, Maria; Jacox, Ward B.; John, Catharine; Johnson, John P.; Jonsson, Jon J.; Karg, Eszter; Kasper, David; Klopper, Brenda; Katakouzinos, Dimitris; Khneisser, Issam; Knoll, Detlef; Kobayashi, Hirinori; Koneski, Ronald; Kozich, Viktor; Kouapei, Rasoul; Kohlmueller, Dirk; Kremensky, Ivo; la Marca, Giancarlo; Lavochkin, Marcia; Lee, Soo-Youn; Lehotay, Denis C.; Lemes, Aida; Lepage, Joyce; Lesko, Barbara; Lewis, Barry; Lim, Carol; Linard, Sharon; Lindner, Martin; Lloyd-Puryear, Michele A.; Lorey, Fred; Loukas, Yannis L.; Luedtke, Julie; Maffitt, Neil; Magee, J. Fergall; Manning, Adrienne; Manos, Shawn; Marie, Sandrine; Hadachi, Sonia Marchezi; Marquardt, Gregg; Martin, Stephen J.; Matern, Dietrich; Gibson, Stephanie K. Mayfield; Mayne, Philip; McCallister, Tonya D.; McCann, Mark; McClure, Julie; McGill, James J.; McKeever, Christine D.; McNeilly, Barbara; Morrissey, Mark A.; Moutsatsou, Paraskevi; Mulcahy, Eleanor A.; Nikoloudis, Dimitris; Norgaard-Pedersen, Bent; Oglesbee, Devin; Oltarzewski, Mariusz; Ombrone, Daniela; Ojodu, Jelili; Papakonstantinou, Vagelis; Reoyo, Sherly Pardo; Park, Hyung-Doo; Pasquali, Marzia; Pasquini, Elisabetta; Patel, Pallavi; Pass, Kenneth A.; Peterson, Colleen; Pettersen, Rolf D.; Pitt, James J.; Poh, Sherry; Pollak, Arnold; Porter, Cory; Poston, Philip A.; Price, Ricky W.; Queijo, Cecilia; Quesada, Jonessy; Randell, Edward; Ranieri, Enzo; Raymond, Kimiyo; Reddic, John E.; Reuben, Alejandra; Ricciardi, Charla; Rinaldo, Piero; Rivera, Jeff D.; Roberts, Alicia; Rocha, Hugo; Roche, Geraldine; Greenberg, Cheryl Rochman; Egea Mellado, Jose Maria; Jess Juan-Fita, Maria; Ruiz, Consuelo; Ruoppolo, Margherita; Rutledge, S. Lane; Ryu, Euijung; Saban, Christine; Sahai, Inderneel; Salazar Garcia-Blanco, Maria Isabel; Santiago-Borrero, Pedro; Schenone, Andrea; Schoos, Roland; Schweitzer, Barb; Scott, Patricia; Seashore, Margretta R.; Seeterlin, Mary A.; Sesser, David E.; Sevier, Darrin W.; Shone, Scott M.; Sinclair, Graham; Skrinska, Victor A.; Stanley, Eleanor L.; Strovel, Erin T.; Jones, April L. Studinski; Sunny, Sherlykutty; Takats, Zoltan; Tanyalcin, Tijen; Teofoli, Francesca; Thompson, J. Robert; Tomashitis, Kathy; Domingos, Mouseline Torquado; Torres, Jasmin; Torres, Rosario; Tortorelli, Silvia; Turi, Sandor; Turner, Kimberley; Tzanakos, Nick; Valiente, Alf G.; Vallance, Hillary; Vela-Amieva, Marcela; Vilarinho, Laura; von Doebeln, Ulrika; Vincent, Marie-Francoise; Vorster, B. Chris; Watson, Michael S.; Webster, Dianne; Weiss, Sheila; Wilcken, Bridget; Wiley, Veronica; Williams, Sharon K.; Willis, Sharon A.; Woontner, Michael; Wright, Katherine; Yahyaoui, Raquel; Yamaguchi, Seiji; Yssel, Melissa; Zakowicz, Wendy M.

    Purpose: To achieve clinical validation of cutoff values for newborn screening by tandem mass spectrometry through a worldwide collaborative effort. Methods: Cumulative percentiles of amino acids and acylcarnitines in dried blood spots of approximately 25-30 million normal newborns and 10,742

  7. Identification of the C3H7 moiety of isopropyl- and propylphosphonates by electrospray tandem mass spectrometry

    NARCIS (Netherlands)

    Baar, B.L.M. van; Hulst, A.G.; Wils, E.R.J.

    1998-01-01

    Structure analysis of phosphorus compounds within the framework of the Chemical Weapons Convention requires the specific identification of alkyl substituents on phosphorus. In this work the distinction of the P-propyl substituent in propylphosphonic acid derivatives by electrospray tandem mass

  8. Infrared spectrum of potassium-cationized triethylphosphate generated using tandem mass spectrometry and infrared multiple photon dissociation

    NARCIS (Netherlands)

    Groenewold, G. S.; Leavitt, C. M.; Dain, R. P.; Oomens, J.; Steill, J. D.; van Stipdonk, M. J.

    2009-01-01

    Tandem mass spectrometry and wavelength-selective infrared photodissociation were used to generate an infrared spectrum of gas-phase triethylphosphate cationized by attachment of K+. Prominent absorptions were observed in the region of 900 to 1300 cm(-1) that are characteristic of phosphate P=O and

  9. Structure of [M + H − H2O]+ from Protonated Tetraglycine Revealed by Tandem Mass Spectrometry and IRMPD Spectroscopy

    NARCIS (Netherlands)

    Bythell, B. J.; Dain, Ryan P.; Curtice, Stephanie S.; Oomens, Jos; Steill, Jeffrey D.; Groenewold, Gary S.; la Paizs, Bé; van Stipdonk, M. J.

    2010-01-01

    Multiple-stage tandem mass spectrometry and collision-induced dissociation were used to investigate loss of H2O or CH3OH from protonated versions of GGGX (where X = G, A, and V), GGGGG, and the methyl esters of these peptides. In addition, wavelength-selective infrared multiple photon dissociation

  10. Regioisomers of octanoic acid-containing structured triacylglycerols analyzed by tandem mass spectrometry using ammonia negative ion chemical ionization

    DEFF Research Database (Denmark)

    Kurvinen, J.P.; Mu, Huiling; Kallio, H.

    2001-01-01

    Tandem mass spectrometry based on ammonia negative ion chemical ionization and sample introduction via direct exposure probe was applied to analysis of regioisomeric structures of octanoic acid containing structured triacylglycerols (TAG) of type MML, MLM, MLL, and LML (M, medium-chain fatty acid...

  11. Electrospray ionization quadrupole time-of-flight tandem mass spectrometric analysis of hexamethylenediamine-modified maltodextrin and dextran

    NARCIS (Netherlands)

    Sisu, E.; Bosker, W.T.E.; Norde, W.; Slaghek, T.M.; Timmermans, J.W.; Peter-Katalinić, J.; Cohen-Stuart, M.A.; Zamfir, A.D.

    2006-01-01

    A combined methodology for obtaining at the preparative scale and characterization by nanoelectrospray ionization (nanoESI) quadrupole time-of-flight (QTOF) mass spectrometry (MS) and tandem MS (MS/MS) of linear polysaccharides modified at the reducing end is presented. Two polydisperse

  12. Structural Elucidation of DNA-Protein Crosslinks Using Reductive Desulfurization and Liquid Chromatography-Tandem Mass Spectrometry

    Science.gov (United States)

    Wickramaratne, Susith

    2014-01-01

    Structural characterization of DNA-protein crosslinks involving cysteine using reductive desulfurization in combination with liquid chromatography-tandem mass spectrometry is highlighted. The novel approach was used to identify hydrolytically stable DNA-protein lesions involving alkylguanine DNA alkyltransferase (AGT). PMID:24436288

  13. Liquid chromatography-tandem mass spectrometry assay for the quantification of free and total sialic acid in human cerebrospinal fluid.

    NARCIS (Netherlands)

    Ham, M. van der; Koning, T.J. de; Lefeber, D.J.; Fleer, A.; Prinsen, B.H.; Sain-van der Velden, M.G. de

    2010-01-01

    BACKGROUND: Analysis of sialic acid (SA) metabolites in cerebrospinal fluid (CSF) is important for clinical diagnosis. In the present study, a high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) method for free sialic acid (FSA) and total sialic acid (TSA) in human CSF was

  14. Liquid chromatography-tandem mass spectrometry assay for the quantification of free and total sialic acid in human cerebrospinal fluid

    NARCIS (Netherlands)

    van der Ham, Maria; de Koning, Tom J; Lefeber, Dirk; Fleer, André; Prinsen, Berthil H C M T; de Sain-van der Velden, Monique G M

    2010-01-01

    BACKGROUND: Analysis of sialic acid (SA) metabolites in cerebrospinal fluid (CSF) is important for clinical diagnosis. In the present study, a high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) method for free sialic acid (FSA) and total sialic acid (TSA) in human CSF was

  15. Simultaneous determination of estrogens and progestogens in honey using high performance liquid chromatography-tandem mass spectrometry

    Science.gov (United States)

    This work describes the development and validation of a method for the simultaneous determination of 13 estrogens and progestogens in honey by high performance liquid chromatography-tandem mass spectrometry. The target compounds were preconcentrated by solid phase extraction. Pretreatment variables ...

  16. Profiling ABA metabolites in Nicotiana tabacum L. leaves by ultra-performance liquid chromatography–electrospray tandem mass spectrometry

    Czech Academy of Sciences Publication Activity Database

    Turečková, Veronika; Novák, Ondřej; Strnad, Miroslav

    2009-01-01

    Roč. 80, č. 1 (2009), s. 390-399 ISSN 0039-9140 R&D Projects: GA AV ČR KAN200380801 Institutional research plan: CEZ:AV0Z50380511 Keywords : Abscisic acid * Ultra-performance liquid chromatography (UPLC) * Tandem mass spectrometry (MS/MS) Subject RIV: EC - Immunology Impact factor: 3.290, year: 2009

  17. Generic solid phase extraction-liquid chromatography-tandem mass spectrometry method for fast determination of drugs in biological fluids

    NARCIS (Netherlands)

    Schellen, A.; Ooms, B.; Lagemaat, D. van de; Vreeken, R.; Dongen, W.D. van

    2003-01-01

    A generic method was developed for the fast determination of a wide range of drugs in serum or plasma. The methodology comprises generic solid-phase extraction, on-line coupled to gradient HPLC with tandem mass spectrometric detection (SPE-LC-MS/MS). The individual components of the SPE-LC-MS/MS

  18. Determination of olanzapine in whole blood using simple protein precipitation and liquid chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, Marie Katrine Klose; Johansen, Sys Stybe

    2009-01-01

    A simple, sensitive, and reproducible liquid chromatography-tandem mass spectrometry method has been developed and validated for the quantification of the antipsychotic drug olanzapine in whole blood using dibenzepine as internal standard (IS). After acidic methanol-induced protein precipitation...

  19. Solid phase extraction for removal of matrix effects in lipophilic marine toxin analysis by liquid chromatography-tandem mass spectrometry

    NARCIS (Netherlands)

    Gerssen, A.; McElhinney, A. M.; Mulder, P.P.J.; Bire, L.; Hess, P.; de Boer, J.

    2009-01-01

    The potential of solid phase extraction (SPE) clean-up has been assessed to reduce matrix effects (signal suppression or enhancement) in the liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of lipophilic marine toxins. A large array of ion-exchange, silica-based, and mixed-function

  20. Solid phase extraction for removal of matrix effects in lipophilic marine toxin analysis by liquid chromatography-tandem mass spectrometry

    NARCIS (Netherlands)

    Gerssen, A.; McElhinney, M.; Mulder, P.P.J.; Bire, R.; Hess, P.; Boer, de J.

    2009-01-01

    The potential of solid phase extraction (SPE) clean-up has been assessed to reduce matrix effects (signal suppression or enhancement) in the liquid chromatography-tandem mass spectrometry (LC¿MS/MS) analysis of lipophilic marine toxins. A large array of ion-exchange, silica-based, and mixed-function

  1. Liquid chromatography coupled with tandem mass spectrometry for the quantitative analysis of anticancer drugs in biological matrices

    NARCIS (Netherlands)

    Stokvis, Ellen

    2004-01-01

    In this thesis, the development and validation of liquid chromatography tandem mass spectrometric (LC-MS/MS) methods for the quantitative bioanalysis of anticancer drugs are described. The monitoring of these drugs in biological fluids and tissues is important during both pre-clinical and clinical

  2. Value of tandem mass spectrometry in etiological diagnosis of cholestasis in infants

    Directory of Open Access Journals (Sweden)

    XU Lingfen

    2015-08-01

    Full Text Available Objective To investigate the value of tandem mass spectrometry (MS/MS in the etiological diagnosis of cholestasis in infants. Methods A total of 153 infants with cholestasis who visited the Department of Pediatrics, Shengjing Hospital, China Medical University, from January 2013 to March 2015 were studied. All of them underwent blood and urine examinations by MS/MS. The patients′ medical history and physical examination characteristics were recorded. Clinical examination results in biochemistry, etiology, and imageology were analyzed. Blood test and urine test were carried out by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS and gas chromatography-mass spectrometry (GC-MS, respectively. For the patients with abnormal blood or urine MS/MS results, potential pathogenic genes were determined. Comparison of continuous data was made by non-parametric Mann-Whitney U test and comparison of categorical data was made by chi-square test. Results Among the 153 infants with cholestasis, 19 (12.4% had abnormal blood or urine MS/MS results. According to clinical data and gene analysis, 15 infants among them were diagnosed with neonatal intrahepatic cholestasis caused by citrin deficiency, 2 infants with tyrosinemia, 1 infant with methioninemia, and another 1 infant with propionic acidemia. Compared with the normal MS/MS group of infants, the abnormal MS/MS group had significantly longer jaundice duration (Z=-2.227, P<0.05 and significantly higher levels of alkaline phosphatase, gamma-glutamyl transferase, and total bile acids (830.0 vs 523.0 U/L, Z=-3.185, P<0.05; 215.0 vs 160.0 U/L, Z=-2.130, P<0.05; 174.8 vs 125.7 μmol/L, Z=-2.351, P<0.05 Significant differences were also found in prothrombin time and activated partial thromboplastin time (Z=-4.300, P<0.001; Z=-3.526, P<0.001Cytomegalovirus was detected in 58.8% (90/153 of all patients and in 78.9% (15/19 of patients with abnormal MS/MS results Conclusions Given the

  3. Determination of high-energy fragmentation of protonated peptides using a beqq hybrid mass spectrometer.

    Science.gov (United States)

    Burlet, O; Orkiszewski, R S; Gaskell, S J

    1993-06-01

    A hybrid tandem instrument of BEqQ geometry was used to determine high-energy decomposition of protonated peptides, such as side-chain fragmentation yielding d n and w n ions. The transmission through both E and Q of such product ions, formed in the second field-free region, permits improved mass resolution and confident mass assignment. The experimental technique may involve synchronous scanning of E and Q, or, for the purpose of identification of specific products, limited-range scanning of either E or Q with the other analyzer fixed. These techniques are not equivalent, with respect to product ion transmission, to the double focusing of product ions achieved with four-sector instruments but nevertheless represent a critical improvement over conventional mass-analyzed ion kinetic energy spectrometry analyses. Fragmentation of protonated peptides occurring in the second field-free region inside and outside the collision cell were distinguished by floating the collision cell above ground potential. Mass filtering using Q confirmed the mass assignments. The data indicate that product ions resulting from spontaneous decomposition are in some instances quantitatively more significant than those resulting from high-energy collisional activation. Furthermore, the differentiation of the products of low- and high-energy processes should facilitate spectral interpretation.

  4. Quick elucidation of cyclodepsipeptide sequence from sacoglossan Elysia grandifolia using electrospray ionisation-tandem mass spectrometry.

    Science.gov (United States)

    Tilvi, Supriya; Devi, Prabha; Majik, Mahesh S

    2017-06-01

    Butanol fraction of sacoglossan Elysia grandifolia was investigated for identifying peptides using electrospray ionisation-tandem mass spectrometry (ESI-MS/MS). Without prior isolation, the structural determination is achieved on the basis of mass fragmentation pattern and comparison with the previously established data. The ESI-MS of the fraction in the positive ion mode gave clusters of singly and doubly charged molecular ion peaks. The ESI-MS spectrum showed peaks for the presence of the peptides kahalalides F, G, R and S reported earlier. In addition, it also showed molecular ion peaks at m/z 1557.8 [M+H]+ and doubly charged ions at m/z 779.4 [M+2H]2+, 790.4 [M+Na]2+ and 796.4 [M+K]2+. The MS/MS at m/z 779.4 [M+2H]+2 at collision energy 40 V obtained series of b and y fragment ions. The MS/MS spectrum showed identical fragment ion y6 at m/z 643 which revealed that cyclic part is identical with kahalalide F, R and S. Careful examination of the fragment ions b1 to b7 with their corresponding y fragment ions y12 to y6, respectively and by comparison of MS/MS pattern of kahalalide S, established that proline can be replaced by tyrosine amino acid residue. The mass difference between b4 ( m/z 511) and b5 ( m/z 674) is equal to 163 which is equivalent to mass residue of tyrosine. Their y fragment ions also quickly helped in fixing the puzzle. This resulted in the identification of the peptide sequence cyclo-[Val-(5-MeHex-Val-Thr-Val-Val-Tyr-Lys-Ile)Thr-Ile-Val-Phe-Dhb)] for the new cyclodepsipeptide, kahalalide Z3. Thus, ESI-MS/MS has set a trend in quick identification of new marine molecules.

  5. Liquid chromatography-tandem mass spectrometry for analysis of intestinal permeability of loperamide in physiological buffer.

    Directory of Open Access Journals (Sweden)

    Miriam S Rubelt

    Full Text Available Analysis of in vitro samples with high salt concentrations represents a major challenge for fast and specific quantification with liquid chromatography-tandem mass spectrometry (LC-MS/MS. To investigate the intestinal permeability of opioids in vitro employing the Ussing chamber technique, we developed and validated a fast, sensitive and selective method based on LC-MS/MS for the determination of loperamide in HEPES-buffered Ringer's solution. Chromatographic separation was achieved with an Atlantis dC18 column, 2.1 mm×20 mm, 3 µm particle size and a gradient consisting of methanol/0.1% formic acid and ammonium acetate. The flow rate was 0.7 ml/min, and the total run time was 3 min. For quantification, two mass transitions for loperamide and a deuterated internal standard (methadone-d(3 were used. The lower limit of loperamide quantification was 0.2 ng/ml. This new LC-MS/MS method can be used for the detection of loperamide in any experimental setup using HEPES-buffered Ringer's solution as a matrix compound.

  6. De Novo Sequencing of Peptides from Top-Down Tandem Mass Spectra.

    Science.gov (United States)

    Vyatkina, Kira; Wu, Si; Dekker, Lennard J M; VanDuijn, Martijn M; Liu, Xiaowen; Tolić, Nikola; Dvorkin, Mikhail; Alexandrova, Sonya; Luider, Theo M; Paša-Tolić, Ljiljana; Pevzner, Pavel A

    2015-11-06

    De novo sequencing of proteins and peptides is one of the most important problems in mass spectrometry-driven proteomics. A variety of methods have been developed to accomplish this task from a set of bottom-up tandem (MS/MS) mass spectra. However, a more recently emerged top-down technology, now gaining more and more popularity, opens new perspectives for protein analysis and characterization, implying a need for efficient algorithms to process this kind of MS/MS data. Here, we describe a method that allows for the retrieval, from a set of top-down MS/MS spectra, of long and accurate sequence fragments of the proteins contained in the sample. To this end, we outline a strategy for generating high-quality sequence tags from top-down spectra, and introduce the concept of a T-Bruijn graph by adapting to the case of tags the notion of an A-Bruijn graph widely used in genomics. The output of the proposed approach represents the set of amino acid strings spelled out by optimal paths in the connected components of a T-Bruijn graph. We illustrate its performance on top-down data sets acquired from carbonic anhydrase 2 (CAH2) and the Fab region of alemtuzumab.

  7. Accelerator mass spectrometry of the heaviest long-lived radionuclides with a 3-MV tandem accelerator

    Science.gov (United States)

    Vockenhuber, Christof; Golser, Robin; Kutschera, Walter; Priller, Alfred; Steier, Peter; Winkler, Stephan; Liechtenstein, Vitaly

    2002-12-01

    A 3-MV pelletron tandem accelerator is the heart of the Vienna environmental research accelerator (VERA). The original design of the beam transport components allows the transport of ions of all elements, from the lightest to the heaviest. For light ions the suppression of neighboring masses was sufficient to measure isotopic ratios of {(14}) C/{(12}) C and {(26}) Al/{(27}) Al as low as 10{(-15}) and {(10}) Be/{(9}) Be down to 10{(-13}) . To suppress neighboring masses for the heaviest radionuclides in the energy range of 10-20 MeV, the resolution of VERA was increased both by improving the ion optics of existing elements at the injection side and by installing a new high-resolution electrostatic separator at the high-energy side. Interfering ions which pass all beam filters are identified with a Bragg-type ionization detector and a high-resolution time-of-flight system. Two ultra-thin diamond-like carbon (DLC) foils are used in the start and stop detector, which substantially reduces losses due to beam straggling. This improved set up enables us to measure even the heaviest long-lived radionuclides, where stable isobaric interferences are absent (e.g. {(236}) U and {(244}) Pu), down to environmental levels. Moreover, the advantage of a `small' and well manageable machine like VERA lies in its higher stability and reliability which allows to measure these heavy radionuclides more accurately, and also a large number of samples.

  8. Microfluidic platform for liquid chromatography-tandem mass spectrometry analyses of complex peptide mixtures.

    Science.gov (United States)

    Xie, Jun; Miao, Yunan; Shih, Jason; Tai, Yu-Chong; Lee, Terry D

    2005-11-01

    A microfluidic chip that integrates all the fluidic components of a gradient liquid chromatography (LC) system is described. These chips were batch-fabricated on a silicon wafer using photolithographic processes and with Parylene as the main structural material. The fabricated chip includes three electrolysis-based electrochemical pumps, one for loading the sample and the other two for delivering the solvent gradient; platinum electrodes for delivering current to the pumps and establishing the electrospray potential; a low-volume static mixer; a column packed with silica-based reversed-phase support; integrated frits for bead capture; and an electrospray nozzle. The fabricated structures were able to withstand pressures in excess of 250 psi. The device was used to perform a liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of a mixture of peptides from the trypsin digestion of bovine serum albumen (BSA). Gradient elution through the 1.2-cm column was performed at a flow rate of 80 nL/min. Compared to the analysis of the same sample using a commercial nanoflow LC system, the chromatographic resolution was nearly as good, and the total cycle time was significantly reduced because of the minimal volume between the pumps and the column. Results demonstrate the potential of mass-produced, low-cost microfluidic systems capable of performing LC separations for proteomics applications.

  9. Quantitative analysis of the tumor suppressor dendrogenin A using liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Noguer, Emmanuel; Soules, Régis; Netter, Claude; Nagarathinam, Citra; Leignadier, Julie; Huc-Claustre, Emilie; Serhan, Nizar; Rives, Arnaud; de Medina, Philippe; Silvente-Poirot, Sandrine; Poirot, Marc

    2017-10-01

    Dendrogenin A (DDA) was recently identified as a mammalian cholesterol metabolite that displays tumor suppressor and neurostimulating properties at low doses. In breast tumors, DDA levels were found to be decreased compared to normal tissues, evidencing a metabolic deregulation of DDA production in cancers. DDA is an amino-oxysterol that contains three protonatable nitrogen atoms. This makes it physico-chemically different from other oxysterols and it therefore requires specific analytical methods We have previously used a two-step method for the quantification of DDA in biological samples: 1) DDA purification from a Bligh and Dyer extract by RP-HPLC using a 250×4.6mm column, followed by 2) nano-electrospray ionization mass spectrometry (MS) fragmentation to analyze the HPLC fraction of interest. We report here the development a liquid chromatography tandem mass spectrometry method for the analysis of DDA and its analogues. This new method is fast (10min), resolving (peak width <4s) and has a weak carryover (<0.01%). We show that this technique efficiently separates DDA from its C17 isomer and other steroidal alkaloids from the same family establishing a proof of concept for the analysis of this family of amino-oxysterols. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Quantitative analysis of mitragynine in human urine by high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Lu, Shijun; Tran, Buu N; Nelsen, Jamie L; Aldous, Kenneth M

    2009-08-15

    Mitragynine is the primary active alkaloid extracted from the leaves of Mitragyna speciosa Korth, a plant that originates in South-East Asia and is commonly known as kratom in Thailand. Kratom has been used for many centuries for their medicinal and psychoactive qualities, which are comparable to that of opiate-based drugs. Kratom abuse can lead to a detectable content of mitragynine residue in urine. Ultra trace amount of mitragynine in human urine was determined by a high performance liquid chromatography coupled to an electrospray tandem mass spectrometry (HPLC-ESI/MS/MS). Mitragynine was extracted by methyl t-butyl ether (MTBE) and separated on a HILIC column. The ESI/MS/MS was accomplished using a triple quadrupole mass spectrometer in positive ion detection and multiple reactions monitoring (MRM) mode. Ajmalicine, a mitragynine's structure analog was selected as internal standard (IS) for method development. Quality control (QC) performed at three levels 0.1, 1 and 5 ng/ml of mitragynine in urine gave mean recoveries of 90, 109, and 98% with average relative standard deviation of 22, 12 and 16%, respectively. The regression linearity of mitragynine calibration ranged from 0.01 to 5.0 ng/ml was achieved with correlation coefficient greater than 0.995. A detection limit of 0.02 ng/ml and high precision data within-day and between days analysis were obtained.

  11. Analysis of isotopic labeling in peptide fragments by tandem mass spectrometry.

    Directory of Open Access Journals (Sweden)

    Doug K Allen

    Full Text Available Phenotype in multicellular organisms is the consequence of dynamic metabolic events that occur in a spatially dependent fashion. This spatial and temporal complexity presents challenges for investigating metabolism; creating a need for improved methods that effectively probe biochemical events such as amino acid biosynthesis. Isotopic labeling can provide a temporal-spatial recording of metabolic events through, for example, the description of enriched amino acids in the protein pool. Proteins are therefore an important readout of metabolism and can be assessed with modern mass spectrometers. We compared the measurement of isotopic labeling in MS2 spectra obtained from tandem mass spectrometry under either higher energy collision dissociation (HCD or collision induced dissociation (CID at varied energy levels. Developing soybean embryos cultured with or without 13C-labeled substrates, and Escherichia coli MG1655 enriched by feeding 7% uniformly labeled glucose served as a source of biological material for protein evaluation. CID with low energies resulted in a disproportionate amount of heavier isotopologues remaining in the precursor isotopic distribution. HCD resulted in fewer quantifiable products; however deviation from predicted distributions were small relative to the CID-based comparisons. Fragment ions have the potential to provide information on the labeling of amino acids in peptides, but our results indicate that without further development the use of this readout in quantitative methods such as metabolic flux analysis is limited.

  12. Analysis of 2-methylthio-derivatives of isoprenoid cytokinins by liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tarkowski, Petr, E-mail: petr.tarkowski@upol.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Biochemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Vaclavikova, Katerina, E-mail: katka.vaclavik@seznam.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Biochemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Novak, Ondrej, E-mail: ondrej.novak@upol.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Pertry, Ine, E-mail: ine.pertry@ugent.BE [Department of Plant Biotechnology and Genetics, Ghent University, K.L.Ledeganckstraat 35, B-9000 Gent (Belgium); Hanus, Jan, E-mail: helehan@seznam.cz [Isotope Laboratory, Institute of Experimental Botany ASCR, Videnska 1083, 142 20 Prague (Czech Republic); Whenham, Robert [Apex Organics, Devon, England (United Kingdom); Vereecke, Danny, E-mail: danny.vereecke@hogent.BE [Department of Plant Production, University College Ghent, Ghent University, Schoonmeersstraat 52, B-9000 Gent (Belgium); Sebela, Marek, E-mail: marek.sebela@upol.cz [Department of Biochemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Strnad, Miroslav, E-mail: miroslav.strnad@upol.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic)

    2010-11-08

    A sensitive and reliable high-performance liquid chromatographic method with tandem mass spectrometric detection has been developed and used for the determination of 2-methylthio-cytokinin derivatives produced by the phytopathogenic actinomycete Rhodococcus fascians. The cultivation medium containing secreted cytokinins was concentrated and subjected to a solid-phase extraction (C18 and ion-exchange). The purified samples were further separated and analyzed by HPLC-ESI-MS/MS. This allowed to achieve chromatographic resolution of six highly hydrophobic cytokinin species including 2-methylthio-isopentenyladenine, 2-methylthio-isopentenyladenosine, 2-methylthio-trans-zeatin and 2-methylthio-trans-zeatin riboside and their cis-isomers when a reversed-phase chromatographic column (C4) and a mobile phase consisting of acetonitrile and 20 mM ammonium formate, pH 5, were used. Quantification was performed by a standard isotope dilution method using a multiple-reaction monitoring (MRM) mode. In the MRM mode, limits of detection reached 20-30 fmol and linear ranges spanned four orders of magnitude. Recovery values were between 35% and 65% and the analytical accuracy between 95% and 149%. The proposed bioanalytical method, which takes advantage of effective chromatographic separation of six 2-methyltio-derivatives (including isomers of zeatin-type cytokinins) and sensitive mass spectrometric detection, may become useful for plant biologists studying the significance of these substances in plant-microbe interactions.

  13. Analysis of 2-methylthio-derivatives of isoprenoid cytokinins by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Tarkowski, Petr; Václavíková, Kateřina; Novák, Ondřej; Pertry, Ine; Hanuš, Jan; Whenham, Robert; Vereecke, Danny; Šebela, Marek; Strnad, Miroslav

    2010-11-08

    A sensitive and reliable high-performance liquid chromatographic method with tandem mass spectrometric detection has been developed and used for the determination of 2-methylthio-cytokinin derivatives produced by the phytopathogenic actinomycete Rhodococcus fascians. The cultivation medium containing secreted cytokinins was concentrated and subjected to a solid-phase extraction (C18 and ion-exchange). The purified samples were further separated and analyzed by HPLC-ESI-MS/MS. This allowed to achieve chromatographic resolution of six highly hydrophobic cytokinin species including 2-methylthio-isopentenyladenine, 2-methylthio-isopentenyladenosine, 2-methylthio-trans-zeatin and 2-methylthio-trans-zeatin riboside and their cis-isomers when a reversed-phase chromatographic column (C4) and a mobile phase consisting of acetonitrile and 20 mM ammonium formate, pH 5, were used. Quantification was performed by a standard isotope dilution method using a multiple-reaction monitoring (MRM) mode. In the MRM mode, limits of detection reached 20-30 fmol and linear ranges spanned four orders of magnitude. Recovery values were between 35% and 65% and the analytical accuracy between 95% and 149%. The proposed bioanalytical method, which takes advantage of effective chromatographic separation of six 2-methyltio-derivatives (including isomers of zeatin-type cytokinins) and sensitive mass spectrometric detection, may become useful for plant biologists studying the significance of these substances in plant-microbe interactions. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. The inclusion of ADA-SCID in expanded newborn screening by tandem mass spectrometry.

    Science.gov (United States)

    la Marca, Giancarlo; Giocaliere, Elisa; Malvagia, Sabrina; Funghini, Silvia; Ombrone, Daniela; Della Bona, Maria Luisa; Canessa, Clementina; Lippi, Francesca; Romano, Francesca; Guerrini, Renzo; Resti, Massimo; Azzari, Chiara

    2014-01-01

    Severe combined immunodeficiency due to adenosine-deaminase defect (ADA-SCID) is usually deadly in childhood because of severe recurrent infections. When clinical diagnosis is done, permanent damages due to infections or metabolite accumulation are often present. Gene therapy, bone marrow transplantation or enzyme replacement therapy may be effective if started early. The aim of this study was to set-up a robust method suitable for screening with a minimized preparation process and with inexpensive running costs, for diagnosing ADA-SCID by tandem mass spectrometry. ADA-SCID satisfies all the criteria for inclusion in a newborn screening program. We describe a protocol revised to incorporate adenosine and 2-deoxyadenosine testing into an expanded newborn screening program. We assessed the effectiveness of this approach testing dried blood spots from 4 genetically confirmed early-onset and 5 delayed-onset ADA-SCID patients. Reference values were established on 50,000 healthy newborns (deoxyadenosine <0.09μmol/L, adenosine <1.61μmol/L). We also developed a second tier test to distinguish true positives from false positives and improve the positive predictive value of an initial abnormal result. In the first 18 months, the pilot project has identified a newborn with a genetically confirmed defect in adenosine deaminase (ADA) gene. The results show that the method having great simplicity, low cost and low process preparations can be fully applicable to a mass screening program. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Effect of metal cationization on the tandem mass spectra of glycosyl dithioacetals.

    Science.gov (United States)

    Madhusudanan, K P; Kumar, Brijesh; Tiwari, Pallavi; Madhusudan, Soni Kamlesh; Misra, A K

    2005-01-01

    The effect of metal cationization on the tandem mass spectra of glycosyl dithioacetals of glucose, mannose, galactose, rhamnose, arabinose and xylose was studied by electrospray ionization mass spectrometry under ammonium and metal (Li, Na, Ag and Cu) ion cationization conditions. The ammonium-cationized glycosyl dithioacetals fragment by loss of ammonia followed by either two molecules of EtSH or one molecule of EtSH and one molecule of H2O. Lithium cationization leads to additional eliminations such as EtSEt and EtSSEt and C-C cleavages. Elimination of EtSH is not observed under sodium cationization. Silver cationization, on the other hand, leads to additional fragmentations involving the elimination of silver as AgOH and AgSEt. Copper cationization results in adducts where copper has undergone a change of oxidation state from II to I. Li+, Ag+ and Cu+ cationization seem to favour cyclization resulting in elimination of EtSH. However, the mechanisms seem to be differently affected by different metal ions. Li+ and Ag+ cationization appear to be non-specific and favour cyclization involving C2-, C4- and C5-hydroxyl hydrogens, whereas Cu+ cationization seems to favour cyclization involving C4-hydroxyl hydrogen.

  16. Simultaneous determination of eight illegal dyes in chili products by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Li, Juan; Ding, Xiao-Ming; Liu, Dan-Dan; Guo, Fei; Chen, Yu; Zhang, Yan-Bing; Liu, Hong-Min

    2013-12-30

    A sensitive and accurate method based on the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of eight illegal synthetic dyes (Sudan (I-IV), Para Red, Rhodamine B, Chrysoidin and Auramine O) in chili products. A simple sample treatment procedure entailing the use of an extraction step with acetonitrile/H2O (9/1) without further cleanup was developed. HPLC was performed on a C18 column using a multistep gradient elution with 5mM ammonium acetate (pH 3.0 with formic acid) and methanol as the mobile phase. Mass spectral acquisition was done in multiple reaction monitoring (MRM) mode using positive electrospray ionization (ESI). Linear calibrations were obtained with correlation coefficients R(2)>0.99. Limit of detection (LOD) and limit of quantification (LOQ) for the studied dyes were in the ranges of 0.05-0.6μgkg(-1) and 0.3-3.0μgkg(-1) depending on matrices, respectively. The recoveries of the eight synthetic dyes in five matrices ranged from 70.5% to 119.2%. The intra- and inter-day precisions (RSDs) were between 2.3-15.8% and 5.7-15.6%, respectively. The applicability of the method to the determination of eight banned dyes in chili products was demonstrated. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Determination of synthetic dyes in bean and meat products by liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Li, Juan; Ding, Xiaoming; Zheng, Jiaxin; Liu, Dandan; Guo, Fei; Liu, Hongmin; Zhang, Yanbing

    2014-09-01

    A sensitive and efficient method was developed for the simultaneous determination of eight synthetic dyes (Chrysoidin, Auramine O, Sudan(I-IV), Para Red, and Rhodamine B) in bean and meat products using high-performance liquid chromatography with tandem mass spectrometry. A simple extraction procedure using acetonitrile has been applied for the extraction of these dyes from spiked bean and meat samples. Chromatographic separation was achieved on a Waters XTerra C18 column (2.1 × 150 mm, 5 μm) with a multistep gradient elution. Detection and quantification were performed using mass spectrometry in multiple reaction monitoring mode. Linear calibrations were obtained with correlation coefficients R(2) > 0.99. The limits of detection and quantification for the eight dyes were in the ranges of 0.03-0.75 and 0.1-2.0 μg/kg depending on matrices, respectively. The recoveries of these dyes in different food matrices were between 71.2 and 116.9% with relative standard deviations dyes at trace levels in bean and meat products. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Comparative Lipidomics of Caenorhabditis elegans Metabolic Disease Models by SWATH Non-Targeted Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Jeevan K. Prasain

    2015-11-01

    Full Text Available Tandem mass spectrometry (MS/MS with Sequential Window Acquisition of all Theoretical (SWATH mass spectra generates a comprehensive archive of lipid species within an extract for retrospective, quantitative MS/MS analysis. Here we apply this new technology in Caenorhabditis elegans (C. elegans to identify potential lipid mediators and pathways. The DAF-1 type I TGF-β and DAF-2 insulin receptors transmit endocrine signals that couple metabolic status to fertility and lifespan. Mutations in daf-1 and daf-2 reduce prostaglandin-endoperoxide synthase (i.e., Cox-independent prostaglandin synthesis, increase triacylglyceride storage, and alter transcription of numerous lipid metabolism genes. However, the extent to which DAF-1 and DAF-2 signaling modulate lipid metabolism and the underlying mechanisms are not well understood. MS/MSALL with SWATH analysis across the groups identified significant changes in numerous lipids, including specific triacylglycerols, diacylglycerols, and phosphatidylinositols. Examples are provided, using retrospective neutral loss and precursor ion scans as well as MS/MS spectra, to help identify annotated lipids and search libraries for lipids of interest. As proof of principle, we used comparative lipidomics to investigate the prostaglandin metabolism pathway. SWATH data support an unanticipated model: Cox-independent prostaglandin synthesis may involve lysophosphatidylcholine and other lyso glycerophospholipids. This study showcases the power of comprehensive, retrospectively searchable lipid archives as a systems approach for biological discovery in genetic animal models.

  19. De Novo Sequencing of Peptides from Top-Down Tandem Mass Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Vyatkina, Kira; Wu, Si; Dekker, Lennard J. M.; VanDuijn, Martijn M.; Liu, Xiaowen; Tolić, Nikola; Dvorkin, Mikhail; Alexandrova, Sonya; Luider, Theo M.; Paša-Tolić, Ljiljana; Pevzner, Pavel A.

    2015-11-06

    De novo sequencing of proteins and peptides is one of the most important problems in mass spectrometry-driven proteomics. A variety of methods have been developed to accomplish this task from a set of bottom-up tandem (MS/MS) mass spectra. However, a more recently emerged top-down technology, now gaining more and more popularity, opens new perspectives for protein analysis and characterization, implying a need in efficient algorithms for processing this kind of MS/MS data. Here we describe a method that allows to retrieve from a set of top-down MS/MS spectra long and accurate sequence fragments of the proteins contained in a sample. To this end, we outline a strategy for generating high-quality sequence tags from top-down spectra, and introduce the concept of a T-Bruijn graph by adapting to the case of tags the notion of an A-Bruijn graph widely used in genomics. The output of the proposed approach represents the set of amino acid strings spelled out by optimal paths in the connected components of a T-Bruijn graph. We illustrate its performance on top-down datasets acquired from carbonic anhydrase 2 (CAH2) and the Fab region of alemtuzumab.

  20. Absolute quantification method and validation of airborne snow crab allergen tropomyosin using tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Anas M. Abdel, E-mail: anasar@mun.ca [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada); Lopata, Andreas L. [School of Applied Science, Marine Biomedical Sciences and Health Research Group, RMIT University, Bundoora, 3083 Victoria (Australia); Randell, Edward W. [Department of Laboratory Medicine, Memorial University of Newfoundland, Eastern Health, St. John' s, Newfoundland and Labrador A1B 3V6 (Canada); Helleur, Robert J. [Department of Chemistry, Memorial University of Newfoundland, St. John' s, Newfoundland A1B 3X7 (Canada)

    2010-11-29

    Measuring the levels of the major airborne allergens of snow crab in the workplace is very important in studying the prevalence of crab asthma in workers. Previously, snow crab tropomyosin (SCTM) was identified as the major aeroallergen in crab plants and a unique signature peptide was identified for this protein. The present study advances our knowledge on aeroallergens by developing a method of quantification of airborne SCTM by using isotope dilution mass spectrometry. Liquid chromatography tandem mass spectrometry was developed for separation and analysis of the signature peptides. The tryptic digestion conditions were optimized to accomplish complete digestion. The validity of the method was studied using international conference on harmonization protocol, Where 2-9% for CV (precision) and 101-110% for accuracy, at three different levels of quality control. Recovery of the spiked protein from PTFE and TopTip filters was measured to be 99% and 96%, respectively. To further demonstrate the applicability and the validity of the method for real samples, 45 kg of whole snow crab were processed in an enclosed (simulated) crab processing line and air samples were collected. The levels of SCTM ranged between 0.36-3.92 {mu}g m{sup -3} and 1.70-2.31 {mu}g m{sup -3} for butchering and cooking stations, respectively.

  1. [Simultaneous determination of bromate and perchlorate in vegetable by ion chromatography tandem mass spectrometry].

    Science.gov (United States)

    Yang, Jiajia; Yang, Yi; Zhang, Jing; Shao, Bing; Wu, Yongning

    2012-03-01

    To develop a method for simultaneous determination of bromate and perchiorate in vegetable using ion chromatography tandem mass spectrometry. Target ions in vegetable matrix were extracted by water and purified using a GCB cartridge. With the hydrophilic Ion Pac AS19 column and linear gradient potassium hydroxide used as eluent, bromate and perchlorate were analyzed by a triple quadrupole mass spectrometer under negative electronspray ionization mode and multiple reaction monitoring (MRM). Internal standard calibration was used for quantification. Good linearity was achieved for bromate and perchlorate over the range of 0.1- 50 microg/L and 0.05-50 microg/L, respectively, with correlation coefficients R2 > 0.998. The quantification limits of the method were 2.5 microg/kg and 0.7 microg/kg for bromate and perchlorate, respectively. Mean recoveries of two target analytes (spiked at three concentration levels in 5 kinds of vegetables) ranged from 80.3% to 124%, with within-day precisions no more than 21.4% and intraday precisions no more than 12.2%. This method could be applied in the simultaneous detection of bromate and perchlorate in vegetable.

  2. Hybrid Mesons Masses in a Quark-Gluon Constituent Model

    CERN Document Server

    Iddir, F; CERN. Geneva; Iddir, Farida; Semlala, Lahouari

    2002-01-01

    QCD theory allows the existence of states which cannot be built by the naive quark model; both theoretical arguments and experimental data confirm the hypothesis that gluons may have freedom degrees at the constituent level, and should be confined. In this work, we use a phenomenological potential motivated by QCD (with some relativistic corrections) to determine the masses and the wavefunctions of several hybrid mesons, within the context of a constituent q-qbar-g model. We compare our estimates of the masses with the predictions of other theoretical models and with the observed masses of candidates.

  3. Analysis of perfluoroalkyl substances in cord blood by turbulent flow chromatography coupled to tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Llorca, Marta; Perez, Francisca [Department of Environmental Chemistry, IDAEA-CSIC, Barcelona (Spain); Farre, Marinella, E-mail: mfuqam@cid.csic.es [Department of Environmental Chemistry, IDAEA-CSIC, Barcelona (Spain); Agramunt, Silvia [Centre for Research in Environmental Epidemiology (CREAL), Barcelona (Spain); IMIM (Hospital del Mar Research Institute), Barcelona (Spain); Kogevinas, Manolis [Centre for Research in Environmental Epidemiology (CREAL), Barcelona (Spain); IMIM (Hospital del Mar Research Institute), Barcelona (Spain); CIBER Epidemiologia y Salud Publica (CIBERESP), Barcelona (Spain); National School of Public Health, Athens (Greece); Barcelo, Damia [Department of Environmental Chemistry, IDAEA-CSIC, Barcelona (Spain); Catalan Institute for Water Research (ICRA), Girona (Spain); King Saud University, Riyadh (Saudi Arabia)

    2012-09-01

    A fast on-line analytical method based on turbulent flow chromatography (TFC) in combination with tandem mass spectrometry has been applied for the first time for the analysis of eighteen perfluoroalkyl substances (PFASs), in cord blood. A simple and rapid sample pre-treatment was optimised consisting on protein precipitation of 100 {mu}L of sample with acetonitrile (1:1) followed by centrifugation during 10 min. The method was adapted to be sensitive enough and robust with minimum sample injection volume requirements (20 {mu}L). The optimised methodology presented method limits of detection (MLOD) between 0.031 and 0.76 {mu}g/L, detection capabilities (CC{alpha}) in the range between 0.005 and 0.99 {mu}g/L and decision limits (CC{beta}) ranging from 0.006 to 1.16 {mu}g/L. The recoveries in blank blood were calculated by spiking experiments with a mixture of 18 PFASs and established between 70 and 126% for most of compounds. Isotopic dilution was carried out for quantification of selected analytes. In-house validation of this new approach was carried out according to the requirements in the 2002/657/EC Decision. Finally the good applicability of this new approach was proved by the analysis of 60 cord blood samples from two different Mediterranean cities, Barcelona (Spain) and Heraklion (Greece). Ions perfluorohexanesulfonate (PFHxS) and perfluorooctanesulfonate (PFOS) were found at highest concentration and the more frequently compounds were PFHxS, PFOS and perfluorooctanoic acid (PFOA). The newly developed method proved to be suitable for large-scale epidemiologic studies, and to the data on PFASs exposure during pregnancy. -- Highlights: Black-Right-Pointing-Pointer An on-line method has been developed for the analysis of 18 perfluoroalkyl substances. Black-Right-Pointing-Pointer The method is based on turbulent flow chromatography tandem mass spectrometry. Black-Right-Pointing-Pointer The method was applied in 60 cord blood samples from 2 Mediterranean cities

  4. Matrix effect on the determination of synthetic corticosteroids and diuretics by liquid chromatography-tandem mass spectrometry

    Science.gov (United States)

    Dikunets, M. A.; Appolonova, S. A.; Rodchenkov, G. M.

    2009-04-01

    This work presents a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) procedure for selective and reliable screening of corticosteroids and diuretics in human urine. Sample preparation included the extraction, evaporation of the organic extract under nitrogen, and solution of the dry residue. The extract was analyzed by HPLC combined with tandem mass spectrometry using electro-spraying ionization at atmospheric pressure with negative ion recording. The mass spectra of all compounds were recorded, and the characteristic ions, retention times, and detection limits were determined. The procedure was validated by evaluating the degree of the matrix suppression of ionization, extraction of analytes from human biological liquid, and the selectivity and specificity of determination.

  5. Quantitative, Multidrug Pain Medication Testing by Liquid Chromatography: Tandem Mass Spectrometry (LC-MS/MS).

    Science.gov (United States)

    Bodor, Geza S

    2016-01-01

    Chronic pain is often treated with narcotic analgesics. The most commonly used narcotic analgesics are the opiates (natural or modified compounds of the poppy plant) or opioids (synthetic chemicals that act on opiate receptors). While opiates and opioids are excellent analgesics, they can also have significant side effects that include respiratory depression, coma, or death. Tolerance, physical dependence, and addiction (psychological dependence) are other severe side effects of opioid use. Patients who develop dependence or addiction often times abuse other, non-opioid narcotics and may trade their prescription medication for illegal street drugs (called "diversion"). In order to minimize side effects, detect possible multidrug abuse and prove diversion, simultaneous monitoring of numerous prescription and illicit drugs is required. The method described in this chapter is for the quantitative measurement of 43 different drugs in urine. The panel includes narcotic pain medications, benzodiazepines, NIDA drugs, and other, commonly abused medications. The analytes of interests are injected in the presence of deuterated internal standards to correct for possible extraction inefficiencies, ion suppression, or other interferences. The sample is prepared by adding dilution buffer with the deuterated internal standards to the sample, followed by reversed-phase, gradient HPLC separation on a Phenyl-Hexyl column using water and methanol as mobile phases. Detection of the analytes of interest is done by isotope-dilution mass spectrometry on a triple-quadrupole tandem mass spectrometer following electrospray ionization in the positive mode. Mass spectrometric (MS) data are collected in the scheduled MRM (sMRM) mode. Two MRM transitions are monitored for each analyte and one MRM transition is monitored for each IS. Quantitation of the unknown analytes is achieved by comparing the peak area ratios of the analytes to that of the internal standards and reading the unknown

  6. Similarity of High-Resolution Tandem Mass Spectrometry Spectra of Structurally Related Micropollutants and Transformation Products

    Science.gov (United States)

    Schollée, Jennifer E.; Schymanski, Emma L.; Stravs, Michael A.; Gulde, Rebekka; Thomaidis, Nikolaos S.; Hollender, Juliane

    2017-12-01

    High-resolution tandem mass spectrometry (HRMS2) with electrospray ionization is frequently applied to study polar organic molecules such as micropollutants. Fragmentation provides structural information to confirm structures of known compounds or propose structures of unknown compounds. Similarity of HRMS2 spectra between structurally related compounds has been suggested to facilitate identification of unknown compounds. To test this hypothesis, the similarity of reference standard HRMS2 spectra was calculated for 243 pairs of micropollutants and their structurally related transformation products (TPs); for comparison, spectral similarity was also calculated for 219 pairs of unrelated compounds. Spectra were measured on Orbitrap and QTOF mass spectrometers and similarity was calculated with the dot product. The influence of different factors on spectral similarity [e.g., normalized collision energy (NCE), merging fragments from all NCEs, and shifting fragments by the mass difference of the pair] was considered. Spectral similarity increased at higher NCEs and highest similarity scores for related pairs were obtained with merged spectra including measured fragments and shifted fragments. Removal of the monoisotopic peak was critical to reduce false positives. Using a spectral similarity score threshold of 0.52, 40% of related pairs and 0% of unrelated pairs were above this value. Structural similarity was estimated with the Tanimoto coefficient and pairs with higher structural similarity generally had higher spectral similarity. Pairs where one or both compounds contained heteroatoms such as sulfur often resulted in dissimilar spectra. This work demonstrates that HRMS2 spectral similarity may indicate structural similarity and that spectral similarity can be used in the future to screen complex samples for related compounds such as micropollutants and TPs, assisting in the prioritization of non-target compounds. [Figure not available: see fulltext.

  7. Product ion tandem mass spectrometric differentiation of regioisomeric side-chain groups in cathinone derivatives.

    Science.gov (United States)

    Abiedalla, Younis; DeRuiter, Jack; Clark, C Randall

    2016-07-30

    Precursor materials are available to prepare aminoketone drugs containing regioisomeric propyl and isopropyl side-chain groups related to the drug alpha-pyrrovalerone (Flakka) and MDPV (3,4-methylenedioxypyrrovalerone). These compounds yield equivalent regioisomeric iminium cation base peaks in electron ionization mass spectrometry (EI-MS). The propyl and isopropyl side-chain groups related to alpha-pyrrovalerone and MDPV were prepared and evaluated in EI-MS and tandem mass spectrometry (MS/MS) product ion experiments. Deuterium labeling in both the pyrrolidine and alkyl side-chain groups allowed for the confirmation of the structures for the major product ions formed from the regioisomeric EI-MS iminium cation base peaks. These iminium cation base peaks show characteristic product ion spectra which allow differentiation of the side-chain propyl and isopropyl groups in the structure. The n-propyl side chain containing iminium cation base peak (m/z 126) in the EI-MS spectrum yields a major product ion at m/z 84 while the regioisomeric m/z 126 base peak for the isopropyl side chain yields a characteristic product ion at m/z 70. Deuterium labeling in both the pyrrolidine ring and the alkyl side chain confirmed the process for the formation of these major product ions. Product ion fragmentation provides useful data for differentiation of n-propyl and isopropyl side-chain iminium cations from cathinone derivative drugs of abuse. Regioisomeric n-propyl and isopropyl iminium cations of equal mass yield characteristic product ions identifying the alkyl side-chain regioisomers in the pyrrolidine cathinone derivatives. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  8. [Determination of strobilurin fungicides in fruits and their mass fragmentation routes by ultra performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Zhou, Yao; Yang, Huiqin; Shi, Yiyin; Chen, Jiaxian; Zhu, Jian; Deng, Xiaojun; Guo, Dehua

    2017-09-08

    A method was developed for the simultaneous determination of six strobilurin fungicide (E-metominostrobin, azoxystrobin, kresoxim-methyl, picoxystrobin, pyraclostrobin and trifloxystrobin) residues in orange, banana, apple and pineapple samples by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The fragmentation routes of all the compounds were explained by the aid of a fragment predicting software ACD Lab/MS Fragmenter. The samples were extracted by acetonitrile, then cleaned up by amino solid phase extraction cartridges (SupelClean LC-NH2). The extracts were separated on a ACQUITY UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) with gradient elution. Acetonitrile containing 0.1% (v/v) formic acid and 10 mmol/L ammonium acetate containing 0.1% (v/v) formic acid were used as mobile phases. The samples were detected by electrospray ionization (ESI)-MS/MS in positive ion and multiple reaction monitoring (MRM) mode, quantified by external standard method. Good linearities were obtained in the range of 5-100 μg/L (for pyraclostrobin, 1-20 μg/L) with correlation coefficients (r2) greater than 0.999. The recoveries ranged from 60.4% to 120% with the relative standard deviations between 2.15% and 15.1% (n=6). The developed method can meet the inspection of the six strobilurin residues in the orange, banana, apple and pineapple samples.

  9. Determination of the toluene diisocyanate binding sites on human serum albumin by tandem mass spectrometry.

    Science.gov (United States)

    Hettick, Justin M; Siegel, Paul D

    2011-07-15

    Diisocyanates are highly reactive chemical compounds widely used in the manufacture of polyurethanes. Although diisocyanates have been identified as causative agents of allergic respiratory diseases, the specific mechanism by which these diseases occur is largely unknown. To better understand the chemical species produced when diisocyanates react with protein, tandem mass spectrometry was employed to unambiguously identify the binding sites of the industrially important isomers, 2,4- and 2,6-toluene diisocyanate, on human serum albumin at varying diisocyanate/protein ratios. The 2,4-isomer results in approximately 2-fold higher conjugation product ion abundances than does the 2,6-isomer, suggesting that the 2,4-isomer has a higher reactivity toward albumin. Both isomers preferentially react with the N-terminal amine of the protein and the ε-NH(2) of lysine. At a low (1:2) diisocyanate/protein ratio, five binding sites are identified, whereas at a high (40:1) ratio, near-stoichiometric conjugation is observed with a maximum of 37 binding sites identified. Binding sites observed at the lowest conjugation ratios are conserved at higher binding ratios, suggesting a subset of 5-10 preferential binding sites on albumin. Diisocyanate-protein conjugation results in a variety of reaction products, including intra- and intermolecular crosslinking, diisocyanate self-polymerization, and diisocyanate hydrolysis. Published by Elsevier Inc.

  10. Sensitive quantification of diphemanil methyl sulphate in human plasma by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Do, B; Goulay-Dufaÿ, S; Le Hoang, M D; Adoui, N; Graffard, H; Guyon, F; Pradeau, D

    2007-01-01

    A simple detection system with a high-performance liquid chromatography (HPLC) with positive ionisation-tandem mass spectrometry (ESI-MS/MS) for determining diphemanil methylsulphate (DMS) levels in human plasma using 4-diphemanylmethylene,1-methylpiperidine as an internal standard (I.S.), is proposed. The acquisition was performed with the multiple reactional monitoring (MRM) mode, by monitoring the transitions: m/z 278>262 for DMS and m/z 263>247 for the I.S. The method involved a simple single-step deproteinisation with acetonitrile. The analyte was chromatographed on a Zorbax C18 reversed-phase chromatographic column by isocratic elution with 10(-3)M ammonium acetate and 10(-3)M hexafluorobutyric acid, adjusted to pH 7.0 with ammoniac/acetonitrile (40/60, v/v). The results were linear over the studied range (0.5-50.0 ng mL(-1)) and the total analysis time for each run was 10 min. The mean extraction apparent recoveries expressed at the 95% intervals of confidence were 94-104% for DMS and 92-106% for the I.S. The intra- and inter-assay precisions were 4.6-8.4% and 2.9-10.6%, respectively. The limit of quantification was 0.15 ng mL(-1). The devised assay was successfully applied to the residual concentrations monitoring in infant.

  11. Determination of levofloxacin in human serum using liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Samiksha Ghimire

    2018-01-01

    Full Text Available A rapid liquid chromatography tandem-mass spectrometry method was developed for the determination of levofloxacin and its metabolite (desmethyl-levofloxacin in human serum. Sample preparation was done using protein precipitation technique. Our method had a run time of 2.5 min and retention times of 1.6 min for all analytes. The standard curves were linear within the concentration range of 0.10 to 5.00 mg/L for levofloxacin and 0.10 to 4.99 mg/L for desmethyl- levofloxacin; a correlation coefficient (R2 of 0.999 and 0.998 respectively. The lower limit of quantification for both analytes was 0.10 mg/L. Within-day precision ranged from 1.4% and 2.4% for levofloxacin, 1.5% to 5% for desmethyl-levofloxacin and between-day precision ranged from 3.6% to 4.1% for levofloxacin and 0.0% to 3.3% for desmethyl-levofloxacin; whereas, accuracy ranged from 0.1% to 12.7% for levofloxacin and 0.2% to 15.6% for desmethyl-levofloxacin. This method could be a useful asset for routine therapeutic drug monitoring of levofloxacin in multi-drug resistant tuberculosis patients.

  12. Rapid screening of clenbuterol in urine samples by desorption electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Lin, Ziqing; Zhang, Sichun; Zhao, Mengxia; Yang, Chengdui; Chen, Depu; Zhang, Xinrong

    2008-06-01

    Rapid screening of clenbuterol in urine was performed by combining desorption electrospray ionization (DESI) and tandem mass spectrometry (MS/MS). Optimization experiments were carried out including the selection of substrates, spray solutions, nebulizing gas pressures, high-voltage power supplies and flow rates of spray solution. The limit of detection (LOD), defined as the lowest quantity that can be detected, was 5.0 pg for the pure compound. Using DESI coupled with solid-phase extraction (SPE), the linear response range was from 10 to 400 ng/mL (R(2) = 0.993) and the concentration LOD for urine sample was 2.0 ng/mL. The analysis for one spiked urine sample was achieved within 4 min. In addition to the fast analysis speed, MS/MS provided structural information for the confirmation of clenbuterol. Urine samples from different people were investigated and the recoveries were within 100 +/- 20%. The developed method can potentially be used for screening of clenbuterol in doping control.

  13. Determination of streptomycin and dihydrostreptomycin in milk and honey by liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    van Bruijnsvoort, Michel; Ottink, Stef J M; Jonker, Klaas M; de Boer, Enne

    2004-11-26

    Two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were developed for the determination of streptomycin (STR) and its derivative dihydrostreptomycin (DHSTR) in milk and honey. These aminoglycoside antibiotics are used as veterinary drugs. In the EU, the presence of dihydro- and streptomycin residues in honey is forbidden, the maximum residue level (MRL) in milk is 200 microg/kg. The methods were optimised with regard to sensitivity and chromatographic efficiency, and validated by a procedure consistent with EU directive 2002/657. Average recoveries and accompanying standard deviations were satisfactory. The limit of quantification of STR was 2 microg/kg in honey and 10 microg/kg in milk, of DHSTR it was a factor two lower. The precision of the milk analysis was improved by using STR as the internal standard for DHSTR and vice versa. In a survey of 186 honeys available on the Dutch market, 26% of the honeys of foreign origin were positive for (DH)STR. This occurence rate was consistent with previous surveys, but lower concentrations were found.

  14. Multiresidue analysis of environmental pollutants in edible vegetable oils by gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Zhou, Rui-Ze; Jiang, Jie; Mao, Ting; Zhao, Ya-Song; Lu, Yong

    2016-09-15

    A novel multiresidue determination of polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PAEs) and alkylphenols (APs) in edible vegetable oils was developed. The samples were extracted with hexane-saturated acetonitrile, and after concentration, the extract was directly qualitatively and quantitatively analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS) with multiple reaction monitoring (MRM) in positive ion mode. The calibration curve displayed good linearity in the range of 2-100 μg/L, with correlation coefficients greater than 0.99. The mean recoveries were 70.0-110.8% by analysis of spiked oil, and the relative standard deviations (RSDs) were 2.1-10.2% (n=6), respectively. The limits of detection (LODs) for the 23 PAHs, 17 PAEs and 3 APs were 0.1-1.0 μg/kg, 0.1-4.0 μg/kg and 1.2-3.0 μg/kg, respectively. The established method effectively avoided interference from large amounts of lipids and pigments. It was applied to real sample and shown to be a rapid and reliable alternative for determination and confirmation in routine analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Determination of trinexapac in wheat by liquid chromatography-electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Hiemstra, Maurice; de Kok, André

    2003-09-24

    A quantitative and confirmatory method for the analysis of trinexapac (free acid metabolite of trinexapac-ethyl) in wheat is described. Residues were extracted from wheat with acetonitrile in aqueous phosphate buffer (pH 7) overnight. The extract was directly injected into the HPLC system. Chromatographic separation was achieved on an octadecylsilica column, and detection was performed by negative ion electrospray ionization tandem mass spectrometry. The precursor ion of trinexapac [M - H](-) at m/z 223 was subjected to collisional fragmentation with argon to yield two intense diagnostic product ions at m/z 135 and 179, respectively. Accuracy and specificity for routine analysis of trinexapac were demonstrated. The validated concentration range was 10-200 microg/kg based on a 0.10 g/mL wheat sample extract. Recoveries were within the range of 71-94%, with associated relative standard deviations better than 10%. The limit of detection for trinexapac in wheat was estimated at 5 microg/kg. The method has been applied to a survey of 100 samples of wheat. In 46% of the samples analyzed, a quantifiable amount of trinexapac was detected, ranging from 10 to 110 microg/kg. It has been demonstrated that analyses of trinexapac accurately reflect the total amount of residues of the plant growth regulator, trinexapac-ethyl, in the wheat samples following field application. No residues of the parent compound, trinexapac-ethyl, in wheat were detected.

  16. Capillary-HPLC with tandem mass spectrometry in analysis of alkaloid dyestuffs - a new approach.

    Science.gov (United States)

    Dąbrowski, Damian; Lech, Katarzyna; Jarosz, Maciej

    2017-11-10

    Development of the identification method of alkaloid compounds in Amur cork tree as well as not examined so far Oregon grape and European Barberry shrubs are presented. The novel approach to separation of alkaloids was applied and the capillary-high-performance liquid chromatography (capillary-HPLC) system was used, which has never previously been reported for alkaloid-based dyestuffs analysis. Its optimization was conducted with three different stationary phases (unmodified octadecylsilane-bonded silica, octadecylsilane modified with polar groups and silica-bonded pentaflourophenyls) as well as with different solvent buffers. Detection of the isolated compounds was carried out using diode-array detector (DAD) and tandem mass spectrometer with electrospray ionization (ESI MS/MS). The working parameters of ESI were optimized, whereas the multiple reactions monitoring (MRM) parameters of MS/MS detection were chosen based on the product ion spectra of the quasi-molecular ions. Calibration curve of berberine has been estimated (y = 1712091x + 4785.03 with the correlation coefficient 0.9999). Limit of detection and limit of quantification were calculated to be 3.2 and 9.7 ng/mL, respectively. Numerous alkaloids (i.e., berberine, jatrorrhizine and magnoflorine, as well as phellodendrine, menisperine and berbamine) were identified in the extracts from alkaloid plants and silk and wool fibers dyed with these dyestuffs, among them their markers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Multi-detection of preservatives in cheeses by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Fuselli, Fabio; Guarino, Chiara; La Mantia, Alessandro; Longo, Lucia; Faberi, Angelo; Marianella, Rosa Maria

    2012-10-01

    The incorrect use of preservatives in cheeses may compromise food safety and damage consumers. According to the law, more than one preservative may be contemporarily used in cheeses. So a method for their contemporary detection may be useful for both manufacturers and control agencies quality control. In this research a liquid chromatography-tandem mass spectrometric with electrospray ionization method for the multi-determination of seven preservatives (benzoic acid, citric acid, hexamethylenetetramine, lysozyme, natamycin, nisin and sorbic acid) in cheese was developed. The preservatives were contemporarily extracted from cheese by a single procedure, and analyzed by RP-LC/ESI-MS/MS (Ion Trap) in positive ionization mode, with single reaction monitoring (SRM) acquisition. Three sample types (hard, pasta filata and fresh cheese) were used for method evaluation. Recoveries were mostly higher than 90%; MDLs ranged from 0.02 to 0.26 mgkg(-1), and MQLs were included between 0.07 and 0.88 mgkg(-1). Due to matrix effect, quantitation was performed by referring to a matrix matched calibration curve, for each cheese typology. This method was also applied to commercial cheese samples, with good results. It appears fast, reliable and suitable for both screening and confirmation of the presence and quantitation of the preservatives in a single, multi-detection analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Determination of streptomycin residues in honey by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Granja, Rodrigo H M M; Niño, Alfredo M Montes; Zucchetti, Roberto A M; Niño, Rosario E Montes; Patel, Raj; Salerno, Alessandro G

    2009-04-01

    Streptomycin is an aminoglycoside antibiotic used in apiculture to protect bees against a variety of brood diseases. Brazilian authorities have included it in the National Regulatory Monitoring Program for honey production. A simple and reliable method using liquid chromatography-tandem mass spectrometry has been developed and validated for the determination of streptomycin in honey. The chromatography separation was performed on a Gemini 5 microm C18 (50 mm x 2 mm) column using 5mM heptafluorbutiric acid/acetonitrile (85:15) as the mobile phase at a flow rate of 0.2 mLmin(-1). The detection of the analyte was achieved by positive ionization electrospray in multiple reaction-monitoring modes. Two characteristic transitions were monitored for streptomycin. Some analytical parameters were validated according to the guidelines laid down by European Commission Decision 2002/657/EC: decision limit, detection capability, recovery, precision and ruggedness. The recoveries of streptomycin from honey fortified at 2.5, 10, 15 and 20 microgkg(-1) levels are around 100%. The decision limit and detection capability of streptomycin was 3 microgkg(-1) and 4.7 microgkg(-1) respectively.

  19. Glycoalkaloid content in pet food by UPLC-tandem mass spectrometry.

    Science.gov (United States)

    Sheridan, Robert S; Kemnah, Jennifer L

    2010-11-01

    The glycoalkaloid content of pet food containing potatoes is investigated using a liquid-liquid solvent extraction followed by analysis by ultra-high pressure liquid chromatography tandem mass spectrometry (UPLC-MS-MS). Pet food samples are homogenized and extracted with a solution of 50:50 (v/v) acetonitrile-deionized water containing 5% acetic acid. Following vortexing and centrifugation, 3 mL of the supernatant is filtered and diluted in deionized water. The extract is injected onto a reverse phase C18 UPLC column with an initial mobile phase composed of 0.15% acetic acid in water (A) and 0.15% acetic acid in methanol (B) in a ratio of 70:30, respectively. The mobile phase reaches a final concentration of 15% A and 85% B over 10 min, at which point it is returned to the initial conditions. α-Solanine is measured by monitoring transitions m/z = 868.50 → 398.40 and 868.50 → 722.50, while α-chaconine is measure by monitoring transitions m/z = 852.60 → 97.80 and 852.60 → 706.50. Each analyte is measured and combined to determine total glycoalkaloid content (TGA). The results of the analysis of 52 pet food samples indicate both glycoalkaloids are present in all samples and two pet foods were found to contain > 100 μg/g total glycoalkaloid.

  20. [Determination of gossypol in edible vegetable oil with high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Zhang, Wenhua; Huang, Chaoqun; Xie, Wen; Shen, Li

    2014-06-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of gossypol in edible vegetable oil. The sample was extracted with ethyl alcohol by vortex-excited oscillation. The extract was cleaned up by 0.22 microm filter membrane and centrifuged for 5 min at 4 000 r/min after standing in a fridge at 4 degrees C for 30 min. The compound was separated on a C18 column (100 mm x 2.1 mm, 3.5 microm) with acetonitrile and 1% (v/v) formic acid aqueous solution as mobile phase. The detection of gossypol was carried out by LC-MS/MS with positive electrospray ionization under multiple reaction monitoring (MRM) mode using external standard method. The limits of quantification (S/N > 10) of gossypol in edible vegetable oil was 1 mg/kg. The recoveries were from 87.4% to 100% at the spiked levels of 1, 2, 200 mg/kg of gossypol in edible vegetable oil with the relative standard deviations (RSDs) between 3.9% and 12.2%. The method, with high sensitivity, good precision and high recovery, was suitable for the confirmation and quantification of gossypol residue in edible vegetable oil.

  1. Analysis of plant nucleotide sugars by hydrophilic interaction liquid chromatography and tandem mass spectrometry.

    Science.gov (United States)

    Ito, Jun; Herter, Thomas; Baidoo, Edward E K; Lao, Jeemeng; Vega-Sánchez, Miguel E; Michelle Smith-Moritz, A; Adams, Paul D; Keasling, Jay D; Usadel, Björn; Petzold, Christopher J; Heazlewood, Joshua L

    2014-03-01

    Understanding the intricate metabolic processes involved in plant cell wall biosynthesis is limited by difficulties in performing sensitive quantification of many involved compounds. Hydrophilic interaction liquid chromatography is a useful technique for the analysis of hydrophilic metabolites from complex biological extracts and forms the basis of this method to quantify plant cell wall precursors. A zwitterionic silica-based stationary phase has been used to separate hydrophilic nucleotide sugars involved in cell wall biosynthesis from milligram amounts of leaf tissue. A tandem mass spectrometry operating in selected reaction monitoring mode was used to quantify nucleotide sugars. This method was highly repeatable and quantified 12 nucleotide sugars at low femtomole quantities, with linear responses up to four orders of magnitude to several 100pmol. The method was also successfully applied to the analysis of purified leaf extracts from two model plant species with variations in their cell wall sugar compositions and indicated significant differences in the levels of 6 out of 12 nucleotide sugars. The plant nucleotide sugar extraction procedure was demonstrated to have good recovery rates with minimal matrix effects. The approach results in a significant improvement in sensitivity when applied to plant samples over currently employed techniques. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. [Determination of 25 quinolones in cosmetics by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Lin, Li; Zhang, Yi; Tu, Xiaoke; Xie, Liqi; Yue, Zhenfeng; Kang, Haining; Wu, Weidong; Luo, Yao

    2015-03-01

    An analytical method was developed for the simultaneous determination of 25 quinolones, including danofloxacin mesylate, enrofloxacin, flumequine, oxloinic acid, ciprofloxacin, sarafloxacin, nalidixic acid, norfloxacin, and ofloxacin etc in cosmetics using direct extraction and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Cosmetic sample was extracted by acidified acetonitrile, defatted by n-hexane and separated on Poroshell EC-C18 column with gradient elution program using acetonitrile and water (both containing 0. 1% formic acid) as the mobile phases and analyzed by LC-ESI-MS/MS under the positive mode using multiple reaction monitoring (MRM). The interference of matrix was reduced by the matrix-matched calibration standard curve. The method showed good linearities over the range of 1-200 mg/kg for the 25 quinolones with good linear correlation coefficients (r ≥ 0.999). The method detection limit of the 25 quinolones was 1.0 mg/kg, and the recoveries of all analytes in lotion, milky and cream cosmetics matrices ranged from 87.4% to 105% at the spiked levels of 1, 5 and 10 mg/kg with the relative standard deviations (RSD) of 4.54%-19.7% (n = 6). The results indicated that this method is simple, fast and credible, and suitable for the simultaneous determination of the quinolones in the above three types of cosmetics.

  3. Quantitative analysis of heterocyclic amines in urine by liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Shin, Jeoung Hwa; Na, Yun-Cheol; Chung, Joo Hee; Gorinstein, Shela; Ahn, Yun Gyong

    2014-02-15

    A sensitive, reproducible, and rapid analytical method for the analysis of trace-level heterocyclic amines (HCAs) that are expected to have high levels of human exposure was developed. Liquid-liquid extraction (LLE) with dichloromethane (DCM) followed by solid-phase extraction (SPE) was carried out. Liquid extraction with DCM under basic conditions was efficient in extracting HCAs from urine samples. For further purification, mixed mode cationic exchange (MCX) cartridges were applied to eliminate the remaining interferences after liquid extraction. Separation and quantification were performed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in selected reaction monitoring (SRM) mode. The overall recoveries ranged between 71.0% and 113.6% with relative standard deviations (RSDs) of 5.1% to 14.7% for the entire procedure. The limits of detection (LODs) and limits of quantification (LOQs) of the proposed analytical method were in the ranges of 0.04 to 0.10 ng/ml and 0.15 to 0.36 ng/ml, respectively. This method was applied to the analysis of monitoring in urine samples for Korean school children, and the results demonstrated that the method can be used for the trace determination of HCAs in urine samples. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Optimized method for quantification of total F(2)-isoprostanes using gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Briskey, David R; Wilson, Gary R; Fassett, Robert G; Coombes, Jeff S

    2014-03-01

    F2-isoprostanes are produced from the oxidative degradation of arachidonic acid and are considered the gold standard marker of lipid peroxidation in biological samples. We developed a liquid-liquid extraction method for the determination of total isoprostanes using negative chemical ionization gas chromatography-tandem mass spectrometry in plasma and tissue homogenates. Incorporating liquid-liquid extraction allows for greater sample through-put than current approaches. Here we describe the protocol and include numerous trouble-shooting suggestions. The method found healthy individuals with 150-250 pg of isoprostanes per ml of plasma and end stage kidney disease patients to have the highest measured values of up to 1100 pg/ml. This assay has an accurate working linear range of 40-1000 pg of isoprostanes (100-2500 pg/ml) and an average coefficient of variance of 7%. Tissue values for healthy mice liver were 50-70 pg/μg protein. This method provides increased ion selectivity and detection capabilities with economical sample through-put. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. [Determination of ribavirin and amantadine in chicken by ultra performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Yun, Huan; Cui, Fengyun; Yan, Hua; Liu, Xin; He, Yue; Zhang, Zhaohui

    2013-08-01

    A method for the determination of ribavirin and amantadine in chicken has been developed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS). After extracted by 1% (volume percentage) trichloroacetic acid solution-acetonitrile (1:1, v/v) and purified by a Supelco LC-SCX cartridge, the samples were loaded onto an Acquity UPLC BEH Hillic column (150 mm x 2.1 mm, 1.7 microm) and separated with gradient elution. The electrospray was operated in the positive mode and the samples were monitored by the multiple reaction monitoring (MRM) mode. The limits of quantification (LOQs, S/N = 10) of ribavirin and amantadine were 4.0 microg/kg. The calibration curves showed good linearity in the range of 10.0 - 100.0 microg/L, and the correlation coefficients (r(2)) were not lower than 0.99. When the spiked levels were 4.0, 8.0 and 20.0 microg/kg, the recoveries of ribavirin and amantadine in chicken ranged from 78% to 102.5%, with the relative standard deviations (RSDs) of 2.2% - 7.6%. The results indicate that the method is simple, rapid, sensitive and suitable for the qualitative and quantitative analyses of ribavirin and amantadine in chicken samples.

  6. Quantitation of retinaldehyde in small biological samples using ultrahigh-performance liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Wang, Jinshan; Yoo, Hong Sik; Obrochta, Kristin M; Huang, Priscilla; Napoli, Joseph L

    2015-09-01

    We report an ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method to quantify all-trans-retinal in biological samples of limited size (15-35mg), which is especially advantageous for use with adipose. To facilitate recovery, retinal and the internal standard 3,4-didehydroretinal were derivatized in situ into their O-ethyloximes. UHPLC resolution combined with high sensitivity and specificity of MS/MS allowed quantification of retinal-O-ethyloximes with a 5-fmol lower limit of detection and a linear range from 5fmol to 1pmol. This assay revealed that extraocular concentrations of retinal range from approximately 2 to 40pmol/g in multiple tissues-the same range as all-trans-retinoic acid. All-trans-retinoic acid has high affinity (kd⩽0.4nM) for its nuclear receptors (RARα, -β, and -γ), whereas retinal has low (if any) affinity for these receptors, making it unlikely that these retinal concentrations would activate RAR. We also show that the copious amount of vitamin A used in chow diets increases retinal in adipose depots 2- to 5-fold relative to levels in adipose of mice fed a vitamin A-sufficient diet, as recommended for laboratory rodents. This assay also is proficient for quantifying conversion of retinol into retinal in vitro and, therefore, provides an efficient method to study metabolism of retinol in vivo and in vitro. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Determination of the Thyreostats in Animal Feeding Stuffs Using Liquid Chromatography-Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Woźniak Barbara

    2014-10-01

    Full Text Available A rapid liquid chromatography tandem mass spectrometry method was developed and validated to detect and confirm five thyreostatic drugs: tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil in animal feeding stuff samples. Thyreostats were extracted from feed with methanol, and then degreasing of the extract with petroleum ether was performed, followed by the derivatisation of the compounds with 3-iodobenzylbromide in basic medium (pH 8.0. The derivatives were extracted with diethyl ether and analysed by gradient elution on a Poroshell 120-EC C18 column with triple quadrupole MS detection with turbo spray source in positive ionisation mode. The method was validated in accordance with the Commission Decision 2002/657/EC. For validation level of 10 ļig kg-1, the recovery ranged from 82% to 97.5% for all examined compounds. The repeatability and reproducibility did not exceed the limit of 20% for all analytes. The linearity was good for all thyreostats in the whole range of tested concentrations, as proved by the correlation coefficients greater than 0.99. The decision limits (CCa ranged from 1.63 ļig kg-1 to 3.95 ļig kg-1, whereas the detection capabilities (CCß ranged from 2.74 ļig kg-1 to 6.73 ļig kg-1. The developed analysis is sensitive and robust, and therefore useful for quantification and confirmation of thyreostats in residue control programme.

  8. Determination of porphyrins in oral bacteria by liquid chromatography electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Fyrestam, Jonas; Bjurshammar, Nadja; Paulsson, Elin; Johannsen, Annsofi; Östman, Conny

    2015-09-01

    Biofilms in the oral cavity can be visualized by fluorescence and a common assumption is that the endogenously produced porphyrins in certain bacteria give rise to this fluorescence. Porphyrin content in oral bacteria has been sparingly investigated, and non-selective detection techniques such as utilizing the Soret fluorescence band of porphyrins are often used. In the present study, a quantitative and selective method for the determination of porphyrins in oral bacteria has been developed and validated using high performance liquid chromatography-tandem mass spectrometry. Lysis of bacteria using Tris-EDTA buffer together with ultrasonication showed high microbial killing efficiency ≥99.98%, and sample clean-up using C18-solid phase extraction resulted in low matrix effects ≤14% for all analytes. Using this method, the porphyrin content was determined in the two oral pathogens Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, as well as for baker's yeast, Saccharomyces cerevisiae. Uroporphyrin, 7-carboxylporphyrin, 6-carboxylporphyrin, coproporphyrin, and protoporphyrin IX were identified in the investigated microorganisms, and it was shown that the porphyrin profile differs between the two bacteria, as well as for S. cerevisiae. To our knowledge, this is the first time the porphyrin profile has been determined for the bacterium A. actinomycetemcomitans.

  9. [Determination of commonly abused dyes in food by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Yi, Xionghai; Deng, Xiaojun; Yang, Huiqin; Guo, Dehua; Zhu, Jian

    2011-11-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of commonly abused dyes in candy, sirup, liquid milk and fruit juice. The test sample was dissolved and diluted with water, then cleaned up by polyamide solid phase extraction. The LC separation was performed on an Agilent XDB-C18 column with 20 mmol/L ammonium acetate solution and acetonitrile as the mobile phase in a gradient elution mode. The dyes were determined by MS/MS in negative electrospray ionization mode, and quantified by matrix-matched external standard method. The calibration curves showed good linearity in the range of 0.5 - 50 mg/L with the correlation coefficients (r) greater than 0.99. The limits of quantitation (S/N > 10) were 0.5 mg/kg, and the limits of detection (S/N > 3) were 0.1 mg/kg. The recoveries of dyes in food samples at the three spiked levels of 0.5, 5 and 50 mg/kg were in the range of 62.6% - 115.3% with the relative standard deviations (RSDs) of 2.6% - 26.3%. The method can meet the requirements for the determination of the dyes in food samples for import and export inspection.

  10. Simultaneous quantification of twenty Amadori products in soy sauce using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Katayama, Hiroshi; Tatemichi, Yuki; Nakajima, Ayako

    2017-08-01

    A liquid chromatography-tandem mass spectrometry method using a pentafluorophenylpropyl-bonded silica column was developed to simultaneously quantify twenty Amadori products (APs), including N-(1-Deoxy-d-fructosyl-1-yl)-l-isoleucine (Fru-Ile) and N-(1-Deoxy-d-fructosyl-1-yl)-l-leucine (Fru-Leu), in soy sauce, without the need for an ion-pairing reagent or sample derivatization. The method was applied to six types of soy sauce, to determine the total AP levels and the levels of individual APs. The level of total APs widely varied between the eight samples, from 358mg/L to 24347mg/L. The concentrations of N-ε-(1-deoxy-d-fructosyl-1-yl)-l-lysine (Fru-Lys) and N-(1-deoxy-d-fructosyl-1-yl)-l-pyroglutamic acid (Fru-pGlu) were the highest among the APs and the level of Fru-pGlu was similar to that of Fru-Lys. Furthermore, fermentation periods of up to six months greatly influenced AP levels in soy sauce but the levels remained constant thereafter. Thermal treatment of soy sauce had little effect on AP levels. Copyright © 2017. Published by Elsevier Ltd.

  11. Tissue distribution study of naringin in rats by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Zou, W; Yang, C; Liu, M; Su, W

    2012-04-01

    Naringin (CAS 10236-47-2), a flavanone glucoside widely present in fruits of citrus plants, has received extensive studies on its potential effects on health benefits and was recently demonstrated to be a putative antitussive. In this study, we determined the tissue distributions of naringin and its metabolites (naringenin and naringenin's conjugates) in rats to examine whether they undergo selective uptake by specific organs. Naringin was administered orally to rats at the dose of 42 mg/kg and the concentrations of naringin and its metabolites in tissue compartments were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The areas under curve values in the individual tissues decreased as follows: stomach, small intestine, liver, trachea, muscle, kidney, lung, fat, heart, spleen, ovary, testis, brain for naringin; and liver, stomach, small intestine, kidney, trachea, lung, testis, heart, ovary, fat, spleen, muscle, brain for total naringenin (including free and its conjugates). Naringin and total naringenin were rapidly and widely distributed to all the tissues except brain in rats. They had difficulties in crossing the blood-brain barrier. There are no accumulations in rats. This study identifying naringin in several organs including lung and trachea may explain its effects as antitussive. © Georg Thieme Verlag KG Stuttgart · New York.

  12. Identification and quantification of dimethylamylamine in geranium by liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Li, J S; Chen, M; Li, Z C

    2012-01-01

    A sensitive and reliable method of liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI/MS/ MS) was developed and validated for determining 1,3-dimethylamylamine (1,3-DMAA) and 1,4-dimethylamylamine (1,4-DMAA) in geranium plants (Pelargonium graveolens). The sample was extracted with 0.5 M HCl and purified by liquid-liquid partition with hexane. The parameters for reverse-phase (C18) LC and positive ESI/MS/MS were optimized. The matrix effect, specificity, linearity, precision, accuracy and reproducibility of the method were determined and evaluated. The method was linear over a range of 0.10-10.00 ng/mL examined, with R(2) of 0.99 for both 1,3-DMAA and 1,4-DMAA. The recoveries from spiked concentrations between 5.00-40.00 ng/g were 85.1%-104.9% for 1,3-DMAA, with relative standard deviation (RSD) of 2.9%-11.0%, and 82.9%-101.8% for 1,4-DMAA, with RSD of 3.2%-11.7%. The instrument detection limit was 1-2 pg for both DMAAs. The quantification limit was estimated to be 1-2 ng/g for the plant sample. This method was successfully applied to the quantitative determination of 1,3- and 1,4-DMAA in both geranium plant and geranium oil.

  13. A liquid chromatography tandem mass spectroscopy approach for quantification of protein methylation stoichiometry.

    Science.gov (United States)

    Cooper, Grace L; Huseby, Carol J; Chandler, Claire N; Cocuron, Jean-Christophe; Alonso, Ana P; Kuret, Jeff

    2018-02-02

    Post-translational modifications are biologically important and wide-spread modulators of protein function. Although methods for detecting the presence of specific modifications are becoming established, approaches for quantifying their mol modification/mol protein stoichiometry are less well developed. Here we introduce a ratiometric, label-free, targeted liquid chromatography tandem mass spectroscopy-based method for estimating Lys and Arg methylation stoichiometry on post-translationally modified proteins. Methylated Lys and Arg were detected with limits of quantification at low fmol and with linearity extending from 20 to 5000 fmol. This level of sensitivity allowed estimation of methylation stoichiometry from microgram quantities of various proteins, including those derived from either recombinant or tissue sources. The method also disaggregated total methylation stoichiometry into its elementary mono-, di-, and tri-methylated residue components. In addition to being compatible with kinetic experiments of protein methylation, the approach will be especially useful for characterizing methylation states of proteins isolated from cells and tissues. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Affinity chromatographic selection of carbonylated proteins followed by identification of oxidation sites using tandem mass spectrometry.

    Science.gov (United States)

    Mirzaei, Hamid; Regnier, Fred

    2005-04-15

    It has been shown that oxidatively modified forms of proteins accumulate during oxidative stress, aging, and in some age-related diseases. One of the unique features of a wide variety of routes by which proteins are oxidized is the generation of carbonyl groups. This paper reports a method for the isolation of oxidized proteins, which involves (1) biotinylation of oxidized proteins with biotin hydrazide and (2) affinity enrichment using monomeric avidin affinity chromatography columns. The selectivity of the method was validated by adding in vitro oxidized biotinylated BSA to a yeast lysate and showing that the predominant protein recovered was BSA. This method was applied to the question of whether large doses of 2-nitropropane produce oxidized proteins. A study of rat liver homogenates showed that animals dosed with 2-nitropropane produced 17 times more oxidized protein than controls in 6 h. Tryptic digestion of these oxidized proteins followed by reversed-phase chromatography and tandem mass spectrometry led to the identification of 14 peptides and their parent proteins. Nine of the 14 identified peptides were found to carry 1 or 2 oxidation sites and 5 of the 9 peptides were biotinylated. The significance of this affinity method is that it allows the isolation of oxidized proteins from the rest of the proteome and facilitates their identification. In some cases, it is even possible to identify the site of oxidation.

  15. Comparison of automated 25-OH vitamin D immunoassays with liquid chromatography isotope dilution tandem mass spectrometry.

    Science.gov (United States)

    Koivula, Marja-Kaisa; Turpeinen, Ursula; Laitinen, Päivi; Risteli, Juha

    2012-01-01

    Comparing two fully automated 25-OH-D immunoassays with a validated liquid chromatography isotope dilution tandem mass spectrometry (LC-IDMS/MS) method in human serum samples. 180 samples were analyzed with the Liaison TOTAL Vitamin D, the IDS-iSYS 25-Hydroxy Vitamin D, and a validated LC-IDMS/MS 25-OH D method. The Liaison method mean +/- standard deviation (SD) was 64.3 +/- 23.5 nmol/L; the IDS-iSYS 70.1 +/- 27.0 nmol/L, and the LC-IDMS/MS 68.9 +/- 24.6 nmol/L. The correlation coefficient (r) between the Liaison and LC-IDMS/MS was 0.723, and the r between the IDS-iSYS and LC-IDMS/MS was 0.799. When the samples were grouped by females and males, the r between the Liaison and LC-IDMS/MS was 0.680 and 0.846, being 0.781 and 0.863 between the IDS-iSYS and LC-IDMS/MS, respectively. With the Passing-Bablok analysis, only the IDS-iSYS gave equivalent results to LC-IDMS/MS. The automated 25-OH-D immunoassays were in clinically good overall agreement with the LC-IDMS/MS method.

  16. Optimized experimental workflow for tandem mass spectrometry molecular networking in metabolomics.

    Science.gov (United States)

    Olivon, Florent; Roussi, Fanny; Litaudon, Marc; Touboul, David

    2017-09-01

    New omics sciences generate massive amounts of data, requiring to be sorted, curated, and statistically analyzed by dedicated software. Data-dependent acquisition mode including inclusion and exclusion rules for tandem mass spectrometry is routinely used to perform such analyses. While acquisition parameters are well described for proteomics, no general rule is currently available to generate reliable metabolomic data for molecular networking analysis on the Global Natural Product Social Molecular Networking platform (GNPS). Following on from an exploration of key parameters influencing the quality of molecular networks, universal optimal acquisition conditions for metabolomic studies are suggested in the present paper. The benefit of data pre-clustering before initiating large datasets for GNPS analyses is also demonstrated. Moreover, an efficient workflow dedicated to Agilent Technologies instruments is described, making the dereplication process easier by unambiguously distinguishing isobaric isomers eluted at different retention times, annotating the molecular networks with chemical formulas, and giving access to semi-quantitative data. This specific workflow foreshadows future developments of the GNPS platform.

  17. Quantification of ionophores in aged poultry litter using liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Biswas, Saptashati; McGrath, Joshua M; Sapkota, Amir

    2012-01-01

    Veterinary anticoccidials, biochemically known as ionophores, are widely used in poultry feed at therapeutic levels to treat Coccidiosis and at sub-therapeutic levels for growth- promotion. Commonly used ionophores in the US poultry industry are monensin, salinomycin, lasalocid and narasin. There is an increasing concern regarding the persistence of these anticoccidials in the environment. However, little attention has been directed to methods development for quantitatively measuring ionophores in complex environmental matrices such as poultry litters that are land applied. Here, we describe a rapid and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS)-based method developed for simultaneous quantification of monensin, lasalocid, salinomycin, and narasin in aged poultry litter samples. Results show significant level of monensin (97.8 ± 3.2 μg kg⁻¹), lasalocid (19.2 ± 6.6 μg kg⁻¹), salinomycin (70 ± 2.7 μg kg⁻¹) and narasin (57.3 ± 2.6 μg kg⁻¹) in poultry litter stored for over three years at ionophores may continue to persist in this matrix, raising the possibility of prolonged release into the environment.

  18. Confirmatory method for the determination of nitroimidazoles in milk by liquid chromatography - tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Mitrowska Kamila

    2014-12-01

    Full Text Available A multiresidue method for the determination of seven nitroimidazoles and their hydroxy metabolites in milk was developed. Milk samples were extracted with acetonitrile and cleaned up on strong cation-exchange solid phase extraction cartridges. Evaporated to dryness first, the extracts obtained were then reconstituted in 0.1% formic acid and injected onto a liquid chromatography-tandem mass spectrometer (LC-MS/MS. The separation of analytes was achieved on gradient mode using a C18 column and a mobile phase consisting of 0.1% formic acid in acetonitrile and 0.1% formic acid in water. Multiple reaction monitoring mode was set for the MS/MS with positive electrospray ionisation. For quantification, the isotope dilution method was used with isotopically labeled analogues of the target analytes. The method was evaluated entirely in accordance with EU Commission Decision 2002/657/EC and all validation criteria were in the required ranges. The method can easily detect and confirm metronidazole, dimetridazole, ronidazole, ipronidazole, and their hydroxy metabolites below the recommended concentration level of 3 μg/kg. The decision limits and detection capabilities ranged from 0.11 μg/kg to 0.22 μg/kg and from 0.19 μg/kg to 0.37 μg/kg respectively. The overall recoveries were between 96.6% and 105.2% with a good coefficient of variation, less than 8.7% under within-laboratory reproducibility conditions.

  19. Liquid chromatography-tandem mass spectrometry analysis of nitazoxanide and its major metabolites in goat.

    Science.gov (United States)

    Zhao, Zhanzhong; Zhang, Lifang; Xue, Feiqun; Wang, Xiaoyang; Zheng, Wenli; Zhang, Tao; Fei, Chenzhong; Zhang, Keyu; Qiu, Minqi; Xin, Ruixiang; Yang, Fengkun

    2008-11-15

    A rapid, sensitive and specific liquid chromatography-electrospray ionization (ESI) tandem mass spectrometry (LC-MS-MS) method has been developed for the identification of nitazoxanide metabolites in goat plasma and urine. The purified samples was separated using an XTerra MS C8 column with the mobile phase consisted of acetonitrile and 10-mM ammonium acetate buffer (pH 2.5) followed a linear gradient elution, and detected by MS-MS. Identification and structural elucidation of the metabolites were performed by comparing their retention-times, full scan, product ion scan, precursor ion scan and neutral loss scan MS-MS spectra with those of the parent drug or other available standard. Four metabolites (tizoxanide, tizoxanide glucuronide, tizoxanide sulfate and hydroxylated tizoxanide sulfate) were found and identified in goat after single oral administration of 200mg/kg dose of nitazoxanide. In addition, the possible metabolic pathway was proposed for the first time. The results proved that the established method was simple, reliable and sensitive, revealing that it could be used to rapid screen and identify the structures of active metabolites responsible for pharmacological effects of nitazoxanide and to better understand its in vivo metabolism.

  20. [Determination of pyriproxyfen residue in vegetables and fruits by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Zhao, Guangyu; Guo, Dehua; Zhao, Shanzhen; Sheng, Yonggang; Deng, Xiaojun

    2009-07-01

    A method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established for the determination of pyriproxyfen residue in vegetables and fruits. The pyriproxyfen residue in the sample was extracted by acidified acetonitrile with the presence of sodium acetate buffer, and cleaned up by PSA (primary secondary amine) sorbent, and the separation was performed by ultrafast liquid chromatography (UFLC) on a CAPCELL PAK C18 column (50 mm x 2.0 mm, 3 microm) and the gradient elution of acetonitrile (containing 0.1% formic acid) and 2 mmol/L ammonium acetate solution (containing 0.1% formic acid) at a flow rate of 0.3 mL/min. The calibration curve was linear between the peak area and the con centration of 2.5 - 50 microg/L with the correlation coefficient more than 0.9999. The limit of quantification of pyriproxyfen was 5 microg/kg. The average recoveries spiked at three concentrations of 5, 50 and 100 microg/kg ranged 84.7% -91.5%. The relative standard deviations (n = 10) were all less than 10%. The method is selective without interference and suitable for the determination of pyriproxyfen residue in vegetables and fruits.

  1. Assay reproducibility of serum androgen measurements using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Trabert, Britton; Xu, Xia; Falk, Roni T; Guillemette, Chantal; Stanczyk, Frank Z; McGlynn, Katherine A

    2016-01-01

    Valid and precise measures of androgen concentrations are needed for etiologic studies of hormonally-related cancers. We developed a high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with two sample preparations to measure 11 androgens, including adrenal and gonadal androgenic precursors and their 5α-reduced metabolites. Androgen levels were measured in serum from 20 healthy volunteers (5 men, 10 premenopausal women, 5 postmenopausal women). Two blinded, randomized aliquots per individual were assayed in each of three batches. A fourth batch of samples was measured at an external laboratory using comparable methodology to measure 9 of the 11 androgens. Coefficients of variation (CV) and intraclass correlation coefficients (ICC) were calculated from the individual components of variance. Comparability of 9 androgens across laboratories was assessed using Spearman ranked correlations, Deming regression and bias plots. The laboratory CVs were 95%) for all androgens measured across sex/menopausal status groups. Spearman ranked correlations for 9 hormones measured in the comparison laboratory were high (>0.85), suggesting good agreement. Our high-performance LC-MS/MS assays of 11 androgens, including adrenal and gonadal androgenic precursors and their 5α-reduced metabolites demonstrated excellent laboratory reproducibility, and good comparability with an established method that measured 9 of the 11 hormones tested. The serum androgen metabolite assays are suitable for use in epidemiologic research. Published by Elsevier Ltd.

  2. Liquid chromatography coupled to tandem mass spectrometry for detecting ten allergens in complex and incurred foodstuffs.

    Science.gov (United States)

    Planque, M; Arnould, T; Dieu, M; Delahaut, P; Renard, P; Gillard, N

    2017-12-29

    Food allergy is a considerable heath problem, as undesirable contaminations by allergens during food production are still widespread and may be dangerous for human health. To protect the population, laboratories need to develop reliable analytical methods in order to detect allergens in various food products. Currently, a large majority of allergen-related food recalls concern bakery products. It is therefore essential to detect allergens in unprocessed and processed foodstuffs. In this study, we developed a method for detecting ten allergens in complex (chocolate, ice cream) and processed (cookie, sauce) foodstuffs, based on ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Using a single protocol and considering a signal-to-noise ratio higher than 10 for the most abundant multiple reaction monitoring (MRM) transition, we were able to detect target allergens at 0.5mg/kg for milk proteins, 2.5mg/kg for peanut, hazelnut, pistachio, and cashew proteins, 3mg/kg for egg proteins, and 5mg/kg for soy, almond, walnut, and pecan proteins. The ability of the method to detect 10 allergens with a single protocol in complex and incurred food products makes it an attractive alternative to the ELISA method for routine laboratories. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Simultaneous determination of cosmetics ingredients in nail products by fast gas chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Zhou, Wanlong; Wang, Perry G; Wittenberg, James B; Rua, Diego; Krynitsky, Alexander J

    2016-05-13

    A rapid and sensitive gas chromatography with tandem mass spectrometry (GC-MS/MS) method has been developed and validated to quantitatively determine cosmetic ingredients, such as toluene, N-methylpyrrolidone, 2,4-dihydroxybenzophenone (benzophenone-1, BP-1), and diethylene glycol dimethacrylate, in nail products. In this procedure, test portions were extracted with acetone, followed by vortexing, sonication, centrifugation, and filtration. During the extraction procedure, BP-1 was derivatized making it amenable to GC-MS analysis, using N,O-​bis(trimethylsilyl)​trifluoroacetamide. The four ingredients were quantified by GC-MS/MS in an electron ionization mode. Four corresponding stable isotopically labeled analogues were selected as internal standards, which were added at the beginning of the sample preparation to correct for recoveries and matrix effects. The validated method was used to screen 34 commercial nail products for these four cosmetic ingredients. The most common ingredients detected in the nail products were toluene and BP-1. Toluene was detected in 26 products and ranged from 1.36 to 173,000μg/g. BP-1 ranged from 18.3 to 2,370μg/g in 10 products. Published by Elsevier B.V.

  4. Identification and Quantification of Glucosinolates in Kimchi by Liquid Chromatography-Electrospray Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Ho Jin Kim

    2017-01-01

    Full Text Available A novel and simple method for detecting five glucosinolates (glucoalyssin, gluconapin, glucobrassicanapin, glucobrassicin, and 4-methoxyglucobrassicin in kimchi was developed using liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS. The chromatographic peaks of the five glucosinolates were successfully identified by comparing their retention times, mass spectra. The mobile phase was composed of A (acetonitrile and B (water. As for glucosinolate, the relative quantities were found through sinigrin, and five different compounds that have not been previously discovered in kimchi were observed. Monitoring was carried out on the glucosinolate in 20 kimchis distributed in markets, and this study examined the various quality and quantity compositions of the five components. The glucoalyssin content ranged from 0.00 to 7.07 μmol/g of day weight (DW, with an average content of 0.86 μmol/g of DW, whereas the gluconapin content ranged from 0.00 to 5.85 μmol/g of DW, with an average of 1.17 μmol/g of DW. The content of glucobrassicanapin varied between 0.00 and 11.87 μmol/g of DW (average = 3.03 μmol/g of DW, whereas that of glucobrassicin varied between 0.00 and 0.42 μmol/g of DW (average = 0.06 μmol/g of DW. The 4-methoxyglucobrassicin content ranged from 0.12 to 9.36 μmol/g of DW (average = 3.52 μmol/g of DW. A comparison of the contents revealed that, in most cases, the content of 4-methoxyglucobrassicin was the highest.

  5. [Determination of aflatoxins in cashew by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Bi, Ruifeng; Fan, Zhixian; Fu, Meng

    2011-12-01

    A method for the determination of four aflatoxins in cashew using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The sample was extracted with methanol-water (8: 2, v/v) solution, followed by a cleanup procedure with Florisil column. The target compounds were eluted using 5 mL acetone-water-formic acid (96: 3.5:0.5, v/v/v) solution. The eluate was dried under N2, then dissolved in 1 mL methanol. Four aflatoxins were separated in MG C18 column (100 mm x 3.0 mm, 3 microm) adopting a gradient program within 15 min. A triple quadrupole mass spectrometry equipped with an electrospray ionization source operated in the positive ion mode was used to detect the aflatoxins. The good correlation coefficients (r2 > 0.997) of the four aflatoxins were obtained within their respective linear ranges. The limits of detection (S/N = 3) were between 0.009 microg/kg and 0.04 microg/kg, and the limits of quantification (S/N = 10) were between 0.03 microg/kg and 0.12 microg/kg. The recoveries were in a range of 63.0% -78.5% with the relative standard deviations (RSDs) varied from 2.8% to 9.1%. The validation results meet the requirements of trace assay. Matrix effects were estimated and the signal suppression/enhancement ranged from 88.8% to 99.4%. The results indicate that the developed method is simple, fast, accurate, and can be applied for the determination of fours aflatoxins in cashew.

  6. Liquid chromatography tandem mass spectrometry quantitation of intracellular concentrations of ganciclovir and its phosphorylated forms.

    Science.gov (United States)

    Billat, Pierre-André; Sauvage, François-Ludovic; Picard, Nicolas; Tafzi, Naїma; Alain, Sophie; Essig, Marie; Marquet, Pierre; Saint-Marcoux, Franck

    2015-05-01

    Ganciclovir (GCV) is prescribed for cytomegalovirus infection which is a major issue in immunodepressed patients. It is however characterized by hematological toxicity. A better understanding of GCV concentration-effects relationships implies the measurement of intracellular forms. The objective of this study was to develop a method to measure GCV and its derivatives in cells. A four-stage procedure was developed with the following strategy: (1) to separate into different fractions the different intracellular forms of GCV (GCV itself and its phosphorylated forms) by solid-phase extraction (SPE) from blood cells, (2) to dephosphorylate the different phosphorylated forms into GCV, (3) to perform a second SPE to desalt samples and concentrate GCV, and (4) to measure GCV concentrations in the different extracts using a triple-quadrupole, linear ion trap mass spectrometer. Finally, the procedure was tested in 17 patients receiving GCV. From lysed cells, the different forms of GCV were fractionated, the phosphorylated forms were eluted with different KCl solutions, and the obtained fractions were treated with acid phosphatase to transform the phosphorylated metabolites back into GCV. The method was validated from 5 to 500 μg L(-1) with a limit of detection of 1 μg L(-1). The whole procedure was validated according to the US Food and Drug Administration guidelines and successfully applied in 17 patients receiving GCV. The method liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) allowing the measurement of GCV and its phosphorylated forms in blood cells was developed and can be used in developing clinical studies to explore the role of these biomarkers in the event of toxicity.

  7. Neutron-encoded signatures enable product ion annotation from tandem mass spectra.

    Science.gov (United States)

    Richards, Alicia L; Vincent, Catherine E; Guthals, Adrian; Rose, Christopher M; Westphall, Michael S; Bandeira, Nuno; Coon, Joshua J

    2013-12-01

    We report the use of neutron-encoded (NeuCode) stable isotope labeling of amino acids in cell culture for the purpose of C-terminal product ion annotation. Two NeuCode labeling isotopologues of lysine, (13)C6(15)N2 and (2)H8, which differ by 36 mDa, were metabolically embedded in a sample proteome, and the resultant labeled proteins were combined, digested, and analyzed via liquid chromatography and mass spectrometry. With MS/MS scan resolving powers of ~50,000 or higher, product ions containing the C terminus (i.e. lysine) appear as a doublet spaced by exactly 36 mDa, whereas N-terminal fragments exist as a single m/z peak. Through theory and experiment, we demonstrate that over 90% of all y-type product ions have detectable doublets. We report on an algorithm that can extract these neutron signatures with high sensitivity and specificity. In other words, of 15,503 y-type product ion peaks, the y-type ion identification algorithm correctly identified 14,552 (93.2%) based on detection of the NeuCode doublet; 6.8% were misclassified (i.e. other ion types that were assigned as y-type products). Searching NeuCode labeled yeast with PepNovo(+) resulted in a 34% increase in correct de novo identifications relative to searching through MS/MS only. We use this tool to simplify spectra prior to database searching, to sort unmatched tandem mass spectra for spectral richness, for correlation of co-fragmented ions to their parent precursor, and for de novo sequence identification.

  8. Electrospray ionization tandem mass spectrometry for the simultaneous determination of opiates and cocaine in human hair.

    Science.gov (United States)

    Míguez-Framil, Martha; Moreda-Piñeiro, Antonio; Bermejo-Barrera, Pilar; Cocho, José Ángel; Tabernero, María Jesús; Bermejo, Ana María

    2011-10-17

    A fast and highly sensitive electrospray ionization tandem mass spectrometry (ESI-MS/MS) method has been developed for the simultaneous determination of morphine, 6-methylacetylmorphine (6-MAM), codeine, cocaine and benzoylecgonine (BZE) in hair from drug abusers. Pulverized hair samples were subjected to an optimized matrix solid phase dispersion (MSPD) procedure with alumina, followed by diluted hydrochloric acid elution on column solid-phase extraction (SPE) clean-up/pre-concentration. Alternatively, samples were also subjected to an optimized ultrasound assisted enzymatic hydrolysis (USEH) with Pronase E, followed by an off-line SPE clean up/pre-concentration procedure. Positive electrospray ionization and multiple reaction monitoring (MRM) with one precursor ion/product ion transition were used for the identification and quantification (deuterated analogues of each target as internal standards) of each analyte. The chromatographic pump and the autosampler were used for injecting the standards and the hair extracts (20 μL) as a flow injection analysis mode. The highest sensitivity was achieved when delivering the targets with an acetonitrile/water/formic acid (80/19.875/0.125) mixture. The limits of detection of the method were 39.2, 4.4, 6.8, 7.0 and 7.4 ng g(-1) for morphine, 6-MAM, codeine, cocaine and BZE, respectively. Relative standard deviations of intra- and inter-day precision were lower than 9 and 12%, respectively; whereas, analytical recoveries ranged from 96±5 to 106±4%. The developed method (MSPD-ESI-MS/MS) was applied to different hair samples from polydrug abusers, and results were statistically compared to those obtained after a conventional gas chromatography-mass spectrometry (GC-MS) analysis and also after USEH and ESI-MS/MS or GC-MS determinations. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Direct Analysis in Real Time (DART of an Organothiophosphate at Ultrahigh Resolution by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry and Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Laszlo Prokai

    2016-01-01

    Full Text Available Direct analysis in real time (DART is a recently developed ambient ionization technique for mass spectrometry to enable rapid and sensitive analyses with little or no sample preparation. After swab-based field sampling, the organothiophosphate malathion was analyzed using DART-Fourier transform ion cyclotron resonance (FT-ICR mass spectrometry (MS and tandem mass spectrometry (MS/MS. Mass resolution was documented to be over 800,000 in full-scan MS mode and over 1,000,000 for an MS/MS product ion produced by collision-induced dissociation of the protonated analyte. Mass measurement accuracy below 1 ppm was obtained for all DART-generated ions that belonged to the test compound in the mass spectra acquired using only external mass calibration. This high mass measurement accuracy, achievable at present only through FTMS, was required for unequivocal identification of the corresponding molecular formulae.

  10. Determination of Thiophanate-methyl in Tamoto by High Performance Liquid Chromatography-triple Quadrupole Tandem Mass Spectometry

    OpenAIRE

    XU, WEI-FENG; Han, Kai; SUN Yu-jie; PAN Kang-biao

    2014-01-01

    To evaluate the safety of use of 70% thiophanate-methyl wettable powders in tomato, a supervised trial experiment was conducted to study the residues in tomato. A method of determining thiophanate-methyl by high performance liquid chromatography-tandem mass spectrometry(LC-MSMS)was established. Acetonitrile was used as an extraction solvent, and PSA and anhydrous magnesium were used for sample purifying. Samples were determined and quantified by LC-MSMS in the multiple reaction monitoring mod...

  11. Gas-phase fragmentation of protonated piplartine and its fungal metabolites using tandem mass spectrometry and computational chemistry.

    Science.gov (United States)

    da Silva-Junior, E A; Paludo, C R; Gouvea, D R; Kato, M J; Furtado, N A J C; Lopes, N P; Vessecchi, R; Pupo, M T

    2017-08-01

    Piplartine, an alkaloid produced by plants in the genus Piper, displays promising anticancer activity. Understanding the gas-phase fragmentation of piplartine by electrospray ionization tandem mass spectrometry can be a useful tool to characterize biotransformed compounds produced by in vitro and in vivo metabolism studies. As part of our efforts to understand natural product fragmentation in electrospray ionization tandem mass spectrometry, the gas-phase fragmentation of piplartine and its two metabolites 3,4-dihydropiplartine and 8,9-dihydropiplartine, produced by the endophytic fungus Penicillium crustosum VR4 biotransformation, were systematically investigated. Proposed fragmentation reactions were supported by ESI-MS/MS data and computational thermochemistry. Cleavage of the C-7 and N-amide bond, followed by the formation of an acylium ion, were characteristic fragmentation reactions of piplartine and its analogs. The production of the acylium ion was followed by three consecutive and competitive reactions that involved methyl and methoxyl radical eliminations and neutral CO elimination, followed by the formation of a four-member ring with a stabilized tertiary carbocation. The absence of a double bond between carbons C-8 and C-9 in 8,9-dihydropiplartine destabilized the acylium ion and resulted in a fragmentation pathway not observed for piplartine and 3,4-dihydropiplartine. These results contribute to the further understanding of alkaloid gas-phase fragmentation and the future identification of piplartine metabolites and analogs using tandem mass spectrometry techniques. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  12. Binomial probability distribution model-based protein identification algorithm for tandem mass spectrometry utilizing peak intensity information.

    Science.gov (United States)

    Xiao, Chuan-Le; Chen, Xiao-Zhou; Du, Yang-Li; Sun, Xuesong; Zhang, Gong; He, Qing-Yu

    2013-01-04

    Mass spectrometry has become one of the most important technologies in proteomic analysis. Tandem mass spectrometry (LC-MS/MS) is a major tool for the analysis of peptide mixtures from protein samples. The key step of MS data processing is the identification of peptides from experimental spectra by searching public sequence databases. Although a number of algorithms to identify peptides from MS/MS data have been already proposed, e.g. Sequest, OMSSA, X!Tandem, Mascot, etc., they are mainly based on statistical models considering only peak-matches between experimental and theoretical spectra, but not peak intensity information. Moreover, different algorithms gave different results from the same MS data, implying their probable incompleteness and questionable reproducibility. We developed a novel peptide identification algorithm, ProVerB, based on a binomial probability distribution model of protein tandem mass spectrometry combined with a new scoring function, making full use of peak intensity information and, thus, enhancing the ability of identification. Compared with Mascot, Sequest, and SQID, ProVerB identified significantly more peptides from LC-MS/MS data sets than the current algorithms at 1% False Discovery Rate (FDR) and provided more confident peptide identifications. ProVerB is also compatible with various platforms and experimental data sets, showing its robustness and versatility. The open-source program ProVerB is available at http://bioinformatics.jnu.edu.cn/software/proverb/ .

  13. Comprehensive analysis of the mouse renal cortex using two-dimensional HPLC – tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Denner Larry

    2008-05-01

    Full Text Available Abstract Background Proteomic methodologies increasingly have been applied to the kidney to map the renal cortical proteome and to identify global changes in renal proteins induced by diseases such as diabetes. While progress has been made in establishing a renal cortical proteome using 1-D or 2-DE and mass spectrometry, the number of proteins definitively identified by mass spectrometry has remained surprisingly small. Low coverage of the renal cortical proteome as well as our interest in diabetes-induced changes in proteins found in the renal cortex prompted us to perform an in-depth proteomic analysis of mouse renal cortical tissue. Results We report a large scale analysis of mouse renal cortical proteome using SCX prefractionation strategy combined with HPLC – tandem mass spectrometry. High-confidence identification of ~2,000 proteins, including cytoplasmic, nuclear, plasma membrane, extracellular and unknown/unclassified proteins, was obtained by separating tryptic peptides of renal cortical proteins into 60 fractions by SCX prior to LC-MS/MS. The identified proteins represented the renal cortical proteome with no discernible bias due to protein physicochemical properties, subcellular distribution, biological processes, or molecular function. The highest ranked molecular functions were characteristic of tubular epithelium, and included binding, catalytic activity, transporter activity, structural molecule activity, and carrier activity. Comparison of this renal cortical proteome with published human urinary proteomes demonstrated enrichment of renal extracellular, plasma membrane, and lysosomal proteins in the urine, with a lack of intracellular proteins. Comparison of the most abundant proteins based on normalized spectral abundance factor (NSAF in this dataset versus a published glomerular proteome indicated enrichment of mitochondrial proteins in the former and cytoskeletal proteins in the latter. Conclusion A whole tissue extract of

  14. Development of hybrid mass damper (TRIGON) for high-rise buildings; Chokoso biruyo hybrid mass damper (TRIGON) no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-10-31

    The hybrid mass damper TRIGON has been developed to reduce wind-and earthquake-induced vibrations of high-rise buildings. The present paper describes an experimental result executed to confirm the outline of the hybrid mass damper TRIGON and the control effect of the same. The present apparatus is a mass damper for reducing the response of a building by supporting a weight with a V shaped bottom with a roller and rocking the weight into a pendulum motion. A driving method is a hybrid one where there are both used a passive system in which an apparatus period defined by the angle of the weight bottom is tuned with a building period and an active system using an AC servo motor. It is further intended that the apparatus is made compact by neglecting the length of the pendulum by employing the V-shaped weight for supporting the roller. Building vibration tests are conducted to compare responses of the apparatus upon non-control and control. It is hereby confirmed that there can be added about 4 % of a damping factor of the first mode in the direction of the short side of the building as a control object for a satisfactory improvement of the dwelling property. 4 refs., 14 figs., 3 tabs.

  15. [Measurement of sialic acid from lipoproteins and human plasma by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Guo, Shoudong; Sang, Hui; Yang, Nana; Kan, Yujie; Li, Fuyu; Li, Yu; Li, Fangyuan; Qin, Shucun

    2014-11-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established to quantify sialic acid (N-acetylneuraminic acid, NANA) from lipoproteins and human plasma. The method was used to investigate the different contents of NANA from lipoproteins between diabetic with an average age of 51.6 years and healthy participants with an average age of 50.7 years. The NANA from lipoprotein samples was hydrolyzed by acetic acid (pH = 2) at 80 °C for 2 h and analyzed by the optimized LC-MS/MS method after high speed centrifugation and filtration. The limits of detection and quantification of NANA were 7.4 and 24.5 pg, respectively. The linear range was 2.5-80 ng/mL for NANA and the correlation coefficient (R2) was more than 0.998. The levels of NANA in the plasma of type II diabetics and healthy participants were (548.3 ± 88.9) and (415.3 ± 55.5) mg/L, respectively; and the levels of NANA from very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) of the type II diabetics and the healthy participants were (4.91 ± 0.19), (6.95 ± 0.28), (3.61 ± 0.22) μg/mg and (2.90 ± 0.27), (7.03 ± 0.04), (2.40 ± 0.09) μg/mg, respectively. The sialic acid levels of VLDL and HDL from the type II diabetics were markedly higher than those of the corresponding healthy participants with the similar ages (P lipoproteins, and is reproducible and time saving.

  16. Analysis of Alkaloids in Areca Nut-Containing Products by Liquid Chromatography-Tandem Mass Spectrometry.

    Science.gov (United States)

    Jain, Vipin; Garg, Apurva; Parascandola, Mark; Chaturvedi, Pankaj; Khariwala, Samir S; Stepanov, Irina

    2017-03-08

    Chewing of areca nut in different forms such as betel quid or commercially produced pan masala and gutkha is common practice in the Indian subcontinent and many parts of Asia and is associated with a variety of negative health outcomes, particularly oral and esophageal cancers. Areca nut-specific alkaloids arecoline, arecaidine, guvacoline, and guvacine have been implicated in both the abuse liability and the carcinogenicity of the areca nut. Therefore, variations in the levels of areca alkaloids could potentially contribute to variations in addictive and carcinogenic potential across areca nut-containing products. Here, we developed an accurate and robust liquid chromatography-tandem mass-spectrometry (LC-MS/MS) method for simultaneous quantitation of all four areca alkaloids and applied this method to the analysis of a range of products obtained from India, China, and the United States. The results of the analyses revealed substantial variations in the levels of alkaloids across the tested products, with guvacine being the most abundant (1.39-8.16 mg/g), followed by arecoline (0.64-2.22 mg/g), arecaidine (0.14-1.70 mg/g), and guvacoline (0.17-0.99 mg/g). Substantial differences in the relative contribution of individual alkaloids to the total alkaloid content were also observed among the different products. Our results highlight the need for systematic surveillance of constituent levels in areca nut-containing products and a better understanding of the relationship between the chemical profile and the harmful potential of these products.

  17. Simultaneous Determination of Cortisol and Cortisone from Human Serum by Liquid Chromatography-Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Sanghoo Lee

    2014-01-01

    Full Text Available A fast, sensitive, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS method was validated and then the levels of cortisol and cortisone from sera of healthy adults were determined by the LC-MS/MS method. One hundred μL of serum sample was directly extracted by adding 2 mL ethyl acetate, followed by chromatographic separation on a C18 column with a mobile phase consisting of 5 mM ammonium acetate and methanol (25 : 75, v/v. The precision, accuracy, and average recovery of the method were 1.5–5.3%, 95.4–102.5%, and 96.4% for cortisol, and 1.9–6.0%, 89.2–98.8%, and 79.9% for cortisone, respectively. The method was linear from 1.0 to 500.0 ng/mL r2=0.999 for cortisol and 2.5 to 100.0 ng/mL r2=0.998 for cortisone. The limits of detection (LOD and quantification (LOQ were 0.2 and 1.0 ng/mL for cortisol, and 1.0 and 2.5 ng/mL for cortisone, respectively. The average cortisol concentration (133.9±63.7 ng/mL of samples collected between 9:00 and 11:00 a.m. was higher approximately 4.4 times than that of cortisone (30.5±10.7 ng/mL P<0.0001. The average cortisone/cortisol ratio was 0.225. Therefore, the LC-MS/MS method may be useful for the diagnosis of some adrenal diseases and the assessment of 11β-hydroxysteroid dehydrogenase (11β-HSD activity in clinical laboratories.

  18. A gas chromatography-tandem quadrupole mass spectrometric analysis of policosanols in commercial vegetable oils.

    Science.gov (United States)

    Jung, Dong Min; Lee, Mi Jin; Yoon, Suk Hoo; Jung, Mun Yhung

    2011-08-01

    Reportedly policosanols (PCs) have various beneficial functionalities on health. A gas chromatography-tandem mass spectrometry (GC-MS/MS) with a low limit of detection (LOD), and high specificity, recovery, and precision was successfully established for the PC analysis in vegetable oils. The LODs for the PCs were in the range of 0.002 to 0.016 μg/mL. The relative standard deviation (RSD) for the repeated analysis of PCs was less than 3.356%. The mean recoveries for spiked heptacosanol and octacosanol in vegetable oil were 102.3% and 106.3%, respectively. The total PC contents in the vegetable oils varied from 3.01 to 427.83 mg/kg oil. Perilla seed, grape seed, and rice bran oils were found to be highly rich sources of PCs, containing 427.83, 245.15, and 171.17 mg PCs/kg oil, respectively. Corn, sesame, and soybean oils contained only a negligible quantity of PCs. The PC composition in vegetable oils was greatly source dependent. In perilla seed oil, octacosanol was the single most predominant component, representing 55.93% of the total PC. In grape seed oil, however, hexacosanol is the most abundant PC, followed by octacosanol, tetracosanol, and triacontanol in a decreasing order. The major PCs in rice bran oil were triacontanol, octacosanol, hexacosanol, and tetracosanol, which constituted over 87.3% of the total PC. This represents the 1st report on the composition and contents of PC in most vegetable oils analyzed here. The information might be used for the development of vegetable oil products with beneficial functionality. © 2011 Institute of Food Technologists®

  19. msmsEval: tandem mass spectral quality assignment for high-throughput proteomics

    Directory of Open Access Journals (Sweden)

    Cartwright Hugh M

    2007-02-01

    Full Text Available Abstract Background In proteomics experiments, database-search programs are the method of choice for protein identification from tandem mass spectra. As amino acid sequence databases grow however, computing resources required for these programs have become prohibitive, particularly in searches for modified proteins. Recently, methods to limit the number of spectra to be searched based on spectral quality have been proposed by different research groups, but rankings of spectral quality have thus far been based on arbitrary cut-off values. In this work, we develop a more readily interpretable spectral quality statistic by providing probability values for the likelihood that spectra will be identifiable. Results We describe an application, msmsEval, that builds on previous work by statistically modeling the spectral quality discriminant function using a Gaussian mixture model. This allows a researcher to filter spectra based on the probability that a spectrum will ultimately be identified by database searching. We show that spectra that are predicted by msmsEval to be of high quality, yet remain unidentified in standard database searches, are candidates for more intensive search strategies. Using a well studied public dataset we also show that a high proportion (83.9% of the spectra predicted by msmsEval to be of high quality but that elude standard search strategies, are in fact interpretable. Conclusion msmsEval will be useful for high-throughput proteomics projects and is freely available for download from http://proteomics.ucd.ie/msmseval. Supports Windows, Mac OS X and Linux/Unix operating systems.

  20. Proteomic analysis of Moroccan cobra Naja haje legionis venom using tandem mass spectrometry.

    Science.gov (United States)

    Malih, Ibtissam; Ahmad rusmili, Muhamad Rusdi; Tee, Ting Yee; Saile, Rachid; Ghalim, Noreddine; Othman, Iekhsan

    2014-01-16

    The proteome of the venom of Naja haje legionis, the only medically important elapid species in Morocco, has been elucidated by using a combination of proteomic techniques that includes size exclusion chromatography, reverse-phase HPLC, Tricine/SDS-Page, tryptic digestion, Q-TOF tandem mass spectrometry and database search. The sequence analysis of venom fractions revealed a highly complex venom proteome which counts a total of 76 proteins identified from database that can be assigned into 9 proteins families. We report the identification of: cobra venom factor (CVF), l-amino-acid oxidases (LAAO), acetylcholinesterase (AChE), snake venom metalloproteinases (SVMP), cysteine rich secretory proteins (CRISP), venom nerve growth factor (vNGF), phospholipases A2 (PLA2), vespryns, kunitz-type inhibitor, short neurotoxins, long neurotoxins, weak neurotoxins, neurotoxin like proteins, muscarinic toxins, cardiotoxins and cytotoxins. Comparison of these proteins showed high sequence homology with proteins from other African and Asian cobras. Further works are needed to assess the contribution of individual toxins in venom toxicity. Naja haje legionis is one of the medically important snakes implicated in the pathogenesis of snake bite in Morocco. The absence of information about venom composition and clinical manifestations of envenomation by this cobra represents an obstacle for the management of this environmental disease in the country. The elucidation of Moroccan cobra venom composition will provide a reasonable guidance for clinician to understand the pathophysiological conditions associated with cobra envenomation and the elaboration of better management strategies. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Applying liquid chromatography-tandem mass spectrometry to assess endodontic sealer microleakage

    Directory of Open Access Journals (Sweden)

    André Luiz da Costa MICHELOTTO

    2015-01-01

    Full Text Available The objective of this study was to describe a new method for the quantitative analysis of a microleakage of endodontic filling materials. Forty extracted single-rooted teeth were randomly divided into three experimental groups. After root canal shaping, the experimental groups were filled using the lateral condensation technique with the Epiphany system (G1, with gutta-percha + Sealapex (G2, and with gutta-percha + AH Plus (G3. Each root was mounted on a modified leakage testing device, and caffeine solution was used as a tracer (2000 ng mL-1, pH 6.0, applied in the coronal direction towards the tooth apex, creating a hydrostatic pressure of 2.55 kPa. Presence of caffeine in the receiving solution was measured after 10, 30, and 60 days, using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS. None of the groups presented microleakage at 10 days. At 30 days, G2 and G3 showed similar infiltration patterns (means: 16.0 and 13.9 ng mL-1, respectively, whereas G1 showed significantly higher values (mean: 105.2 ng mL-1. At 60 days, leakage values were 182.6 ng mL-1for G1, 139.0 ng mL-1 for G2, and 53.5 ng mL-1 for G3. AH Plus showed the best sealing ability and HPLC-MS/MS showed high sensitivity and specificity for tracer quantification.

  2. Newborn screening of inherited metabolic disorders by tandem mass spectrometry: past, present and future

    Directory of Open Access Journals (Sweden)

    G. Scaturro

    2013-04-01

    Full Text Available Inborn errors of metabolism are inherited biochemical disorders caused by lack of a functional enzyme, transmembrane transporter, or similar protein, which then results in blockage of the corresponding metabolic pathway. Taken individually, inborn errors of metabolism are rare. However, as a group these diseases are relatively frequent and they may account for most of neonatal mortality and need of health resources. The detection of genetic metabolic disorders should occur in a pre-symptomatic phase. Recently, the introduction of the tandem mass spectrometric methods for metabolite analysis has changed our ability to detect intermediates of metabolism in smaller samples and provides the means to detect a large number of metabolic disorders in a single analytical run. Screening panels now include a large number of disorders that may not meet all the criteria that have been used as a reference for years. The rationale behind inclusion or exclusion of a respective disorder is difficult to understand in most cases and it may impose an ethical dilemma. The current organization is an important tool of secondary preventive medicine, essential for children’s healthcare, but the strong inhomogeneity of the regional models of screening applied today create in the Italian neonatal population macroscopic differences with regards to healthcare, which is in effect mainly diversified by the newborn’s place of birth, in possible violation of the universal criterion of the equality of all citizens. Carefully weighed arguments are urgently needed since patient organizations, opinion leaders and politicians are pressing to proceed with expansion of neonatal population screening.

  3. Direct total and free testosterone measurement by liquid chromatography tandem mass spectrometry across two different platforms.

    Science.gov (United States)

    Rhea, Jeanne M; French, Deborah; Molinaro, Ross J

    2013-05-01

    To develop and validate liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for the direct measurement of total and free testosterone in patient samples on two different analytical systems. An API 4000 and 5000 triple quadropoles were used and compared; the former is reported to be 3-5 times less sensitive, as was used to set the quantitation limits. Free testosterone was separated from the protein-bound fraction by equilibrium dialysis followed by derivatization. Either free or total testosterone, and a deuterated internal standard (d3-testosterone) were extracted by liquid-liquid extraction. The validation results were compared to two different clinical laboratories. The use of d2-testosterone was found to be unacceptable for our method. The total testosterone LC-MS/MS methods on both systems were linear over a wide concentration range of 1.5-2000ng/dL. Free testosterone was measured directly using equilibrium dialysis coupled LC-MS/MS and linear over the concentration range of 2.5-2500pg/mL. Good correlation (total testosterone, R(2)=0.96; free testosterone, R(2)=0.98) was observed between our LC-MS/MS systems and comparator laboratory. However, differences in absolute values for both free and total testosterone measurements were observed while a comparison to a second published LC-MS/MS method showed excellent correlation. Free and total testosterone measurements correlated well with clinical observations. To our knowledge, this is the first published validation of free and total testosterone methods across two analytical systems of different analytical sensitivities. A less sensitive system does not sacrifice analytical or clinical sensitivity to directly measure free and total testosterone in patient samples. Copyright © 2013 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  4. Determination of aflatoxins in medicinal plants by high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Siddique, Nadeem A; Mujeeb, Mohd; Ahmad, Sayeed; Panda, Bibhu P; Makhmoor, Mohd

    2013-01-01

    The intention of the proposed work is to study the presence of the aflatoxins B1, B2, G1 and G2 in medicinal plants, namely Mucuna pruriens, Delphinium denudatum and Portulaca oleraceae. The aflatoxins were extracted, purified by immunoaffinity column chromatography and analysed by high-performance liquid chromatography-tandem quadrupole mass spectrometry with electrospray ionisation (HPLC-MS/MS). Fungal count was carried out in PDA media. A good linear relationship was found for AFB1, AFB2, AFG1 and AFG2 at 1-10 ppb (r>0.9995). The analyte accuracy under three different spiking levels was 86.7-108.1 %, with low per cent relative standard deviations in each case. The aflatoxins can be separated within 5 to7 min using an Agilent XDB C18-column. We found that AFB1 and AFB2 were in trace amounts below the detection limit in M. pruriens whilst they were not detected in D. denudatum. P. oleraceae was found to be contaminated with AFB1 and AFB2. AFG1 and AFG2 were not detected in M. pruriens, P. oleraceae and were below the detection limit in D. denudatum. This was consistent with very low numbers of fungal colonies observed after 6 hr of incubation. The analytical method developed is simple, precise, accurate, economical and can be effectively used to determine the aflatoxins in medicinal plants and therefore to control the quality of products. The aflatoxin levels in the plant extracts examined were related to the minimal fungal load in the medicinal plants examined.

  5. [Determination of aniline in water and fish by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    He, Dechun; Zhao, Bo; Tang, Caiming; Xu, Zhencheng; Zhang, Sukun; Han, Jinglei

    2014-09-01

    A fast analytical method for the determination of aniline in water and fish meat by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. The water sample was mixed with acetonitrile by 4:1 (v/v) and the fish sample was extracted by 2.00 mL acetonitrile for each gram of sample, and then the extracts of water and fish samples were centrifuged at 5,000 r/min for 5 min. The separation was performed on a reversed-phase C18 column using mobile phases of acetonitrile-0.5% (v/v) formic acid aqueous solution (85:15, v/v). Aniline was separated within 3 min. The calibration curve was linear in the range of 0.5-500 pg/L with R2 > 0.999. The limits of detection (LODs) were 0.50 μg/L and 1.00 μg/kg and the limits of quantification (LOQs) were 1.00 μg/L and 2.00 μg/kg for aniline in water and fish meat, respectively. The average recoveries of aniline in water were 93.7% at the spiked level of 40 ng and 86.7% at the spiked level of 400 ng (n = 5). The average recoveries of aniline in fish were 96.8%, 92.6% and 81.8% at the spiked levels of 5, 50 and 500 ng respectively (n = 5). The relative standard deviations were 1.5%-9.2%. Thirteen water samples and twelve fish samples were collected from a reservoir polluted by aniline and the maximum contents found were 1,943. 6 μg/L in water and 60.8 μg/kg in fish. The method is suitable for the determination of aniline residues in water and fish with the characteristics of easy operation, high accuracy and precision.

  6. Nitroproteins in Human Astrocytomas Discovered by Gel Electrophoresis and Tandem Mass Spectrometry

    Science.gov (United States)

    Peng, Fang; Li, Jianglin; Guo, Tianyao; Yang, Haiyan; Li, Maoyu; Sang, Shushan; Li, Xuejun; Desiderio, Dominic M.; Zhan, Xianquan

    2015-12-01

    Protein tyrosine nitration is involved in the pathogenesis of highly fatal astrocytomas, a type of brain cancer. To understand the molecular mechanisms of astrocytomas and to discover new biomarkers/therapeutic targets, we sought to identify nitroproteins in human astrocytoma tissue. Anti-nitrotyrosine immunoreaction-positive proteins from a high-grade astrocytoma tissue were detected with two-dimensional gel electrophoresis (2DGE)-based nitrotyrosine immunoblots, and identified with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Fifty-seven nitrotyrosine immunopositive protein spots were detected. A total of 870 proteins (nitrated and non-nitrated) in nitrotyrosine-immunopositive 2D gel spots were identified, and 18 nitroproteins and their 20 nitrotyrosine sites were identified with MS/MS analysis. These nitroproteins participate in multiple processes, including drug-resistance, signal transduction, cytoskeleton, transcription and translation, cell proliferation and apoptosis, immune response, phenotypic dedifferentiation, cell migration, and metastasis. Among those nitroproteins that might play a role in astrocytomas was nitro-sorcin, which is involved in drug resistance and metastasis and might play a role in the spread and treatment of an astrocytoma. Semiquantitative immune-based measurements of different sorcin expressions were found among different grades of astrocytomas relative to controls, and a semiquantitative increased nitration level in high-grade astrocytoma relative to control. Nitro-β-tubulin functions in cytoskeleton and cell migration. Semiquantitative immunoreactivity of β-tubulin showed increased expression among different grades of astrocytomas relative to controls and semiquantitatively increased nitration level in high-grade astrocytoma relative to control. Each nitroprotein was rationalized and related to the corresponding functional system to provide new insights into tyrosine nitration and its potential role in the

  7. Designer psychostimulants in urine by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kerrigan, Sarah; Mott, Ashley; Jatzlau, Breanna; Ortiz, Francisco; Perrella, Laura; Martin, Sarah; Bryand, Kelsie

    2014-01-01

    Designer psychostimulants are known by recreational drug users to produce a complex array of adrenergic and hallucinogenic effects. Many of these drugs are not targeted during routine toxicology testing and as a consequence, they are rarely reported. The purpose of this study was to develop a procedure for the detection of 15 psychostimulants in urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS), specifically 2,5-dimethoxy-4-bromophenethylamine (2C-B), 2,5-dimethoxy-4-chlorophenethylamine (2C-C), 2,5-dimethoxy-4-methylphenethylamine (2C-D), 2,5-dimethoxy-4-ethylphenethylamine (2C-E), 2,5-dimethoxyphenethylamine (2C-H), 2,5-dimethoxy-4-iodophenethylamine (2C-I), 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2), 2,5-dimethoxy-4-isopropylthiophenethylamine (2C-T-4), 2,5-dimethoxy-4-propylthiophenethylamine (2C-T-7), 2,5-dimethoxy-4-bromoamphetamine (DOB), 2,5-dimethoxy-4-chloroamphetamine (DOC), 2,5-dimethoxy-4-ethylamphetamine (DOET), 2,5-dimethoxy-4-iodoamphetamine (DOI), 2,5-dimethoxy-4-methylamphetamine (DOM), and 4-methylthioamphetamine (4-MTA). Analytical recoveries using solid-phase extraction were 64-92% and the limit of detection was 0.5 ng/mL for all drugs except 2C-B (1 ng/mL). The assay was evaluated in terms of analytical recovery, precision, accuracy, linearity, matrix effect, and interferences. The technique allows for the simultaneous detection of 15 psychostimulants at sub-ng/mL concentrations. © 2013 American Academy of Forensic Sciences.

  8. Optimization of a liquid chromatography-tandem mass spectrometry method for quantification of the plant lignans secoisolariciresinol, matairesinol, lariciresinol and pinoresinol in foods

    NARCIS (Netherlands)

    Milder, I.E.J.; Arts, I.C.W.; Venema, D.P.; Lasaroms, J.J.P.; Wähälä, K.; Hollman, P.C.H.

    2004-01-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of the four major enterolignan precursors [secoisolariciresinol, matairesinol, lariciresinol, and pinoresinol] in foods. The method consists of alkaline methanolic extraction, followed by

  9. Single Laboratory Validated Method for Determination of Cylindrospermopsin and Anatoxin-a in Ambient Freshwaters by Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

    Science.gov (United States)

    This document is a standardized single laboratory validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the detection and quantification of cyanotoxins (combined intracellular and extracellular) in ambient freshwaters.

  10. EPA CRL MS014: Analysis of Aldicarb, Bromadiolone, Carbofuran, Oxamyl and Methomyl in Water by Multiple Reaction Monitoring Liquid Chromatography / Tandem Mass Spectrometry (LC/MS/MS)

    Science.gov (United States)

    Method MS014 describes procedures for solvent extraction of aldicarb, bromadiolone, carbofuran, oxamyl and methomyl from water samples, followed by analysis using liquid chromatography tandem mass spectrometry (LC-MS-MS).

  11. Boosting Sensitivity in Liquid Chromatography-Fourier Transform Ion Cyclotron Resonance-Tandem Mass Spectrometry for Product Ion Analysis of Monoterpene Indole Alkaloids

    National Research Council Canada - National Science Library

    Nakabayashi, Ryo; Tsugawa, Hiroshi; Kitajima, Mariko; Takayama, Hiromitsu; Saito, Kazuki

    2015-01-01

    .... However, the development of relevant analytical methods are less advanced. Here, we developed a method to boost sensitivity in liquid chromatography-Fourier transform ion cyclotron resonance-tandem mass spectrometry analysis...

  12. Application of liquid chromatography-tandem mass spectrometry in quantitative bioanalyses of organic molecules in aquatic environment and organisms.

    Science.gov (United States)

    Bussy, Ugo; Li, Ke; Li, Weiming

    2016-05-01

    Analytical methods using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of metabolites or contaminants (or both) in various tissues of aquatic organisms and in the aquatic environment have received increasing attention in the last few years. This review discusses the findings relevant to such procedures published between 2005 and 2015. The aim is to evaluate the advantages, restrictions, and performances of the procedures from sample preparation to mass spectrometry measurement. To support these discussions, a general knowledge on LC-MS/MS is also provided.

  13. Newborn screening and diagnosis of mucopolysaccharidoses: application of tandem mass spectrometry

    Science.gov (United States)

    Tomatsu, Shunji; Kubaski, Francyne; Sawamoto, Kazuki; Mason, Robert W.; Yasuda, Eriko; Shimada, Tsutomu; Montaño, Adriana M.; Yamaguchi, Seiji; Suzuki, Yasuyuki; Orii, Tadao

    2015-01-01

    Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by the deficiency of lysosomal enzymes. The enzymes are required to break down glycosaminoglycans (GAGs) that help build bone, cartilage, tendons, corneas, skin and connective tissue. In patients with MPS, a missing enzyme leads to the accumulation of GAGs in the cells, blood, connective tissues, and multiple organs. The consequence is permanent, with progressive cellular damage affecting patients’ appearance, physical abilities, organ and system function, and skeletal and mental development. The measurement of each specific GAG in a variety of specimens is required to establish the correlation between GAGs and physiological status of patients and/or prognosis and pathogenesis of the disease and to separate the patients with MPS from the healthy controls. We have developed a highly accurate, sensitive, and cost-effective liquid chromatography tandem mass spectrometry (LC-MS/MS) method for measurements of disaccharides derived from four specific GAGs [chondroitin sulfate (CS), dermatan sulfate (DS), heparan sulfate (HS), and keratan sulfate (KS)]. Disaccharides were produced by specific enzyme digestion of each GAG, and subsequently, quantified by negative ion mode of multiple reaction monitoring. Subclasses of GAGs with the same molecular weights can be separated by liquid chromatography. We have also developed another GAG assay by high-throughput mass spectrometry (HT-MS/MS). The HT-MS/MS consists of an integrated solid phase extraction robot that binds and de-salts samples from assay plates and directly injects them into a MS/MS detector, reducing sample processing time to within ten seconds. HT-MS/MS consequently yields much faster throughput than conventional LC-MS/MS-based methods; however, the HT-MS/MS system does not use a chromatographic step, and therefore, cannot separate GAGs that have the same molecular weights. Both techniques can be applied to the analysis of dried blood

  14. 10.5% efficient polymer and amorphous silicon hybrid tandem photovoltaic cell

    Science.gov (United States)

    Kim, Jeehwan; Hong, Ziruo; Li, Gang; Song, Tze-Bin; Chey, Jay; Lee, Yun Seog; You, Jingbi; Chen, Chun-Chao; Sadana, Devendra K.; Yang, Yang

    2015-03-01

    Thin-film solar cells made with amorphous silicon (a-Si:H) or organic semiconductors are considered as promising renewable energy sources due to their low manufacturing cost and light weight. However, the efficiency of single-junction a-Si:H or organic solar cells is typically photovoltaic cell by employing an a-Si:H film as a front sub-cell and a low band gap polymer:fullerene blend film as a back cell on planar glass substrates. Monolithic integration of 6.0% efficienct a-Si:H and 7.5% efficient polymer:fullerene blend solar cells results in a power conversion efficiency of 10.5%. Such high-efficiency thin-film tandem cells can be achieved by optical management and interface engineering of fully optimized high-performance front and back cells without sacrificing photovoltaic performance in both cells.

  15. Deciphering modifications in swine cardiac troponin I by top-down high-resolution tandem mass spectrometry.

    Science.gov (United States)

    Zhang, Jiang; Dong, Xintong; Hacker, Timothy A; Ge, Ying

    2010-06-01

    Cardiac troponin I (cTnI) is an important regulatory protein in cardiac muscle, and its modification represents a key mechanism in the regulation of cardiac muscle contraction and relaxation. cTnI is often referred to as the "gold-standard" serum biomarker for diagnosing patients with acute cardiac injury since it is unique to the heart and released into the circulation following necrotic death of cardiac tissue. The swine (Sus scrofa) heart model is extremely valuable for cardiovascular research since the heart anatomy and coronary artery distribution of swine are almost identical to those of humans. Herein, we report a comprehensive characterization of the modifications in swine cTnI using top-down high-resolution tandem mass spectrometry in conjugation with immunoaffinity chromatography purification. High-resolution high accuracy mass spectrometry revealed that swine cTnI affinity purified from domestic pig hearts was N-terminally acetylated and phosphorylated. Electron capture disassociation is uniquely suited for localization of labile phosphorylations, which unambiguously identified Ser22/Ser23 as the only basally phosphorylated sites that are well-known to be regulated by protein kinase A and protein kinase C. Moreover, a combination of tandem mass spectrometry with sequence homology alignment effectively localized a single amino acid polymorphism, V116A, representing a novel genetic variant of swine cTnI. Overall, our studies demonstrated the unique power of top-down high-resolution tandem mass spectrometry in the characterization of protein modifications, including labile phosphorylation and unexpected sequence variants. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

  16. Characterization of thin film tandem solar cells by radiofrequency pulsed glow discharge - Time of flight mass spectrometry.

    Science.gov (United States)

    Fernandez, Beatriz; Lobo, Lara; Reininghaus, Nies; Pereiro, Rosario; Sanz-Medel, Alfredo

    2017-04-01

    Beside low production costs and the use of nontoxic and abundant raw materials, silicon based thin-film solar cells have the advantage to be built up as multi junction devices like tandem or triple junction solar cells. Silicon thin film modules made of tandem cells with hydrogenated amorphous silicon (a-Si:H) top cell and microcrystalline (μc) Si:H bottom cell are available on the market. In this work, the analytical potential of state-of-the art radiofrequency (rf) pulsed glow discharge (PGD) time of flight mass spectrometry (TOFMS) commercial instrumentation is investigated for depth profiling analysis of tandem-junctions solar cells on 2mm thick glass substrate with 1µm thick ZnO:Al. Depth profile characterization of two thin film tandem photovoltaic devices was compared using millisecond and sub-millisecond rf-PGD regimes, as well as the so-called "low mass mode" available in the commercial instrument used. Two procedures for sample preparation, namely using flat or rough cell substrates, were compared and the distribution of dopant elements (phosphorous, boron and germanium) was investigated in both cases. Experimental results obtained by rf-PGD-TOFMS as well as electrical measurements of the samples showed that a worse depth resolution of dopant elements in the silicon layers (e.g. distribution of boron in a thicker region that suggests a diffusion of this dopant in the coating of the sample) found using a rough sample substrate was related to a higher power conversion efficiency. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Deciphering Modifications in Swine Cardiac Troponin I by Top-Down High-Resolution Tandem Mass Spectrometry

    Science.gov (United States)

    Zhang, Jiang; Dong, Xintong; Hacker, Timothy A.; Ge, Ying

    2011-01-01

    Cardiac troponin I (cTnI) is an important regulatory protein in cardiac muscle and its modification represents a key mechanism in the regulation of cardiac muscle contraction and relaxation. cTnI is often referred to as the “gold-standard” serum biomarker for diagnosing patients with acute cardiac injury since it is unique to the heart and released into the circulation following necrotic death of cardiac tissue. The swine (Sus scrofa) heart model is extremely valuable for cardiovascular research since the heart anatomy and coronary artery distribution of swine are almost identical to those of humans. Herein we report a comprehensive characterization of the modifications in swine cTnI using top-down high-resolution tandem mass spectrometry in conjugation with immunoaffinity chromatography purification. High-resolution high accuracy mass spectrometry revealed that swine cTnI affinity purified from domestic pig hearts was N-terminally acetylated and phosphorylated. Electron capture disassociation is uniquely suited for localization of labile phosphorylations, which unambiguously identified Ser22/Ser23 as the only basally phosphorylation sites that are well-known to be regulated by protein kinase A and protein kinase C. Moreover, a combination of tandem mass spectrometry with sequence homology alignment effectively localized a single amino acid polymorphism, V116A, representing a novel genetic variant of swine cTnI. Overall, our studies demonstrated the unique power of top-down high-resolution tandem mass spectrometry in the characterization of protein modifications including labile phosphorylation and unexpected sequence variants. PMID:20223681

  18. Structural Characterisation of Acetogenins from Annona muricata by Supercritical Fluid Chromatography Coupled to High-Resolution Tandem Mass Spectrometry.

    Science.gov (United States)

    Laboureur, Laurent; Bonneau, Natacha; Champy, Pierre; Brunelle, Alain; Touboul, David

    2017-11-01

    Acetogenins are plant polyketides known to be cytotoxic and proposed as antitumor candidates. They are also suspected to be alimentary neurotoxins. Their occurrence as complex mixtures renders their dereplication and structural identification difficult using liquid chromatography coupled to tandem mass spectrometry and efforts are required to improve the methodology. To develop a supercritical fluid chromatography (SFC) high-resolution tandem mass spectrometry method, involving lithium post-column cationisation, for the structural characterisation of Annonaceous acetogenins in crude extracts. The seeds of Annona muricata L. were extracted with methanol. Supercritical fluid chromatography of the extract, using a 2-ethylpyridine stationary phase column, was monitored using a high-resolution quadrupole time-of-flight mass spectrometer. Lithium iodide was added post-column in the make-up solvent. For comparison, the same extract was analysed using high-pressure liquid chromatography coupled to the same mass spectrometer, with a column based on solid core particles. Sensitivity was similar for both HPLC and SFC approaches. Retention behaviour and fragmentation pathways of three different isomer groups are described. A previously unknown group of acetogenins was also evidenced for the first time. The use of SFC-MS/MS allows the reduction of the time of analysis, of environmental impact and an increase in the chromatographic resolution, compared to liquid chromatography. This new methodology enlightened a new group of acetogenins, isomers of montanacin-D. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Oligosaccharide sequence determination using B/E linked field scanning or tandem mass spectrometry of phosphatidylethanolamine derivatives.

    Science.gov (United States)

    Chai, W; Cashmore, G C; Stoll, M S; Gaskell, S J; Orkiszewski, R S; Lawson, A M

    1991-05-01

    Product ion mass spectral data of [M + H]+ ions of oligosaccharides, mainly tetra- and pentasaccharides, as their dipalmitoyl phosphatidylethanolamine derivatives were obtained using both liquid secondary ion mass spectrometry with B/E linked scanning and fast atom bombardment ionization with collision-induced dissociation/tandem mass spectrometry. Both methods give similar positive product ion spectra of equivalent high sensitivity (detection limits of approximately 50 pmol) that principally contain glycosidic cleavage ions retaining the reducing end of the molecule from which monosaccharide sequence can be deduced. A series of ions from fission of the phosphate ester bond together with glycosidic cleavage are present in the tandem mass spectra and B/E linked scan spectra when helium collision gas is used. Monosaccharide linkage position of isomeric molecules is reflected in the intensity of glycosidic fragmentation, without retention of the oxygen atom, with decreasing cleavage in the order 1-3 greater than 1-4 greater than 1-6 linkage. Fucose and N-acetylhexosamines show an increased degree of fragmentation over hexose sugars. The application of product ion spectra of derivatized oligosaccharides is demonstrated for characterizing mixed samples and also the acquisition of spectra directly from the silica surface of high-performance thin-layer chromatography plates.

  20. Multiplexed steroid profiling of gluco- and mineralocorticoids pathways using a liquid chromatography tandem mass spectrometry method.

    Science.gov (United States)

    Travers, Simon; Martinerie, Laetitia; Bouvattier, Claire; Boileau, Pascal; Lombès, Marc; Pussard, Eric

    2017-01-01

    Serum steroid assays are major tools in the clinical evaluation of adrenal disorders. The main adrenal steroids are routinely measured with immunoassays. However, chromatographic methods are known to offer better specificity. We report a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for simultaneous quantification of 15 adrenal steroids targeting the mineralo- and gluco-corticosteroid pathways. Serum steroids combined with deuterated internal standards were extracted using successive protein precipitation and solid phase extraction steps. Cortisol, cortisone, 11-deoxycortisol, 17-hydroxyprogesterone, 21-deoxycortisol, progesterone, 11-deoxycorticosterone, corticosterone, 11-dehydrocorticosterone, 18-hydroxycorticosterone, 18-hydroxy-11-deoxycorticosterone, aldosterone, dehydroepiandrosterone sulfate, testosterone and androstenedione were resolved in fourteen minutes using a BEH C18 column coupled to a methanol-ammonium formate gradient. Detection was performed using multiple reaction monitoring quantitation. Routinely determined steroid levels by immunoassays were compared to those measured by LC-MS/MS. This method was applied to assess steroid profiles in congenital adrenal hyperplasia (CAH) patients with 21-hydroxylase deficiency. Low quantification limits depending on each steroid (ranging from 0.015ng/mL for aldosterone to 20ng/mL for DHEAS) are adapted to the clinical use. Recoveries of steroids range from 64% for 21-deoxycortisol to 101% for cortisol and are fully corrected by internal standards. A good linearity with R>0.989 is obtained for each compound. The inter-day variation coefficients ranged from 4.7% for cortisol to 16.3% for 11-deoxycorticosterone. The immunoassay for cortisol (Immulite 2000, Siemens) showed acceptable agreement with LC-MS/MS (bias +7.2%). However, Bland-Altman plots revealed large negative bias for aldosterone (-33.4%, AldoCT, CisBio international), for 17-hydroxyprogesterone at concentrations below 2ng/mL (-74

  1. Matrix interference evaluation employing GC and LC coupled to triple quadrupole tandem mass spectrometry.

    Science.gov (United States)

    Uclés, S; Lozano, A; Sosa, A; Parrilla Vázquez, P; Valverde, A; Fernández-Alba, A R

    2017-11-01

    Gas and liquid chromatography coupled to triple quadrupole tandem mass spectrometry are currently the most powerful tools employed for the routine analysis of pesticide residues in food control laboratories. However, whatever the multiresidue extraction method, there will be a residual matrix effect making it difficult to identify/quantify some specific compounds in certain cases. Two main effects stand out: (i) co-elution with isobaric matrix interferents, which can be a major drawback for unequivocal identification, and therefore false negative detections, and (ii) signal suppression/enhancement, commonly called the "matrix effect", which may cause serious problems including inaccurate quantitation, low analyte detectability and increased method uncertainty. The aim of this analytical study is to provide a framework for evaluating the maximum expected errors associated with the matrix effects. The worst-case study contrived to give an estimation of the extreme errors caused by matrix effects when extraction/determination protocols are applied in routine multiresidue analysis. Twenty-five different blank matrices extracted with the four most common extraction methods used in routine analysis (citrate QuEChERS with/without PSA clean-up, ethyl acetate and the Dutch mini-Luke "NL" methods) were evaluated by both GC-QqQ-MS/MS and LC-QqQ-MS/MS. The results showed that the presence of matrix compounds with isobaric transitions to target pesticides was higher in GC than under LC in the experimental conditions tested. In a second study, the number of "potential" false negatives was evaluated. For that, ten matrices with higher percentages of natural interfering components were checked. Additionally, the results showed that for more than 90% of the cases, pesticide quantification was not affected by matrix-matched standard calibration when an interferent was kept constant along the calibration curve. The error in quantification depended on the concentration level. In a

  2. Quantification of six cannabinoids and metabolites in oral fluid by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Desrosiers, Nathalie A; Scheidweiler, Karl B; Huestis, Marilyn A

    2015-08-01

    Δ(9) -Tetrahydrocannabinol (THC) is the most commonly analyzed cannabinoid in oral fluid (OF); however, its metabolite 11-nor-9-carboxy-THC (THCCOOH) offers the advantage of documenting active consumption, as it is not detected in cannabis smoke. Analytical challenges such as low (ng/L) THCCOOH OF concentrations hampered routine OF THCCOOH monitoring. Presence of minor cannabinoids like cannabidiol and cannabinol offer the advantage of identifying recent cannabis intake. Published OF cannabinoids methods have limitations, including few analytes and lengthy derivatization. We developed and validated a sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for THC, its metabolites, 11-hydroxy-THC and THCCOOH quantification, and other natural cannabinoids including tetrahydrocannabivarin (THCV), cannabidiol (CBD), and cannabigerol (CBG) in 1 mL OF collected with the Quantisal device. After solid-phase extraction, chromatography was performed on a Selectra PFPP column with a 0.15% formic acid in water and acetonitrile gradient with a 0.5 mL/min flow rate. All analytes were monitored in positive mode atmospheric pressure chemical ionization (APCI) with multiple reaction monitoring. Limits of quantification were 15 ng/L THCCOOH and 0.2 µg/L for all other analytes. Linear ranges extended to 3750 ng/L THCCOOH, 100 µg/L THC, and 50 µg/L for all other analytes. Inter-day analytical recoveries (bias) and imprecision at low, mid, and high quality control (QC) concentrations were 88.7-107.3% and 2.3-6.7%, respectively (n = 20). Mean extraction efficiencies and matrix effects evaluated at low and high QC were 75.9-86.1% and 8.4-99.4%, respectively. This method will be highly useful for workplace, criminal justice, drug treatment and driving under the influence of cannabis OF testing. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  3. Detection of 10 sweeteners in various foods by liquid chromatography/tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Chui-Shiang Chang

    2014-09-01

    Full Text Available The analytical method for sweeteners in various food matrixes is very important for food quality control and regulation enforcement. A simple and rapid method for the simultaneous determination of 10 sweeteners [acesulfame potassium (ACS-K, aspartame (ASP, cyclamate (CYC, dulcin (DUL, glycyrrhizic acid (GA, neotame (NEO, neohesperidin dihydrochalcone (NHDC, saccharin (SAC, sucralose (SCL, and stevioside (STV] in various foods by liquid chromatography/tandem mass chromatography (LC–MS/MS was developed. The chromatographic separation was performed on a Phenomenex Luna Phenyl-Hexyl (5 μm, 4.6 mm × 150 mm column with gradient elution of 10 mM ammonium acetate in water and 10 mM ammonium acetate in methanol. The recoveries of the 10 sweeteners were between 75% and 120%, and the coefficients of variation were less than 20%. The limits of quantification were 0.5 μg/kg for NHDC and SCL. For the other sweeteners, the limits of quantification were 0.1 μg/kg. Compared to the traditional high-performance liquid chromatography method, the LC–MS/MS method could provide better sensitivity, higher throughput, enhanced specificity, and more sweeteners analyzed in a single run. The samples included 27 beverages (16 alcoholic and 11 nonalcoholic beverages and 15 pickled foods (1 pickled pepper, 3 candies, and 11 candied fruits. Two remanufactured wines were found to contain 7.2, 8.5 μg/g SAC and 126.5, 123 μg/g CYC, respectively. ACS-K, ASP, SCL, and NEO were detected in five beverages and drinks. The pickled peppers and candied fruits were found to contain SAC, GA, CYC, ASP, STV, NEO, and ACS-K. The wine with sweeteners detected was remanufactured wine, not naturally fermented wine. Therefore, the ingredient label for the sweeteners of remanufactured wine should be regulated by the proper authority for inspection of sweeteners.

  4. Multiresidue analysis of multiclass plant growth regulators in grapes by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Oulkar, Dasharath P; Banerjee, Kaushik; Ghaste, Manoj S; Ramteke, Sahadeo D; Naik, Dattatraya G; Patil, Shubhangi B; Jadhav, Manjusha R; Adsule, Pandurang G

    2011-01-01

    A selective and rapid multiresidue analysis method is presented for simultaneous estimation of 12 plant growth regulators (PGRs), namely, auxins (indol-3-acetic acid, indol-3-butyric acid, and naphthyl acetic acid), cytokinins (kinetin, zeatin, and 6-benzyladenine), gibberellic acid (GA3), abscisic acid, and synthetic compounds, namely, forchlorfenuron, paclobutrazole, isoprothiolane, and 2,4-dichlorophenoxy acetic acid (2,4-D) in bud sprouts and grape berries at the development stages of 2-3 and 6-8 mm diameters, which are the critical phases when exogenous application of PGRs may be necessary to achieve desired grape quality and yield. The sample preparation method involved extraction of plant material with acidified methanol (50%) by homogenization for 2 min at 15000 rpm. The pH of the extract was enhanced up to 6 by adding ammonium acetate, followed by homogenization and centrifugation. The supernatant extract was cleaned by SPE on an Oasis HLB cartridge (200 mg, 6 cc). The final extract was measured directly by LC/MS/MS with electrospray ionization in positive mode, except for 2,4-D, GA3, and abscisic acid extracts, which required analysis in negative mode. Quantification by multiple reaction monitoring (MRM) was supported with full-scan mass spectrometric confirmation using "information-dependent acquisition" triggered with MRM to "enhanced product ionization" mode of the hybrid quadrupole-ion trap mass analyzer. The LOQ of the test analytes varied between 1 and 10 ng/g with associated recoveries of 80-120% and precision RSD <25% (n = 8). Significant matrix-induced signal suppression was recorded when the responses for pre- and postextraction spikes of analytes were compared; this could be resolved by using matrix-matched calibration standards. The method could successfully be applied in analyzing incurred residue samples and would, therefore, be useful in precisely deciding the necessity and dose of exogenous applications of PGRs on the basis of measured

  5. Liquid chromatography-mass spectrometric and liquid chromatography-tandem mass spectrometric determination of hallucinogenic indoles psilocin and psilocybin in "magic mushroom" samples.

    Science.gov (United States)

    Kamata, Tooru; Nishikawa, Mayumi; Katagi, Munehiro; Tsuchihashi, Hitoshi

    2005-03-01

    Accurate and sensitive analytical methods for psilocin (PC) and psilocybin (PB), tryptamine-type hallucinogens contained in "magic mushrooms," were investigated using liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The chromatographic separation on an ODS column and mass spectral information gave complete discrimination between PC and PB without derivatization. The mass spectrometric detection had a high sensitivity, and the tandem mass spectrometric detection provided more specificity and accuracy, as well as high sensitivity. The detection limits ranged from 1 to 25 pg by LC-MS in the selected ion monitoring mode, and the intra- and inter-day coefficients of variation were estimated to be 4.21-5.93% by LC-MS-MS in the selected reaction monitoring mode. By applying the present LC-MS-MS technique to four real samples, the contents of PC and PB were found to vary over a wide range (0.60-1.4 and 0.18-3.8 mg/g dry wt. for PC and PB, respectively) between samples.

  6. Quantitative Thin-Layer Chromatography/Mass Spectrometry Analysis of Caffeine Using a Surface Sampling Probe Electrospray Ionization Tandem Mass Spectrometry System

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Michael J [ORNL; Deibel, Michael A. [Earlham College; Tomkins, Bruce A [ORNL; Van Berkel, Gary J [ORNL

    2005-01-01

    Quantitative determination of caffeine on reversed-phase C8 thin-layer chromatography plates using a surface sampling electrospray ionization system with tandem mass spectrometry detection is reported. The thin-layer chromatography/electrospray tandem mass spectrometry method employed a deuterium-labeled caffeine internal standard and selected reaction monitoring detection. Up to nine parallel caffeine bands on a single plate were sampled in a single surface scanning experiment requiring 35 min at a surface scan rate of 44 {mu}m/s. A reversed-phase HPLC/UV caffeine assay was developed in parallel to assess the mass spectrometry method performance. Limits of detection for the HPLC/UV and thin-layer chromatography/electrospray tandem mass spectrometry methods determined from the calibration curve statistics were 0.20 ng injected (0.50 {mu}L) and 1.0 ng spotted on the plate, respectively. Spike recoveries with standards and real samples ranged between 97 and 106% for both methods. The caffeine content of three diet soft drinks (Diet Coke, Diet Cherry Coke, Diet Pepsi) and three diet sport drinks (Diet Turbo Tea, Speed Stack Grape, Speed Stack Fruit Punch) was measured. The HPLC/UV and mass spectrometry determinations were in general agreement, and these values were consistent with the quoted values for two of the three diet colas. In the case of Diet Cherry Coke and the diet sports drinks, the determined caffeine amounts using both methods were consistently higher (by 8% or more) than the literature values.

  7. Determination of aminoglycoside residues in kidney and honey samples by hydrophilic interaction chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kumar, Praveen; Rúbies, Antoni; Companyó, Ramon; Centrich, Francesc

    2012-10-01

    Two methods based on liquid chromatography-tandem mass spectrometry were developed for the determination of ten aminoglycosides (streptomycin, dihydrostreptomycin, spectinomycin, apramycin, paromomycin, kanamycin A, gentamycin C1, gentamycin C2/C2a, gentamycin C1a, and neomycin B) in kidney samples from food-producing animals and in honey samples. The methods involved extraction with an aqueous solution (for the kidney samples) or sample dissolution in water (for the honey samples), solid-phase extraction with a weak cation exchange cartridge and injection of the eluate into a liquid chromatography-tandem mass spectrometry system. A zwitterionic hydrophilic interaction chromatography column was used for separation of aminoglycosides and a triple quadrupole mass analyzer was used for detection. The methods were validated according to Decision 2002/657/EC. The limits of quantitation ranged from 2 to 125 μg/kg in honey and 25 to 264 μg/kg in the kidney samples. Interday precision (RSD%) ranged from 6 to 26% in honey and 2 to 21% in kidney. Trueness, expressed as the percentage of error, ranged from 7 to 20% in honey and 1 to 11% in kidney. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Quantification of citalopram or escitalopram and their demethylated metabolites in neonatal hair samples by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Frison, Giampietro; Favretto, Donata; Vogliardi, Susanna; Terranova, Claudio; Ferrara, Santo Davide

    2008-08-01

    Citalopram and escitalopram are highly selective serotonin reuptake inhibitors widely used in the treatment of depression. They exhibit adverse drug reactions and side effects, however, and the development of specific methods for their determination is of great interest in clinical and forensic toxicology. A liquid chromatography-tandem mass spectrometry method has been developed and validated for the assay of citalopram, escitalopram, and their demethylated metabolites in 10-mg hair samples. The analytes were extracted by incubation in methanol and liquid/liquid extraction with diethyl ether/dichloromethane. Gradient elution on a narrow bore C18 column was realized using clomipramine-d3 as an internal standard. Positive ion electrospray ionization and tandem mass spectrometry determination by collision-induced dissociation were performed in an ion trap mass spectrometer. The method exhibited a linear range of 25 to 2000 pg/mg, a quantification limit of 25 pg/mg for all analytes, relative standard deviations in the range of 12.10 to 9.80 (intraassay), and 13.80 to 11.78 (interassay), and accuracies (as percent recovery of the spiked standards) in the range of 90% to 110%; it was applied to the determination of citalopram and escitalopram and their metabolites in hair samples of two newborns to document their in utero exposure to the drugs. The method proved suitable for neonatal hair analysis of citalopram or escitalopram and was applied to two real cases of gestational exposure.

  9. [Simultaneous determination of polyether antibiotics and macrolide anthelmintics in livestock products by liquid chromatography/tandem mass spectrometry].

    Science.gov (United States)

    Yamaguchi, Mizuka; Kakimoto, Kensaku; Yamaguchi, Takahiro; Obana, Hirotaka

    2011-01-01

    A method using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of polyether antibiotics and macrolide anthelmintics in livestock products. The polyether antibiotics and macrolide anthelmintics were extracted from livestock products with acetonitrile and cleaned up with dispersive solid-phase extractions and a silica gel column. The quantification limits of polyether antibiotics and macrolide anthelmintics were 0.00005-0.0005 µg/g. Except for narasin and lasalocid in bovine liver and milk, the recoveries were 70 to 117%. The relative standard deviations met the required guideline. The developed method was applied to six kinds of livestock products.

  10. Identification of Ceftiofur Oxidation Products by High-Performance Liquid Chromatography/Electrospray Ionization/Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Hye-Sung Cho

    2011-03-01

    Full Text Available Oxidation products of ceftiofur were formed in hydrogen peroxide solution. The structures of the ceftiofur oxidationproducts were characterized by high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry(HPLC/ESI/MS/MS. The products were identified as compounds oxidized at the sulfur of a cephem ring. For further analysis,experiments were performed using O18-labeled hydrogen peroxide. In addition, density-functional calculations were carried out forsix possible oxidation products to support the experimental results.

  11. Variations in IBD (ACAD8) in children with elevated C4-carnitine detected by tandem mass spectrometry newborn screening

    DEFF Research Database (Denmark)

    Pedersen, Christina B; Bischoff, Claus; Christensen, Ernst

    2006-01-01

    or compound heterozygous for variations in the IBD gene have been reported. We present IBD deficiency in an additional four newborns with elevated C(4)-carnitine identified by tandem mass spectrometry (MS/MS) screening in Denmark and the United States. Three showed urinary excretions of isobutyryl......-CoA dehydrogenase (SCAD) gene revealed heterozygosity for the prevalent c.625G>A susceptibility variation in all newborns and in the first reported IBD patient. Functional studies in isolated mitochondria demonstrated that the IBD variations present in the Danish newborn (c.409G>A and c.958G>A) together...

  12. High-Performance Liquid Chromatographic-Tandem Mass Spectrometric Determination of Itraconazole in Human Plasma for Bioavailability and Bioequivalence Studies

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Wook; Nam, Dae Young; Kang, Kyoung Hoon; Ha, Kyung Wook; Han, In Hee; Chang, Byung Kon; Yoon, Mi Kyeong; Lee, Jae Hwi [Chung-Ang University, Seoul (Korea, Republic of)

    2006-02-15

    A highly sensitive high-performance liquid chromatographic-tandem mass spectrometric method (HPLC-MSMS) has been developed to quantify itraconazole in human plasma for the purpose of pharmacokinetic studies. Sample preparation was carried out by liquid-liquid extraction using loratadine as an internal standard. Chromatographic separation used a YMC C{sub 18} column, giving an extremely fast total run time of 3 min. The method was validated and used for the bioequivalence study of itraconazole tablets in healthy male volunteers (n = 31). The lower limit of detection proved to be 0.2 ng /mL for itraconazole.

  13. Pivotal role of computers and software in mass spectrometry - SEQUEST and 20 years of tandem MS database searching.

    Science.gov (United States)

    Yates, John R

    2015-11-01

    Advances in computer technology and software have driven developments in mass spectrometry over the last 50 years. Computers and software have been impactful in three areas: the automation of difficult calculations to aid interpretation, the collection of data and control of instruments, and data interpretation. As the power of computers has grown, so too has the utility and impact on mass spectrometers and their capabilities. This has been particularly evident in the use of tandem mass spectrometry data to search protein and nucleotide sequence databases to identify peptide and protein sequences. This capability has driven the development of many new approaches to study biological systems, including the use of "bottom-up shotgun proteomics" to directly analyze protein mixtures. Graphical Abstract ᅟ.

  14. Detection of nicotine as an indicator of tobacco smoke by direct analysis in real time (DART) tandem mass spectrometry

    Science.gov (United States)

    Kuki, Ákos; Nagy, Lajos; Nagy, Tibor; Zsuga, Miklós; Kéki, Sándor

    2015-01-01

    The residual tobacco smoke contamination (thirdhand smoke, THS) on the clothes of a smoker was examined by direct analysis in real time (DART) mass spectrometry. DART-MS enabled sensitive and selective analysis of nicotine as the indicator of tobacco smoke pollution. Tandem mass spectrometric (MS/MS) experiments were also performed to confirm the identification of nicotine. Transferred thirdhand smoke originated from the fingers of a smoker onto other objects was also detected by DART mass spectrometry. DART-MS/MS was utilized for monitoring the secondhand tobacco smoke (SHS) in the air of the laboratory using nicotine as an indicator. To the best of our knowledge, this is the first report on the application of DART-MS and DART-MS/MS to the detection of thirdhand smoke and to the monitoring of secondhand smoke.

  15. Analysis of small carbohydrates in several bioactive botanicals by gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Moldoveanu, Serban; Scott, Wayne; Zhu, Jeff

    2015-11-01

    Bioactive botanicals contain natural compounds with specific biological activity, such as antibacterial, antioxidant, immune stimulating, and taste improving. A full characterization of the chemical composition of these botanicals is frequently necessary. A study of small carbohydrates from the plant materials of 18 bioactive botanicals is further described. The study presents the identification of the carbohydrate using a gas chromatographic-mass spectrometric analysis that allows detection of molecules as large as maltotetraose, after changing them into trimethylsilyl derivatives. A number of carbohydrates in the plant (fructose, glucose, mannose, sucrose, maltose, xylose, sorbitol, and myo-, chiro-, and scyllo-inositols) were quantitated using a novel liquid chromatography with tandem mass spectrometric technique. Both techniques involved new method developments. The gas chromatography with mass spectrometric analysis involved derivatization and separation on a Rxi(®)-5Sil MS column with H2 as a carrier gas. The liquid chromatographic separation was obtained using a hydrophilic interaction type column, YMC-PAC Polyamine II. The tandem mass spectrometer used an electrospray ionization source in multiple reaction monitoring positive ion mode with the detection of the adducts of the carbohydrates with Cs(+) ions. The validated quantitative procedure showed excellent precision and accuracy allowing the analysis in a wide range of concentrations of the analytes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Searching molecular structure databases with tandem mass spectra using CSI:FingerID.

    Science.gov (United States)

    Dührkop, Kai; Shen, Huibin; Meusel, Marvin; Rousu, Juho; Böcker, Sebastian

    2015-10-13

    Metabolites provide a direct functional signature of cellular state. Untargeted metabolomics experiments usually rely on tandem MS to identify the thousands of compounds in a biological sample. Today, the vast majority of metabolites remain unknown. We present a method for searching molecular structure databases using tandem MS data of small molecules. Our method computes a fragmentation tree that best explains the fragmentation spectrum of an unknown molecule. We use the fragmentation tree to predict the molecular structure fingerprint of the unknown compound using machine learning. This fingerprint is then used to search a molecular structure database such as PubChem. Our method is shown to improve on the competing methods for computational metabolite identification by a considerable margin.

  17. Simplified analysis of glyphosate and aminomethylphosphonic acid in water, vegetation and soil by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Marek, LeEtta J; Koskinen, William C

    2014-07-01

    There is a need for a simple, fast, efficient and sensitive method for analysis of glyphosate and its degradate aminomethylphosphonic acid (AMPA) in diverse matrices such as water, vegetation and soil. Aqueous extracts from water, vegetation and soil were passed through reverse-phase and cation-exchange columns and directly injected into a tandem mass spectrometer using only a guard column for separation. Extraction efficiencies from the three matrices were >80% for both glyphosate and AMPA. The method reporting levels (MRLs) for glyphosate in water, vegetation and soil were 3.04 µg L(-1) , 0.05 mg kg(-1) and 0.37 mg kg(-1) respectively. AMPA MRLs were 5.06 µg L(-1) for water, 0.08 mg kg(-1) for vegetation and 0.61 mg kg(-1) for soil. A validated, simple and efficient liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for routine analysis of glyphosate and AMPA in water, vegetation and soil that uses minimal sample handling and clean-up will facilitate the additional environmental research needed to address the continuing concerns related to increasing glyphosate use. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  18. Determination of nifedipine in dog plasma by high-performance liquid chromatography with tandem mass spectrometric detection.

    Science.gov (United States)

    Pan, Xigui; Zhou, Shunchang; Fu, Qinqin; Hu, Xianming; Wu, Jianhong

    2014-07-01

    Nifedipine is a dihydropyridine calcium channel blocker used widely in the management of hypertension and other cardiovascular disorders. In this work, a simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated to determine nifedipine in dog plasma using nimodipine as the internal standard. Chromatographic separation was carried out on a C₈ column. The mobile phase consisted of a mixture of acetonitrile, water and formic acid (60:40:0.2, v/v/v) at a flow rate of 0.5 mL/min. Detection was performed on a triple quadrupole tandem mass spectrometer in selected reaction monitoring mode via an atmospheric pressure chemical ionization source. The method has a lower limit of quantification of 0.20 ng/mL with consumption of plasma as low as 0.05 mL. The linear calibration curves were obtained in the concentration range of 0.20-50.0 ng/mL (r = 0.9948). The recoveries of the liquid extraction method were 74.5-84.1%. Intra-day and inter-day precisions were 4.1-8.8 and 6.7-7.4%, respectively. The quantification was not interfered with by other plasma components and the method was applied to determine nifedipine in plasma after a single oral administration of two controlled-release nifedipine tablets to beagle dogs. Copyright © 2013 John Wiley & Sons, Ltd.

  19. Quantification of fat-soluble vitamins in human breast milk by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kamao, Maya; Tsugawa, Naoko; Suhara, Yoshitomo; Wada, Akimori; Mori, Toshiyuki; Murata, Kazuo; Nishino, Riichiro; Ukita, Tetsuya; Uenishi, Kazuhiro; Tanaka, Kiyoshi; Okano, Toshio

    2007-11-15

    Sensitive quantification method for fat-soluble vitamins in human breast milk by liquid chromatography-tandem mass spectrometry was developed. Vitamins A, D and E were extracted from 10.0 mL of breast milk after saponifying by basic condition. Vitamin K derivatives were extracted from 3.0 mL of breast milk after lipase treatment. The corresponding stable isotope-labeled compounds were used as internal standards. For the determination of vitamin D compounds, derivatization with a Cookson-type reagent was performed. All fat-soluble vitamins were determined by liquid chromatography-tandem mass spectrometry in the positive ion mode. The detection limits of all analytes were 1-250 pg per 50 microL. The recoveries of fat-soluble vitamins were 91-105%. Inter-assay CV values of each vitamin were 1.9-11.9%. The mean concentrations of retinol, vitamin D3, 25-hydroxyvitamin D3, alpha-tocopherol, phylloquinone and menaquinone-4 were 0.455 microg/mL, 0.088 ng/mL, 0.081 ng/mL, 5.087 microg/mL, 3.771 ng/mL, and 1.795 ng/mL, respectively (n=82). This method makes possible to determine fat-soluble vitamins with a wide range of polarities in human breast milk. The assay may be useful for large-scale studies.

  20. [High-sensitivity analysis of purines in alcoholic beverages using hydrophilic interaction chromatography coupled with tandem mass spectrometry].

    Science.gov (United States)

    Kakigi, Yasuhiro; Yoshioka, Toshiaki; Nagatomi, Yasushi; Uyama, Atsuo; Mochizuki, Naoki

    2014-01-01

    In this study, we established a high-sensitivity analytical method for purines in alcoholic beverages using hydrophilic interaction chromatography coupled with tandem mass spectrometry. The alcoholic beverages were hydrolyzed with perchloric acid (60%) and subjected to strong cation exchange solid-phase extraction (Bond Elut SCX). The four purine bases (hypoxanthine, adenine, xanthine, guanine) in the extracted solution were separated by hydrophilic interaction chromatography with TSKgel Amide-80 as a separation column, 10 mM ammonium formate (pH 2.0) as mobile phase A, and acetonitrile/100 mM ammonium formate (pH 2.0) (90/10) as mobile phase B. The detection of purine bases was performed by tandem mass spectrometry with ESI. The linearity of this analytical method was not less than 0.996, and the repeatability was not more than 8.4% for each purine base. The recovery was in the range of 60-105%, and the detection limit was not more than 0.005 mg/100 mL. This established method is expected to be useful for quality control and surveillance of purines in alcoholic beverages.

  1. Determination of caprolactam and 6-aminocaproic acid in human urine using hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Wu, Ya-Hsueh; Wu, Ming-Ling; Lin, Chun-Chi; Chu, Wei-Lan; Yang, Chen-Chang; Lin, Robert Tate; Deng, Jou-Fang

    2012-02-15

    A simple and rapid assay based on hydrophilic interaction liquid chromatography with tandem mass spectrometry has been first developed and validated for simultaneous determination of caprolactam (CA) and 6-aminocaproic acid (6-ANCA) in human urine using 8-aminocaprylic acid as internal standard. A 20μL aliquot of urine was injected directly into the liquid chromatography tandem mass spectrometry (LC-MS-MS) system. The analytes were separated on a Phenomenex Luna HILIC column with gradient elution. Detection was performed on Triple Quadrupole LC-MS in positive ions multiple reaction monitoring mode using electrospray ionization. The calibration curves were linear (r(2)≥0.995) over the concentration range from 62.5 to 1250ng/mL for CA and 31.25 to 1000ng/mL for 6-ANCA. The detection limits of CA and 6-ANCA were 62.5 and 15.6ng/mL, respectively. The intra-day and inter-day precisions were within 8.7% and 9.9%, respectively. The intra-day and inter-day accuracy were between 5.3% and 3.5%, and between 6.1% and 6.6%, respectively. The method proved to be simple and time efficient, and was successfully applied to evaluate the kinetics of caprolactam in one unusual case of caprolactam poisoning. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. A simple and selective liquid chromatography- tandem mass spectrometry method for determination of ε-aminocaproic acid in human plasma

    Directory of Open Access Journals (Sweden)

    Ganesh S. Moorthy

    2015-07-01

    Full Text Available Understanding the clinical pharmacology of the antifibrinolytic drug epsilon-aminocaproic acid (EACA is critical for rational drug administration in children. The aim of this study is to develop a reliable assay for the determination of EACA in human plasma. We describe a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS assay for EACA in human plasma. Sample preparation involved plasma dilution (1:2040, followed by reversed-phase chromatographic separation and selective detection using tandem mass spectrometry. EACA had a linear range of 1 - 250 μg/mL. The intraday precision based on the standard deviation of replicates of quality control samples ranged from 4.7 to 10.4% and the accuracy ranged from 92-106%. The interday precision ranged from 4.6 to 9.8% and the accuracy ranged from 95-103%. Stability studies showed that EACA was stable during the conditions for sample preparation and storage. The described method is robust and successfully employed for clinical studies of EACA in children

  3. Quantitative determination of chromium picolinate in animal feeds by solid phase extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Han, Miaomiao; Tian, Ying; Li, Zhen; Chen, Yiqiang; Yang, Wenjun; Zhang, Liying

    2017-12-01

    Chromium picolinate is one of the important Cr(3+) resources and is widely used in animal production. A convenient, reliable and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitative determination of chromium picolinate in animal feeds. Feed samples were extracted with acetonitrile and subsequently cleaned up by solid phase extraction cartridges Supelclean™ LC-18. Chromium picolinate was efficiently separated with a Waters ACQUITY UPLC(®) BEH C18 column, ionized with electrospray ion source in positive mode (ESI(+)), and quantitatively determined by tandem mass spectrometry in multiple reaction monitoring mode. Standard calibration curve of chromium picolinate in the concentration range from 0.5 to 1000ng/mL was obtained with good linearity correlation coefficient (R(2)=0.9982). Average recoveries ranged from 95.37%∼105.54%, as detected by spiking 0.02∼640mg/kg of chromium picolinate in complete feed, concentrated feed and premix. Intra-day and inter-day coefficient of variation were 0.59%∼6.67% and 2.36%∼6.97%, respectively. The limits of quantitation were 0.02mg/kg, 0.025mg/kg, and 2mg/kg for complete feed, concentrated feed, and premix, respectively. Actual sample analysis indicated that the developed method can be an effective tool to monitoring CrPic content in animal feed. Copyright © 2017. Published by Elsevier B.V.

  4. Screening for estrogen residues in calf urine: Comparison of a validated yeast estrogen bioassay and gas chromatography-tandem mass spectrometry

    NARCIS (Netherlands)

    Nielen, M.W.F.; Bovee, T.F.H.; Heskamp, H.H.; Lasaroms, J.J.P.; Sanders, M.B.; Rhijn, van J.A.; Groot, M.J.; Hoogenboom, L.A.P.

    2006-01-01

    Within the European Union, the control for residues of illegal hormones in food-producing animals is based on urine analysis for a few target analytes using gas chromatography/mass spectrometry and/or liquid chromatography¿tandem mass spectrometry. Recently, we developed a robust yeast bioassay

  5. SHAMS: Combining chemical modification of RNA with mass spectrometry to examine polypurine tract-containing RNA/DNA hybrids

    Science.gov (United States)

    Turner, Kevin B.; Yi-Brunozzi, Hye Young; Brinson, Robert G.; Marino, John P.; Fabris, Daniele; Le Grice, Stuart F.J.

    2009-01-01

    Selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE) has gained popularity as a facile method of examining RNA structure both in vitro and in vivo, exploiting accessibility of the ribose 2′-OH to acylation by N-methylisatoic anhydride (NMIA) in unpaired or flexible configurations. Subsequent primer extension terminates at the site of chemical modification, and these products are fractionated by high-resolution gel electrophoresis. When applying SHAPE to investigate structural features associated with the wild-type and analog-substituted polypurine tract (PPT)–containing RNA/DNA hybrids, their size (20–25 base pairs) rendered primer extension impractical. As an alternative method of detection, we reasoned that chemical modification could be combined with tandem mass spectrometry, relying on the mass increment of RNA fragments containing the NMIA adduct (Mr = 133 Da). Using this approach, we demonstrate both specific modification of the HIV-1 PPT RNA primer and variations in its acylation pattern induced by replacing template nucleotides with a non-hydrogen-bonding thymine isostere. Our selective 2′-hydroxyl acylation analyzed by mass spectrometry strategy (SHAMS) should find utility when examining the structure of small RNA fragments or RNA/DNA hybrids where primer extension cannot be performed. PMID:19535461

  6. De Novo Sequencing of Top-Down Tandem Mass Spectra: A Next Step towards Retrieving a Complete Protein Sequence.

    Science.gov (United States)

    Vyatkina, Kira

    2017-02-08

    De novo sequencing of tandem (MS/MS) mass spectra represents the only way to determine the sequence of proteins from organisms with unknown genomes, or the ones not directly inscribed in a genome-such as antibodies, or novel splice variants. Top-down mass spectrometry provides new opportunities for analyzing such proteins; however, retrieving a complete protein sequence from top-down MS/MS spectra still remains a distant goal. In this paper, we review the state-of-the-art on this subject, and enhance our previously developed Twister algorithm for de novo sequencing of peptides from top-down MS/MS spectra to derive longer sequence fragments of a target protein.

  7. Identification of plasmalogen cardiolipins from Pectinatus by liquid chromatography-high resolution electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Řezanka, Tomáš; Matoulková, Dagmar; Kyselová, Lucie; Sigler, Karel

    2013-12-01

    High resolution electrospray ionization tandem mass spectrometry (HR-ESI-MS/MS) was used to analyze cardiolipins (Ptd2Gro) including their plasmalogen forms from three species of the anaerobic beer-spoilage bacterial genus Pectinatus. Cardiolipins including their plasmalogens were analyzed by HR-ESI-MS/MS on Orbitrap and almost 100 cardiolipins (i.e. tetra-acyl--Ptd2Gro, plasmenyl-tri-acyl--PlsPtd2Gro, and di-plasmenyl-di-acyl--Pls2Ptd2Gro) of three classes were identified. The structures of the molecular species that consist of various regioisomers and structurally similar compounds were revealed in detail. The high resolution mass spectrometry allowed the unambiguous structural assignment of Ptd2Gro, PlsPtd2Gro, and Pls2Ptd2Gro in the three species of Pectinatus, which contain predominantly odd numbered fatty acids.

  8. A New Liquid Chromatography-Tandem Mass Spectrometry Method for Determination of Bisoprolol in Human Plasma Samples

    Directory of Open Access Journals (Sweden)

    Gabriela Peste

    2009-01-01

    Full Text Available Liquid chromatography (LC coupled with mass spectrometry (MS detection is one of the most powerful analytical tools for organic compound analysis. The advantages of using LC/MS methods over HPLC methods include: selectivity, chromatographic integrity, peak assignment, structural information, and rapid method development. In this paper, a new liquid chromatography-tandem mass spectrometry (LC-MS/MS method has been developed and validated for the determination of bisoprolol in human plasma samples, using metoprolol as internal standard and liquid-liquid extraction procedure. The assay has proven to be sensitive, specific and reproducible, suitable to determine the bisoprolol concentration, following a single oral administration of a 10 mg bisoprolol tablet in 22 healthy volunteers, in the bioequivalence study of Bisoprolol 10 mg coated tablets, produced by Antibiotice S.A. versus Concor 10 mg, produced by Merck.

  9. Preparation and structural elucidation of the picolinyl ester of aldosterone for liquid chromatography-electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Yamashita, Kouwa; Tadokoro, Yumiko; Takahashi, Madoka; Numazawa, Mitsuteru

    2008-06-01

    Treatment of aldosterone with 35% HCl in EtOH or in MeOH followed by the picolinyl derivatization gave the picolinyl derivative of aldosterone-ethyl ether, 8, or methyl ether, 9, as a single and well-shaped liquid chromatographic peak. Picolinyl derivatization of aldosterone produced 21-picolinyl derivative of 18,20-anhydro-hemiacetal derivatives, 6, with poor chromatographic peak with wide half-width. Further conversion of 6 to 8 required long reaction time (>4 h). Structure of each picolinyl or alkyl ether-picolinyl derivative, was carefully elucidated by nuclear magnetic resonance spectroscopy, electron ionization mass spectrometry and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Enhancement of sensitivity (approximately 10-fold) in positive-LC-ESI-MS/MS of aldosterone was confirmed by the use of the alkyl ether-picolinyl derivatization when compared to the underivatized molecule.

  10. Data in support for the measurement of serum 25-hydroxyvitamin D (25OHD by tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    M.E. Jensen

    2016-09-01

    Full Text Available This article provides data and a method related to a research paper entitled “Assessing vitamin D nutritional status: is capillary blood adequate?” (Jensen et al., 2016 [1]. Circulating 25OHD, the accepted biomarker of the vitamin D nutritional status, is routinely measured by automated immunoassays, that although may be performed in hospital central laboratories, often suffer from a lack of specificity with regards to the different vitamin D metabolites, “Measurement of circulating 25-hydroxyvitamin D: a historical review” (Le Goff et al., 2015 [2]. Mass spectrometry offers this specificity. This article describes the performance of an in-house tandem mass spectrometry method for the individual measurement of 25OHD3, 25OHD2 and 3-épi-25OHD3.

  11. General unknown screening for pesticides in whole blood and Korean gastric contents by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kim, Hyung-seung; Kim, Junghyun; Suh, Joon Hyuk; Han, Sang Beom

    2014-10-01

    A method of simultaneously screening 215 types of pesticides has been established by liquid chromatography with tandem mass spectrometry, quadrupole/time of flight mass spectrometry and triple quadrupole mass spectrometry. Samples of blood and gastric contents were prepared through the modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method. A modified QuEChERS that uses dispersive solid phase extraction for a small amount of sample, mini-QuEChERS, was applied to blood and gastric contents for quick and convenient preparation of the sample and to reduce matrix effect. This method of simultaneous identification needs the upmost reliability because these results are employed by forensic toxicology and may lead to issues with the law. In this study, we incorporated the following two concepts to demonstrate its reliability: One concept is that two tandem mass spectrometers are applied for the confirmation and then a precise compound identification is conducted synchronously at the same retention time. The other concept for reliability adopts the approved criterion as identification points, defined by EU. Validation of the method was performed to assess selectivity, linearity, limit of quantification (LOQ), and recovery by standard addition procedure. The result of linearity was almost satisfactory, and the LOQ of pesticides detected in whole blood and Korean characteristic gastric contents was between 2.5-50 ng/mL. About 90 % of the pesticides had 80-120 % recovery in whole blood, and about 78 % of the pesticides had 80-120 % recovery in Korean gastric contents.

  12. Determination and characterization of site-specific N-glycosylation using MALDI-Qq-TOF tandem mass spectrometry: case study with a plant protease.

    Science.gov (United States)

    Bykova, Natalia V; Rampitsch, Christof; Krokhin, Oleg; Standing, Kenneth G; Ens, Werner

    2006-02-15

    MALDI tandem mass spectrometry analysis on a hybrid quadrupole-quadrupole time-of-flight (Qq-TOF) instrument was used in combination with two-dimensional gel electrophoresis, proteolytic digestion, and liquid chromatography for identification and structural characterization of glycosylation in a novel glycoprotein, pathogenesis-related subtilisin-like proteinase P69B from tomato. Glycopeptide fractions from microcolumn reversed-phase HPLC deposited on MALDI targets were identified from MS by their specific m/z spacing patterns (203, 162, 146 u) between glycoforms. In most cases, MS/MS spectra of [M + H]+ ions of glycopeptides featured peaks useful for determining sugar compositions, peptide sequences, and thus probable glycosylation sites. Furthermore, peptide-related product ions could readily be used in database search procedures to identify the glycoprotein. Four out of five predicted glycosylation sites were biologically relevant and occupied by five N-linked glycan side chains each. In addition, the fragmentation efficiency allowed detection of further modification of methionine-containing glycoforms with either oxidized or iodoacetamide alkylated methionine. The high resolution furnished by MALDI-Qq-TOF allowed rapid and sensitive structural characterization of site-specific N-glycosylation from a limited quantity of material and revealed heterogeneity at different levels, including different glycan side-chain modifications, and heterogeneity of oligosaccharide structures on the same glycosylation site.

  13. Species-specific identification of collagen components in Colla corii asini using a nano-liquid chromatography tandem mass spectrometry proteomics approach.

    Science.gov (United States)

    Li, Xue; Shi, Feng; Gong, Liping; Hang, Baojian; Li, Daoyuan; Chi, Lianli

    2017-01-01

    Colla corii asini (CCA) is a protein-based traditional Chinese medicine made from donkey skins. Because it has the ability to nourish blood, its demand is increasing rapidly. The shortage of donkey skins increases the risk of the adulteration of CCA products with other animal skins. To ensure the drug efficacy and safety of CCA products, a proteomics technique was applied to reveal proteins in the skins of donkey, horse, cattle, and pig. Species-specific peptides for each animal species were predicted using bioinformatics, and their presence in the skins and gelatin samples was examined by nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS). One unique marker peptide for each animal species was selected to develop an LC-MS/MS multiple reaction monitoring method. The capability of this method to identify donkey, horse, cattle, and pig materials was demonstrated by analyzing in-house-made donkey gelatins containing different amounts of other animal skins and commercial CCA products. The adulteration of non-donkey species could be sensitively detected at a low level of 0.5%. Hybrid animals, such as mules and hinnies, were also differentiated from donkeys. We provide a practical tool for the quality control of CCA products. The strategy can also be used to study other important traditional Chinese medicines which contain animal proteins.

  14. High-energy photon activation tandem mass spectrometry provides unprecedented insights into the structure of highly sulfated oligosaccharides extracted from macroalgal cell walls.

    Science.gov (United States)

    Ropartz, David; Giuliani, Alexandre; Hervé, Cécile; Geairon, Audrey; Jam, Murielle; Czjzek, Mirjam; Rogniaux, Hélène

    2015-01-20

    Extreme ultraviolet photon activation tandem mass spectrometry (MS) at 69 nm (18 eV) was used to characterize mixtures of oligo-porphyrans, a class of highly sulfated oligosaccharides. Porphyrans, hybrid polymers whose structures are far from known, continue to provide a challenge for analytical method development. Activation by 18 eV photons led to a rich fragmentation of the oligo-porphyrans, with many cross-ring and glycosidic cleavages. In contrast to multistage MSn strategies such as activated electron photodetachment dissociation, a single step of irradiation by energetic UV of multiply charged anions led to a complete fragmentation of the oligo-porphyrans. In both ionization modes, the sulfate groups were retained on the backbone, which allowed the pattern of these modifications along the porphyran backbone to be described in unprecedented detail. Many structures released by the enzymatic degradation of the porphyran were completely resolved, including isomers. This work extends the existing knowledge of the structure of porphyrans. In addition, it provides a new demonstration of the potential of activation by high-energy photons for the structural analysis of oligosaccharides, even in unseparated mixtures, with a particular focus on sulfated compounds.

  15. Proteomic Analysis of Bacillus thuringiensis at Different Growth Phases by Using an Automated Online Two-Dimensional Liquid Chromatography-Tandem Mass Spectrometry Strategy

    Science.gov (United States)

    Huang, Shaoya; Sun, Yunjun; Yang, Qi; Xiao, Xiuqing; Cao, Zhenping

    2012-01-01

    The proteome of a new Bacillus thuringiensis subsp. kurstaki strain, 4.0718, from the middle vegetative (T1), early sporulation (T2), and late sporulation (T3) phases was analyzed using an integrated liquid chromatography (LC)-based protein identification system. The system comprised two-dimensional (2D) LC coupled with nanoscale electrospray ionization (ESI) tandem mass spectrometry (MS/MS) on a high-resolution hybrid mass spectrometer with an automated data analysis system. After deletion of redundant proteins from the different batches and B. thuringiensis subspecies, 918, 703, and 778 proteins were identified in the respective three phases. Their molecular masses ranged from 4.6 Da to 477.4 Da, and their isoelectric points ranged from 4.01 to 11.84. Function clustering revealed that most of the proteins in the three phases were functional metabolic proteins, followed by proteins participating in cell processes. Small molecular and macromolecular metabolic proteins were further classified according to the Kyoto Encyclopedia of Genes and Genome and BioCyc metabolic pathway database. Three protoxins (Cry2Aa, Cry1Aa, and Cry1Ac) as well as a series of potential intracellular active factors were detected. Many significant proteins related to spore and crystal formation, including sporulation proteins, help proteins, chaperones, and so on, were identified. The expression patterns of two identified proteins, CotJc and glutamine synthetase, were validated by Western blot analysis, which further confirmed the MS results. This study is the first to use shotgun technology to research the proteome of B. thuringiensis. Valuable experimental data are provided regarding the methodology of analyzing the B. thuringiensis proteome (which can be used to produce insecticidal crystal proteins) and have been added to the related protein database. PMID:22636013

  16. Proteomic analysis of Bacillus thuringiensis at different growth phases by using an automated online two-dimensional liquid chromatography-tandem mass spectrometry strategy.

    Science.gov (United States)

    Huang, Shaoya; Ding, Xuezhi; Sun, Yunjun; Yang, Qi; Xiao, Xiuqing; Cao, Zhenping; Xia, Liqiu

    2012-08-01

    The proteome of a new Bacillus thuringiensis subsp. kurstaki strain, 4.0718, from the middle vegetative (T(1)), early sporulation (T(2)), and late sporulation (T(3)) phases was analyzed using an integrated liquid chromatography (LC)-based protein identification system. The system comprised two-dimensional (2D) LC coupled with nanoscale electrospray ionization (ESI) tandem mass spectrometry (MS/MS) on a high-resolution hybrid mass spectrometer with an automated data analysis system. After deletion of redundant proteins from the different batches and B. thuringiensis subspecies, 918, 703, and 778 proteins were identified in the respective three phases. Their molecular masses ranged from 4.6 Da to 477.4 Da, and their isoelectric points ranged from 4.01 to 11.84. Function clustering revealed that most of the proteins in the three phases were functional metabolic proteins, followed by proteins participating in cell processes. Small molecular and macromolecular metabolic proteins were further classified according to the Kyoto Encyclopedia of Genes and Genome and BioCyc metabolic pathway database. Three protoxins (Cry2Aa, Cry1Aa, and Cry1Ac) as well as a series of potential intracellular active factors were detected. Many significant proteins related to spore and crystal formation, including sporulation proteins, help proteins, chaperones, and so on, were identified. The expression patterns of two identified proteins, CotJc and glutamine synthetase, were validated by Western blot analysis, which further confirmed the MS results. This study is the first to use shotgun technology to research the proteome of B. thuringiensis. Valuable experimental data are provided regarding the methodology of analyzing the B. thuringiensis proteome (which can be used to produce insecticidal crystal proteins) and have been added to the related protein database.

  17. Evaluation of hybrids algorithms for mass detection in digitalized mammograms

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, Jose; Garzon Reyes, Johnson, E-mail: josecorderog@hotmail.com [Grupo de Optica y Espectroscopia GOE, Centro de Ciencia Basica, Universidad Pontifica Bolivariana de Medellin (Colombia)

    2011-01-01

    The breast cancer remains being a significant public health problem, the early detection of the lesions can increase the success possibilities of the medical treatments. The mammography is an image modality effective to early diagnosis of abnormalities, where the medical image is obtained of the mammary gland with X-rays of low radiation, this allows detect a tumor or circumscribed mass between two to three years before that it was clinically palpable, and is the only method that until now achieved reducing the mortality by breast cancer. In this paper three hybrids algorithms for circumscribed mass detection on digitalized mammograms are evaluated. In the first stage correspond to a review of the enhancement and segmentation techniques used in the processing of the mammographic images. After a shape filtering was applied to the resulting regions. By mean of a Bayesian filter the survivors regions were processed, where the characteristics vector for the classifier was constructed with few measurements. Later, the implemented algorithms were evaluated by ROC curves, where 40 images were taken for the test, 20 normal images and 20 images with circumscribed lesions. Finally, the advantages and disadvantages in the correct detection of a lesion of every algorithm are discussed.

  18. FiD: a software for ab initio structural identification of product ions from tandem mass spectrometric data.

    Science.gov (United States)

    Heinonen, Markus; Rantanen, Ari; Mielikäinen, Taneli; Kokkonen, Juha; Kiuru, Jari; Ketola, Raimo A; Rousu, Juho

    2008-10-01

    We present FiD (Fragment iDentificator), a software tool for the structural identification of product ions produced with tandem mass spectrometric measurement of low molecular weight organic compounds. Tandem mass spectrometry (MS/MS) has proven to be an indispensable tool in modern, cell-wide metabolomics and fluxomics studies. In such studies, the structural information of the MS(n) product ions is usually needed in the downstream analysis of the measurement data. The manual identification of the structures of MS(n) product ions is, however, a nontrivial task requiring expertise, and calls for computer assistance. Commercial software tools, such as Mass Frontier and ACD/MS Fragmenter, rely on fragmentation rule databases for the identification of MS(n) product ions. FiD, on the other hand, conducts a combinatorial search over all possible fragmentation paths and outputs a ranked list of alternative structures. This gives the user an advantage in situations where the MS/MS data of compounds with less well-known fragmentation mechanisms are processed. FiD software implements two fragmentation models, the single-step model that ignores intermediate fragmentation states and the multi-step model, which allows for complex fragmentation pathways. The software works for MS/MS data produced both in positive- and negative-ion modes. The software has an easy-to-use graphical interface with built-in visualization capabilities for structures of product ions and fragmentation pathways. In our experiments involving amino acids and sugar-phosphates, often found, e.g., in the central carbon metabolism of yeasts, FiD software correctly predicted the structures of product ions on average in 85% of the cases. The FiD software is free for academic use and is available for download from www.cs.helsinki.fi/group/sysfys/software/fragid.

  19. Dereplication of Flavonoid Glycoconjugates from Adenocalymma imperatoris-maximilianii by Untargeted Tandem Mass Spectrometry-Based Molecular Networking.

    Science.gov (United States)

    de Oliveira, Gibson Gomes; Carnevale Neto, Fausto; Demarque, Daniel Pecoraro; de Sousa Pereira-Junior, José Antônio; Sampaio Peixoto Filho, Rômulo César; de Melo, Sebastião José; da Silva Almeida, Jackson Roberto Guedes; Lopes, João Luiz Callegari; Lopes, Norberto Peporine

    2017-05-01

    The interpretation of large datasets acquired using high performance liquid chromatography coupled with tandem mass spectrometry represents one of the major challenges in natural products research. Here we propose the use of molecular networking to rapid identify the known secondary metabolites from untargeted MS/MS analysis of Adenocalymma imperatoris-maximilianii plant extracts. The leaves, stems and roots of A. imperatoris-maximilianii were extracted using different solvents according to Snyder selectivity triangle. The samples were analyzed by HPLC coupled with ion trap mass spectrometer in a collision-induced dissociation MS/MS configuration in both positive and negative electrospray ionization modes. Molecular networking simultaneously organized the spectra by cosine similarity. The chemical identification was performed based on the systematic study of the main fragmentation pathways observed for the resulting network. The untargeted tandem mass spectrometry-based molecular networking allowed for the identification of 63 metabolites, mainly mono-, di- and tri-, C - and/or O -glycosyl flavones. Molecular networking was capable not only to dereplicate known flavonoids, but also to point out related prenyl derivatives, described for the first time in Adenocalymma species. The gas-phase reaction route to form the characteristic [M-H 2 O-(30/60/90)] + fragments in C -glycosyl flavones was suggested as sequential sugar ring opening followed by retro-aldol elimination involving aldose-ketose isomerization. The use of molecular networking with LC-CID-MS/MS assisted the identification of various isomeric and isobaric flavonoid glycoconjugates by establishing clusters according to the fragmentation similarities. Additionally, the proposed cross-ring sugar cleavages can contribute to the identification of C -glycosides by MS/MS analysis. Georg Thieme Verlag KG Stuttgart · New York.

  20. Quantitative statistical analysis of standard and human blood proteins from liquid chromatography, electrospray ionization, and tandem mass spectrometry.

    Science.gov (United States)

    Bowden, Peter; Thavarajah, Thanusi; Zhu, Peihong; McDonell, Mike; Thiele, Herbert; Marshall, John G

    2012-04-06

    It will be important to determine if the parent and fragment ion intensity results of liquid chromatography, electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS) experiments have been randomly and independently sampled from a normal population for the purpose of statistical analysis by general linear models and ANOVA. The tryptic parent peptide and fragment ion m/z and intensity data in the mascot generic files from LC-ESI-MS/MS of purified standard proteins, and human blood protein fractionated by partition chromatography, were parsed into a Structured Query Language (SQL) database and were matched with protein and peptide sequences provided by the X!TANDEM algorithm. The many parent and/or fragment ion intensity values were log transformed, tested for normality, and analyzed using the generic Statistical Analysis System (SAS). Transformation of both parent and fragment intensity values by logarithmic functions yielded intensity distributions that closely approximate the log-normal distribution. ANOVA models of the transformed parent and fragment intensity values showed significant effects of treatments, proteins, and peptides, as well as parent versus fragment ion types, with a low probability of false positive results. Transformed parent and fragment intensity values were compared over all sample treatments, proteins or peptides by the Tukey-Kramer Honestly Significant Difference (HSD) test. The approach provided a complete and quantitative statistical analysis of LC-ESI-MS/MS data from human blood.

  1. Liquid chromatography tandem mass spectrometry method for the estimation of lamotrigine in human plasma: Application to a pharmacokinetic study

    Directory of Open Access Journals (Sweden)

    Santosh Ghatol

    2013-04-01

    Full Text Available A reliable, selective and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of lamotrigine in human plasma using lamotrigine-13C3, d3 as an internal standard. Analyte and internal standard were extracted from human plasma by solid-phase extraction and detected in positive ion mode by tandem mass spectrometry with electrospray ionization (ESI interface. Chromatographic separation was performed on a Chromolith® SpeedROD; RP-18e column (50−4.6 mm i.d. using acetonitrile: 5±0.1 mM ammonium formate solution (90:10, v/v as the mobile phase at a flow rate of 0.500 mL/min. The calibration curves were linear over the range of 5.02–1226.47 ng/mL with the lower limit of quantitation validated at 5.02 ng/mL. The analytes were found stable in human plasma through three freeze (−20 °C-thaw (ice-cold water bath cycles and under storage on bench-top in ice-cold water bath for at least 6.8 h, and also in the mobile phase at 10 °C for at least 57 h. The method has shown good reproducibility, as the intra- and inter-day precisions were within 3.0%, while the accuracies were within ±6.0% of nominal values. The validated LC–MS/MS method was applied for the evaluation of pharmacokinetic and bioequivalence parameters of lamotrigine after an oral administration of 50 mg lamotrigine tablet to thirty-two healthy adult male volunteers. Keywords: Lamotrigine, Liquid chromatography/tandem mass spectrometry, Solid phase extraction, Pharmacokinetic study

  2. Determination of Sulfite in Food by Liquid Chromatography Tandem Mass Spectrometry: Collaborative Study.

    Science.gov (United States)

    Carlos, Katherine S; de Jager, Lowri S

    2017-11-01

    Sulfites are added to a wide range of food and beverage products to prevent browning or oxidation. Although most of the population do not experience side effects from consuming sulfites, a small subset has been shown to experience an "allergic-like" response. For this reason, the U.S. Food and Drug Administration requires that sulfites be labeled on all products that contain more than 10 mg/kg (parts per million) sulfur dioxide. The current regulatory method, optimized Monier-Williams (OMW) Official Method 990.28, has been successful in quantifying sulfites in most matrixes, but is time-consuming and has a method detection limit at the regulatory-labeling threshold. Recently, an LC-tandem MS (MS/MS) method was published that was applicable to a wide range of sulfite-containing matrixes. This method converts free and reversibly bound sulfite to the formaldehyde adduct hydroxymethylsulfonate, which could then be separated from matrix constituents using a hydrophilic interaction LC analytical column and subsequently be detected with tandem MS (MS/MS). In this study, multilaboratory validation was conducted with 11 laboratories in the United States and Canada. Four matrixes were spiked at varying concentrations and three additional commercially sulfited matrixes were included. An abbreviated comparison study between the LC-MS/MS and OMW methods was conducted for select samples. Average recoveries for all matrixes ranged from 86 to 114% with RSDr and RSDR values of 4.5-17.5 and 8.6-22.5%, respectively. Further comparisons will be necessary to draw comparisons between the two methods. This method proved to be a faster and more sensitive way to determine sulfites in food and beverages, showing promise for the continuing improvement of enforcement of sulfite labeling requirements to protect individuals who have sulfite sensitivity.

  3. Evaluation of gas chromatography-tandem quadrupole mass spectrometry for the determination of organochlorine pesticides in fats and oils.

    Science.gov (United States)

    Patel, Katan; Fussell, Richard J; Hetmanski, Mike; Goodall, David M; Keely, Brendan J

    2005-03-18

    A gas chromatography-tandem quadrupole mass spectrometry multi-residue method for the analysis of 19 organochlorine pesticides in fats and oils has been developed. Gel permeation chromatography was employed to remove lipid material prior to GC-MS/MS analysis. Average recoveries of the pesticides spiked at 10 and 50 microg kg(-1) into fish oil, pork fat, olive oil and hydrogenated vegetable oil were typically in the range 70-110% with relative standard deviations generally less than 10%. Calculated limits of detection are between 0.1 and 2.0 microg kg(-1) and results obtained for the analysis of proficiency test materials are in good agreement with assigned values. The higher selectivity of the GC-MS/MS compared to electron capture detection and GC-MS in selective ion monitoring mode allowed unambiguous identification and confirmation of all the target pesticides at low microg kg(-1) levels in fats and oils in a single analysis.

  4. Analysis of 10 systemic pesticide residues in various baby foods using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Yang, Angel; Abd El-Aty, A M; Park, Jong-Hyouk; Goudah, Ayman; Rahman, Md Musfiqur; Do, Jung-Ah; Choi, Ok-Ja; Shim, Jae-Han

    2014-06-01

    Ten systemic pesticides, comprising methomyl, thiamethoxam, acetamiprid, carbofuran, fosthiazate, metalaxyl, azoxystrobin, diethofencarb, propiconazole, and difenoconazole, were detected in 13 baby foods (cereals, boiled potatoes, fruit and milk) using QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) for sample preparation and liquid chromatography tandem mass spectrometry for analysis. The matrix-matched calibration curves showed good linearity with determination coefficients (R(2) ) >0.992. The limits of detection and quantitation were 0.0015-0.003 and 0.005-0.01 mg/kg, respectively. The mean recoveries of three different concentrations ranged from 69.2 to 127.1% with relative standard deviations market, and none of the samples were found to contain pesticide residues. This method is suitable for the identification and quantification of systemic pesticides with matrix-matched standards in various baby foods. Copyright © 2013 John Wiley & Sons, Ltd.

  5. Determination of seven bisphenol analogues in reed and Callitrichaceae by ultra performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Lu, Libin; Yang, Yunjia; Zhang, Jing; Shao, Bing

    2014-03-15

    An analytical procedure was developed to simultaneously determine bisphenol S, bisphenol F, bisphenol B, bisphenol A, bisphenol AF, tetrachlorobisphenol A, and tetrabromobisphenol A in reed and Callitrichaceae. Homogenized samples were extracted with acetonitrile and purified using an ENVI™-Carb cartridge followed by an NH2 cartridge. The analytes were separated and quantified by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The recoveries at three fortified levels in reed and Callitrichaceae were 57-108% and 68-106%, respectively, with relative standard deviations of no more than 15% (n=6). The method limits of quantification and detection for the seven bisphenol analogues were 0.005-0.500μg/kg and 0.002-0.150μg/kg, respectively. This method was used to analyze the seven compounds in ten reed and Callitrichaceae samples collected from Zhejiang, China. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Residue analysis of fipronil and difenoconazole in okra by liquid chromatography tandem mass spectrometry and their food safety evaluation.

    Science.gov (United States)

    Hingmire, Sandip; Oulkar, Dasharath P; Utture, Sagar C; Ahammed Shabeer, T P; Banerjee, Kaushik

    2015-06-01

    A liquid chromatography tandem mass spectrometry (LC-MS/MS) based method is reported for simultaneous analysis of fipronil (plus its metabolites) and difenoconazole residues in okra. The sample preparation method involving extraction with ethyl acetate provided 80-107% recoveries for both the pesticides with precision RSD within 4-17% estimated at the limits of quantification (LOQ, fipronil=1ngg(-1), difenoconazole=5ngg(-1)) and higher fortification levels. In field, both the pesticides dissipated with half-life of 2.5days. The estimated pre-harvest intervals (PHI) for fipronil and difenoconazole were 15 and 19.5days, and 4 and 6.5days at single and double dose of field applications, respectively. Decontamination of incurred residues by washing and different cooking treatments was quite efficient in minimizing the residue load of both the chemicals. Okra samples harvested after the estimated PHIs were found safe for human consumption. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Characterization of Aromatase Binding Agents from the Dichloromethane Extract of Corydalis yanhusuo Using Ultrafiltration and Liquid Chromatography Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Jing Shi

    2010-05-01

    Full Text Available Aromatase represents an important target for the treatment of hormone-dependent breast cancer. In the present study, nine alkaloids from the dichloromethane extract of Corydalis yanhusuo were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS and tested for their aromatase binding activities using an ultrafiltration LC-MS method by investigating the differences of peak areas of compounds before and after incubations with aromatase. It was demonstrated that the quaternary protoberberine alkaloids and the tertiary protoberberine alkaloids exhibited potent aromatase binding activities. The quaternary ammonium group and the methyl group at C-13 position of tertiary protoberberine alkaloids might be necessary for the activity. The findings should provide guidance for the discovery of potential aromatase inhibitors from natural products.

  8. Determination of Thiophanate-methyl in Tamoto by High Performance Liquid Chromatography-triple Quadrupole Tandem Mass Spectometry

    Directory of Open Access Journals (Sweden)

    XU Wei-feng

    2014-06-01

    Full Text Available To evaluate the safety of use of 70% thiophanate-methyl wettable powders in tomato, a supervised trial experiment was conducted to study the residues in tomato. A method of determining thiophanate-methyl by high performance liquid chromatography-tandem mass spectrometry(LC-MSMSwas established. Acetonitrile was used as an extraction solvent, and PSA and anhydrous magnesium were used for sample purifying. Samples were determined and quantified by LC-MSMS in the multiple reaction monitoring mode(MRM. The field trial recommended spraying 70% thiophanate-methyl WP on tomato with 562.5 gai· hm-2 in three times, which the safe interval was not less than three days from the last time to harvest. The results showed that the thiophanate methyl residue in tomato was lower than 0.05 mg· kg -1, both from field trials and market sampling samples.

  9. Determination of 24 pesticide residues in fortified wines by solid-phase microextraction and gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Martins, Joana; Esteves, Cristina; Simoes, Tomas; Correia, Manuela; Delerue-Matos, Cristina

    2011-07-13

    The present work describes a solid-phase microextraction (SPME) gas chromatography-tandem mass spectrometry (MS/MS) method to quantify 24 pesticides in fortified white wine and fortified red wine. In this study "fortified wine" refers to a wine in which fermentation is arrested before completion by alcohol distillate addition, allowing sugar and alcoholic contents to be higher (around 80-100 g/L total sugars and 19-22% alcohol strength (v/v)). The analytical method showed good linearity, presenting correlation coefficients (R(2)) ≥ 0.989 for all compounds. Limits of detection (LOD) and quantitation (LOQ) in the ranges of 0.05-72.35 and 0.16-219.23 μg/L, respectively, were obtained. LOQs are below the maximum residue levels (MRL) set by European Regulation for grapes. The proposed method was applied to 17 commercial fortified wines. The analyzed pesticides were not detected in the wines tested.

  10. The use of liquid chromatography tandem mass spectrometry to detect proteins in saliva from horses with and without systemic inflammation

    DEFF Research Database (Denmark)

    Jacobsen, Stine; Top Adler, Ditte Marie; Bundgaard, Louise

    2014-01-01

    The objective of the study was to assess global expression of proteins in equine saliva using liquid chromatography tandem mass spectrometry (LC-MS/MS). Saliva was obtained from seven horses with and six horses without evidence of systemic inflammatory disease. Tryptic peptides from saliva were...... analysed by LC-MS/MS. Of 195 unique proteins identified, 57 were detected only in saliva samples from horses with systemic inflammation (in two to six of the seven horses). Among the differentially expressed proteins were several acute phase proteins (APPs) such as serum amyloid A, fibrinogen, haptoglobin......, and alpha1-acid glycoprotein. The study is the first to describe detection of inflammatory proteins in horse saliva. The proteins detected were similar to those described in saliva from cattle, small ruminants and pigs. Detection of APPs in horses with systemic inflammation suggests that saliva may be used...

  11. Quantification of Dehydroepiandrosterone, 11-Deoxycortisol, 17-Hydroxyprogesterone, and Testosterone by Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS).

    Science.gov (United States)

    Munar, Ada; Frazee, Clint; Garg, Uttam

    2016-01-01

    Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive disorders due to enzymatic defects in the biosynthetic pathway of cortisol and/or aldosterone. The analysis of cortisol, 17-hydroxyprogesterone (OHPG), dehydroepiandrosterone (DHEA), 11-deoxycortisol, and testosterone is generally performed in the diagnosis and/or follow-up of CAH. Cortisol is generally analyzed by immunoassays whereas other hormones are preferably assayed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). A multiple reaction monitoring, positive mode atmospheric pressure chemical ionization, LC/MS/MS method is described for the simultaneous quantification of 17-hydroxyprogesterone, DHEA, 11-deoxycortisol, and testosterone. Stable-isotope labeled internal standards are added to serum samples and steroids are extracted by liquid-liquid extraction using methyl tert-butyl ether. The extract is evaporated under stream of nitrogen and the residue is reconstituted in methanol and analyzed by LC/MS/MS.

  12. Separation of nucleobases, nucleosides, and nucleotides using two zwitterionic silica-based monolithic capillary columns coupled with tandem mass spectrometry.

    Science.gov (United States)

    Moravcová, Dana; Haapala, Markus; Planeta, Josef; Hyötyläinen, Tuulia; Kostiainen, Risto; Wiedmer, Susanne K

    2014-12-19

    The capability of employing synthesized zwitterionic silica-based monolithic capillary columns (140 mm × 0.1mm) for separation of highly polar and hydrophilic nucleobases, nucleosides, and nucleotides in hydrophilic interaction chromatography is reported. The suitability of the columns for on-line conjunction with electrospray tandem mass spectrometry was explored. Our results show that the grafted layer of zwitterionic monomer ([2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide or 2-methacryloyloxyethyl phosphorylcholine) on the silica monolithic surface significantly improved the separation selectivity and reproducibility, as compared to the bare silica monolith. The stepwise elution from 90% to 70% of acetonitrile enabled separation of a complex sample mixture containing 21 compounds with a total analysis time less than 40 min. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Utility of immonium ions for assignment of epsilon-N-acetyllysine-containing peptides by tandem mass spectrometry

    DEFF Research Database (Denmark)

    Trelle, Morten B; Jensen, Ole Nørregaard

    2008-01-01

    Tandem mass spectrometry (MS/MS) is a powerful tool for characterization of post-translationally modified proteins, including epsilon-N-acetyllysine-containing species. Previous reports indicate that epsilon-N-acetyllysine immonium ions are useful marker ions for peptides containing epsilon......-N-acetyllysine, but the specificity and sensitivity of these ions for assignment of lysine acetylation by MS/MS have not been studied in detail. We investigated MS/MS data sets of 172 epsilon-N-acetyllysine tryptic peptides and 268 nonacetylated tryptic peptides to establish the utility and reliability of epsilon...... of acetyllysine-containing peptides by MS/MS. Our analysis of epsilon-N-acetyllysine immonium ions provide a framework for investigation of MS/MS marker ion specificity and sensitivity that can be applied in studies of other types of post-translational modifications....

  14. Liquid chromatography-tandem mass spectrometry determination of synthetic cathinones and phenethylamines in influent wastewater of eight European cities

    DEFF Research Database (Denmark)

    Bade, Richard; Bijlsma, Lubertus; Sancho, Juan V.

    2017-01-01

    (SPE) with Oasis MCX cartridges. Isotopically labelled internal standards were used to correct for matrix effects and potential SPE losses. Following chromatographic separation on a C18 column within 6 min, the compounds were measured by tandem mass spectrometry in positive ionization mode. The method...... relatively stable for up to 7 days. The method was then applied to influent wastewater samples from eight European countries, in which mephedrone, methylone and MDPV were detected. This work reveals that although NPS use is not as extensive as for classic illicit drugs, the application of a highly sensitive...... analytical procedure makes their detection in wastewater possible. The developed analytical methodology forms the basis of a subsequent model-based back-calculation of abuse rate in urban areas (i.e. wastewater-based epidemiology)....

  15. Detection of lysergic acid diethylamide (LSD) in urine by gas chromatography-ion trap tandem mass spectrometry.

    Science.gov (United States)

    Sklerov, J H; Kalasinsky, K S; Ehorn, C A

    1999-10-01

    A confirmatory method for the detection and quantitation of lysergic acid diethylamide (LSD) is presented. The method employs gas chromatography-tandem mass spectrometry (GC-MS-MS) using an internal ionization ion trap detector for sensitive MS-MS-in-time measurements of LSD extracted from urine. Following a single-step solid-phase extraction of 5 mL of urine, underivatized LSD can be measured with limits of quantitation and detection of 80 and 20 pg/mL, respectively. Temperature-programmed on-column injections of urine extracts were linear over the concentration range 20-2000 pg/mL (r2 = 0.999). Intraday and interday coefficients of variation were LSD-positive samples in this laboratory. Comparisons with alternate GC-MS methods and extraction procedures are discussed.

  16. Quantification of antidepressants and antipsychotics in human serum by precipitation and ultra high pressure liquid chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Hasselstrøm, Jørgen Bo

    2011-01-01

    precipitated with zinc sulphate and methanol containing a stable isotope labelled analog for each analyte. Quantitative analysis was performed by ultra high pressure liquid chromatography combined with a tandem mass spectrometer using a Zorbax SB-C8 column (2.0×50mm; 1.8m) with a mobile phase consisting of 0.......1% formic acid in water and methanol, respectively. The total run time of the chromatography was 4 min. Precision and trueness varied from 2.6% to 14.9% and 87.6% to 103.5%, respectively. At the lower limit of quantification, precision was up to 17.9% and trueness varied from 89.5% to 111.5%. A five point...

  17. [Analysis of metribuzin and its metabolites in livestock products and seafoods by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Kai, Shigemi; Akaboshi, Takeshi; Waki, Masumi; Fuzimaki, Teruhisa; Kanazawa, Hideko

    2011-01-01

    A method for simultaneous determination of metribuzin (MET) and three metribuzin metabolites in livestock products and seafoods by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. MET and its metabolites were extracted from a sample with acetonitrile, followed by InertSepC18 and BondElut SAX cartridge cleanup. The LC separation was performed on a C18 column using 0.01 mol/L ammonium formate-acetonitrile-methanol (70 :21 : 9) as the mobile phase and MS detection with both positive and negative ion electrospray ionization. The mean recoveries from 10 livestock products and seafoods were generally >60%, and the relative standard deviations were <20%

  18. Colostrum protein uptake in neonatal lambs examined by descriptive and quantitative liquid chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Hernandez-Castellano, Lorenzo E; Argueello, Anastasio; Almeida, Andre M

    2015-01-01

    dodecyl sulfate-PAGE for protein separation and in-gel digestion, followed by liquid chromatography-tandem mass spectrometry of resulting tryptic peptides for protein identification. An isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics approach was subsequently used to provide...... the importance of specific colostrum proteins has gained significant attention in recent years. However, proteomics studies of sheep colostrum and their uptake in neonate lambs has not yet been presented. The aim of this study was to describe the proteomes of sheep colostrum and lamb blood plasma, using sodium...... relative quantification of how neonatal plasma protein concentrations change as an effect of colostrum intake. The results of this study describe the presence of 70 proteins in the ovine colostrum proteome. Furthermore, colostrum intake resulted in an increase of 8 proteins with important immune functions...

  19. [Determination of nine beta-agonist residues in pig tissues by liquid chromatography-tandem mass spectrometry combining with library search].

    Science.gov (United States)

    Cai, Qinren; Wu, Jieshan; Qian, Zhenjie; Peng, Yufen; Cai, Jie; Du, Zhifeng

    2013-03-01

    A new method has been developed using a hybrid triple-quadrupole linear ion trap (QTrap) mass spectrometer for the fast detection and identification of nine beta-agonists, clenbuterol, salbutamol, ractopamine, ritodrine, terbutaline, isoxsuprine, tulobuterol, cimaterol and bambuterol, in one single liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The homogenized tissue samples were purified with liquid-liquid extraction after enzymatic hydrolysis by P-glucuronidase/aryl sulfatase. After gradient elution separation on C(18) LC column using acetonitrile and formic acid aqueous solution as the mobile phases, a multiple reaction monitoring (MRM) scan as survey scan and an enhanced product ion (EPI) scan as dependent scan were performed in an information dependent acquisition (IDA) experiment. Finally, the identification of the drugs was carried out by library search with a newly developed MS/MS library based on EPI spectra at three different collision energies in positive mode. The analytical method in the present study was well validated and good results were obtained with respect to precision, repeatability and spiked recovery. The limits of detection of residues were 0.1 -0.2 micro g/kg for beta-agonists, and with a linear range from 0.1 to 50.0 micro g/L. Three concentration levels of 0. 5, 1. 0 and 5. 0 pg/kg were spiked in pig tissues, and the overall recoveries were between 72.0% and 95.1% with the relative standard deviations (RSDs) between 3. 1% and 12.1%. The real sample test showed that this method could be used for sensitive and accurate determination of beta-agonist residues in pig tissue

  20. [Qualitative and quantitative analysis of amygdalin and its metabolite prunasin in plasma by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry].

    Science.gov (United States)

    Gao, Meng; Wang, Yuesheng; Wei, Huizhen; Ouyang, Hui; He, Mingzhen; Zeng, Lianqing; Shen, Fengyun; Guo, Qiang; Rao, Yi

    2014-06-01

    A method was developed for the determination of amygdalin and its metabolite prunasin in rat plasma after intragastric administration of Maxing shigan decoction. The analytes were identified by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and quantitatively determined by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry. After purified by liquid-liquid extraction, the qualitative analysis of amygdalin and prunasin in the plasma sample was performed on a Shim-pack XR-ODS III HPLC column (75 mm x 2.0 mm, 1.6 microm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on a Triple TOF 5600 quadrupole time of flight mass spectrometer. The quantitative analysis of amygdalin and prunasin in the plasma sample was performed by separation on an Agilent C18 HPLC column (50 mm x 2.1 mm, 1.7 microm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on an AB Q-TRAP 4500 triple quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operated in negative ion mode and multiple-reaction monitoring (MRM) mode. The qualitative analysis results showed that amygdalin and its metabolite prunasin were detected in the plasma sample. The quantitative analysis results showed that the linear range of amygdalin was 1.05-4 200 ng/mL with the correlation coefficient of 0.999 0 and the linear range of prunasin was 1.25-2 490 ng/mL with the correlation coefficient of 0.997 0. The method had a good precision with the relative standard deviations (RSDs) lower than 9.20% and the overall recoveries varied from 82.33% to 95.25%. The limits of detection (LODs) of amygdalin and prunasin were 0.50 ng/mL. With good reproducibility, the method is simple, fast and effective for the qualitative and quantitative analysis of the amygdalin and prunasin in plasma sample of rats which were administered by Maxing shigan decoction.

  1. Determination of polymer electrolyte membrane (PEM) degradation products in fuel cell water using electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Zedda, Marco; Tuerk, Jochen; Peil, Stefan; Schmidt, Torsten C

    2010-12-30

    Within the scope of research of membrane degradation phenomena during fuel cell operation a reliable analytical procedure for the extraction, detection and quantification of possible membrane oxidation products has been developed. These oxidation products originate from the attack of hydroxyl or peroxyl radicals on the membrane polymer. Such radicals are formed in situ (during fuel cell operation) or ex situ (Fenton test as oxidative stress simulation). The analysis of membrane oxidation products was carried out by electrospray ionization tandem mass spectrometry. Five potential membrane oxidation products (4-hydroxybenzoic acid (4-HBA), 4-hydroxybenzaldehyde (4-HBAD), 4,4-biphenol (4,4-BP), 4-hydroxybenzenesulfonate (4-HBS), and 4,4-sulfonylbiphenol (4,4-SBP)) were selected based on the molecular structure of the sulfonated polyarylether membrane used. In conjunction with the development of a multiple reaction monitoring (MRM) method, the ionization and fragmentation of the selected compounds were investigated. For 4,4-BP a molecular ion (M(+•) ) was observed in the positive ionization mode and used for MRM method development. Reproducible extraction of the model compounds was achieved using a mixed-mode sorbent material with both weak anion-exchange and reversed-phase retention properties. By using the developed analytical procedure, the identities of two membrane degradation products (4-HBA and 4-HBAD) were determined in situ and ex situ. In addition to the investigation of membrane degradation phenomena, the combination of extraction on a mixed-mode sorbent material and tandem mass spectrometric detection is attractive for the analysis of aromatic sulfonic acids, phenolic acids and phenols. Copyright © 2010 John Wiley & Sons, Ltd.

  2. Analysis of perchlorate, thiocyanate, nitrate and iodide in human amniotic fluid using ion chromatography and electrospray tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Blount, Benjamin C. [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341 (United States)]. E-mail: bblount@cdc.gov; Valentin-Blasini, Liza [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341 (United States)

    2006-05-10

    Because of health concerns surrounding in utero exposure to perchlorate, we developed a sensitive and selective method for quantifying iodide, as well as perchlorate and other sodium-iodide symporter (NIS) inhibitors in human amniotic fluid using ion chromatography coupled with electrospray ionization tandem mass spectrometry. Iodide and NIS inhibitors were quantified using a stable isotope-labeled internal standards (Cl{sup 18}O{sub 4} {sup -}, S{sup 13}CN{sup -} and {sup 15}NO{sub 3} {sup -} with excellent assay accuracy of 100%, 98%, 99%, 95% for perchlorate, thiocyanate, nitrate and iodide, respectively, in triplicate analysis of spiked amniotic fluid sample). Excellent analytical precision (<5.2% RSD for all analytes) was found when amniotic fluid quality control pools were repetitively analyzed for iodide and NIS-inhibitors. Selective chromatography and tandem mass spectrometry reduced the need for sample cleanup, resulting in a rugged and rapid method capable of routinely analyzing 75 samples/day. Analytical response was linear across the physiologically relevant concentration range for the analytes. Analysis of a set of 48 amniotic fluid samples identified the range and median levels for perchlorate (0.057-0.71, 0.18 {mu}g/L), thiocyanate (<10-5860, 89 {mu}g/L), nitrate (650-8900, 1620 {mu}g/L) and iodide (1.7-170, 8.1 {mu}g/L). This selective, sensitive, and rapid method will help assess exposure of the developing fetus to low levels of NIS-inhibitors and their potential to inhibit thyroid function.

  3. Simultaneous Testing for 6 Lysosomal Storage Disorders and X-Adrenoleukodystrophy in Dried Blood Spots by Tandem Mass Spectrometry.

    Science.gov (United States)

    Tortorelli, Silvia; Turgeon, Coleman T; Gavrilov, Dimitar K; Oglesbee, Devin; Raymond, Kimiyo M; Rinaldo, Piero; Matern, Dietrich

    2016-09-01

    Newborn screening for lysosomal storage disorders (LSD) has revealed that late-onset variants of these conditions are unexpectedly frequent and therefore may evade diagnosis. We developed an efficient and cost-effective multiplex assay to diagnose six LSDs and several peroxisomal disorders in patients presenting with diverse phenotypes at any age. Three 3-mm dried blood spot (DBS) punches were placed into individual microtiter plates. One disc was treated with a cocktail containing acid sphingomyelinase-specific substrate and internal standard (IS). To the second DBS we added a cocktail containing substrate and IS for β-glucosidase, acid α-glucosidase, α-galactosidase A, galactocerebrosidase, and α-L-iduronidase. The third DBS was extracted with methanol containing d4-C26 lysophosphatidylcholine as IS and stored until the enzyme plates were combined and purified by liquid-liquid and solid-phase extraction. The extracts were evaporated, reconstituted with the extract from the lysophosphatidylcholine plate, and analyzed by flow injection tandem mass spectrometry. Reference intervals were determined by analysis of 550 samples from healthy controls. DBS from confirmed patients with 1 of the 6 LSDs (n = 33), X-adrenoleukodystrophy (n = 9), or a peroxisomal biogenesis disorder (n = 5), as well as carriers for Fabry disease (n = 17) and X-adrenoleukodystrophy (n = 5), were analyzed for assay validation. Prospective clinical testing of 578 samples revealed 25 patients affected with 1 of the detectable conditions. Our flow injection tandem mass spectrometry approach is amenable to high-throughput population screening for Hurler disease, Gaucher disease, Niemann-Pick A/B disease, Pompe disease, Krabbe disease, Fabry disease, X-adrenoleukodystrophy, and peroxisomal biogenesis disorder in DBS. © 2016 American Association for Clinical Chemistry.

  4. Characterization of polysorbate 85, a nonionic surfactant, by liquid chromatography vs. ion mobility separation coupled with tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Solak Erdem, Nilüfer; Alawani, Nadrah; Wesdemiotis, Chrys, E-mail: wesdemiotis@uakron.edu

    2014-01-15

    Graphical abstract: -- Highlights: •Liquid chromatography (LC) separates amphiphilic blends according to hydrophobicity. •Ion mobility (IM) spectrometry separates these blends based on molecular size/shape. •LC–MS provides the separation resolution needed for quantifying fatty acid content. •IM–MS enables rapid, solvent-free separation and the detection of trace components. •With either method, tandem MS allows to count the hydrophobic substituents. -- Abstract: Liquid chromatography (LC) and ion mobility (IM) separation have been coupled with mass spectrometry (MS) and tandem mass spectrometry (MS{sup 2}) to characterize a commercially important nonionic surfactant, polysorbate 85. The constituents of this amphiphilic blend contained a sorbitan or isosorbide core that was chain extended with poly(ethylene oxide) (PEO) and partially esterified at the PEO termini with oleic acid or, to a lesser extent, other fatty acids. Using interactive LC in reverse-phase mode, the oligomers of the surfactant were separated according to their hydrophobicity/hydrophilicity balance. On the other hand, IM spectrometry dispersed the surfactant oligomers by their charge and collision cross section (i.e. size/shape). With either separation method, an increased number of fatty ester groups and/or lack of the polar sorbitan (or isosorbide) core led to higher retention/drift times, enabling the separation of isobaric species or species with superimposed isotope patterns, so that their ester content could be conclusively identified by MS{sup 2}. LC–MS and IM–MS permitted the detection of several byproducts besides the major PEO-sorbitan oleate oligomers. LC–MS provides the separation resolution needed for quantitative determination of the degree of esterification. IM–MS, which minimizes analysis time and solvent use, is ideally suitable for a fast, qualitative survey of samples differing in their minor constituents or impurities.

  5. Comparative analysis of the uropathogenic Escherichia coli surface proteome by tandem mass-spectrometry of artificially induced outer membrane vesicles.

    Science.gov (United States)

    Wurpel, Daniël J; Moriel, Danilo G; Totsika, Makrina; Easton, Donna M; Schembri, Mark A

    2015-02-06

    Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections. For successful colonisation of the urinary tract, UPEC employ multiple surface-exposed or secreted virulence factors, including adhesins and iron uptake systems. Whilst individual UPEC strains and their virulence factors have been the focus of extensive research, there have been no outer membrane (OM) proteomic studies based on large clinical UPEC collections, primarily due to limitations of traditional methods. In this study, a high-throughput method based on tandem mass-spectrometry of EDTA heat-induced outer membrane vesicles (OMVs) was developed for the characterisation of the UPEC surface-associated proteome. The method was applied to compare the OM proteome of fifty-four UPEC isolates, resulting in the identification of 8789 proteins, consisting of 619 unique proteins, which were subsequently interrogated for their subcellular origin, prevalence and homology to characterised virulence factors. Multiple distinct virulence-associated proteins were identified, including two novel putative iron uptake proteins, an uncharacterised type of chaperone-usher fimbriae and various highly prevalent hypothetical proteins. Our results give fundamental insight into the physiology of UPEC and provide a framework for understanding the composition of the UPEC OM proteome. In this study a high-throughput method based on tandem mass-spectrometry of EDTA heat-induced outer membrane vesicles was used to define the outer membrane proteome of a large uropathogenic E. coli (UPEC) collection. Our results provide an inventory of proteins expressed on the surface of UPEC, and provide a framework for understanding the composition of the UPEC OM proteome. The method enables the rapid characterisation of the E. coli surface proteome and could easily be applied to the large-scale outer membrane protein profiling of other Gram-negative bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Determination of multi-class pesticides in wines by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Economou, Anastasios; Botitsi, Helen; Antoniou, Spyros; Tsipi, Despina

    2009-07-31

    This work reports a new sensitive multi-residue liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for detection, confirmation and quantification of forty-six pesticides and transformation products belonging to different chemical classes in wines. The proposed method makes use of a solid-phase extraction (SPE) procedure with Oasis HLB cartridges that combines isolation of the pesticides and sample clean-up in a single step. Analysis is performed by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-MS/MS) operated in the selected reaction monitoring (SRM) mode, acquiring two specific precursor-product ion transitions per target compound. An investigation of matrix effects has been performed during method validation showing medium to low effects for the majority of the compounds. Limits of detection (LODs) were in the range 0.0003-0.003 mg L(-1) and limits of quantification (LOQs) were in the range 0.001-0.01 mg L(-1). The average recoveries, measured at two concentration levels (0.010 and 0.050 mg L(-1)), were in the range 70-110% for most of the compounds tested with % relative standard deviations below 20%, while a value of 0.010 mg L(-1) has been established as the method limit of quantification (MLOQ) for all target species. Expanded uncertainty values were in the range 10-40% while the Horrat ratios were below 1. The method has been successfully applied to the analysis of 60 wine samples in the course of an annual monitoring study with carbendazim-benomyl, thiophanate-methyl and carbaryl being the most frequently determined pesticides.

  7. Determination of pharmaceuticals in wastewaters using solid-phase extraction-liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Gilart, Núria; Marcé, Rosa Maria; Borrull, Francesc; Fontanals, Núria

    2012-04-01

    Four different commercial sorbents for solid-phase extraction have been evaluated for the extraction of a group of acidic pharmaceuticals in terms of selectivity and capacity: Oasis hydrophilic-lipophilic balance (HLB), Oasis MAX (strong anion exchange), Oasis WAX (weak anion exchange) and a commercial available molecularly imprinted polymer specific for non-steroidal anti-inflammatory drugs. Among the sorbents studied, molecularly imprinted polymer proved to be very effective in the reduction of matrix interferences and the selective extraction of acidic pharmaceuticals, such as salicylic acid, ibuprofen, fenoprofen, diclofenac and naproxen, among others, from effluent wastewater samples. Moreover, molecularly imprinted solid-phase extraction protocol was applied to liquid chromatography coupled to tandem mass spectrometry (MS/MS) with the purpose of evaluating the clean-up effect on ion suppression/enhancement when the complexity of the samples increases and a reduction of this effect was observed. Molecularly imprinted solid-phase extraction followed by liquid chromatography coupled to ultraviolet detection and liquid chromatography coupled to tandem mass spectrometry validation methodologies with effluent wastewaters were developed, obtaining recoveries between 70 and 85% and limits of detection at low levels of μg/L (0.15-1 μg/L) and ng/L (0.5-2 ng/L), respectively. The final application of molecularly imprinted solid-phase extraction and liquid chromatography coupled to MS/MS detection showed the presence of acidic pharmaceuticals studied in this work in effluent wastewaters (

  8. Rapid and reliable steroid hormone profiling in Tursiops truncatus blubber using liquid chromatography tandem mass spectrometry (LC-MS/MS).

    Science.gov (United States)

    Boggs, Ashley S P; Schock, Tracey B; Schwacke, Lori H; Galligan, Thomas M; Morey, Jeanine S; McFee, Wayne E; Kucklick, John R

    2017-08-01

    Monitoring of marine mammal steroid hormone status using matrices alternative to blood is desirable due to the ability to remotely collect samples, which minimizes stress to the animal. However, measurement techniques in alternative matrices such as blubber described to date are limited in the number and types of hormones measured. Therefore, a new method using bead homogenization to QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction, C18 post extraction cleanup and analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and applied to the measurement of hormone suites in bottlenose dolphin blubber. Validations were conducted in blubber from fresh dead stranded bottlenose dolphin. The final method consisting of two LC separations and garnet bead homogenization was tested for extraction efficiencies. Steroids were separated using a biphenyl column for reproductive hormones and C18 column for corticosteroids. Three hormones previously noted in blubber, testosterone, progesterone, and cortisol, were quantified in addition to previously unmeasured androstenedione, 17-hydroxyprogesterone, 11-deoxycortisol, 11-deoxycorticosterone, and cortisone in a single sample (0.4 g blubber). Extraction efficiencies of all hormones from blubber ranged from 84% to 112% and all RSDs were comparable to those reported using immunoassay methods (< 15%). The method was successfully applied to remote biopsied blubber samples to measure baseline hormone concentrations. Through this method, increased coverage of steroid hormone pathways from a single remotely collected sample potentially enhances the ability to interpret biological phenomena such as reproduction and stress in wild dolphin populations. Graphical abstract The steroid hormone profile is quantifiable from a single sample of bottlenose dolphin blubber using liquid chromatography tandem mass spectrometry. This profile can be applied to remotely collected dart biopsies and be used to

  9. [Determination of propargite, tebuconazole and bromopropylate pesticide residues in Taiwan green jujubes by gas chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Zhang, Qun; Liu, Chunhua; Wu, Nancun; Wu, Xiaofang; Li, Shuhuai

    2014-08-01

    An analytical method was established for the determination of propargite, tebuconazole and bromopropylate in Taiwan green jujubes (Zizyphus mauritiana Lam) by gas chromatography-tandem mass spectrometry (GC-MS/MS). The sample was extracted with acetonitrile from the Taiwan green jujubes after treated with a homogenizer. The organic phase was then separated from water phase by adding NaCl. The extract was further purified on a carbon/ NH2 cartridge with elution solvents of acetonitrile/toluene (3:1, v/v). Finally, the target analytes were separated by a capillary gas chromatographic column SLB-5MS (30 m x 0. 25 mm x 0. 25 μm). A tandem quadrupole mass spectrometer operated in either full scan mode or in MS/MS mode for multiple reaction monitoring (MRM) was used for the qualitative and quantitative analysis of the constituents, respectively. The results showed that the average recoveries of the three pesticides ranged from 75. 8% to 103. 6% with the RSDs of 1. 7%-9. 3% at the spiking levels from 0.01 mg/kg to 0. 50 mg/kg (n= 5). The calibration curves showed good linearity in the range of 0.01-0.50 mg/kg, with the determination coefficients over 0.99 (R2>0.99). The limits of quantification (LOQs) were 0.01 mg/kg for propargite, tebuconazole and bromopropylate in Taiwan green jujubes. The method is available for the determination of propargite, tebuconazole and bromopropylate pesticide residues in Taiwan green jujubes.

  10. Potential of fermentation profiling via rapid measurement of amino acid metabolism by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Dalluge, Joseph J; Smith, Sean; Sanchez-Riera, Fernando; McGuire, Chris; Hobson, Russell

    2004-07-16

    Monitoring amino acid metabolism during fermentation has significant potential from the standpoint of strain selection, optimizing growth and production in host strains, and profiling microbial metabolism and growth state. A method has been developed based on rapid quantification of underivatized amino acids using liquid chromatography-electrospray tandem mass spectrometry (LC-MS-MS) to monitor the metabolism of 20 amino acids during microbial fermentation. The use of a teicoplanin-based chiral stationary phase coupled with electrospray tandem mass spectrometry allows complete amino acid analyses in less than 4 min. Quantification is accomplished using five isotopically labeled amino acids as internal standards. Because comprehensive chromatographic separation and derivatization are not required, analysis time is significantly less than traditional reversed- or normal-phase LC-based amino acid assays. Intra-sample precisions for amino acid measurements in fermentation supernatants using this method average 4.9% (R.S.D.). Inter-day (inter-fermentation) precisions for individual amino acid measurements range from 4.2 to 129% (R.S.D.). Calibration curves are linear over the range 0-300 microg/ml, and detection limits are estimated at 50-450 ng/ml. Data visualization techniques for constructing semi-quantitative fermentation profiles of nitrogen source utilization have also been developed and implemented, and demonstrate that amino acid profiles generally correlate with observed growth profiles. Further, cellular growth events, such as lag-time and cell lysis can be detected using this methodology. Correlation coefficients for the time profiles of each amino acid measured illustrate that while several amino acids are differentially metabolized in similar fermentations, a select group of amino acids display strong correlations in these samples, indicating a sub-population of analytes that may be most useful for fermentation profiling.

  11. Metabolism of cycloate in radish leaf: metabolite identification by packed capillary flow fast atom bombardment tandem mass spectrometry.

    Science.gov (United States)

    Onisko, B C; Barnes, J P; Staub, R E; Walker, F H; Kerlinger, N

    1994-10-01

    The metabolism of cycloate, a thiocarbamate herbicide, was investigated in mature radish leaf. Twelve new metabolites were identified by liquid chromatographic/mass spectrometric analysis using fast atom bombardment and packed capillary liquid chromatography columns. Full-scan and tandem mass spectrometric methods were employed. Application of the on-column focusing technique resulted in identifications with injections of as little as 15 ng of metabolite (20 ppb in radish). This injection technique allows the practical use of packed capillary liquid chromatography/mass spectrometry in sample-limited applications. Cycloate is oxidized to several ring-hydroxylated isomers that are subsequently glucosylated and esterified with malonic acid. Cycloate is also conjugated with glutathione. Metabolic hydrolysis of the glutathione conjugate formed a cysteine conjugate that is further metabolized by amidation with either malonic or acetic acid. Transamination of the cysteine conjugate gave a thiolactic acid derivative. Metabolites were also identified that were the result of both ring-hydroxylation and conjugation with glutathione. One of these, an N-acetylcysteine conjugate, is the first report of a mercapturic acid in plants. The structures of two of the new metabolites were confirmed by chemical synthesis.

  12. Measurement of human plasma proteome dynamics with (2)H(2)O and liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Price, John C; Holmes, William E; Li, Kelvin W; Floreani, Nicholas A; Neese, Richard A; Turner, Scott M; Hellerstein, Marc K

    2012-01-01

    Dysfunction of protein turnover is a feature of many human diseases, and proteins are substrates in important biological processes. Currently, no method exists for the measurement of global protein turnover (i.e., proteome dynamics) that can be applied in humans. Here we describe the use of metabolic labeling with deuterium ((2)H) from (2)H(2)O and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of mass isotopomer patterns to measure protein turnover. We show that the positions available for (2)H label incorporation in vivo can be calculated using peptide sequence. The isotopic incorporation values calculated by combinatorial analysis of mass isotopomer patterns in peptides correlate very closely with values established for individual amino acids. Inpatient and outpatient heavy water labeling protocols resulted in (2)H label incorporation sufficient for reproducible quantitation in humans. Replacement rates were similar for peptides deriving from the same protein. Using a kinetic model to account for the time course of each individual's (2)H(2)O enrichment curves, dynamics of approximately 100 proteins with half-lives ranging from 0.4 to 40 days were measured using 8 μl of plasma. The measured rates were consistent with literature values. This method can be used to measure in vivo proteome homeostasis in humans in disease and during therapeutic interventions. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Quantification of immunoreactive viral influenza proteins by immunoaffinity capture and isotope-dilution liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Pierce, Carrie L; Williams, Tracie L; Moura, Hercules; Pirkle, James L; Cox, Nancy J; Stevens, James; Donis, Ruben O; Barr, John R

    2011-06-15

    An immunocapture isotope dilution mass spectrometry (IC-IDMS) method was developed to quantify antibody-bound influenza hemagglutinins (HA) in trivalent influenza vaccines (TIV). Currently, regulatory potency requirements for TIV require HA quantification based on the single radial immunodiffusion (SRID) assay, which is time-consuming, laborious, and requires production of large quantities of reagents globally. In IC-IDMS, antiserum to the HA of interest captured viral proteins that were in the correct conformation to be recognized by the antibodies. The captured proteins were digested, and evolutionarily conserved tryptic peptides were quantified using isotope-dilution liquid chromatography-tandem mass spectrometry. IC-IDMS relies on antibody-antigen binding similar to SRID but incorporates the accuracy and precision of IDMS. Polyclonal antibodies (pAb-H3) prepared by injection of sheep with purified H3 HA captured 82.9% (55.26 fmol/μL) of the total H3 HA (66.69 fmol/μL) from the commercial TIV and 93.6% (57.23 fmol/μL) of the total H3 HA (61.14 fmol/μL) in purified virus. While other HA (H1, B), neuraminidase (N1, N2, NB), viral matrix proteins, and nucleoproteins were also captured by this antiserum, our results were not affected due to the specificity of the mass spectrometer. IC-IDMS is an accurate, precise, sensitive, and selective method to measure antibody-bound HA in purified virus and commercial vaccines.

  14. Evaluation of the Consensus of Four Peptide Identification Algorithms for Tandem Mass Spectrometry Based Proteomics.

    Science.gov (United States)

    Dagda, Ruben K; Sultana, Tamanna; Lyons-Weiler, James

    2010-02-05

    The availability of different scoring schemes and filter settings of protein database search algorithms has greatly expanded the number of search methods for identifying candidate peptides from MS/MS spectra. We have previously shown that consensus-based methods that combine three search algorithms yield higher sensitivity and specificity compared to the use of a single search engine (individual method). We hypothesized that union of four search engines (Sequest, Mascot, X!Tandem and Phenyx) can further enhance sensitivity and specificity. ROC plots were generated to measure the sensitivity and specificity of 5460 consensus methods derived from the same dataset. We found that Mascot outperformed individual methods for sensitivity and specificity, while Phenyx performed the worst. The union consensus methods generally produced much higher sensitivity, while the intersection consensus methods gave much higher specificity. The union methods from four search algorithms modestly improved sensitivity, but not specificity, compared to union methods that used three search engines. This suggests that a strategy based on specific combination of search algorithms, instead of merely 'as many search engines as possible', may be key strategy for success with peptide identification. Lastly, we provide strategies for optimizing sensitivity or specificity of peptide identification in MS/MS spectra for different user-specific conditions.

  15. The performance of atmospheric pressure gas chromatography–tandem mass spectrometry compared to gas chromatography–high resolution mass spectrometry for the analysis of polychlorinated dioxins and polychlorinated biphenyls in food and feed samples

    NARCIS (Netherlands)

    Dam, ten Guillaume; Pussente, Igor Cabreira; Scholl, Georges; Eppe, Gauthier; Schaechtele, Alexander; Leeuwen, van Stefan

    2016-01-01

    Recently, gas chromatography tandem mass spectrometry (GC–MS/MS) has been added in European Union (EU) legislation as an alternative to magnetic sector high resolution mass spectrometry (HRMS) for the analysis of dioxins and dioxin like polychlorinated biphenyls (dl-PCB) in food and feed. In this

  16. High-Resolution Liquid Chromatography Tandem Mass Spectrometry Enables Large Scale Molecular Characterization of Dissolved Organic Matter

    Directory of Open Access Journals (Sweden)

    Daniel Petras

    2017-12-01

    Full Text Available Dissolved organic matter (DOM is arguably one of the most complex exometabolomes on earth, and is comprised of thousands of compounds, that together contribute more than 600 × 1015 g carbon. This reservoir is primarily the product of interactions between the upper ocean's microbial food web, yet abiotic processes that occur over millennia have also modified many of its molecules. The compounds within this reservoir play important roles in determining the rate and extent of element exchange between inorganic reservoirs and the marine biosphere, while also mediating microbe-microbe interactions. As such, there has been a widespread effort to characterize DOM using high-resolution analytical methods including nuclear magnetic resonance spectroscopy (NMR and mass spectrometry (MS. To date, molecular information in DOM has been primarily obtained through calculated molecular formulas from exact mass. This approach has the advantage of being non-targeted, accessing the inherent complexity of DOM. Molecular structures are however still elusive and the most commonly used instruments are costly. More recently, tandem mass spectrometry has been employed to more precisely identify DOM components through comparison to library mass spectra. Here we describe a data acquisition and analysis workflow that expands the repertoire of high-resolution analytical approaches available to access the complexity of DOM molecules that are amenable to electrospray ionization (ESI MS. We couple liquid chromatographic separation with tandem MS (LC-MS/MS and a data analysis pipeline, that integrates peak extraction from extracted ion chromatograms (XIC, molecular formula calculation and molecular networking. This provides more precise structural characterization. Although only around 1% of detectable DOM compounds can be annotated through publicly available spectral libraries, community-wide participation in populating and annotating DOM datasets could rapidly increase the

  17. Ultra-high-performance liquid chromatography-tandem mass spectrometry measurement of climbazole deposition from hair care products onto artificial skin and human scalp

    NARCIS (Netherlands)

    Chen, G.; Hoptroff, M.; Fei, X.; Su, Y.; Janssen, H.-G.

    2013-01-01

    A sensitive and specific ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the measurement of climbazole deposition from hair care products onto artificial skin and human scalp. Deuterated climbazole was used as the internal

  18. Liquid chromatography-tandem mass spectrometry analysis of free and esterified fatty acid N-acyl ethanolamines in plasma and blood cells

    NARCIS (Netherlands)

    Balvers, M.G.J.; Wortelboer, H.M.; Witkamp, R.F.; Verhoeckx, K.C.M.

    2013-01-01

    The origin of N-acyl ethanolamides (NAEs) in plasma is not well understood, and it is possible that NAEs are present in plasma in esterified form. To test this hypothesis, a new and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the

  19. Simultaneous identification of multiple β-lactamases in Acinetobacter baumannii in relation to carbapenem and ceftazidime resistance, using liquid chromatography-tandem mass spectrometry

    NARCIS (Netherlands)

    Trip, H.; Mende, K.; Majchrzykiewicz-Koehorst, J.A.; Sedee, N.J.A.; Hulst, A.G.; Jansen, H.J.; Murray, C.K.; Paauw, A.

    2015-01-01

    Shotgun proteomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to detect β-lactamases in clinical Acinetobacter baumannii isolates. The correlation of the detection of β-lactamase proteins (rather than PCR detection of the corresponding genes) with the resistance

  20. Liquid chromatography–tandem mass spectrometry analysis of free and esterified fatty acid N-acyl ethanolamines in plasma and blood cells

    NARCIS (Netherlands)

    Balvers, M.G.J.; Wortelboer, H.M.; Witkamp, R.F.; Verhoeckx, K.C.M.

    2013-01-01

    The origin of N-acyl ethanolamides (NAEs) in plasma is not well understood, and it is possible that NAEs are present in plasma in esterified form. To test this hypothesis, a new and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the

  1. Liquid chromatography-tandem mass spectrometric assay for the T790M mutant EGFR inhibitor osimertinib (AZD9291) in human plasma

    NARCIS (Netherlands)

    Rood, Johannes J M; van Bussel, Mark T J; Schellens, Jan H M; Beijnen, Jos H; Sparidans, Rolf W

    2016-01-01

    A method for the quantitative analysis by ultra-performance liquid chromatography-tandem mass spectrometry of the highly selective irreversible covalent inhibitor of EGFR-TK, osimertinib in human plasma was developed and validated, using pazopanib as an internal standard. The validation was

  2. Simultaneous quantification of purine and pyrimidine bases, nucleosides and their degradation products in bovine blood plasma by high performance liquid chromatography tandem mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Stentoft; Vestergaard, Mogens; Løvendahl, Peter

    2014-01-01

    ), and their degradation products (uric acid, allantoin, β-alanine, β-ureidopropionic acid, β-aminoisobutyric acid) in blood plasma of dairy cows. The high performance liquid chromatography-based technique coupled to electrospray ionization tandem mass spectrometry (LC–MS/MS) was combined with individual matrix...

  3. Comprehensive analysis of B-Lactam antibiotics including penicillins, cephalosporins and carbapenems in poultry muscle using liquid chromatography coupled to tandem mass spectrometry

    NARCIS (Netherlands)

    Berendsen, B.J.A.; Gerritsen, H.W.; Wegh, R.S.; Lameris, S.L.; Sebille, van R.; Stolker, A.A.M.; Nielen, M.W.F.

    2013-01-01

    A comprehensive method for the quantitative residue analysis of trace levels of 22 ß-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, in poultry muscle by liquid chromatography in combination with tandem mass spectrometric detection is reported. The samples analyzed for

  4. Analysis of vitamin K-1 in fruits and vegetables using accelerated solvent extraction and liquid chromatography tandem mass spectrometry with atmospheric pressure chemical ionization

    DEFF Research Database (Denmark)

    Jäpelt, Rie Bak; Jakobsen, Jette

    2016-01-01

    The objective of this study was to develop a rapid, sensitive, and specific analytical method to study vitamin K-1 in fruits and vegetables. Accelerated solvent extraction and solid phase extraction was used for sample preparation. Quantification was done by liquid chromatography tandem mass...

  5. Liquid chromatography with tandem mass spectrometry quantification of urinary proanthocyanin A2 dimer and its potential use as a biomarker of cranberry intake

    Science.gov (United States)

    The lack of a biomarker for the consumption of cranberries has confounded the interpretation of several studies investigating the effect of cranberry products, especially juices, on health outcomes. The objectives of this pilot study were to develop a liquid chromatography tandem mass spectrometric ...

  6. Specific determination of 20 primary aromatic amines in aqueous food simulants by liquid chromatography-electrospray ionization-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Mortensen, Sarah Kelly; Trier, Xenia Thorsager; Foverskov, Annie

    2005-01-01

    A multi-analyte method without any pre-treatment steps using reversed-phase liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was developed and applied for the determination of 20 primary aromatic amines (PAA) associated with polyurethane (PUR) products or azo...

  7. Development of a new ultra-high performance liquid chromatography - tandem mass spectrometry method for determination of ambroxol hydrochloride in serum with pharmacokinetic application

    OpenAIRE

    Vujović Maja M.; Jokanović Milan; Nikolić Goran M.

    2016-01-01

    Ambroxol hydrochloride is an expectorant agent, successfully applied in mucolytic therapy for acute and chronic bronchopulmonary diseases. The drug regulates not only mucus secretion but also showed antioxidant, anti-inflammatory and local anesthetic properties. To supplement the pharmacokinetic and toxicological studies of ambroxol, a rapid ultra-high performance liquid chromatography-tandem mass spectrometry method for the quantitation of ambroxol in rabb...

  8. Identification of glyceollin metabolites derived from conjugation with glutathione and glucuronic acid in rats by on-line liquid chromatography-electrospray ionization tandem mass spectrometry

    Science.gov (United States)

    Glyceollin-related metabolites produced in rats following oral glyceollin administration were screened and identified by precursor and product ion scanning using liquid chromatography, coupled on-line with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS), to identify all glyceollin me...

  9. Enantioselective determination of methylphenidate and ritalinic acid in whole blood from forensic cases using automated solid-phase extraction and liquid chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Thomsen, Ragnar; B. Rasmussen, Henrik; Linnet, Kristian

    2012-01-01

    A chiral liquid chromatography tandem mass spectrometry (LC–MS-MS) method was developed and validated for quantifying methylphenidate and its major metabolite ritalinic acid in blood from forensic cases. Blood samples were prepared in a fully automated system by protein precipitation followed...

  10. Fluconazole Pharmacokinetics in Galleria mellonella Larvae and Performance Evaluation of a Bioassay Compared to Liquid Chromatography-Tandem Mass Spectrometry for Hemolymph Specimens

    DEFF Research Database (Denmark)

    Astvad, Karen Marie Thyssen; Meletiadis, Joseph; Whalley, Sarah

    2017-01-01

    the fluconazole pharmacokinetics and pharmacodynamics in larval hemolymph in order to estimate a humanized dose for future experiments. A bioassay using 4-mm agar wells, 20 μl hemolymph, and the hypersusceptible Candida albicans DSY2621 was established and compared to a validated liquid chromatography-tandem mass...

  11. A mass graph-based approach for the identification of modified proteoforms using top-down tandem mass spectra.

    Science.gov (United States)

    Kou, Qiang; Wu, Si; Tolic, Nikola; Paša-Tolic, Ljiljana; Liu, Yunlong; Liu, Xiaowen

    2017-05-01

    Although proteomics has rapidly developed in the past decade, researchers are still in the early stage of exploring the world of complex proteoforms, which are protein products with various primary structure alterations resulting from gene mutations, alternative splicing, post-translational modifications, and other biological processes. Proteoform identification is essential to mapping proteoforms to their biological functions as well as discovering novel proteoforms and new protein functions. Top-down mass spectrometry is the method of choice for identifying complex proteoforms because it provides a 'bird's eye view' of intact proteoforms. The combinatorial explosion of various alterations on a protein may result in billions of possible proteoforms, making proteoform identification a challenging computational problem. We propose a new data structure, called the mass graph, for efficient representation of proteoforms and design mass graph alignment algorithms. We developed TopMG, a mass graph-based software tool for proteoform identification by top-down mass spectrometry. Experiments on top-down mass spectrometry datasets showed that TopMG outperformed existing methods in identifying complex proteoforms. http://proteomics.informatics.iupui.edu/software/topmg/. xwliu@iupui.edu. Supplementary data are available at Bioinformatics online.

  12. A mass graph-based approach for the identification of modified proteoforms using top-down tandem mass spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kou, Qiang; Wu, Si; Tolić, Nikola; Paša-Tolić, Ljiljana; Liu, Yunlong; Liu, Xiaowen

    2016-12-21

    Motivation: Although proteomics has rapidly developed in the past decade, researchers are still in the early stage of exploring the world of complex proteoforms, which are protein products with various primary structure alterations resulting from gene mutations, alternative splicing, post-translational modifications, and other biological processes. Proteoform identification is essential to mapping proteoforms to their biological functions as well as discovering novel proteoforms and new protein functions. Top-down mass spectrometry is the method of choice for identifying complex proteoforms because it provides a “bird’s eye view” of intact proteoforms. The combinatorial explosion of various alterations on a protein may result in billions of possible proteoforms, making proteoform identification a challenging computational problem. Results: We propose a new data structure, called the mass graph, for efficient representation of proteoforms and design mass graph alignment algorithms. We developed TopMG, a mass graph-based software tool for proteoform identification by top-down mass spectrometry. Experiments on top-down mass spectrometry data sets showed that TopMG outperformed existing methods in identifying complex proteoforms.

  13. A universal SI-traceable isotope dilution mass spectrometry method for protein quantitation in a matrix by tandem mass tag technology.

    Science.gov (United States)

    Li, Jiale; Wu, Liqing; Jin, Youxun; Su, Ping; Yang, Bin; Yang, Yi

    2016-05-01

    Isotope dilution mass spectrometry (IDMS), an important metrological method, is widely used for absolute quantification of peptides and proteins. IDMS employs an isotope-labeled peptide or protein as an internal standard although the use of a protein provides improved accuracy. Generally, the isotope-labeled protein is obtained by stable isotope labeling by amino acids in cell culture (SILAC) technology. However, SILAC is expensive, laborious, and time-consuming. To overcome these drawbacks, a novel universal SI-traceable IDMS method for absolute quantification of proteins in a matrix is described with human transferrin (hTRF). The hTRF and a human serum sample were labeled with different tandem mass tags (TMTs). After mixing the TMT-labeled hTRF and serum sample together followed by digestion, the peptides were separated by nano-liquid chromatography and analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Using the signature peptides, we calculated the ratios of reporter ions from the TMT-labeled peptides which, in turn, allowed determination of the mass fraction of hTRF. The recovery ranged from 97% to 105% with a CV of 3.9%. The LOD and LOQ were 1.71 × 10(-5) g/g and 5.69 × 10(-5) g/g of hTRF in human serum, respectively, and the relative expanded uncertainty was 4.7% with a mass fraction of 2.08 mg/g. For comparison, an enzyme-linked immunosorbent assay (ELISA) method for hTRF yielded a mass fraction of 2.03 mg/g. This method provides a starting point for establishing IDMS technology to accurately determine the mass fractions of protein biomarkers in a matrix with traceability to SI units. This technology should support the development of a metrological method useful for quantification of a wide variety of proteins.

  14. Improved specificity of serum phosphatidylcholine detection based on side-chain losses during negative electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Ritchie, Shawn A; Jayasinge, Dushmanthi; Wang, Li; Goodenowe, Dayan B

    2016-11-01

    Many current tandem mass spectrometry (MS) methods for measuring phosphatidylcholines (PtdChos) rely only on precursor ion scanning of the common 184 m/z phosphocholine fragment with positive electrospray ionization (+ESI), and thus measure pools of PtdChos rather than specific isoforms. In this paper, we developed and compared an isotope dilution, tandem MS method capable of quantifying PtdChos based on specific fatty acid side-chains to the traditional 184 m/z method. The method is based on the detection of PtdCho ammonium formate (AmF) adduct as parent ions and fatty acid fragment daughter ions under negative electrospray ionization (-ESI). Accuracy, imprecision, and recovery were below 15 %, with acceptable linearity (R 2 > 0.99) up to 5 μg/mL. We used the method to analyze the distributions of PtdChos with common side-chain combinations among 60 subjects and showed that it was possible for two individuals to have the same PtdCho pool concentration based on detection of the 184 m/z fragment, but up to a fourfold difference in the levels of specific isoforms comprising the pool based on our method. We then compared the results of both methods across 572 patients with mild cognitive impairment (MCI), Alzheimer's disease (AD), or no impairment (NI), which showed that statistically significant associations between specific PtdCho isoforms and AD were masked with the 184 m/z method. Our findings demonstrate the importance of isoform specificity for quantifying PtdChos, and suggest caution when interpreting analytical data based on pools of biomarkers.

  15. Simultaneous determination of 9 heterocyclic aromatic amines in pork products by liquid chromatography coupled with triple quadrupole tandem mass spectrometry

    Science.gov (United States)

    Shen, X. C.; Zhang, Y. L.; Cui, Y. Q.; Xu, L. Y.; Li, X.; Qi, J. H.

    2017-07-01

    Heterocyclic aromatic amines (HAAs) are potent mutagens that formed at high temperature in cooked, protein-rich food. Owing to their frequent intake, an accurate method is essential to access human health risk of HAAs exposure through detecting these compounds in various heat-treated meat products. In this study, a liquid chromatography-electrospray tandem mass spectrometry (LC--ESI-MS/MS) method was developed to perform the determination of 9 mutagenic heterocyclic amines (HAAs) in meat samples with multiple reaction monitoring (MRM) mode. Ultrasound assisted extraction and diatomaceous earth was employed to extract HAAs from food samples, and the analytes were purified and enriched using tandem solid phase extraction, with propyl sulfonic acid coupled to a C18 cartridge. Two parameters, extraction time and eluent, were carefully optimized to improve the extraction and purification efficiency. The LC separation was carried out using a Zorbax SB-C18 (3.5 μm particle size, 2.1 × 150 mm i.d.) column and optimized some parameters, such as pH, concentration and volume. Under the optimal experimental conditions, recoveries ranged from 52.97% to 97.11% with good quality parameters: limit of detection values between 0.02 and 0.24 ng mL-1, linearity (R2>0.998), and run-to-run and day-to-day precisions lower than 9.81% achieved. To evaluate the performance of the method in high throughput analysis of complex meat samples, the LC-MS/MS method was applied to the analysis of HAAs in three food samples, and the results demonstrated that the method can be used for the trace determination of HAAs in pork samples.

  16. Determination of sulfadiazine in phosphate- and DOC-rich agricultural drainage water using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry

    DEFF Research Database (Denmark)

    Bouyou, P.A. Léon; Weisser, Johan Juhl; Strobel, Bjarne W.

    2014-01-01

    obtained ranged from 104 to 109 % (relative standard deviation 2.8–5.2 %). The new methods enable determination of the veterinary antibiotic compound SDZ in agricultural drainage water from field experiments and monitoring schemes for phosphate- and dissolved organic carbon (DOC)-rich water samples......, spiked with common and high levels of dissolved organic carbon (2, 6, and 15 mg/L) confirmed the possible adaptation of a tandem solid-phase extraction (strong anion exchange (SAX)-hydrophilic-lipophilic balance (HLB)) followed by liquid chromatography-tandem mass spectrometry methodology. Recoveries...

  17. Rose-like Pd-Fe3O4 hybrid nanocomposite-supported Au nanocatalysts for tandem synthesis of 2-phenylindoles

    Science.gov (United States)

    Woo, Hyunje; Park, Ji Chan; Park, Sungkyun; Park, Kang Hyun

    2015-04-01

    A facile synthesis of rose-like Pd-Fe3O4 nanocomposites via controlled thermal decomposition of Fe(CO)5 and reduction of Pd(OAc)2, followed by the immobilization of Au nanoparticles (NPs) onto the Pd-Fe3O4 supports, is reported. The morphology of these hybrid nanostructures could be easily controlled by varying the amount of Fe(CO)5 and the reaction temperature. Moreover, the synthesized Au/Pd-Fe3O4 catalyst exhibited high catalytic activity for the tandem synthesis of 2-phenylindoles and demonstrated magnetic recyclability.A facile synthesis of rose-like Pd-Fe3O4 nanocomposites via controlled thermal decomposition of Fe(CO)5 and reduction of Pd(OAc)2, followed by the immobilization of Au nanoparticles (NPs) onto the Pd-Fe3O4 supports, is reported. The morphology of these hybrid nanostructures could be easily controlled by varying the amount of Fe(CO)5 and the reaction temperature. Moreover, the synthesized Au/Pd-Fe3O4 catalyst exhibited high catalytic activity for the tandem synthesis of 2-phenylindoles and demonstrated magnetic recyclability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01441g

  18. Analysis of fungal cyclopentenone derivatives from Hygrophorus spp. by liquid chromatography/electrospray-tandem mass spectrometry.

    Science.gov (United States)

    Lübken, Tilo; Arnold, Norbert; Wessjohann, Ludger; Böttcher, Christoph; Schmidt, Jürgen

    2006-03-01

    Fruitbodies of the genus Hygrophorus (Basidiomycetes) contain a series of anti-biologically active compounds. These substances named hygrophorones possess a cyclopentenone skeleton. LC/ESI-MS/MS presents a valuable tool for the identification of such compounds. The mass spectral behaviour of typical selected members of this group under positive and negative ion electrospray conditions is discussed. Using the ESI collision-induced dissociation (CID) mass spectra of the [M + H]+ and [M - H]- ions, respectively, the compounds can be classified with respect to the substitution pattern at the cyclopentenone ring and the type of oxygenation at C-6 (hydroxy/acetoxy or oxo function) of the side chain. The elemental composition of the fragment ions was determined by ESI-QqTOF measurements. Thus, in case of the negative ion CID mass spectra an unusual loss of CO2 from the deprotonated molecular ions could be observed.

  19. Molecular characterization and tandem mass spectrometry of the lectin extracted from the seeds of Dioclea sclerocarpa Ducke.

    Science.gov (United States)

    Correia, Jorge Luis Almeida; do Nascimento, Antônia Sâmia Fernandes; Cajazeiras, João Batista; Gondim, Ana Cláudia Silva; Pereira, Ronniery Ilario; de Sousa, Bruno Lopes; da Silva, André Luiz Coelho; Garcia, Wanius; Teixeira, Edson Holanda; do Nascimento, Kyria Santiago; da Rocha, Bruno Anderson Matias; Nagano, Celso Shiniti; Sampaio, Alexandre Holanda; Cavada, Benildo Sousa

    2011-10-28

    Lectin from the seeds of Dioclea sclerocarpa (DSL) was purified in a single step by affinity chromatography on a Sephadex G-50 column. The primary sequence, as determined by tandem mass spectrometry, revealed a protein with 237 amino acids and 81% of identity with ConA. DSL has a molecular mass of 25,606 Da. The β and γ chains weigh 12,873 Da and 12,752 Da, respectively. DSL hemagglutinated rabbit erythrocytes (both native and treated with proteolytic enzymes), showing stability even after one hour of exposure to a specific pH range. The hemagglutinating activity of DSL was optimal between pH 6.0 and 8.0, but was inhibited after incubation with D-galactose and D-glucose. The pure protein possesses a molecular mass of 25 kDa by SDS-PAGE and 25,606 Da by mass spectrometry. The secondary structure content was estimated using the software SELCON3. The results indicate that b-sheet secondary structures are predominant in DSL (approximately 42.3% antiparallel b-sheet and 6.7% parallel b-sheet). In addition to the b-sheet, the predicted secondary structure of DSL features 4.1% a-helices, 15.8% turns and 31.3% other contributions. Upon thermal denaturation, evaluated by measuring changes in ellipticity at 218 nm induced by a temperature increase from 20 °C to 98 °C, DSL displayed cooperative sigmoidal behavior with transition midpoint at 84 °C and permitted the observation of two-state model (native and denatured).

  20. Determination of MS-222 in Water Samples by Solid-phase Extraction Coupled with Liquid Chromatography/Tandem Mass Spectrometry.

    Science.gov (United States)

    Zhao, Dong-Hao; Wang, Qiang; Wang, Xu-Feng; Li, Zhi-Guang; Li, Yong-Xian; Huang, Ke; Li, Liu-Dong

    2017-09-01

    A practical solid-phase extraction (SPE) method coupled with liquid chromatography/tandem mass spectrometry (LC-MS/MS) has been developed for the determination of the fish anesthetic MS-222 in water. Water samples were concentrated and purified using three SPE cartridges of different specifications. Elution curves of MS-222 were constructed using various methanol-water solutions on the different cartridges, and SPE conditions were optimized in accordance with the elution curves. The mobile phase containing methanol and 0.1% formic acid solution with a linear gradient elution was utilized to separate MS-222 on a C18 column. Detection was carried out by a triple-quadrupole mass spectrometry with an electrospray ion source in positive mode. Recoveries of three MS-222 fortified levels of 0.05, 0.5 and 5 μg/L ranged of 82.6-101% with relative standard deviations (RSDs) below 9.36%. The limit of detection (LOD) and limit of quantification (LOQ) of MS-222 were 0.01 μg/L and 0.03 μg/L, respectively. This method was satisfactorily applied to the determination of MS-222 in actual water samples collected from aquatic product transportation vehicles or from the natural water catchments. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Simultaneous detection of bacitracin and polymyxin B in livestock products using liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Zhang, Dan; Park, Jin-A; Kim, Dong-Soon; Kim, Na-Hyun; Kim, Seong-Kwan; Cho, Kyeong-Su; Jeong, Dana; Shim, Jae-Han; Abd El-Aty, A M; Shin, Ho-Chul

    2015-07-01

    With the overarching aim to develop a simple and reliable method for the quantitative analysis of polypeptide antibiotics in various livestock products, the content of bacitracin, and polymyxin B in pork, beef, chicken, milk, and eggs was analyzed using colistin sulfate as an internal standard. The extracted samples were eluted via solid-phase extraction using 2% formic acid in acetonitrile/methanol (1:1, v/v). The two polypeptides were identified and quantified based on the intensities of mass fragments from the respective triply charged precursor ions (bacitracin: 474.97 amu and polymyxin B: 402 amu) at the defined retention time windows using liquid chromatography with electrospray ionization tandem mass spectrometry in time-scheduled multiple reaction monitoring mode. The calibration curves showed good linearity over the concentration range 50-2500 ng/mL with determination coefficients ≥ 0.991. The mean recoveries were in the range 80.3-88.8% with relative standard deviations <13% for all samples. The limits of quantitation ranged from 30-250 ng/g. The developed method was applied to market samples, but the target analytes were not detected in any of the samples. The developed method is reliable for the simultaneous detection of bacitracin and polymyxin B in pork, beef, chicken, milk, and eggs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Butyrolactone I Quantification from Lovastatin Producing Aspergillus terreus Using Tandem Mass Spectrometry—Evidence of Signalling Functions

    Directory of Open Access Journals (Sweden)

    Elina K. Palonen

    2014-06-01

    Full Text Available Aspergillus terreus is an industrially important filamentous fungus producing a wide spectrum of secondary metabolites, including lovastatin and itaconic acid. It also produces butyrolactone I which has shown potential as an antitumour agent. Additionally, butyrolactone I has been implicated to have a regulating role in the secondary metabolism and morphology of A. terreus. In this study, a quantitative time-course liquid chromatography—electrospray ionisation—tandem mass spectrometry (LC-ESI-MS-MS analysis of butyrolactone I is reported for the first time in nine-day long submerged cultures of A. terreus. Butyrolactone I was fragmented in the mass analysis producing a reproducible fragmentation pattern of four main daughter ions (m/z 307, 331, 363 and 393 in all the samples tested. Supplementing the cultures with 100 nM butyrolactone I caused a statistically significant increase (up to two-fold in its production, regardless of the growth stage but was constitutive when butyrolactone I was added at high cell density during the stationary phase. Furthermore, the extracellular butyrolactone I concentration peaked at 48 h post inoculation, showing a similar profile as has been reported for bacterial quorum sensing molecules. Taken together, the results support the idea of butyrolactone I as a quorum sensing molecule in A. terreus.

  3. Identification of di(ethylhexyl) phthalate as impurity in the analysis by using chromatography gas tandem mass spectrometry

    Science.gov (United States)

    Pusfitasari, Eka Dian; Hendarsyah, Hendris; Salahuddin, Ariani, Novita

    2017-01-01

    Di(ethylhexyl) phthalate (DEHP) is a plasticizer commonly used in plastics. Physically DEHP has a low vapor pressure. DEHP can seep into the liquid in direct contact with the plastic wrapping materials, and typically can occur rapidly if extractable into food or non-polar solvents, such as oil, once the food is packaged in PVC packaging materials. DEHP has been analyzed by using gas chromatography which has a high sensitivity level. If the equipment used for the analysis is made from plastic containing DEHP, then it may be possible that DEHP can be extracted and appear on the outcome of the injection. It can interfere with the process of analysis, especially for the analysis of food samples. This study has identified the present of DEHP in the blank injection performed by Gas Chromatography tandem Mass Spectrometry with Selected Ion Monitoring mode (SIM). Researchers are required to verify whether the gas chromatographic system used is ready for the analysis process. In addition, the comparison and calculation of the intensity of the ion fragmentation spectra generated by mass spectrometry detector can be used for the qualitative determination to ensure the presence of the target compound. In this study is also discussed the differences between the high-intensity fragmentation of DEHP and dioctyl phthalate (DOP).

  4. Liquid chromatography-electrospray ionization-tandem mass spectrometry method for the determination of epoxidized soybean oil in food products.

    Science.gov (United States)

    Suman, Michele; La Tegola, Stefano; Catellani, Dante; Bersellini, Ugo

    2005-12-28

    Epoxidized soybean oil (ESBO) is widely used as a plasticizer and stabilizer in such polymers [poly(vinyl chloride) in particular] commonly adopted for manufacturing of gaskets of the lids for glass jars and plastic films for food packaging. Human exposure to ESBO and its derivatives is likely to occur over a lifetime with a significant variation according to life stage. A reversed phase liquid chromatography interfaced with electrospray ion trap tandem mass spectrometry method for the determination of ESBO in foods was developed. A simple sample treatment procedure entailing the use of an extraction step with dichloromethane without any further cleanup was proved. Chromatographic separation was performed using two C18 columns with an aqueous acetic acid-acetone-acetonitrile mixture as the mobile phase under gradient conditions. The method was validated in terms of detection limits (4 mg kg(-1)), quantitation limits, linearity (established over 2 orders of magnitude), recovery (good mean recoveries, higher than 90% for all of the signals detected), precision (RSD% oil) was demonstrated, and the performances were compared to those reachable by the commonly well-known gas chromatography-mass spectrometry procedure.

  5. Determination of Platycodin D and Platycodin D3 in Rat Plasma Using Liquid Chromatography-Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Tae-Hyun Kim

    2014-01-01

    Full Text Available Platycodon grandiflorum has long been used as a traditional oriental medicine for respiratory disorder. Platycodin D (PD is known as the main component isolated from the root of PG. A simple and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS method has been developed and validated for the quantitation of PD in rat plasma. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization and multiple reaction monitoring in positive ion mode. The total chromatographic run time was 4.0 min, and the calibration curves of PD were linear over the concentration range of 50–10,000 ng/mL in rat plasma. The coefficient of variation and relative error at five QC levels were 1.0 to 8.8% and 0.7 to 8.7%, respectively. After a single oral administration of 500 mg/kg and a single intravenous administration of 25 mg/kg of 3% PD extract (a PG extract including 3% of PD, platycodin D and platycodin D3 were detected and pharmacokinetic parameters were estimated. The oral bioavailability of platycodin D and platycodin D3 was 0.29% and 1.35% in rats at 500 mg/kg of 3% PD extract of PG, respectively. The present method can be applied to pharmacokinetic analysis of platycodins and platycosides of the PG.

  6. Analysis of zearalenone and alpha-zearalenol in urine of ruminants using gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Plasencia, J; Mirocha, C J; Pawlosky, R J; Smith, J F

    1990-01-01

    The present paper describes a sensitive procedure for quantitative analysis of the Fusarium mycotoxins zearalenone and alpha-zearalenol in urine of ruminants. Extraction is done with an octadecyl (C18) column and cleanup with a silica column providing a preparation that is analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The trimethylsilyl ether derivatives of zearalenone and alpha-zearalenol yield molecular ions with m/z 462 and 536, respectively. These ions are selected in the first mass analyzer and then fragmented in a collision cell to give characteristic daughter ions (m/z 151, 333, 318, and 446). The method is known as multiple reaction monitoring (MRM). Elimination of chemical background noise by selecting proper fragment ions produces chromatograms in which identification and quantitation in a biological matrix is possible. The method was tested with sheep urine from an experimental feeding trial and was used to confirm natural mycotoxicosis of cows affected with zearalenone. Zearalenone (1 ppb) and alpha-zearalenol (14 ppb) were found in 2 different cow urine samples. The detection limit for both zearalenone and zearalenol is 1 ppb (1 ng/mL) in urine and is linear between 1 and 20 ppb for the former and 1 and 10 ppb for the latter.

  7. Hidden aconite poisoning: identification of yunaconitine and related aconitum alkaloids in urine by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Lai, Chi-Kong; Poon, Wing-Tat; Chan, Yan-Wo

    2006-09-01

    Poisoning from aconite occurs worldwide as a result of misuse of the potent plant. Laboratory investigation into suspected intoxication cases is challenging because the content of toxic aconitum alkaloids varies depending on the plant source, market processing, dosing protocol, hydrolytic degradation, and metabolic transformation. Using a triple-quadrupole tandem mass spectrometer, a group screening method was developed based on the mass-fragmentographic scheme of common aconitum alkaloids. The precursor-ion scans of m/z 105 and 135 permitted selective profiling of 14-O-benzoyl-norditerpenoids and the 14-O-anisoyl-norditerpenoids, respectively. Gradient reversed-phase liquid chromatography minimized coelution of isobaric compounds. The screening protocol was applied to a clinical investigation of suspected herbal poisoning. In total, 15 urine samples were thus screened positive for aconitum alkaloid over 5 years. The diagnoses of aconite poisoning in 11 patients were firmly established based on the known prescription history and the positive urine finding. In four patients, without aconitum herbs being listed in the herbal prescriptions, contamination of the herbal remedies by aconite was suspected to be the hidden cause of their acute poisoning. Yunaconitne, a highly toxic aconitum alkaloid, was thus identified in human urine for the first time. The group screening method of aconitum alkaloids in urine is an important diagnostic aid for acute poisoning by aconites of an unclear origin.

  8. [Determination of thyreostats in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Lech, Rodziewicz; Jolanta, MasŁOwiecka; Anna, Sadowska; Halina, Car

    2017-10-08

    Five thyreostats (TSs), namely tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil, were determined in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in positive electrospray ionization mode. Extraction and clean-up were achieved using a ChemElut cartridge with tert -butyl methyl ether, without a derivatization step. Separation was achieved on an Acquity UPLC SS T3 column. The mobile phase was acetonitrile and water containing 0.2% (v/v) formic acid. The mass spectrometer was operated in multiple reaction monitoring mode. Urine samples were spiked with TS solution at levels corresponding to 5, 10, 15, and 20 μg/L. The accuracy (internal standard corrected) ranged from 92% to 107%, with a repeatability precision (relative standard deviation, RSD) less than 15% for all five analytes. The RSDs within-laboratory reproducibility was less than 26%. The decision limits (CCα) and detection capabilities (CCβ) were obtained from a calibration curve and were in the ranges of 3.1-6.1 μg/L and 4.0-7.4 μg/L, respectively. The CCα and CCβ values were below the recommended concentration, which was set at 10 μg/L. The results show that the described method is suitable for the direct detection of TSs in bovine urine. This method can also be used to determine TSs in porcine urine.

  9. Liquid Chromatography with Tandem Mass Spectrometry: A Sensitive Method for the Determination of Dehydrodiisoeugenol in Rat Cerebral Nuclei

    Directory of Open Access Journals (Sweden)

    You-Bo Zhang

    2016-03-01

    Full Text Available A new liquid chromatography–tandem mass spectrometry (LC-MS/MS method is developed for the quantification of dehydrodiisoeugenol (DDIE in rat cerebral nuclei after single intravenous administration. DDIE and daidzein (internal standard were separated on a Diamonsil™ ODS C18 column with methanol–water containing 0.1% formic acid (81:19, v/v as a mobile phase. Detection of DDIE was performed on a positive electrospray ionization source using a triple quadrupole mass spectrometer. DDIE and daidzein were monitored at m/z 327.2→188.0 and m/z 255.0→199.2, respectively, in multiple reaction monitoring mode. This method enabled quantification of DDIE in various brain areas, including, cortex, hippocampus, striatum, hypothalamus, cerebellum and brainstem, with high specificity, precision, accuracy, and recovery. The data herein demonstrate that our new LC-MS/MS method is highly sensitive and suitable for monitoring cerebral nuclei distribution of DDIE.

  10. Identification of metabolites of adonifoline, a hepatotoxic pyrrolizidine alkaloid, by liquid chromatography/tandem and high-resolution mass spectrometry.

    Science.gov (United States)

    Xiong, Aizhen; Yang, Li; He, Yuqi; Zhang, Fang; Wang, Jun; Han, Han; Wang, Changhong; Bligh, S W Annie; Wang, Zhengtao

    2009-12-01

    Hepatotoxic pyrrolizidine alkaloid (HPA)-containing plants have always been a threat to human and livestock health worldwide. Adonifoline, a main HPA in Senecio scandens Buch.-Ham. ex D. Don (Qianli guang), was used officially as an infusion in cases of oral and pharyngeal infections in China. In this study in vivo metabolism of adonifoline was studied for the first time by identifying the metabolites of adonifoline present in bile, urine and feces of rats using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS(n)) (ion trap) as well as liquid chromatography/electrospray ionization high-resolution mass spectrometry (LC/ESI-HRMS) (quadrupole-time of flight). In total 19 metabolites were identified and, among them, retronecine-N-oxides were confirmed by matching their fragmentation patterns with their fully characterized synthetic compounds. These metabolites are all involved in both phase I and phase II metabolic processes and the principal in vivo metabolism pathways of adonifoline were proposed. Copyright 2009 John Wiley & Sons, Ltd.

  11. [Determination of illudin S in Omphalotus guepiniformis and foods that caused food poisoning by liquid chromatography with tandem mass spectrometry].

    Science.gov (United States)

    Kasahara, Yoshimasa; Itou, Takeshi

    2009-08-01

    A simple method was developed for determination of illudin S in fungi (Omphalotus guepiniformis: poisonous mushroom) and a food that caused food poisoning, using liquid chromatography tandem mass spectrometry (LC/MS/MS). Illudin S in fungi and the food that caused food poisoning was extracted with methanol and then cleaned up with an Oasis HLB cartridge. LC separation was performed with an octadecylated silica column (Inertsil ODS-3, 2.1 mm i.d. x 150 mm) and a mobile phase of 0.1% formic acid-methanol (7 : 3) at a flow rate 0.2 mL/min. Mass spectral acquisition was performed in the positive mode and illudin S was targeted using multiple reaction monitoring (MRM) with electrospray ionization (ESI). The recoveries of illudin S were 84-94% from edible fungi (Lentinula edodes, Pleurotus ostreatus and Panellus serotinus). The detection limits of illudin S in the fungi (L. edodes, P. ostreatus and P. serotinus) were 0.08-0.10 microg/g respectively. Illudin S was detected in the food that caused food poisoning at the level of 2.0 and 15.1 microg/g in the soup and fungi, respectively. The recovery of illudin S from a mushroom soup (cooked at 100 degrees C for 10 min) sample which simulated food poisoning was 74.8%. These results indicate that the developed method is suitable for the determination of illudin S in fungi (O. guepiniformis) and foods that caused food poisoning.

  12. Simultaneous quantitation of paracetamol, caffeine, pseudoephedrine, chlorpheniramine and cloperastine in human plasma by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Li, Hao; Zhang, Chao; Wang, Jiang; Jiang, Yao; Fawcett, J Paul; Gu, Jingkai

    2010-02-05

    A rapid and sensitive method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous quantitation of paracetamol, caffeine, pseudoephedrine, chlorpheniramine and cloperastine in human plasma has been developed and validated. After sample preparation by liquid-liquid extraction, the analytes and internal standard (diphenhydramine) were analyzed by reversed-phase HPLC on a Venusil Mp-C(18) column (50mmx4.6mm, 5microm) using formic acid:10mM ammonium acetate:methanol (1:40:60, v/v/v) as mobile phase in a run time of 2.6min. Detection was carried out by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode. The method was linear for all analytes over the following concentration (ng/ml) ranges: paracetamol 5.0-2000; caffeine 10-4000; pseudoephedrine 0.25-100; chlorpheniramine 0.05-20; cloperastine 0.10-40. Intra- and inter-day precisions (as relative standard deviation) were all < or =11.3% with accuracy (as relative error) of +/-5.0%. The method was successfully applied to a study of the pharmacokinetics of the five analytes after administration of a combination oral dose to healthy Chinese volunteers.

  13. Quantitation of protein S-glutathionylation by liquid chromatography-tandem mass spectrometry: correction for contaminating glutathione and glutathione disulfide.

    Science.gov (United States)

    Bukowski, Michael R; Bucklin, Christopher; Picklo, Matthew J

    2015-01-15

    Protein S-glutathionylation is a posttranslational modification that links oxidative stimuli to reversible changes in cellular function. Protein-glutathione mixed disulfide (PSSG) is commonly quantified by reduction of the disulfide and detection of the resultant glutathione species. This methodology is susceptible to contamination by free unreacted cellular glutathione (GSH) species, which are present in 1000-fold greater concentration. A liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method was developed for quantification of glutathione and glutathione disulfide (GSSG), which was used for the determination of PSSG in biological samples. Analysis of rat liver samples demonstrated that GSH and GSSG coprecipitated with proteins similar to the range for PSSG in the sample. The use of [(13)C2,(5)N]GSH and [(13)C4,(5)N2]GSSG validated these results and demonstrated that the release of GSH from PSSG did not occur during sample preparation and analysis. These data demonstrate that GSH and GSSG contamination must be accounted for when determining PSSG content in cellular/tissue preparations. A protocol for rinsing samples to remove the adventitious glutathione species is demonstrated. The fragmentation patterns for glutathione were determined by high-resolution mass spectrometry, and candidate ions for detection of PSSG on protein and protein fragments were identified. Published by Elsevier Inc.

  14. Determination of the plant growth regulator chlormequat in food by liquid chromatography-electrospray ionisation tandem mass spectrometry.

    Science.gov (United States)

    Hau, J; Riediker, S; Varga, N; Stadler, R H

    2000-05-05

    A confirmatory method for the determination of trace levels of chlormequat in a variety of different food matrices was developed. It entails a single clean-up step over a solid-phase cation exchange resin and subsequent liquid chromatography-electrospray ionisation tandem mass spectrometry using a stable isotopically labelled internal standard. Mass spectral acquisition was done in selected reaction monitoring mode, selecting the transitions from both the 35Cl and the 37Cl isotope of chlormequat. Recoveries after extraction and clean-up, determined with radio-labelled chlormequat and averaged over the spiking range (16-65 microg kg(-1)) in four different commodities, were within 88-96%, with a coefficient of variation better than 8%. The method can be applied to pears, pear juice concentrates, fruit purées, and cereal products, with typical limits of detection for chlormequat estimated at 2-5 microg kg(-1). A survey of different food commodities revealed that chlormequat was detectable--albeit at very low levels--in many of the food samples analysed, with the highest concentration recorded in pears purchased in Switzerland and of South African origin (5.5 mg kg(-1)). Measurements were also conducted on two LC-MS instruments and demonstrate the versatility and robustness of the method and its applicability to instruments of different ion source design.

  15. High performance liquid chromatography-tandem mass spectrometric determination of rupatadine in human plasma and its pharmacokinetics.

    Science.gov (United States)

    Tian, Yuan; Zhang, Jingjing; Lin, Hui; Liang, Jiabi; Zhang, Zunjian; Chen, Yun

    2008-08-05

    A simple, rapid, sensitive and selective liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the quantification of rupatadine in human plasma using estazolam as internal standard (IS). Following liquid-liquid extraction, the analytes were separated using a mobile phase of methanol-ammonium acetate (pH 2.2; 5mM) (50:50, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the positive ion and multiple reaction monitoring (MRM) mode, m/z 416-->309 for rupatadine and m/z 295-->267 for the IS. The assay exhibited a linear dynamic range of 0.1-100 ng/ml for rupatadine in human plasma. The lower limit of quantification (LLOQ) was 0.1 ng/ml with a relative standard deviation of less than 20%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated LC-MS/MS method has been successfully applied to study the pharmacokinetics of rupatadine in healthy volunteers.

  16. Rapid and sensitive liquid chromatography tandem mass spectrometry method for the quantification of ambroxol in human plasma.

    Science.gov (United States)

    Hu, Wanqun; Xu, Yu; Liu, Fei; Liu, Aixiang; Guo, Qingxiang

    2008-10-01

    A sensitive, specific and rapid high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was described and validated for the quantification of ambroxol in human plasma using enalaprilat as the internal standard (IS). Chromatographic separation was performed on a Lichrospher CN column with a mobile phase of methanol and water (containing 0.1% formic acid) (70:30, v/v). The total run time was 5.0 min for each sample. The analytes was detected by mass spectrometry with electrospray ionization source in positive selected reaction monitoring mode. The precursor-fragment ion reaction for ambroxol was m/z 378.9 --> 263.8, and for IS was m/z 349.0 --> 205.9. The linearity was established over the concentration range of 1.56-400.00 ng/mL. The inter-day and the intra-day precisions were all within 10%. A simple protein precipitation with methanol was adopted for sample preparation. The extraction recoveries of ambroxol and IS were higher than 90.80%. The validated method was successfully applied in pharmacokinetic study after oral administration of 90 mg ambroxol to 24 healthy volunteers.

  17. Investigation of the immunogenicity of a protein drug using equilibrium dialysis and liquid chromatography tandem mass spectrometry detection.

    Science.gov (United States)

    Ji, Qin C; Rodila, Ramona; Morgan, Sherry J; Humerickhouse, Rod A; El-Shourbagy, Tawakol A

    2005-09-01

    Biotherapeutics such as protein and peptide drugs have attracted significant attention in the medical community and pharmaceutical industry in recent years. Immunogenicity is one of the major concerns in the development and application of biotherapeutics. Although great efforts have been put forth in reducing immunogenicity, monitoring the free ("active") drug concentration and the antibody formation is critical for preclinical and clinical studies. Currently, it is still a challenging task to have a standardized test method monitoring immunogenicity when biotherapeutic compounds such as proteins and peptides are administrated. Combined with liquid chromatography/tandem mass spectrometry detection, the equilibrium dialysis technique that is conventionally used for measuring the free and bound concentration of small organic molecules was extended to the application of measuring the free and bound concentrations of a protein drug with a relative molecular mass over 10,000 from plasma samples containing antibody. This novel approach could also be used for accurately measuring the antibody concentration when a reference standard of the antibody is available.

  18. Gas-phase reactivity of silver and copper coordinated monosaccharide cations studied by electrospray ionization and tandem mass spectrometry.

    Science.gov (United States)

    Boutreau, Laurence; Léon, Emmanuelle; Salpin, Jean-Yves; Amekraz, Badia; Moulin, Christophe; Tortajada, Jeanine

    2003-01-01

    The analytical distinction of the most common isomeric underivatized hexoses was investigated by means of mass spectrometry experiments. Electrospray ionization and tandem mass spectrometry were used in the analysis of silver and copper-coordinated monosaccharides (D-glucose, D-galactose, D-fructose, O-methyl-alpha-D-glucose and O-methyl-beta-D-glucose). The results show that cationization by Ag(+) allows the differentiation of the three first monosaccharides while the complexes formed by association of Cu(+) with these three monosacharides display a similar reactivity that prevents stereoisomer distinction. Unlike copper, silver adduct-ions of both alpha and beta anomeric O-methyl-D-glucoses exhibit specific decomposition patterns (i.e. a loss of methanol for the alpha-anomer and a loss of silver hydride for the beta-anomer), which allow an easy characterization. A theoretical survey of selected complexes, based on the use of DFT calculations were carried out on both anomers in order to rationalize the experimental findings.

  19. Qualitative and quantitative analysis of glucosinolates and nucleosides in Radix Isatidis by HPLC and liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Xiuming Wang

    2013-09-01

    Full Text Available Multi-component fingerprinting and quantitation of the glucosinolates and nucleosides in samples of Radix Isatidis have been carried out using high-performance liquid chromatography with diode-array detection and electrospray ionization tandem mass spectrometry (HPLC–DAD–ESI/MS. Five nucleosides together with one glucosinolate were identified by comparing retention times, ultraviolet spectra, mass spectra and/or empirical molecular formulae of reference compounds. Quantitation of these six compounds was carried out simultaneously by HPLC on a Phenomenex Luna C18 column using gradient elution with methanol and water and detection at 254 nm. All calibration curves were linear (r>0.9994 within test ranges. Limits of detection and quantitation were 0.33 ng and 2.50 ng on column, respectively. Intra- and inter-day precision (as relative standard deviation for all analytes was <2.19% with recoveries in the range 99.6%–101.8% at three concentration levels. The validated method was successfully applied to fingerprinting and assay of 25 batches of Radix Isatidis sourced from different geographical regions of China. The method is simple and reliable and has potential value in the quality control of Radix Isatidis.

  20. Spectrum analysis of common inherited metabolic diseases in Chinese patients screened and diagnosed by tandem mass spectrometry.

    Science.gov (United States)

    Han, Lianshu; Han, Feng; Ye, Jun; Qiu, Wenjuan; Zhang, Huiwen; Gao, Xiaolan; Wang, Yu; Ji, Wenjun; Gu, Xuefan

    2015-03-01

    Information concerning inherited metabolic diseases in China is scarce. We investigated the prevalence and age distributions of amino acid, organic acid, and fatty acid oxidation disorders in Chinese patients. Blood levels of amino acids and acylcarnitines (tandem mass spectrometry) were measured in 18,303 patients with suspected inherited metabolic diseases. Diagnosis was based on clinical features, blood levels of amino acids or acylcarnitines, urinary organic acid levels (gas chromatography-mass spectrometry), and (in some) gene mutation tests. Inherited metabolic diseases were confirmed in 1,135 patients (739 males, 396 females). Median age was 12 months (1 day to 59 years). There were 28 diseases: 12 amino acid disorders (580 patients, 51.1%), with hyperphenylalaninemia (HPA) being the most common; nine organic acidemias (408 patients, 35.9%), with methylmalonic acidemia (MMA) as the most common; and seven fatty acid oxidation defects (147 patients, 13.0%), with multiple acyl-coenzyme A dehydrogenase deficiency (MADD) being the most common. Onset was mainly at 1-6 months for citrin deficiency, 0-6 months for MMA, and in newborns for ornithine transcarbamylase deficiency (OTCD). HPA was common in patients aged 1-3 years, and MADD was common in patients >18 years. In China, HPA, citrin deficiency, MMA, and MADD are the most common inherited disorders, particularly in newborns/infants. © 2014 Wiley Periodicals, Inc.

  1. Development of sensitive derivatization method for aldosterone in liquid chromatography-electrospray ionization tandem mass spectrometry of corticosteroids.

    Science.gov (United States)

    Yamashita, Kouwa; Okuyama, Mitsunobu; Nakagawa, Risa; Honma, Seijiro; Satoh, Fumitoshi; Morimoto, Ryo; Ito, Sadayoshi; Takahashi, Madoka; Numazawa, Mitsuteru

    2008-07-25

    A highly sensitive quantification method of aldosterone by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was investigated in a positive mode using recently developed picolinyl derivatization. Aldosterone was smoothly and quantitatively converted to the ethyl ether-picolinyl derivative by treatment with HCl-ethanol followed by the esterification with picolinic acid in the presence of 2-methyl-6-nitrobenzoic anhydride and 4-dimethylaminopyridine. The positive ion-ESI mass spectrum of the ethyl ether-picolinyl derivative was characterized by an appearance of protonated molecule ([M+H](+)) as a base peak. The ethyl ether-picolinyl derivatization gave a successful result in a separation of aldosterone from corticosterone, dehydrocorticosterone and cortexolone, and also provided an approximately 10-fold higher ESI response in the positive-LC-ESI-MS/MS (selected reaction monitoring; SRM) when compared to that of underivatized molecule (negative mode). The limit of quantification of aldosterone by SRM using ethyl ether-picolinyl derivatization (m/z 494-->m/z 448) was 1 pg/0.2 ml serum with accuracy and precision of 92.6% and 5.6%, respectively.

  2. Simultaneous determination of tetrahydrocortisol, allotetrahydrocortisol and tetrahydrocortisone in human urine by liquid chromatography-electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Yamashita, Kouwa; Nakagawa, Risa; Okuyama, Mitsunobu; Honma, Seijiro; Takahashi, Madoka; Numazawa, Mitsuteru

    2008-08-01

    Simultaneous quantification method of three major metabolites of cortisone and cortisol, tetrahydrocortisol, allotetrahydrocortisol and tetrahydrocortisone by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was investigated in a positive mode using a recently developed picolinyl derivatization. Conversion of each steroid into the corresponding picolinyl derivatives (1b, 2b or 3b) was performed by mixed anhydride method using picolinic acids and 2-methyl-6-nitrobenzoic anhydride. Derivatization proceeded smoothly to afford the corresponding 3, 21-dipicolinyl derivatives. Positive ion-ESI mass spectra of the picolinyl derivatives were dominated by an appearance of [M+H](+) as base peaks in all cases. The picolinyl derivatives provided 15 to 80-fold higher ESI response in the LC-ESI-MS/MS (selected reaction monitoring: SRM) when compared to those of underivatized molecules in a positive LC-ESI mode. The use of the picolinyl ester, solid-phase extraction, and deuterium labeled internal standards enabled the concentrations of these metabolites in human urine to be determined simultaneously by LC-ESI-MS/MS (SRM) with a small sample volume of less than 1microl urine.

  3. Fast quantification of endogenous carbohydrates in plasma using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Zhu, Bangjie; Liu, Feng; Li, Xituo; Wang, Yan; Gu, Xue; Dai, Jieyu; Wang, Guiming; Cheng, Yu; Yan, Chao

    2015-01-01

    Endogenous carbohydrates in biosamples are frequently highlighted as the most differential metabolites in many metabolomics studies. A simple, fast, simultaneous quantitative method for 16 endogenous carbohydrates in plasma has been developed using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry. In order to quantify 16 endogenous carbohydrates in plasma, various conditions, including columns, chromatographic conditions, mass spectrometry conditions, and plasma preparation methods, were investigated. Different conditions in this quantified analysis were performed and optimized. The reproducibility, precision, recovery, matrix effect, and stability of the method were verified. The results indicated that a methanol/acetonitrile (50:50, v/v) mixture could effectively and reproducibly precipitate rat plasma proteins. Cold organic solvents coupled with vortex for 1 min and incubated at -20°C for 20 min were the most optimal conditions for protein precipitation and extraction. The results, according to the linearity, recovery, precision, matrix effect, and stability, showed that the method was satisfactory in the quantification of endogenous carbohydrates in rat plasma. The quantified analysis of endogenous carbohydrates in rat plasma performed excellently in terms of sensitivity, high throughput, and simple sample preparation, which met the requirement of quantification in specific expanded metabolomic studies after the global metabolic profiling research. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Screening, quantification, and confirmation of phenylbutazone and oxyphenbutazone in equine plasma by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    You, Youwen; Uboh, Cornelius E; Soma, Lawrence R; Guan, Fuyu; Li, Xiaoqing; Rudy, Jeffrey A; Chen, Jinwen

    2009-01-01

    A sensitive liquid chromatographic-tandem mass spectrometric method was developed and validated for screening, quantification, and confirmation of phenylbutazone and oxyphenbutazone in equine plasma. Analytes were recovered from plasma by liquid-liquid extraction followed by separation in a reversed-phase column and identification by mass spectrometry with selected reaction monitoring in negative electrospray ionization mode. Extraction recovery for both analytes was >80%. Limits of detection, quantification, and confirmation for both analytes were 0.01 microg/mL (S/N>or= 3), 0.05 microg/mL, and 0.05 microg/mL, respectively. The assay with d9-labeled phenylbutazone as internal standard (IS) was linear over a range of 0.05-20 microg/mL (r2>0.995). Intra- and interday precision in terms of coefficient of variation was less than 15%. Intra- and interday accuracy (bias%) was within 80-120%. Hemolysis of red blood cells decreased analyte signal intensity but did not affect quantification results because an isotope-labeled IS was used. Analytes were stable in plasma for 24 h at room temperature, 9 days at 4 degrees C, and 45 days at -20 degrees C and -70 degrees C. The method was successfully used in screening, quantification, and confirmation of phenylbutazone in post-competition plasma samples obtained from racehorses. The method is simple, rapid, and reliably reproducible.

  5. Quantitative profiling method for phytohormones and betaines in algae by liquid chromatography electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Wang, Xiujuan; Zhao, Peng; Liu, Xuemei; Chen, Juanjuan; Xu, Jilin; Chen, Haimin; Yan, Xiaojun

    2014-02-01

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantitative determination of phytohormones and betaines in algae. The results showed that phytohormones and betaines were separated with high efficiency on Hypersil Gold C18 and Cnwsil SCX columns. Mass spectrometric detection was performed using positive or negative electrospray ionization in selective reaction monitoring mode (SRM). Linearity of the method was good with correlation coefficients (r(2) > 0.9951 in the range of 0.005-5 mg/L. The limits of detection were from 0.004 to 0.86 µg/L and the limits of quantification were in the range from 0.01 to 2.8 µg/L for the investigated phytohormones and betaines. The obtained recoveries varied between 61.33 and 90.39%, and the relative standard deviations were Pyropia haitanensis, which were collected in Xiangshan, Zhejiang Province, China, were determined. Thus, LC-MS/MS was demonstrated to be a powerful tool for the comprehensive analysis of phytohormones and betaines in algae, owing to its large dynamic range and excellent sensitivity. Copyright © 2013 John Wiley & Sons, Ltd.

  6. Multi-residue analysis of eight thioamphetamine designer drugs in human urine by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Nieddu, Maria; Boatto, Gianpiero; Pirisi, Maria Antonietta; Baralla, Elena

    2009-10-01

    An analytical procedure for the simultaneous determination in human urine of several thioamphetamine designer drugs (2C-T and ALEPH series) is reported. The quantitative analysis was performed by liquid chromatography/tandem mass spectrometry and has been fully validated. The mass spectrometer was operated in positive-ion, selected reaction monitoring (SRM) mode. In order to minimize interferences with matrix components and to preconcentrate target analytes, solid-phase extraction was introduced in the method as a clean-up step. The entire method was validated for selectivity, linearity, precision and accuracy. The method turned out to be specific, sensitive, and reliable for the analysis of amphetamine derivatives in urine samples. The calibration curves were linear over the concentration range of 1 to 100 ng mL(-1) for all drugs with correlation coefficients that exceeded 0.996. The lower limits of detection (LODs) and quantification (LOQs) ranged from 1.2 to 4.9 ng mL(-1) and from 3.2 to 9.6 ng mL(-1), respectively. Copyright (c) 2009 John Wiley & Sons, Ltd.

  7. IntelliMS: a platform to efficiently manage and visualize tandem mass spectral data.

    Science.gov (United States)

    Kwon, Min-Seok; Lee, Hyoung-Joo; Jeong, Seul-Ki; Lee, Eun-Young; Cho, Sang Yun; Paik, Young-Ki

    2008-12-01

    With the development of high-speed mass spectrometric techniques, it becomes important to manage large amounts of spectrometric data accurately. We have developed a new data management system with a visualization function named IntelliMS, which can load data into a search engine, filter out the insignificant data, create diagrams of the identification process from spectra to protein and share all the resulting datasets. This software can be used to efficiently manage complicated mass spectral data and the corresponding protein identification information obtained from various proteomics analyses.

  8. Evaluation of phenylthiocarbamoyl-derivatized peptides by electrospray ionization mass spectrometry: selective isolation and analysis of modified multiply charged peptides for liquid chromatography-tandem mass spectrometry experiments.

    Science.gov (United States)

    Sanchez, Aniel; Perez-Riverol, Yasset; González, Luis Javier; Noda, Jesus; Betancourt, Lazaro; Ramos, Yassel; Gil, Jeovanis; Vera, Roberto; Padrón, Gabriel; Besada, Vladimir

    2010-10-15

    Edman degradation in the gas phase has been observed by collision activated dissociation of N-terminal phenylthiocarbamoyl (PTC) protonated peptide to yield abundant complementary b₁ and y(n-1) ion pairs. Here, we demonstrated the relation between the observed losses of aniline and/or the entire PTC derivatizing group with the availability of mobile protons using electrospray ionization mass spectrometry. In order to select the peptides with more efficient fragmentation, while simplifying the mixture of peptides, we extend the phenylisotiocyanate (PITC) derivatization of amino groups to the selective isolation of multiply charged peptides (those having the number of arginines and histidines residues higher than one) using a procedure previously developed in our group. Thus, it was possible to identify in the filtered protein database the sequence of the isolated multiply charged peptides derived from a single protein and a complex mixture of proteins extracted from Escherichia coli using only the molecular mass and the N-terminal amino acid information. For this purpose, we developed a novel bioinformatic tool for automatic identification of peptides from liquid chromatography-tandem mass spectrometry (LC-MS/MS) experiments, which potentially can be used in high-throughput proteomics.

  9. Wax ester profiling of seed oil by nano-electrospray ionization tandem mass spectrometry

    Science.gov (United States)

    2013-01-01

    Background Wax esters are highly hydrophobic neutral lipids that are major constituents of the cutin and suberin layer. Moreover they have favorable properties as a commodity for industrial applications. Through transgenic expression of wax ester biosynthetic genes in oilseed crops, it is possible to achieve high level accumulation of defined wax ester compositions within the seed oil to provide a sustainable source for such high value lipids. The fatty alcohol moiety of the wax esters is formed from plant-endogenous acyl-CoAs by the action of fatty acyl reductases (FAR). In a second step the fatty alcohol is condensed with acyl-CoA by a wax synthase (WS) to form a wax ester. In order to evaluate the specificity of wax ester biosynthesis, analytical methods are needed that provide detailed wax ester profiles from complex lipid extracts. Results We present a direct infusion ESI-tandem MS method that allows the semi-quantitative determination of wax ester compositions from complex lipid mixtures covering 784 even chain molecular species. The definition of calibration prototype groups that combine wax esters according to their fragmentation behavior enables fast quantitative analysis by applying multiple reaction monitoring. This provides a tool to analyze wax layer composition or determine whether seeds accumulate a desired wax ester profile. Besides the profiling method, we provide general information on wax ester analysis by the systematic definition of wax ester prototypes according to their collision-induced dissociation spectra. We applied the developed method for wax ester profiling of the well characterized jojoba seed oil and compared the profile with wax ester-accumulating Arabidopsis thaliana expressing the wax ester biosynthetic genes MaFAR and ScWS. Conclusions We developed a fast profiling method for wax ester analysis on the molecular species level. This method is suitable to screen large numbers of transgenic plants as well as other wax ester samples

  10. Wax ester profiling of seed oil by nano-electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Iven, Tim; Herrfurth, Cornelia; Hornung, Ellen; Heilmann, Mareike; Hofvander, Per; Stymne, Sten; Zhu, Li-Hua; Feussner, Ivo

    2013-07-06

    Wax esters are highly hydrophobic neutral lipids that are major constituents of the cutin and suberin layer. Moreover they have favorable properties as a commodity for industrial applications. Through transgenic expression of wax ester biosynthetic genes in oilseed crops, it is possible to achieve high level accumulation of defined wax ester compositions within the seed oil to provide a sustainable source for such high value lipids. The fatty alcohol moiety of the wax esters is formed from plant-endogenous acyl-CoAs by the action of fatty acyl reductases (FAR). In a second step the fatty alcohol is condensed with acyl-CoA by a wax synthase (WS) to form a wax ester. In order to evaluate the specificity of wax ester biosynthesis, analytical methods are needed that provide detailed wax ester profiles from complex lipid extracts. We present a direct infusion ESI-tandem MS method that allows the semi-quantitative determination of wax ester compositions from complex lipid mixtures covering 784 even chain molecular species. The definition of calibration prototype groups that combine wax esters according to their fragmentation behavior enables fast quantitative analysis by applying multiple reaction monitoring. This provides a tool to analyze wax layer composition or determine whether seeds accumulate a desired wax ester profile. Besides the profiling method, we provide general information on wax ester analysis by the systematic definition of wax ester prototypes according to their collision-induced dissociation spectra. We applied the developed method for wax ester profiling of the well characterized jojoba seed oil and compared the profile with wax ester-accumulating Arabidopsis thaliana expressing the wax ester biosynthetic genes MaFAR and ScWS. We developed a fast profiling method for wax ester analysis on the molecular species level. This method is suitable to screen large numbers of transgenic plants as well as other wax ester samples like cuticular lipid extracts to

  11. Differentiation of 2- and 6-isomers of (2-dimethylaminopropylbenzofuran by tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    V. A. Shevyrin

    2016-07-01

    Full Text Available Reliable identification of new psychoactive substances of 2-(2-methylaminopropylbenzofuran and 6-(2-methylaminopropylbenzofuran is problematic when analyzing by gas chromatography–mass spectrometry method. It found that these two isomers can be reliably differentiated by MS/MS spectra obtained by collision-induced dissociation of their protonated molecules.

  12. Determination of ribavirin in human serum using liquid chromatography tandem mass spectrometry

    NARCIS (Netherlands)

    van der Lijke, Henk; Alffenaar, Jan-Willem C.; Kok, Wim Th.; Greijdanus, Ben; Uges, Donald R. A.

    2012-01-01

    A method has been developed for the determination of ribavirin in human serum for therapeutic drug monitoring purposes, using liquid chromatography electrospray ionization mass spectrometry. Separation was obtained with a mobile phase gradient starting and ending in 100% aqueous conditions using a

  13. Fast atom bombardment mass spectrometric and tandem mass spectrometric studies of some functionalized tetrapyrroles derived from chlorophylls a and b

    Energy Technology Data Exchange (ETDEWEB)

    Keely, B.J.; Maxwell, J.R. (Univ. of Bristol (England))

    Fast atom bombardment (FAB) mass spectra of a number of functionalized tetrapyrroles derived from chlorophylls a and b have been obtained and MS/MS studies used to investigate aspects of the fragmentation behavior of some of them. The application of this approach is demonstrated by the assignment of pheophytin b isolated from a lake sediment where the amount and purity were insufficient for {sup 1}H nuclear magnetic resonance spectroscopic studies.

  14. Use of high-resolution mass spectrometry to investigate a metabolite interference during liquid chromatography/tandem mass spectrometric quantification of a small molecule in toxicokinetic study samples.

    Science.gov (United States)

    Furlong, Michael; Bessire, Andrew; Song, Wei; Huntington, Christopher; Groeber, Elizabeth

    2010-07-15

    During routine liquid chromatography/tandem mass spectrometric (LC/MS/MS) bioanalysis of a small molecule analyte in rat serum samples from a toxicokinetic study, an unexpected interfering peak was observed in the extracted ion chromatogram of the internal standard. No interfering peaks were observed in the extracted ion chromatogram of the analyte. The dose-dependent peak area response and peak area response versus time profiles of the interfering peak suggested that it might have been related to a metabolite of the dosed compound. Further investigation using high-resolution mass spectrometry led to unequivocal identification of the interfering peak as an N-desmethyl metabolite of the parent analyte. High-resolution mass spectrometry (HRMS) was also used to demonstrate that the interfering response of the metabolite in the multiple reaction monitoring (MRM) channel of the internal standard was due to an isobaric relationship between the (13)C-isotope of the metabolite and the internal standard (i.e., common precursor ion mass), coupled with a metabolite product ion with identical mass to the product ion used in the MRM transition of the internal standard. These results emphasize (1) the need to carefully evaluate internal standard candidates with regard to potential interferences from metabolites during LC/MS/MS method development, validation and bioanalysis of small molecule analytes in biological matrices; (2) the value of HRMS as a tool to investigate unexpected interferences encountered during LC/MS/MS analysis of small molecules in biological matrices; and (3) the potential for interference regardless of choice of IS and therefore the importance of conducting assay robustness on incurred in vitro or in vivo study samples. Copyright 2010 John Wiley & Sons, Ltd.

  15. Choosing an Optimal Database for Protein Identification from Tandem Mass Spectrometry Data.

    Science.gov (United States)

    Kumar, Dhirendra; Yadav, Amit Kumar; Dash, Debasis

    2017-01-01

    Database searching is the preferred method for protein identification from digital spectra of mass to charge ratios (m/z) detected for protein samples through mass spectrometers. The search database is one of the major influencing factors in discovering proteins present in the sample and thus in deriving biological conclusions. In most cases the choice of search database is arbitrary. Here we describe common search databases used in proteomic studies and their impact on final list of identified proteins. We also elaborate upon factors like composition and size of the search database that can influence the protein identification process. In conclusion, we suggest that choice of the database depends on the type of inferences to be derived from proteomics data. However, making additional efforts to build a compact and concise database for a targeted question should generally be rewarding in achieving confident protein identifications.

  16. Determination of iohexol in human serum by a semi-automated liquid chromatography tandem mass spectrometry method.

    Science.gov (United States)

    Vicente, Faye B; Vespa, Gina K; Carrara, Fabiola; Gaspari, Flavio; Haymond, Shannon

    2015-07-01

    Measured glomerular filtration rate (mGFR) is the best indicator of renal function in children and adolescents. GFR determination using iohexol clearance has been increasingly accepted and applied in clinical practice because it is accurate, readily available, non-radioactive, safe and is used intravenously even in the presence of renal disease. This study describes the development and evaluation of a semi-automated method for determination of iohexol in human serum using liquid chromatography coupled with electrospray ionization (ESI) tandem mass spectrometry (LC-MS/MS). Iohexol was extracted from serum using a MICROLAB® NIMBUS4 automation robot and supernatant was dried under nitrogen gas and reconstituted in mobile phase. Ioversol was used as the internal standard. Chromatography was performed using a C-8 analytical column (Phenomenex, 3 μm, 50 × 3.0 mm I.D.) at room temperature and a gradient LC method on a Waters 2795 Alliance HT HPLC system. The flow rate was 0.5 mL/min and the retention times were 2.36 min and 2.14 min for iohexol and ioversol, respectively. Detection by MS/MS was achieved using a (Micromass Quattro Micro) tandem mass spectrometer operated in the ESI-positive mode. The multiple-reaction monitoring (MRM) method used ion transitions m/z 821.9 to 803.7 for iohexol and m/z 807.9 to 588.7 for ioversol. Method validation studies were conducted to determine the linearity, accuracy, precision, matrix effects and stability. A method comparison of blinded, residual patient samples was conducted with a well-established method. The method was linear from 7.7 μg/mL to 2000.0 μg/mL. The low limit of quantification and the detection limit were established at 7.7 and 3.0 μg/mL, respectively. Within-run and between-run precisions were found to be serum, enabling determination of mGFR by iohexol clearance. The method is highly correlated to a reference method. Use of an automated liquid handler reduces labor-intensive, manual sample preparation steps

  17. A sensitive and selective liquid chromatography/tandem mass spectrometry method for quantitative analysis of efavirenz in human plasma.

    Directory of Open Access Journals (Sweden)

    Praveen Srivastava

    Full Text Available A selective and a highly sensitive method for the determination of the non-nucleoside reverse transcriptase inhibitor (NNRTI, efavirenz, in human plasma has been developed and fully validated based on high performance liquid chromatography tandem mass spectrometry (LC-MS/MS. Sample preparation involved protein precipitation followed by one to one dilution with water. The analyte, efavirenz was separated by high performance liquid chromatography and detected with tandem mass spectrometry in negative ionization mode with multiple reaction monitoring. Efavirenz and ¹³C₆-efavirenz (Internal Standard, respectively, were detected via the following MRM transitions: m/z 314.20243.90 and m/z 320.20249.90. A gradient program was used to elute the analytes using 0.1% formic acid in water and 0.1% formic acid in acetonitrile as mobile phase solvents, at a flow-rate of 0.3 mL/min. The total run time was 5 min and the retention times for the internal standard (¹³C₆-efavirenz and efavirenz was approximately 2.6 min. The calibration curves showed linearity (coefficient of regression, r>0.99 over the concentration range of 1.0-2,500 ng/mL. The intraday precision based on the standard deviation of replicates of lower limit of quantification (LLOQ was 9.24% and for quality control (QC samples ranged from 2.41% to 6.42% and with accuracy from 112% and 100-111% for LLOQ and QC samples. The inter day precision was 12.3% and 3.03-9.18% for LLOQ and quality controls samples, and the accuracy was 108% and 95.2-108% for LLOQ and QC samples. Stability studies showed that efavirenz was stable during the expected conditions for sample preparation and storage. The lower limit of quantification for efavirenz was 1 ng/mL. The analytical method showed excellent sensitivity, precision, and accuracy. This method is robust and is being successfully applied for therapeutic drug monitoring and pharmacokinetic studies in HIV-infected patients.

  18. Detection of designer steroid methylstenbolone in "nutritional supplement" using gas chromatography and tandem mass spectrometry: elucidation of its urinary metabolites.

    Science.gov (United States)

    Cavalcanti, Gustavo de Albuquerque; Leal, Felipe Dias; Garrido, Bruno Carius; Padilha, Monica Costa; de Aquino Neto, Francisco Radler

    2013-02-01

    The use of "nutritional supplements" containing unapproved substances has become a regular practice in amateur and professional athletes. This represents a dangerous habit for their health once no data about toxicological or pharmacological effects of these supplements are available. Most of them are freely commercialized online and any person can buy them without medical surveillance. Usually, the steroids intentionally added to the "nutritional supplements" are testosterone analogues with some structural modifications. In this study, the analyzed product was bought online and a new anabolic steroid known as methylstenbolone (2,17α-dimethyl-17β-hydroxy-5α-androst-1-en-3-one) was detected, as described on label. Generally, anabolic steroids are extensively metabolized, thus in-depth knowledge of their metabolism is mandatory for doping control purposes. For this reason, a human excretion study was carried out with four volunteers after a single oral dose to determine the urinary metabolites of the steroid. Urine samples were submitted to enzymatic hydrolysis of glucuconjugated metabolites followed by liquid-liquid extraction and analysis of the trimethylsilyl derivatives by gas chromatography coupled to tandem mass spectrometry. Mass spectrometric data allowed the proposal of two plausible metabolites: 2,17α-dimethyl-16ξ,17β-dihydroxy-5α-androst-1-en-3-one (S1), 2,17α-dimethyl-3α,16ξ,17β-trihydroxy-5α-androst-1-ene (S2). Their electron impact mass spectra are compatible with 16-hydroxylated steroids O-TMS derivatives presenting diagnostic ions such as m/z 231 and m/z 218. These metabolites were detectable after one week post administration while unchanged methylstenbolone was only detectable in a brief period of 45 h. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. On comparison of SimTandem with state-of-the-art peptide identification tools, efficiency of precursor mass filter and dealing with variable modifications.

    Science.gov (United States)

    Novák, Jiří; Sachsenberg, Timo; Hoksza, David; Skopal, Tomáš; Kohlbacher, Oliver

    2013-11-14

    The similarity search in theoretical mass spectra generated from protein sequence databases is a widely accepted approach for identification of peptides from query mass spectra produced by shotgun proteomics. Growing protein sequence databases and noisy query spectra demand database indexing techniques and better similarity measures for the comparison of theoretical spectra against query spectra. We employ a modification of previously proposed parameterized Hausdorff distance for comparisons of mass spectra. The new distance outperforms the original distance, the angle distance and state-of-the-art peptide identification tools OMSSA and X!Tandem in the number of identified peptides even though the q-value is only 0.001. When a precursor mass filter is used as a database indexing technique, our method outperforms OMSSA in the speed of search. When variable modifications are not searched, the search time is similar to X!Tandem. We show that the precursor mass filter is an efficient database indexing technique for high-accuracy data even though many variable modifications are being searched. We demonstrate that the number of identified peptides is bigger when variable modifications are searched separately by more search runs of a peptide identification engine. Otherwise, the false discovery rates are affected by mixing unmodified and modified spectra together resulting in a lower number of identified peptides. Our method is implemented in the freely available application SimTandem which can be used in the framework TOPP based on OpenMS.

  20. Global proteomic profiling of phosphopeptides using electron transfer dissociation tandem mass spectrometry

    DEFF Research Database (Denmark)

    Molina, Henrik; Horn, David M; Tang, Ning

    2007-01-01

    Electron transfer dissociation (ETD) is a recently introduced mass spectrometric technique that provides a more comprehensive coverage of peptide sequences and posttranslational modifications. Here, we evaluated the use of ETD for a global phosphoproteome analysis. In all, we identified a total...... of 1,435 phosphorylation sites from human embryonic kidney 293T cells, of which 1,141 ( approximately 80%) were not previously described. A detailed comparison of ETD and collision-induced dissociation (CID) modes showed that ETD identified 60% more phosphopeptides than CID, with an average of 40% more...

  1. Atmospheric-pressure chemical ionization tandem mass spectrometry (APGC/MS/MS) an alternative to high-resolution mass spectrometry (HRGC/HRMS) for the determination of dioxins.

    Science.gov (United States)

    van Bavel, Bert; Geng, Dawei; Cherta, Laura; Nácher-Mestre, Jaime; Portolés, Tania; Ábalos, Manuela; Sauló, Jordi; Abad, Esteban; Dunstan, Jody; Jones, Rhys; Kotz, Alexander; Winterhalter, Helmut; Malisch, Rainer; Traag, Wim; Hagberg, Jessika; Ericson Jogsten, Ingrid; Beltran, Joaquim; Hernández, Félix

    2015-09-01

    The use of a new atmospheric-pressure chemical ionization source for gas chromatography (APGC) coupled with a tandem quadrupole mass spectrometry (MS/MS) system, as an alternative to high-resolution mass spectrometry (HRMS), for the determination of PCDDs/PCDFs is described. The potential of using atmospheric-pressure chemical ionization (APCI) coupled to a tandem quadrupole analyzer has been validated for the identification and quantification of dioxins and furans in different complex matrices. The main advantage of using the APCI source is the soft ionization at atmospheric pressure, which results in very limited fragmentation. APCI mass spectra are dominated by the molecular ion cluster, in contrast with the high energy ionization process under electron ionization (EI). The use of the molecular ion as the precursor ion in MS/MS enhances selectivity and, consequently, sensitivity by increasing the signal-to-noise ratios (S/N). For standard solutions of 2,3,7,8-TCDD, injections of 10 fg in the splitless mode on 30- or 60-m-length, 0.25 mm inner diameter (id), and 25 μm film thickness low-polarity capillary columns (DB5MS type), signal-to-noise (S/N) ratios of >10:1 were routinely obtained. Linearity was achieved in the region (correlation coefficient of r(2) > 0.998) for calibration curves ranging from 100 fg/μL to 1000 pg/μL. The results from a wide variety of complex samples, including certified and standard reference materials and samples from several QA/QC studies, which were previously analyzed by EI HRGC/HRMS, were compared with the results from the APGC/MS/MS system. Results between instruments showed good agreement both in individual congeners and toxic equivalence factors (TEQs). The data show that the use of APGC in combination with MS/MS for the analysis of dioxins has the same potential, in terms of sensitivity and selectivity, as the traditional HRMS instrumentation used for this analysis. However, the APCI/MS/MS system, as a benchtop system, is

  2. Quantitation of α-Lactalbumin by Liquid Chromatography Tandem Mass Spectrometry in Medicinal Adjuvant Lactose

    Directory of Open Access Journals (Sweden)

    Rui Yan

    2014-01-01

    Full Text Available Lactose is a widely used pharmaceutical excipient, sometimes irreplaceable. Traces of residual proteins left during production of lactose are potential allergen to body. The present paper describes a sensitive and specific LC-MS method for the determination of α-lactalbumin (α-La in lactose samples. Chromatographic separation was performed on an Acquity UPLC BEH300 C18 column (2.1×150 mm, 1.7 μm with an isocratic mobile phase consisting of water containing 0.1% TFA and acetonitrile containing 0.1% TFA (80 : 20, v/v. Mass spectrometric detection was achieved by a triple-quadrupole mass spectrometer equipped with an ESI interface operating in positive ionization mode. Quantitation was performed using selected ion monitoring of m/z 2364 for α-La. The calibration curve was linear from 0.2 to 10 µg/mL. The intra- and interday precisions were less than 7.6% and the accuracy ranged from 96.4 to 104.5%. The limit of quantification (LOQ was 0.15 µg/mL and the limit of detection (LOD was 0.05 µg/mL. This method was then successfully applied to investigate 6 different lactose samples. The application can provide technical preparation for the development of specification of lactose.

  3. Liquid chromatography/tandem mass spectrometry for simultaneous determination of undeclared corticosteroids in cosmetic creams.

    Science.gov (United States)

    Golubović, Jelena B; Otašević, Biljana M; Protić, Ana D; Stanković, Aleksandra M; Zečević, Mira L

    2015-12-30

    Undeclared corticosteroids in creams intended for frequent use might cause serious side-effects, especially in children. In order to prevent this or find the cause, it was essential to develop a method for quick detection and quantification of low levels of corticosteroids. Eleven corticosteroids were used in this study: prednisolone, methylprednisolone, prednisolone-21-acetate, fluocinolone acetonide, fluocinolone acetonide-21-acetate, hydrocortisone-21-acetate, dexamethasone, betamethasone, betamethasone dipropionate, clobetasol propionate and triamcinolone. Separation was achieved via liquid chromatography (LC), and mass spectrometric analysis was conducted by electrospray ionization triple-quadrupole mass spectrometry (MS/MS) in the multiple reaction monitoring mode using corticosterone as internal standard. Good separation by using a gradient-elution LC/MS/MS method with run time of 25 min enabled the use of a segmented detection method and consecutive decrease in detection limits. The proposed method has been validated in the linearity range of 10-1000 ng/mL with coefficients of determination higher than 0.990. The method has shown to have very low limits of quantification (0.75-3 ng/mL) with satisfactory precision and accuracy for each of the corticosteroids. An LC/MS/MS method for the rapid and simultaneous determination of low levels of eleven topical corticosteroids in creams was developed, optimized and validated. The proposed method can be used for testing of different products indicated for the treatment of atopic dermatitis, including "natural products", and "herbal creams" with "miraculous effects". Copyright © 2015 John Wiley & Sons, Ltd.

  4. Quantitative determination of ochratoxin A by liquid chromatography/electrospray tandem mass spectrometry.

    Science.gov (United States)

    Lau, B P; Scott, P M; Lewis, D A; Kanhere, S R

    2000-01-01

    Mass spectrometry of ochratoxin A (OTA) and B (OTB) under electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) was studied. ESI offers higher sensitivities and less fragmentation than APCI. A sensitive LC/MS/MS method for the determination of ochratoxin A (OTA) in human plasma samples was developed. The absolute minimum detection limit was around 10-20 pg per injection, corresponding to 0.5 ppb in an injection equivalent to 20-40microg of human plasma. Ochratoxin B (OTB) was used as an internal standard and its absence in real-life samples was carefully checked before samples were spiked with the internal standard. It was found that these two ochratoxins are susceptible to sodium adduct formation. Fragment ions from the [M + H](+) and [M + Na](+) ions of both OTA and OTB were monitored in the multiple reaction monitoring mode. Three quantitative approaches, standard addition method, internal standard method (using ochratoxin B as an internal standard) and external standard method, were compared in the analysis of human blood plasma. Results from the mass spectrometric method were comparable to those from a conventional LC/fluorescence method. The LC/MS/MS method was also applied to the analysis of contaminated coffee samples. Copyright 2000 John Wiley & Sons, Ltd.

  5. Characterizing changes in snow crab (Chionoecetes opilio) cryptocyanin protein during molting using matrix-assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry.

    Science.gov (United States)

    Demian, Wael L L; Jahouh, Farid M; Stansbury, Don; Randell, Edward; Brown, Robert J; Banoub, Joseph H

    2014-02-28

    We report the matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) characterization of the cryptocyanin proteins of the juvenile Chionoecetes opilio crabs during their molting and non-molting phases. In order to assess the structural cryptocyanin protein differences between the molting and non-molting phases, the obtained peptides were sequenced by MALDI low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS). The cryptocyanin protein was isolated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by MALDI-TOF/TOF-MS. The purified cryptocyanin protein was sequenced, using the 'bottom-up' approach. After tryptic digestion, the peptide mixture was analyzed by MALDI-QqTOF-MS/MS and the data obtained were used for the peptide mass fingerprinting (PMF) identification by means of the Mascot database. It was demonstrated using MALDI-TOF/TOF-MS that the actual molecular weights of the non-molting and molting cryptocyanin proteins were different; these were, respectively, 67.6 kDa and 68.1 kDa. Using low-energy CID-MS/MS we have sequenced the trytic peptides to monitor the differences and similarities between the cryptocyanin molecular structures during the molting and non-molting stages. We have demonstrated for the first time that the actual molecular masses of the cryptocyanin protein during the molting and non-molting phases were different. The MALDI-CID-MS/MS analyses allowed the sequencing of the cryptocyanins after tryptic digestion, during the molting and non-molting stages, and showed some similarities and staggering differences between the identified cryptocyanin peptides. Copyright © 2013 John Wiley & Sons, Ltd.

  6. Phytochemical analyses of Ziziphus jujuba Mill. var. spinosa seed by ultrahigh performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Yang, Bao; Yang, Hongshun; Chen, Feng; Hua, Yanglin; Jiang, Yueming

    2013-11-21

    Ziziphus jujuba Mill. var. spinosa (Z. jujuba) seeds have attracted much attention within the field of medicine due to their significant effects against disturbances of the central nervous system. Secondary metabolites composition is key to the influence of the pharmaceutical and commercial qualities of this plant. In this work, the phytochemical profile of Z. jujuba seeds was analysed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS). The UPLC-MS/MS information identified the main secondary metabolites in Z. jujuba seeds, including flavonoid C-glycosides, triterpene acids and unsaturated fatty acids. The leading chemical identified by UPLC-MS/MS was betulinic acid, and oleic acid was the leading volatile from the GC-MS results. All the samples tested showed similar phytochemical profiles, but levels of the chemical compounds varied. Principal component analysis revealed the principal secondary metabolites that could define the differences in quality. It was confirmed that the combination of UPLC-MS/MS and GC-MS was an effective technique to demonstrate the pharmaceutical quality of Z. jujuba seeds.

  7. Quantitative analysis of tetramethylenedisulfotetramine (tetramine) spiked into beverages by liquid chromatography-tandem mass spectrometry with validation by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Owens, Janel; Hok, Saphon; Alcaraz, Armando; Koester, Carolyn

    2009-05-27

    Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD(50) = 0.1 mg/kg) used in hundreds of deliberate and accidental food poisoning events in China. This paper describes a method for the quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water, with cleanup by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography-mass spectrometry (GC-MS) operated in selected ion monitoring mode for ions m/z 212, 240, and 360. The limit of quantitation was 0.10 μg/mL by LC-MS/MS versus 0.15 μg/mL for GC-MS. Fortifications of the beverages at 2.5 and 0.25 μg/mL were recovered ranging from 73 to 128% by liquid-liquid extraction for GC-MS analysis, from 13 to 96% by SPE, and from 10 to 101% by liquid-liquid extraction for LC-MS/MS analysis.

  8. Simultaneous analysis of fourteen tertiary amine stimulants in human urine for doping control purposes by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lu Jianghai; Wang San; Dong Ying; Wang Xiaobing; Yang Shuming; Zhang Jianli; Deng Jing; Qin Yang; Xu Youxuan; Wu Moutian [National Doping Control Laboratory, China Anti-Doping Agency, 1st Anding Road, ChaoYang District, Beijing 100029 (China); Ouyang Gangfeng, E-mail: cesoygf@mail.sysu.edu.cn [Research Center for Microextraction and Separation Technology, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2010-01-04

    A method for the simultaneous screening and confirmation of the presence of fourteen tertiary amine stimulants in human urine by gas chromatography-mass spectrometry (GC-MS) in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. Solid phase extraction (SPE) and liquid-liquid extraction (LLE) approaches were utilized for the pre-treatment of the urine samples. The study indicated that the capillary temperature played a significant role in the signal abundances of the protonated molecules of cropropamide and crotethamide under positive ion electrospray ionization (ESI) conditions. In addition, comparison studies of two different pre-treatment approaches as well as the two ionization modes were conducted. The LODs of the developed method for all the analytes were lower than the minimum required performance limit (MRPL) as set forth in the World Anti-Doping Agency (WADA) technical document for laboratories. The human urine sample obtained after oral administration of prolintane.HCl was successfully analyzed by the developed method, which demonstrated the applicability and reliability of the method for routine doping control analysis.

  9. Quantitative Analysis of Tetramethylenedisulfotetramine ("Tetramine") Spiked into Beverages by Liquid Chromatography Tandem Mass Spectrometry with Validation by Gas Chromatography Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Owens, J; Hok, S; Alcaraz, A; Koester, C

    2008-11-13

    Tetramethylenedisulfotetramine, commonly known as tetramine, is a highly neurotoxic rodenticide (human oral LD{sub 50} = 0.1 mg/kg) used in hundreds of deliberate food poisoning events in China. Here we describe a method for quantitation of tetramine spiked into beverages, including milk, juice, tea, cola, and water and cleaned up by C8 solid phase extraction and liquid-liquid extraction. Quantitation by high performance liquid chromatography tandem mass spectrometry (LC/MS/MS) was based upon fragmentation of m/z 347 to m/z 268. The method was validated by gas chromatography mass spectrometry (GC/MS) operated in SIM mode for ions m/z 212, 240, and 360. The limit of quantitation was 0.10 {micro}g/mL by LC/MS/MS versus 0.15 {micro}g/mL for GC/MS. Fortifications of the beverages at 2.5 {micro}g/mL and 0.25 {micro}g/mL were recovered ranging from 73-128% by liquid-liquid extraction for GC/MS analysis, 13-96% by SPE and 10-101% by liquid-liquid extraction for LC/MS/MS analysis.

  10. Cyclic pentapeptide analogs based on endomorphin-2 structure: cyclization studies using liquid chromatography combined with on-line mass spectrometry and tandem mass spectrometry.

    Science.gov (United States)

    Piekielna, Justyna; Kluczyk, Alicja; Perlikowska, Renata; Janecka, Anna

    2014-05-01

    The cyclization of linear analogs based on endomorphin-2 structure, Tyr/Dmt-d-Lys-Phe-Phe-Asp-NH2 and Tyr/Dmt-d-Cys-Phe-Phe-Cys-NH2 (where Dmt=2',6'-dimethyltyrosine), resulting in obtaining lactam or disulfide derivatives, was studied using liquid chromatography combined with on-line mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS). In case of cyclization via an amide bond, the formation of the cyclic monomers, cyclic but not linear dimers and even traces of cyclic trimers was observed. Disulfide bridge containing peptides was obtained by the solid-phase synthesis of the linear sequences, followed by either in-solution or on-resin cyclization. In case of the in-solution cyclization, the expected cyclic monomers were the only products. When oxidation of the cysteine residues was performed when the peptides were still on the resin, cyclic monomer and two cyclodimers, parallel and antiparallel, were found. Digestion of the isolated cyclodimers with α-chymotrypsin allowed for their unambiguous identification. The comparison of the cyclic monomer/dimer ratios for analogs with Tyr versus Dmt in position 1 revealed that the presence of the exocyclic Dmt favored formation of the cyclic monomer, most likely due to the increased steric bulk of this amino acid side-chain as compared with Tyr. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Determination of exposure of dispensary drug preparers to cyclophosphamide by passive sampling and liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Wakui, Nobuyuki; Ookubo, Tetuo; Iwasaki, Yusuke; Ito, Rie; Mitui, Miyuki; Yano, Yuichi; Saito, Koichi; Nakazawa, Hiroyuki

    2013-03-01

    To determine cyclophosphamide exposure to preparers during tablet crushing and subsequent handling by analyzing indoor air collected using a high-performance volatile organic compounds-solvent desorption (VOC-SD) passive air sampler. The passive sampler was taped to the mask over the mouth of the preparer and indoor air was collected during crushing and preparation of cyclophosphamide tablets (Endoxan®). After collection, the carbon molecular sieve adsorbent of the passive sampler was placed in a centrifuge tube, and 1 mL of carbon disulfide was used to elute cyclophosphamide from the adsorbent. Liquid-liquid extraction with 1 mL of water was performed, and the aqueous phase was used as the test solution. Cyclophosphamide concentration was determined by liquid chromatography with ultraviolet and tandem mass spectrometry detection. Cyclophosphamide concentration was detected in the range of 7.6-157.7 ng/sampler. Our results showed that low-level exposure occurred near the mouth of the preparer, which could present risks for long-term exposure, especially if combined with multiple toxic drug exposures. The anticancer drug monitoring methodology described here is a simple exposure assessment that can be used to ensure the safety of hospital pharmacy tablet preparers. Furthermore, since the anticancer drug exposure risk is very high for preparers, preparation should be in hood or with face mask.

  12. Global analysis of chemical constituents in Shengmai injection using high performance liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Li, Fei; Cheng, Tao-fang; Dong, Xin; Li, Ping; Yang, Hua

    2016-01-05

    This study aimed to develop a specific and reliable method to comprehensively analyze the chemical constituents in Shengmai injection (SMI) using high performance liquid chromatography coupled with tandem mass spectrometry. The qualitative analysis of SMI was achieved on a Kromasil 100-5C18 column, and the results demonstrated that a total of sixty-two compounds in SMI were unambiguously assigned or tentatively identified, and further, twenty-one compounds including fourteen saponins, six lignans and one L-borneol-7-O-[β-D-apiofuranosyl (1→6)]-β-D-gluco-pyranoside were quantified by HPLC-MS. Furthermore, L-borneol-7-O-[β-D-apio-furanosyl (1→6)]-β-D-glucopyranoside, originated from Radix ophiopogonis, was identified and quantified in SMI for the first time. The method validation results indicated that the methods were simple, specific and reliable. All the investigated compounds showed good linearity (r(2)≥0.9992) with a relatively wide concentration range and acceptable recovery at 90.13-109.09%. Consequently, the developed methods were successfully applied to ten batches of SMI samples analysis. The proposed methods may provide a useful and comprehensive reference for the quality control of SMI, and thus to provide supporting data for the quality control and application of SMI clinically. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. [Determination of L-carnitine in milk and dairy products by hydrophilic liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Liu, Yanming; Xue, Xia; Liu, Guoqiang; Ren, Xuemei; Hu, Mei; Zhu, Jianhua

    2015-09-01

    An analytical method was developed for the determination of L-carnitine in milk and dairy products using hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS). The samples were extracted with 2% (v/v) acetic acid solution, and the protein was precipitated with acetonitrile subsequently. The separation of L-carnitine was carried out on an Acquity UPLC BEH HILIC column using ammonium acetate and acetonitrile as mobile phases. The quantification analysis of the target compound was performed under multiple reaction monitoring (MRM) mode by external standard method. A good linear relationship was obtained between the peak area and concentration of L-carnitine in the range of 1-100 µg/L with the correlation coefficient more than 0.99. The limit of quantification (LOQ ) of L-carnitine was 0. 01 mg/kg. The spiked recoveries were 96.0%-103.4%. The precisions (RSDs ) were 1.2%-4.3%. The sample preparation was simple and rapid, and the results were precise and sensitive. The developed method is suitable for the study of concentration of L-carnitine in milk and dairy products, and the technical support for the infant formula is provided.

  14. Food safety evaluation: Detection and confirmation of chloramphenicol in milk by high performance liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Nicolich, Rebecca S. [Dep Quimica Analitica-IQ/UFRJ, C. Tecnologia, BL A, Ilha do Fundao, Rio de Janeiro, RJ CEP 219749-970 (Brazil)]. E-mail: rebecca@ufrj.br; Werneck-Barroso, Eduardo [FIOCRUZ-SEFAR/IPEC, Av. Brasil, 4365, Manguinhos, Rio de Janeiro, RJ CEP 21040-900 (Brazil); Marques, Marlice A. Sipoli [Dep Quimica Analitica-IQ/UFRJ, C. Tecnologia, BL A, Ilha do Fundao, Rio de Janeiro, RJ CEP 219749-970 (Brazil)

    2006-04-13

    A simple and rapid procedure for extraction of chloramphenicol (CAP) in milk and analysis by high-performance liquid chromatography coupled with quadrupole mass spectrometry in tandem was developed. The method consisted of one step of liquid-liquid extraction using ethyl acetate and acidified water (10 mmol L{sup -1} formic acid) and HPLC-MS/MS detection. CAP-D5 was used as internal standard. The method was validated according to Commission Decision 2002/657/EC. The calibration curves were linear, with typical r {sup 2} values higher than 0.98. Absolute recovery of CAP from milk proved to be more than 95%, however CAP-D5 absolute recovery was 75%. The method was accurate and reproducible, being successfully applied to the monitoring of CAP in milk samples obtained from the Brazilian market. Decision limit (CC{alpha}) was 0.05 ng mL{sup -1} and detection capability (CC{beta}) was 0.09 ng mL{sup -1}.

  15. Identification and Validation of SAA4 as a Rheumatoid Arthritis Prescreening Marker by Liquid Chromatography Tandem-mass Spectrometry

    Directory of Open Access Journals (Sweden)

    AeEun Seok

    2017-05-01

    Full Text Available Rheumatoid arthritis (RA is a chronic autoimmune disease that progresses into systemic inflammation and joint deformity. RA diagnosis is a complicated procedure, and early diagnostic methods are insufficient. Therefore, in this study, we attempted to identify new markers to improve the accuracy of RA prescreening. e identified differentially expressed proteins (DEPs by using liquid chromatography tandem-mass spectrometry in health-prescreening sera with high rheumatoid factor (RF values, and compared the findings with those from sera with normal RF values. We identified 93 DEPs; of these, 36 were upregulated, and 57 were downregulated in high-RF sera. Pathway analysis revealed that these DEPs were related to immune responses. Additionally, four DEPs were statistically analyzed by proteomic analysis; of these, SAA4 was significantly validated in individual enzyme-linked immunosorbent assays. Moreover, SAA4 was significantly upregulated in RA patients (n = 40, 66.43 ± 12.97 ng/mL compared with normal controls (n = 40, 4.79 ± 0.95 ng/mL and had a higher area under the curve than C-reactive protein. Thus, we identified SAA4 as a protein that was positively correlated with RF and RA. SAA4 may represent a novel prescreening marker for the diagnosis of RA.

  16. Determination of microcystin-LR in drinking water using UPLC tandem mass spectrometry-matrix effects and measurement.

    Science.gov (United States)

    Li, Wei; Duan, Jinming; Niu, Chaoying; Qiang, Naichen; Mulcahy, Dennis

    2011-10-01

    A simple detection method using ultra-performance liquid chromatography electrospray ionisation tandem mass spectrometry (UPLC-ESI-MS-MS) coupled with the sample dilution method for determining trace microcystin-LR (MC-LR) in drinking water is presented. The limit of detection (LOD) was 0.04 µg/L and the limit of quantitation (LOQ) was 0.1 µg/L. Water matrix effects of ionic strength, dissolved organic carbon (DOC) and pH were examined. The results indicate that signal detection intensity for MC-LR was significantly suppressed as the ionic strength increased from ultrapure water condition, whereas it increased slightly with solution pH and DOC at low concentrations. However, addition of methanol (MeOH) into the sample was able to counter the signal suppression effects. In this study, dilution of the tap water sample by adding 4% MeOH (v/v) was observed to be adequate to compensate for the signal suppression. The recoveries of the samples fortified with MC-LR (0.2, 1, and 10 µg/L) for three different tap water samples ranged from 84.4% to 112.9%.

  17. Determination of methylisothiazolinone and methylchloroisothiazolinone in cosmetic products by ultra high performance liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Wittenberg, James B; Canas, Benjamin J; Zhou, Wanlong; Wang, Perry G; Rua, Diego; Krynitsky, Alexander J

    2015-09-01

    Isothiazolinone biocides are broad-spectrum preservatives that are widely used in cosmetics, household, and industrial products. An increase in the number of cases of allergic contact dermatitis to isothiazolinone preservatives, namely, methylisothiazolinone and methylchloroisothiazolinone, have been recently noticed. The Food and Drug Administration relies on analytical methods to quantify levels of use of cosmetic ingredients and support enforcement action against products that are not in compliance with the law. In this study, an efficient ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the determination of methylisothiazolinone and methylchloroisothiazolinone in selected cosmetic products. The lower limit of quantitation was determined to be 0.1 μg/g for both preservatives. A survey of 24 cosmetic products was conducted and found concentrations of methylisothiazolinone and methylchloroisothiazolinone ranging from not quantified, or below the lower limit of quantitation, to 89.64 μg/g and not quantified to 10.31 μg/g, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Analysis of anabolic androgenic steroids as sulfate conjugates using high performance liquid chromatography coupled to tandem mass spectrometry.

    Science.gov (United States)

    Rzeppa, S; Heinrich, G; Hemmersbach, P

    2015-01-01

    Improvements in doping analysis can be effected by speeding up analysis time and extending the detection time. Therefore, direct detection of phase II conjugates of doping agents, especially anabolic androgenic steroids (AAS), is proposed. Besides direct detection of conjugates with glucuronic acid, the analysis of sulfate conjugates, which are usually not part of the routine doping control analysis, can be of high interest. Sulfate conjugates of methandienone and methyltestosterone metabolites have already been identified as long-term metabolites. This study presents the synthesis of sulfate conjugates of six commonly used AAS and their metabolites: trenbolone, nandrolone, boldenone, methenolone, mesterolone, and drostanolone. In the following these sulfate conjugates were used for development of a fast and easy analysis method based on sample preparation using solid phase extraction with a mixed-mode sorbent and detection by high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Validation demonstrated the suitability of the method with regard to the criteria given by the technical documents of the World Anti-Doping Agency (WADA). In addition, suitability has been proven by successful detection of the synthesized sulfate conjugates in excretion urines and routine doping control samples. Copyright © 2015 John Wiley & Sons, Ltd.

  19. Liquid chromatography-tandem mass spectrometry analysis of human adrenal vein corticosteroids before and after ACTH stimulation

    Science.gov (United States)

    Nakamura, Yasuhiro; Rege, Juilee; Satoh, Fumitoshi; Morimoto, Ryo; Kennedy, Michael R; Ahlem, Clarence N; Honma, Seijiro; Sasano, Hironobu; Rainey, William E

    2014-01-01

    Context Although steroid hormones produced by the adrenal gland play critical roles in human physiology, a detailed quantitative analysis of the steroid products has not been reported. The current study uses a single methodology (liquid chromatography-tandem mass spectrometry, LC-MS/MS) to quantify ten corticosteroids in adrenal vein (AV) samples pre and post adrenocorticotropic hormone (ACTH) stimulation. Design/methods Three men and six women with a diagnosis of an adrenal aldosterone-producing adenoma (APA) were included in the study. Serum was collected from the iliac vein (IV) and the adrenal vein (AV) contralateral to the diseased adrenal. Samples were collected, before and after administration of ACTH. LC-MS/MS was then used to quantify serum concentrations of unconjugated corticosteroids and their precursors. Results Prior to ACTH stimulation the four most abundant steroids in AV were cortisol (90%), cortisone (4%), corticosterone (3%) and 11-deoxycortisol (0.8%). Post ACTH administration, cortisol remained the major adrenal product (79%), however, corticosterone became the second most abundantly produced adrenal steroid (11%) followed by pregnenolone (2.5%) and 17α-hydroxypregnenolone (2%). ACTH significantly increased the absolute adrenal output of all ten corticosteroids measured (Pcorticosteroids in peripheral and adrenal vein serum samples under pre and post ACTH stimulation. This study demonstrates the primary adrenal steroid products and their response to ACTH. PMID:22150161

  20. Liquid chromatography-tandem mass spectrometry analysis of human adrenal vein corticosteroids before and after adrenocorticotropic hormone stimulation.

    Science.gov (United States)

    Nakamura, Yasuhiro; Rege, Juilee; Satoh, Fumitoshi; Morimoto, Ryo; Kennedy, Michael R; Ahlem, Clarence N; Honma, Seijiro; Sasano, Hironobu; Rainey, William E

    2012-06-01

    Although steroid hormones produced by the adrenal gland play critical roles in human physiology, a detailed quantitative analysis of the steroid products has not been reported. The current study uses a single methodology (liquid chromatography-tandem mass spectrometry, LC-MS/MS) to quantify ten corticosteroids in adrenal vein (AV) samples pre- and post-adrenocorticotropic hormone (ACTH) stimulation. Three men and six women with a diagnosis of an adrenal aldosterone-producing adenoma (APA) were included in the study. Serum was collected from the iliac vein (IV) and the AV contralateral to the diseased adrenal. Samples were collected, before and after administration of ACTH. LC-MS/MS was then used to quantify serum concentrations of unconjugated corticosteroids and their precursors. Prior to ACTH stimulation, the four most abundant steroids in AV were cortisol (90%), cortisone (4%), corticosterone (3%) and 11-deoxycortisol (0.8%). Post-ACTH administration, cortisol remained the major adrenal product (79%); however, corticosterone became the second most abundantly produced adrenal steroid (11%) followed by pregnenolone (2.5%) and 17α-hydroxypregnenolone (2%). ACTH significantly increased the absolute adrenal output of all ten corticosteroids measured (P corticosteroids in peripheral and AV serum samples under pre- and post-ACTH stimulation. This study demonstrates the primary adrenal steroid products and their response to ACTH. © 2012 Blackwell Publishing Ltd.

  1. Determination of artificial sweeteners in sewage sludge samples using pressurised liquid extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Ordoñez, Edgar Y; Quintana, José Benito; Rodil, Rosario; Cela, Rafael

    2013-12-13

    An analytical method for the determination of six artificial sweeteners in sewage sludge has been developed. The procedure is based on pressurised liquid extraction (PLE) with water followed by solid-phase extraction (SPE) and subsequent liquid chromatography-tandem mass spectrometry analysis. After optimisation of the different PLE parameters, extraction with aqueous 500mM formate buffer (pH 3.5) at 80°C during a single static cycle of 21min proved to be best conditions. After a subsequent SPE, quantification limits, referred to dry weight (dw) of sewage sludge, ranged from 0.3ng/g for acesulfame (ACE) to 16ng/g for saccharin (SAC) and neohespiridine dihydrochalcone. The trueness, expressed as recovery, ranged between 72% and 105% and the precision, expressed as relative standard deviation, was lower than 16%. Moreover, the method proved its linearity up to the 2μg/g range. Finally, the described method was applied to the determination of the artificial sweeteners in primary and secondary sewage sludge from urban wastewater treatment plants. Four of the six studied artificial sweeteners (ACE, cyclamate, SAC and sucralose) were found in the samples at concentrations ranging from 17 to 628ng/g dw. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Matrix effect-corrected liquid chromatography/tandem mass-spectrometric method for determining acylcarnitines in human urine.

    Science.gov (United States)

    Abe, Kazuki; Suzuki, Hiroyuki; Maekawa, Masamitsu; Shimada, Miki; Yamaguchi, Hiroaki; Mano, Nariyasu

    2017-05-01

    Administration of pivalate-containing antibiotics decreases serum carnitine and increases urinary pivaloylcarnitine, resulting in hypocarnitinemia. Carnitine and acylcarnitines are important biomarkers in the diagnosis of carnitine deficiency, but the relationship between acylcarnitines and drug-induced hypocarnitinemia remains unclear. Quantification of acylcarnitines enables discovery of new biomarkers for prediction and diagnosis of drug-induced hypocarnitinemia. Here we describe a liquid chromatography/tandem mass-spectrometric method for simultaneously quantifying carnitine, 15 acylcarnitines, and cefditoren (the pivoxilated product of an antibiotic prodrug) in human urine. The matrix effect is corrected in 87.8-103% using deuterium-labeled internal standards ( 2 H 9 -carnitine, 2 H 3 -hexanoylcarnitine, and 2 H 3 -stearoylcarnitine). The surrogate matrix method had an error of method. Dynamic ranges were 0.1-100μmol/l for acylcarnitines and 0.3-300μg/ml for cefditoren. Both accuracy and precision were method, urine samples from eight healthy volunteers (five adults and three children) were analyzed, and individual differences were clearly observed. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Determination of Aromatic Amines Released from Azo Dyes in Paper Packaging by Liquid Chromatography-Tandem Mass Spectrometry.

    Science.gov (United States)

    Yang, Fei; Bian, Zhaoyang; Li, Zhonghao; Fan, Ziyan; Wang, Ying; Liu, ShanShan; Deng, Huimin; Tang, Gangling

    2016-09-01

    An LC-tandem MS (LC-MS/MS) method for the determination of 21 kinds of carcinogenic aromatic amines released from azo dyes in food wrappers was used in this research. Sodium dithionite was added to a citric acid buffer medium to reduce and decompose possible azo dyes. The extract was analyzed after liquid-liquid extraction (LLE) and dispersive SPE (d-SPE). The conditions for chromatographic separation, mass spectrum, LLE, and d-SPE were optimized. Under optimal conditions, the LOD was in the range of 0.13-0.35 mg/kg and LOQ in the range of 0.38-1.05 mg/kg, with the addition of standard recoveries of most aromatic amines being ≥80% and RSDs ≤10%. The recoveries for 2,4-diaminotoluene and 2,4-diaminoanisole were significantly lower, being ≤40%. The method was successfully used to analyze 30 practical samples, and the results showed that it is user-friendly, with high sensitivity, rapid control, and low matrix interference.

  4. Simultaneous determination of ten illegal azo dyes in feed by ultra-high performance liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Piątkowska Marta

    2017-09-01

    Full Text Available Introduction: The paper presents the method of simultaneous determination of 10 illegal azo dyes in feed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry technique. Material and Methods: The dyes were extracted with hexane, evaporated to dryness, and analysed. Separation was achieved in 7 min in a gradient elution using acetonitrile (A and 0.1% formic acid (B as a mobile phase. Results: The validation results showed the repeatability of the method, which was evaluated at three levels (50, 500, and 5,000 μg/kg. All the matrix calibration curves for the working ranges were linear (R2 0.9904 to 1.0, the repeatability was between 2.1% and 24%, and recoveries ranged from 77.9% to 120%. The LOD and LOQ were at 1-2 and 5-10 μg/kg for different dyes, respectively. Furthermore, the method was applied in the homogeneity tests of the in-house prepared feed containing Sudan I at the levels of 0.5, 5, and 50 mg/kg. Conclusions: A sensitive, selective, and fast multiresidue method was successfully developed and validated. Its robustness was confirmed by the analysis of an experimental feed containing Sudan I.

  5. Determination of mycotoxins in plant-based beverages using QuEChERS and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Miró-Abella, Eugènia; Herrero, Pol; Canela, Núria; Arola, Lluís; Borrull, Francesc; Ras, Rosa; Fontanals, Núria

    2017-08-15

    A method was developed for the simultaneous determination of 11 mycotoxins in plant-based beverage matrices, using a QuEChERS extraction followed by ultra-high performance liquid chromatography coupled to tandem mass spectrometry detection (UHPLC-(ESI)MS/MS). This multi-mycotoxin method was applied to analyse plant-based beverages such as soy, oat and rice. QuEChERS extraction was applied obtaining suitable extraction recoveries between 80 and 91%, and good repeatability and reproducibility values. Method Quantification Limits were between 0.05μgL(-1) (for aflatoxin G1 and aflatoxin B1) and 15μgL(-1) (for deoxynivalenol and fumonisin B2). This is the first time that plant-based beverages have been analysed, and certain mycotoxins, such as deoxynivalenol, aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, ochratoxin A, T-2 toxin and zearalenone, were found in the analysed samples, and some of them quantified between 0.1μgL(-1) and 19μgL(-1). Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Development of a liquid chromatography-tandem mass spectrometry method for quantitative analysis of trace d-amino acids.

    Science.gov (United States)

    Nakano, Yosuke; Konya, Yutaka; Taniguchi, Moyu; Fukusaki, Eiichiro

    2017-01-01

    d-Amino acids have recently attracted much attention in various research fields including medical, clinical and food industry due to their important biological functions that differ from l-amino acid. Most chiral amino acid separation techniques require complicated derivatization procedures in order to achieve the desirable chromatographic behavior and detectability. Thus, the aim of this research is to develop a highly sensitive analytical method for the enantioseparation of chiral amino acids without any derivatization process using liquid chromatography-tandem mass spectrometry (LC-MS/MS). By optimizing MS/MS parameters, we established a quantification method that allowed the simultaneous analysis of 18 d-amino acids with high sensitivity and reproducibility. Additionally, we applied the method to food sample (vinegar) for the validation, and successfully quantified trace levels of d-amino acids in samples. These results demonstrated the applicability and feasibility of the LC-MS/MS method as a novel, effective tool for d-amino acid measurement in various biological samples. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. Validation of determination of plasma metabolites derived from thyme bioactive compounds by improved liquid chromatography coupled to tandem mass spectrometry.

    Science.gov (United States)

    Rubió, Laura; Serra, Aida; Macià, Alba; Borràs, Xenia; Romero, Maria-Paz; Motilva, Maria-José

    2012-09-15

    In the present study, a selective and sensitive method, based on microelution solid-phase extraction (μSPE) plate and ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) was validated and applied to determine the plasma metabolites of the bioactive compounds of thyme. For validation process, standards of the more representative components of the phenolic and monoterpene fractions of thyme were spiked in plasma samples and then the quality parameters of the method were studied. Extraction recoveries (%R) of the studied compounds were higher than 75%, and the matrix effect (%ME) was lower than 18%. The LODs ranged from 1 to 65 μg/L, except for the thymol sulfate metabolite, which was 240 μg/L. This method was then applied for the analysis of rat plasma obtained at different times, from 0 to 6h, after an acute intake of thyme extract (5 g/kg body weight). Different thyme metabolites were identified and were mainly derived from rosmarinic acid (coumaric acid sulfate, caffeic acid sulfate, ferulic acid sulfate, hydroxyphenylpropionic acid sulfate, dihydroxyphenylpropionic acid sulfate and hydroxybenzoic acid) and thymol (thymol sulfate and thymol glucuronide). The most abundant thyme metabolites generated were hydroxyphenylpropionic acid sulfate and thymol sulfate, their respective concentrations in plasma being 446 and 8464 μM 1h after the intake of the thyme extract. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Microdialysis combined with liquid chromatography-tandem mass spectrometry for the determination of nimodipine in the guinea pig hippocampus.

    Science.gov (United States)

    Wang, Chen; Lu, Xiaojing; Li, Liqin; Zhang, Ruihua; shi, Tong; Li, Shu

    2016-04-01

    Nimodipine is a dihydropyridine calcium-channel blocker that has been recently shown to be effective on the function of central nervous system. It has been reported that treatment against deficits of learning and memory in animals and human by maintain the calcium homeostasis in hippocampus with nimodipine may be promising therapeutic strategies. A rapid and sensitive liquid chromatography-tandem mass spectrometric method was developed to determination the nimodipine in hippocampus using microdialysis technique. The separation was accomplished on an Agilent Zorbax SB-C18 column (100mm×2.1mm ID, 3.5μm) with the mobile phase composed of methanol-water (80:20, v/v) containing 0.2% formic acid at a flow rate of 0.2ml/min. Multiple reaction monitoring of the precursor-product ion transitions 419→343 for nimodipine and 361→315 nitrendipine (IS) was used for quantitation. The method was sensitive with a lower limit of quantitation (LLOQ) of 0.2ng/ml for nimodipine, with good linearity in the range of 0.2-20ng/ml. All the validation data, such as accuracy, precision, intra- and inter-day repeatability and stability were within the required limits. The method was successfully applied to p harmacokinetic study of the nimodipine in the guinea pig hippocampus. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Picogram per liter level determination of hydroxylated polybrominated diphenyl ethers in water by liquid chromatography-electrospray tandem mass spectrometry.

    Science.gov (United States)

    Chang, Hong; Wu, Fengchang; Jin, Fen; Feng, Chenglian; Zhao, Xiaoli; Liao, Haiqing

    2012-02-03

    Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have obtained increasing attention; however, few analytical methods are available for sensitive identification of these compounds in water. In this paper, we developed a highly sensitive method for simultaneous determination of nine OH-PBDEs in water by using hydrophilic-lipophilic balanced cartridge extraction, silica cartridge purification, and the combination of derivatization with liquid chromatography-electrospray tandem mass spectrometry. The effective sample pretreatment process and greatly increased instrumental sensitivity by derivatization allow for the quantification of nine OH-PBDEs at a method detection limit of 0.04-3.5 pg/L with 1-L wastewater treatment plant effluent or river water. This method was applied to wastewater effluent and river water samples collected in Beijing, China, where two OH-tetraPBDEs were detected at concentrations ranging from 0.63 to 1.0 pg/L (5-OH-BDE-47) and from 0.92 to 1.3 pg/L (6-OH-BDE-47). Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Rapid and sensitive detection of carbapenemase activity in Acinetobacter baumannii using superficially porous liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Lin, Huei-Ru; Hu, Anren; Lai, Meng-Jiun; Chiang, Chih-Wei; Liao, Chao-Chuan; Chang, Kai-Chih

    2016-12-01

    The emergence and spread of carbapenem-resistant Acinetobacter baumannii poses a challenge for optimizing antibiotic therapies and preventing outbreaks. Traditional phenotypic assays such as the modified Hodge test (MHT) or polymerase chain reaction (PCR)-based detection of the carbapenemase genes are time-consuming and complicated. Therefore, new approaches for the efficient detection of carbapenemase-producing A. baumannii are urgently required. In this study, we used the superficially porous liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to measure carbapenem hydrolysis in a solution spiked with test strains of A. baumannii. The rate of carbapenem hydrolysis during incubation was expressed as the ratio of the carbapenem peak area of the test A. baumannii strains to the noncarbapenemase-producing A. baumannii ATCC 17978. This method can accurately measure the carbapenem hydrolysis rate and, therefore, can effectively identify carbapenemase-producing strains within 75 minutes. A total of 112 A. baumannii strains were used in this study, including 103 clinical isolates with 68 carbapenem-resistant strains and 35 carbapenem-susceptible strains, seven ATCC strains and two selected mutants. The results of the superficially porous LC-MS/MS assay showed higher detection sensitivity compared to the results of the MHT. Our results demonstrate the ability of the former method to routinely detect carbapenemase-producing A. baumannii. Copyright © 2015. Published by Elsevier B.V.

  11. A graphene tip coupled with liquid chromatography tandem mass spectrometry for the determination of four synthetic adulterants in slimming supplements.

    Science.gov (United States)

    Jin, Renyao; Li, Linqiu; Guo, Lianxian; Li, Weiqiao; Shen, Qing

    2017-06-01

    Slimming supplements were popularly sold online driven by the increasement of obesity and the development of social networking platform. However, events of drug abuse in slimming supplements were also frequently reported. In this study, a graphene tip solid-phase extraction (Gtip SPE) and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established for determining fenfluramine, phenolphthalein, bumetanide, and sibutramine in slimming supplements. It was validated in terms of linearity (0.9985-0.9995), LOD (1.8ngmL -1 ), LOQ (5.6ngmL -1 ), intra-day precision (<5.1%), inter-day precision (<7.3%), and recovery (82.9-95.2%). Sibutramine is the most commonly used drug, which was detected in Bihais, Galong, and Aolist, with content 12.4, 3.6, 20.3mgg -1 , respectively. Phenolphthalein was also found with content lower than 5.2mgg -1 . The successful application of Gtip SPE and UPLC-MS/MS method indicated its advantage in analyzing low level of contaminates resulted from violation of regulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Determination of polychlorinated biphenyls in ambient air by gas chromatography coupled to triple quadrupole tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Ocana, Rosa; Mena Granero, Angela; Egea Gonzalez, Francisco J.; Garrido Frenich, Antonia; Martinez Vidal, Jose L.; Plaza Bolanos, Patricia [University of Almeria, Department of Analytical Chemistry, Almeria (Spain)

    2008-03-15

    A multiresidue method for determining 22 polychlorinated biphenyls (PCBs) in air has been developed and validated by gas chromatography (GC) coupled to tandem mass spectrometry (MS/MS) using a triple quadrupole analyzer (QqQ). The method was validated in terms of both steps of sampling and analysis. The sampling method, which is based on active sampling using polyurethane foam (PUF) as adsorbent, was validated by generating standard atmospheres. The retention capacity of this sampling sorbent allows up to 5 m{sup 3} of air to be sampled without any breakthrough for most compounds. Two solvent extraction methods were compared: sonication and Soxhlet extraction with a mixture of n-hexane:diethyl ether (95:5 v/v). Both extraction methods yielded similar results, but the first one required less solvent and time. The method exhibited good accuracy (80.3-99.8%), precision (2.2-15.2%) and lower limits that allowed quantification and confirmation at levels as low as 0.008 ng/m{sup 3}. Finally, the method was applied to the analysis of PCBs in the air in areas near to a municipal solid-waste landfill and directly above the refuse in the landfill, where it indicated the presence of some of the target compounds. (orig.)

  13. A novel method for analysing key corticosteroids in polar bear (Ursus maritimus) hair using liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Weisser, Johan J; Hansen, Martin; Björklund, Erland; Sonne, Christian; Dietz, Rune; Styrishave, Bjarne

    2016-04-01

    This paper presents the development and evaluation of a methodology for extraction, clean-up and analysis of three key corticosteroids (aldosterone, cortisol and corticosterone) in polar bear hair. Such a methodology can be used to monitor stress biomarkers in polar bears and may provide as a useful tool for long-term and retrospective information. We developed a combined pressurized liquid extraction (PLE)-solid phase extraction (SPE) procedure for corticosteroid extraction and clean-up followed by high pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis. This procedure allows for the simultaneous determination of multiple steroids, which is in contrast to previous polar bear studies based on ELISA techniques. Absolute method recoveries were 81%, 75% and 60% for cortisol, corticosterone and aldosterone, respectively. We applied the developed method on a hair sample pooled from four East Greenland polar bears. Herein cortisol and corticosterone were successfully determined in levels of 0.32±0.02ng/g hair and 0.13±0.02ng/g hair, respectively. Aldosterone was below limit of detection (LODpolar bears was consistent with cortisol levels previously determined in the Southern Hudson Bay and James Bay in Canada using ELISA kits. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. FDRAnalysis: a tool for the integrated analysis of tandem mass spectrometry identification results from multiple search engines.

    Science.gov (United States)

    Wedge, David C; Krishna, Ritesh; Blackhurst, Paul; Siepen, Jennifer A; Jones, Andrew R; Hubbard, Simon J

    2011-04-01

    Confident identification of peptides via tandem mass spectrometry underpins modern high-throughput proteomics. This has motivated considerable recent interest in the postprocessing of search engine results to increase confidence and calculate robust statistical measures, for example through the use of decoy databases to calculate false discovery rates (FDR). FDR-based analyses allow for multiple testing and can assign a single confidence value for both sets and individual peptide spectrum matches (PSMs). We recently developed an algorithm for combining the results from multiple search engines, integrating FDRs for sets of PSMs made by different search engine combinations. Here we describe a web-server and a downloadable application that makes this routinely available to the proteomics community. The web server offers a range of outputs including informative graphics to assess the confidence of the PSMs and any potential biases. The underlying pipeline also provides a basic protein inference step, integrating PSMs into protein ambiguity groups where peptides can be matched to more than one protein. Importantly, we have also implemented full support for the mzIdentML data standard, recently released by the Proteomics Standards Initiative, providing users with the ability to convert native formats to mzIdentML files, which are available to download.

  15. [Determination of S-phenylmercapturic acid in urine by on-line enrichment liquid chromatography tandem mass spectrometry].

    Science.gov (United States)

    Ding, Changming; Lu, Yifu; Wang, Jun; Lin, Shaobin

    2013-09-01

    To develop on-line enrichment liquid chromatography tandem mass (LC-MS/MS) method for determination of S-phenylmercapturic acid (S-PMA) in urine. With d2-S-PMA added as internal standard, the urine samples were cleaned up and concentrated on Hypersil GOLD (20 mm x 2.1 mm x 12.0 microm) columns, and the targeted compounds were analyzed by HPLC-MS/MS under negative ion mode using Hypersil GOLD (50 mm x 2.1 mm x 3.0 microm) columns as analyzed columns. In the process of enrichment, the mobile phase is CH3OH: HCOOH (0.2%) = 5:95 (volume ratio), the flow rate is 1.50 ml/min. During the analysis, the mobile phase is CH3CN and HCOOH (0.2%) gradient elution, the flow rate is 350 microl/min. The linear range was 0-500 ng/ml. The related coefficient was 0.9986. The detection limit was 8.0 ng/ml. The recoveries were 78.2%-84.5%. The relative standard deviation was 1.49% (n = 5). The method uses internal standard method, it was used for determination of S-phenylmercapturic acid in the urine, sample don't need too much pretreatment, the sample volume to reduce, the organic solvent volume decrease. The method was simple, rapid, sensitive and accurate. It was for the detecting for S-phenylmercapturic acid in urine.

  16. Development and evaluation of a liquid chromatography tandem mass spectrometry method for simultaneous determination of salivary melatonin, cortisol and testosterone.

    Science.gov (United States)

    Jensen, Marie Aarrebo; Hansen, Ase Marie; Abrahamsson, Peter; Nørgaard, Asger W

    2011-09-01

    Circadian disruption can have several possible health consequences, but is not well studied. In order to measure circadian disruption, in relation to shift or night work, we developed a simple and sensitive method for the simultaneous determination of melatonin, cortisol and testosterone in human saliva. We used liquid-liquid extraction (LLE) followed by liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI-MS/MS) recorded in positive ion mode. Saliva samples were collected by spitting directly into tubes and 250 μL were used for analysis. The limits of detection were 4.1 pmol/L, 0.27 nmol/L and 10.8 pmol/L for melatonin, cortisol, and testosterone, respectively. The developed method was sensitive enough to measure circadian rhythms of all 3 hormones in a pilot study among four healthy volunteers. It can therefor be used to study the impact of night work and working in artificial light on the workers circadian rhythms. To our knowledge this is the first LC-ESI-MS/MS method for simultaneous determination of salivary melatonin, cortisol and testosterone. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. A liquid chromatography-tandem mass spectrometry method for the detection of economically motivated adulteration in protein-containing foods.

    Science.gov (United States)

    MacMahon, Shaun; Begley, Timothy H; Diachenko, Gregory W; Stromgren, Selen A

    2012-01-13

    A new analytical method was developed to determine the presence of six (6) compounds with the potential to be used in economic adulteration to enhance the nitrogen content in milk products and bulk proteins. Residues were extracted from the matrix with 2% formic acid, after which acetonitrile (ACN) was added to induce precipitation of the proteins. Extracts were analyzed by liquid chromatography using a ZIC-HILIC column with tandem mass spectrometry (LC-MS/MS) using electrospray ionization (ESI). Single-laboratory method validation data was collected in six matrices fortified at concentrations down to 1.0 μg/g (ppm). Average recoveries and average relative standard deviations (RSD) using spiked matrix calibration standard curves were the following: cyromazine (CY) 95.9% (7.5% RSD), dicyandiamide (DC) 98.1% (5.6% RSD), urea 102.5% (8.6% RSD), biuret (BU) 97.2% (6.6% RSD), triuret (TU) 97.7% (5.7% RSD), and amidinourea (AU) 93.4% (7.4% RSD). This method provides a rapid and effective approach to proactively combat economically motivated adulteration in protein-containing products. Published by Elsevier B.V.

  18. A rapid quantitative method for the analysis of synthetic cannabinoids by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Freijo, Tom D; Harris, Steve E; Kala, Subbarao V

    2014-10-01

    Synthetic cannabinoids represent an emerging drug problem in the USA, as these compounds are constantly being modified and rapidly sold as soon as they become available. Laboratories around the world are constantly improving the analytical methods to detect and identify these newly available designer drugs. This study used a simple approach to detect and quantify a variety of synthetic cannabinoids (14 parent compounds and 15 metabolites including series XLR, AM, JWH, UR, RCS, PB, HU and AB-FUBINACA) using LC-MS-MS. Drug-free urine samples spiked with various synthetic cannabinoids and their metabolites were separated on a C18-Hypersil Gold column using an Agilent 1290 ultra-high performance liquid chromatography and detected by an AB Sciex API 4000 tandem mass spectrometer. Studies were carried out to determine limit of detection, limit of quantitation, upper limit of linearity, ion suppression, interference, precision and accuracy to validate the method. Urine samples from patients and known users were hydrolyzed with β-glucuronidase prior to the analysis by LC-MS-MS, and the data are presented. The method described here is rapid, highly sensitive and specific for the identification of a variety of synthetic cannabinoids. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Simultaneous identification of abused drugs, benzodiazepines, and new psychoactive substances in urine by liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Hei-Hwa Lee

    2016-03-01

    Full Text Available A literature search reveals no studies concerning simultaneous identification of commonly abused drugs, benzodiazepines, and new psychoactive substances in urine by liquid chromatography tandem mass spectrometry (LC–MS/MS. We developed and validated an LC–MS/MS method for simultaneous identification of multiple abused drugs, benzodiazepines, and new psychoactive substances in urine from suspected drug abusers. The instrument was operated in multiple-reaction monitoring using an electrospray ionization mode. Chromatograms were separated using an ACE5 C18 column on a gradient of acetonitrile. After liquid–liquid extraction, samples were passed through a 0.22-μm polyvinylidene difluoride filter before injection into the LC–MS/MS. The limits of quantitation ranged from 0.5 ng/mL to 31.3 ng/mL. The linearity ranged from 0.5 ng/mL to 200 ng/mL. The precision results were below 15.4% (intraday and 18.7% (interday. The intraday accuracy ranged from 85.9% to 121.0%; interday accuracy ranged from 66.1% to 128.7%. The proposed method was applied to 769 urine samples. The most common three drugs identified were ketamine, amphetamine, and opiates. The drug positive rate for one or more drugs was 79.6%. Our results demonstrate the suitability of the LC–MS/MS method for simultaneous identification of multiple abused drugs, benzodiazepines, and new psychoactive substances in urine.

  20. Simultaneous analysis of allopurinol and oxypurinol using a validated liquid chromatography–tandem mass spectrometry method in human plasma

    Directory of Open Access Journals (Sweden)

    Dhiraj M. Rathod

    2017-02-01

    Full Text Available The present study describes a simple, reliable and reproducible liquid chromatography–tandem mass spectrometry method (LC–MS/MS for the simultaneous determination of allopurinol and its active metabolite, oxypurinol in human plasma for a pharmacokinetic/bioequivalence study. After protein precipitation (PPT of 100 µL plasma sample with 1.0% formic acid in acetonitrile, the recovery of the analytes and allopurinol-d2 as an internal standard ranged from 85.36% to 91.20%. The analytes were separated on Hypersil Gold (150 mm×4.6 mm, 5 µm column using 0.1% formic acid-acetonitrile (98:2, v/v as the mobile phase. Quantification was done using electrospray ionization in the positive mode. The calibration concentration range was established from 60.0 to 6000 ng/mL for allopurinol and 80.0–8000 ng/mL for oxypurinol. Matrix effect in human plasma, expressed as IS-normalized matrix factors ranged from 1.003 to 1.030 for both the analytes. The developed method was found suitable for a clinical study with 300 mg allopurinol tablet formulation in healthy subjects.

  1. Multi-residue analysis of pesticides in traditional Chinese medicines using gas chromatography-negative chemical ionisation tandem mass spectrometry.

    Science.gov (United States)

    Nie, Jing; Miao, Shui; Lehotay, Steven J; Li, Wen-Ting; Zhou, Heng; Mao, Xiu-Hong; Lu, Ji-Wei; Lan, Lan; Ji, Shen

    2015-01-01

    In this study, a residue analysis method for the simultaneous determination of 107 pesticides in traditional Chinese medicines (TCMs), Angelica sinensis, A. dahurica, Leonurus heterophyllus Sweet, Pogostemon cablin and Lonicera japonica Thunb., was developed using gas chromatography coupled with tandem mass spectrometry in negative chemical ionisation mode (GC-NCI-MS/MS). NCI has advantages of high sensitivity and selectivity to chemicals with electron-withdrawing groups, and yields low background interference. For sample preparation, QuEChERS (quick, easy, cheap, effective, rugged and safe) was applied. Due to the unique characteristics of TCMs, the clean-up step was optimised by adjusting amounts of primary secondary amine, C18, graphitised carbon black and silica sorbents. Validation was mainly performed by determining analyte recoveries at four different spiking concentrations of 10, 50, 100 and 200 ng g(-1), with seven replicates at each concentration. Method trueness, precision, linearity of calibration curves, lowest calibrated levels (LCLs) and matrix effects were determined to demonstrate method and instrument performance. Among the 107 pesticides tested, approximately 80% gave recoveries from 80% to 110% and pesticides were 5 ng g(-1), and as low as 0.1 ng g(-1) for dichlofenthion, endosulfan sulphate, flumetralin, isofenphos-methyl, methyl-pentachlorophenyl sulphide and trifluralin. The results indicate that GC-NCI-MS/MS is an excellent technique for quantitative and qualitative analysis of targeted GC-amenable pesticides at ultra-trace levels, especially in complex matrices such as TCMs.

  2. Amphetamine and derivatives in natural weight loss pills and dietary supplements by capillary electrophoresis-tandem mass spectrometry.

    Science.gov (United States)

    Dos Santos, Vagner Bezerra; Daniel, Daniela; Singh, Melina; do Lago, Claudimir Lucio

    2016-12-01

    A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for amphetamine (AM), phentermine (PTM), methamphetamine (MAM), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), and methylenedioxyethylamphetamine (MDEA) in commercial samples of homeopathic and phytotherapic medicines and dietary supplements is presented. The samples were submitted to a modified QuEChERS extraction procedure (at apparent pH 13) followed by electrophoretic separation in 0.1molL-1 formic acid electrolyte (pH 2.4) and detection by ESI-MS/MS. A polyvinyl alcohol coated capillary was employed to prevent the adsorption of the analytes to the capillary wall. The limits of detection and quantitation were from 0.02 to 0.06μgL-1 and from 0.06 to 0.21μgL-1, respectively, with recovery ranging from 85 to 123% and the standard deviations were not greater than 6.1%. In addition, the separation occurs in less than six minutes. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Direct Analysis of Amphetamine Stimulants in a Whole Urine Sample by Atmospheric Solids Analysis Probe Tandem Mass Spectrometry

    Science.gov (United States)

    Crevelin, Eduardo J.; Salami, Fernanda H.; Alves, Marcela N. R.; De Martinis, Bruno S.; Crotti, Antônio E. M.; Moraes, Luiz A. B.

    2016-05-01

    Amphetamine-type stimulants (ATS) are among illicit stimulant drugs that are most often used worldwide. A major challenge is to develop a fast and efficient methodology involving minimal sample preparation to analyze ATS in biological fluids. In this study, a urine pool solution containing amphetamine, methamphetamine, ephedrine, sibutramine, and fenfluramine at concentrations ranging from 0.5 pg/mL to 100 ng/mL was prepared and analyzed by atmospheric solids analysis probe tandem mass spectrometry (ASAP-MS/MS) and multiple reaction monitoring (MRM). A urine sample and saliva collected from a volunteer contributor (V1) were also analyzed. The limit of detection of the tested compounds ranged between 0.002 and 0.4 ng/mL in urine samples; the signal-to-noise ratio was 5. These results demonstrated that the ASAP-MS/MS methodology is applicable for the fast detection of ATS in urine samples with great sensitivity and specificity, without the need for cleanup, preconcentration, or chromatographic separation. Thus ASAP-MS/MS could potentially be used in clinical and forensic toxicology applications.

  4. [Determination of amanitins and phallotoxins in wild mushrooms by online liquid chromatography-diode array detector-tandem mass spectrometry].

    Science.gov (United States)

    Xu, Xiaomin; Zhang, Jingshun; Cai, Zengxuan; Zhang, Jing; Huang, Baifen; Xu, Jiaojiao; Chen, Qing

    2017-06-08

    A fast and wide linear range method was established for the determination of mushroom toxins amanitins (α-amanitin,β-amanitin and γ-amanitin) and phallotoxins (phallacidin and phalloidin) in wild mushrooms by online liquid chromatography-diode array detector-tandem mass spectrometry (LC-DAD-MS/MS). The mushroom toxins were extracted with methanol, and diluted with water. The extracts were separated on an XBridgeTM BEH C18 column (150 mm×3.0 mm, 2.5 μm) under pH 10.7, measured by DAD and then analyzed by MS/MS. Basic mobile phase conditions were applied to improve the ionization efficiency of hydrogen ion adducts. The baseline separation of the analytes was obtained within 15 min. The limits of detection (LODs) of the sample matrix were 0.005-0.02 mg/kg. The toxins were quantified by the results measured by MS/MS when the toxin contents less than 2 mg/kg, and quantified by the results obtained from DAD when the contents more than 2 mg/kg. The linear range was 0.05-500 mg/kg for the whole method in one injection. The method was successfully applied to the analyses of amanitins and phallotoxins in Lepiota brunneoincarnata and white Amanita.

  5. Simultaneous determination of the flavonoids robinin and kaempferol in human breast cancer cells by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Tsiklauri, Lia; An, Guohua; Ruszaj, Donna M; Alaniya, Mary; Kemertelidze, Ether; Morris, Marilyn E

    2011-04-28

    An accurate, precise and sensitive method was developed and validated for the simultaneous quantification of the flavonoid glycoside robinin, and its algycone kaempferol in human breast cancer MCF-7 cells. The application of liquid chromatography-tandem mass spectrometry (LC/MS/MS) with a TurboIonspray interface in negative mode under multiple reactions monitoring was investigated. Chromatographic separation was achieved on a C(18) column using a mobile phase consisting of (A) water with 0.025% formic acid and 1mM ammonium formate and (B) acetonitrile with 0.025% formic acid. Rutin was used as the internal standard for robinin and fisetin as the internal standard for kaempferol. The assay had a limit of detection of 0.1ng/ml for both compounds when present in cell lysate. The calibration curves were linear from 1 to 250ng/ml (r>0.999) for each compound. The intra- and inter-day coefficients of variation were less than 10% and intra- and inter-day accuracies were within 11%. This assay was successfully applied in a robinin cellular uptake study to determine the intracellular concentrations of robinin in MCF-7 cells. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Determination of tributyltin in marine sediment and waters by pressurised solvent extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Nichols, David S; Jordan, Timothy B; Kerr, Neil

    2014-05-01

    In this study, tributyltin (TBT) was extracted from marine sediment matrix with the use of pressurised solvent extraction (PSE), which uses high-temperature and -pressure conditions to increase extraction efficiency. The analyte was chromatographically resolved using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system with a pentafluorophenyl (PFP) column and a methanol/aqueous formic acid mobile phase gradient, and was detected by MS/MS as product fragments after collisionally induced dissociation (CID) of the cationic parent molecule. This study represents the first application of PSE extraction combined with LC-MS/MS analysis for the determination of TBT in sediments. The method has been validated according to the International Organisation for Standardisation (ISO) 17025:2001 and affords automated extraction of sediment samples with high-sensitivity analysis. The full method limit of detection was established as 1.25 ng Sn g(-1) with an instrument detection limit of 0.01 ng Sn g(-1). The chromatographic procedure may also be applied for the direct analysis of water matrices without the need for sample manipulation, and therefore represents a combined analytical approach for the monitoring of TBT contamination in marine or estuarine ecosystems.

  7. Evaluation of the matrix-like effect in multiresidue pesticide analysis by gas chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Akutsu, Kazuhiko; Yoshimitsu, Masato; Kitagawa, Yoko; Takatori, Satoshi; Fukui, Naoki; Osakada, Masakazu; Yamaguchi, Satoko; Kajimura, Keiji; Obana, Hirotaka; Watanabe, Takaho

    2017-03-01

    In multiresidue pesticide analysis using gas chromatography, it has long been recognized that an increase in the number of pesticides present in a standard solution can result in an enhancement of the peak responses of certain pesticides. Despite being widely acknowledged, this phenomenon has been rarely studied and is poorly understood. In this study, the authors have tentatively called this phenomenon the "matrix-like effect" and demonstrated it clearly using gas chromatography with tandem mass spectrometry. Five selected pesticides, namely, omethoate, terbufos, malathion, procymidone, and permethrin, and four internal standard candidates, namely, triphenyl phosphate, naphthalene-d8 , phenanthrene-d10 , and fluoranthene-d10 , were used to evaluate the matrix-like effect following the addition of 58, 108, and 166 other pesticides. With the exception of naphthalene-d8 , the responses of all evaluated pesticides and internal standard candidates were dramatically enhanced by the addition of up to 166 coexisting pesticides. The relative response factors of the five pesticides to each internal standard candidate were not constant under the conditions studied, meaning that these internal standard candidates did not adequately compensate for the matrix-like effect, at least for the five evaluated pesticides. The results revealed that the presence of various mixtures of pesticides in standard solutions might act as an unintentional analyte protectant, that is, some sort of troublesome "quasi-matrix." © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Stereoselective pharmacokinetic study of rhynchophylline and isorhynchophylline epimers in rat plasma by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Wang, Xin; Zheng, Mei; Liu, Jia; Qiao, Zhou; Liu, Wenyuan; Feng, Feng

    2017-06-01

    1. In this study, the stereoselective pharmacokinetics of rhynchophylline (RIN) and isorhynchophylline (IRN) in rat plasma were investigated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). 2. A rapid, robust and sensitive LC-MS/MS method for simultaneous quantification of RIN and IRN in rat plasma was established and validated. Chromatographic separation was performed on a Poroshell 120 EC-C 18 column under a gradient elution with methanol and water containing 0.01% ammonia as mobile phase. Calibration curve was linear over a concentration range of 1-2000 ng/mL for both epimers. 3. After intravenous administration, there was no apparent difference in pharmacokinetic parameters between two epimers. However, after oral administration, RIN showed remarkable higher plasma exposure than IRN. The bioavailability, C max and AUC 0- t of RIN were about 9.2-fold, 6.4-fold and 9.1-fold higher than those of IRN at 10 mg/kg, and 7.8-fold, 4.3-fold and 7.7-fold at 20 mg/kg, respectively. Additionally, with dosage enhanced from 10 mg/kg to 20 mg/kg, the plasma concentrations of RIN or IRN increased significantly and the bioavailability enhanced about three times. 4. In conclusion, the results of this work demonstrated for the first time that the pharmacokinetics of RIN and IRN have stereoselectivity.

  9. [Rapid determination of 6 pesticide residues in tomato paste by ultra performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Su, Min; Li, Shiyu; Li, Fengge; Gong, Zhiguo; Wang, Jinhua

    2011-11-01

    An ultra performance liquid chromatography-tandem mass spectrometric method (UPLC-MS/MS) was established for the simultaneous determination of imidacloprid, carbendazim, thiophanate-methyl, propamocarb, methomyl and dimethomorph residues in tomato paste. The samples were extracted by methanol-water (1: 1, v/v) containing 0.1% (v/v) acetic acid. The separation was performed on a Waters Acquity UPLC system with a BEH C18 column with the gradient elution of methanol and water (containing 10 mmol/L ammonium acetate). The six pesticides were determined in the modes of electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM). The analytes were quantified by matrix-matched standard solution, and the calibration curves showed good linearity within the concentrations of 0.005 to 0.2 mg/L and the correlation coefficients (r) were more than 0.995. The average recoveries of the six pesticides ranged from 66.8% to 102.9% in the three spiked levels of 0.02, 0.05 and 0.2 mg/kg. The relative standard deviations (RSDs) were all less than 15%. The limits of quantification (LOQ, S/N > 10) were 0.02 mg/kg for the all analytes. The results indicate that the method is easier, faster, more sensitive, and suitable for the qualitative and quantitative confirmation of the six pesticide residues from tomato paste.

  10. Determination of carbendazim, thiophanate, thiophanate-methyl and benomyl residues in agricultural products by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Nakamura, Munetomo; Furumi, Yasuko; Watanabe, Fumiko; Mizukoshi, Kazushi; Taniguchi, Makoto; Nemoto, Satoru

    2011-01-01

    A simple and reliable liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed for carbendazim (MBC), thiophanate (TE), thiophanate-methyl (TM) and benomyl (BM) in agricultural products. These compounds were extracted from agricultural products with methanol after addition of sodium L-ascorbate. BM was hydrolyzed to MBC during the extraction with methanol. TE and TM were cyclized to ethyl 2-benzimidazole carbamate (EBC) and MBC by refluxing at 120 °C for 30 min with copper acetate in 50% acetic acid. MBC and EBC were cleaned up by an n-hexane wash and extraction with ethyl acetate and determined by LC-MS/MS. The mean recoveries from 10 agricultural products were in the range of 75.8-100.0%, and the relative standard deviations of 5 experiments were in the range of 1.5-9.2% at concentrations equal to the maximum residue limits (MRLs). The calibration curves were made by using commercial MBC and EBC as reference analytical standards without refluxing. The quantification limits were 0.01 mg/kg (as MBC), which is the uniform limit in the positive list system for agricultural chemical residues in foods in Japan.

  11. Biomimetic oxidation studies of monensin A catalyzed by metalloporphyrins: identification of hydroxyl derivative product by electrospray tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    José N. Sousa-Junior

    2013-08-01

    Full Text Available Monensin A is an important commercially available natural product isolated from Streptomyces cinnamonensins that shows antibiotic and anti-parasitic activities. This molecule has a significant influence in the antibiotic market, but until now there are no studies on putative metabolite formations. Bioorganic catalysts applying metalloporphyrins and mono-oxygen donors are able to mimic the cytochrome P450 reactions. This model has been employed for natural product metabolism studies affording several new putative metabolites and in vivo experiments confirming the relevance of this procedure. In this work we evaluated the potential of 10,15,20-tetrakis (pentafluorophenyl porphyrin metal(III chloride [Fe(TFPPCl] catalyst models to afford a putative monensin A metabolite. Oxidation agents such as meta-chloroperoxy benzoic acid, iodosylbenzene, hydrogen peroxide 30 wt.% and tert-butyl hydroperoxide 70 wt.%, were used to investigate different reaction conditions, in addition to the analysis of the influence of the solvent. The quantification of total monensin A conversion and the structure of the new hydroxylated putative metabolite were proposed based on electrospray ionization tandem mass spectrometry analysis. The porphyrin tested, afforded moderate conversions of monensin A in all reaction conditions and the selectivity was found to be dependent on the oxidation/medium employed.

  12. Determination of valnemulin in swine and bovine tissues by ultra-high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Li, Hui; Wang, Yingyu; Li, Xiaowei; Fu, Qin; Shan, Yawen; Liu, Tianhe; Xia, Xi

    2016-03-01

    A sensitive and reliable method has been developed and validated for the determination of valnemulin in swine and bovine muscle, liver, and kidney using solid-phase extraction (SPE) and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The tissue samples were extracted with mixture solution of acetonitrile and 0.01mol/L hydrochloric acid, defatted by n-hexane, and further cleaned up using SPE cartridges with polymeric sorbent. Gradient UHPLC separation was performed using an Acquity BEH C18 column with water and acetonitrile as the mobile phase. Multiple reaction monitoring mode of two precursor-product ion transitions for valnemulin was used. Mean recoveries from fortified samples ranged from 93.4 to 104.3% with 3.3-10.7% relative standard deviation. The limit of detection and quantification was 0.2 and 1μg/kg for the analyte, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Determination of itopride in human plasma by liquid chromatography coupled to tandem mass spectrometric detection: application to a bioequivalence study.

    Science.gov (United States)

    Lee, Heon-Woo; Seo, Ji-Hyung; Choi, Seung-Ki; Lee, Kyung-Tae

    2007-01-30

    A simple method using a one-step liquid-liquid extraction (LLE) with butyl acetate followed by high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometric (ESI-MS/MS) detection was developed for the determination of itopride in human plasma, using sulpiride as an internal standard (IS). Acquisition was performed in multiple reaction monitoring (MRM) mode, by monitoring the transitions: m/z 359.5>166.1 for itopride and m/z 342.3>111.6 for IS, respectively. Analytes were chromatographed on an YMC C18 reverse-phase chromatographic column by isocratic elution with 1 mM ammonium acetate buffer-methanol (20: 80, v/v; pH 4.0 adjusted with acetic acid). Results were linear (r2=0.9999) over the studied range (0.5-1000 ng mL(-1)) with a total analysis time per run of 2 min for LC-MS/MS. The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers.

  14. Quantification of ampicillin in bovine milk by coupled-column ultrahigh-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Moura, Franciane; de Almeida, Fernando G; Lopes, Bianca Rebelo; Cass, Quezia Bezerra

    2012-10-01

    This work reports the use of two-dimensional (2D) liquid chromatography system coupled with a tandem mass spectrometry for the quantification of ampicillin in bovine milk. A restrict access media column (RAM-BSA C(8) , 50 × 2.1 mm, Luna, 10 μm, 100 Å) was used in the first dimension in order to exclude macromolecules, while an ACQUITY UPLC BEH C(18) (50 × 2.1 mm, 1.7 μm) column was used in the second dimension. Three different channels of selected reaction monitoring (SRM) were used: 350 > 106 m/z, 350 > 160 m/z, and 350 > 192 m/z. The first transition was used for the quantification (higher intensity), and latter two for confirmation. The developed method is simple and requires a total analysis time of only 14 min/sample. The sample treatment involved only a centrifugation step for 20 min. The validated method has been successfully applied to monitor AMP residues in raw milk samples. To our knowledge, this is the first study to report the use of ultrahigh-performance liquid chromatography (UHPLC) in 2D configuration. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Degradation Behavior of Moroxydine Hydrochloride in Rice Plant and Field Water Using High Performance Liquid Chromatography-Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    ZHAO Lin

    2014-10-01

    Full Text Available Through field experiments, which were conducted in Zhaodong County of Heilongjiang Province, Zhulou County of Henan Province and Jurong County of Jiangsu Province, the degradation dynamics of moroxydine hydrochloride in rice plant and field water were investigated.The detection was performed by tandem mass spectrometry with electrospray ionization in positive mode(ESI+. The results showed that the average recoveries of rice plant and field water at three spiked levels (0.005, 0.05, 0.5 mg·kg -1were found in the range of 92.50%-109.20% with RSD 6.10%-6.90% and 86.40%-107.2% with RSD 0.73%-3.10%, respectively. Limits of detection(LODof plant and water were 0.005 mg·kg -1. The degradation kinetic equation showed that the half-life of moroxydine hydrochloride in rice plant and field water was 1.2-4.7 d,1.0-3.5 d, respectively. The moroxydine hydrochloride was proved to be an easily degradable pesticide.

  16. [Determination of avermectin, diclazuril, toltrazuril and metabolite residues in pork by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Gong, Xiaoming; Sun, Jun; Dong, Jing; Yu, Jinling; Wang, Hongtao

    2011-03-01

    A method for the determination of avermectin, ivermectin, doramectin, moxidectin, eprinomectin, diclazuril, toltrazuril and its two metabolite residues in pork was developed using QuEChERS method with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with acetonitrile and purified through QuEChERS method using ODS as the sorbent. The target compounds were separated on a Venusil ASB C18 column (150 mm x 2.1 mm, 3.0 microm) and detected by HPLC-MS/MS. The linear ranges were 0.005 - 0.2 mg/L and the correlation coefficients were all above 0.990. The average recoveries and the relative standard deviations ranged from 73.2% to 91.5% and from 12% to 17% at the spiked levels of 0.005, 0.01 and 0.02 mg/kg for the 9 analytes in pork matrix. This method is reliable, and suitable for the determination of the residues of avermectin and related compounds in pork.

  17. Determination of artificial sweeteners in water samples by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Ordóñez, Edgar Y; Quintana, José Benito; Rodil, Rosario; Cela, Rafael

    2012-09-21

    The development and performance evaluation of an analytical method for the determination of six artificial sweeteners in environmental waters using solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry are presented. To this end, different SPE alternatives have been evaluated: polymeric reversed-phase (Oasis HLB, Env+, Plexa and Strata X), and mixed-mode with either weak (Oasis WAX) or strong anionic-exchange (Oasis MAX and Plexa PAX) sorbents. Among them, reversed-phase sorbents, particularly Oasis HLB and Strata X, showed the best performance. Oasis HLB provided good trueness (recoveries: 73-112%), precision (RSD<10%) and limits of quantification (LOQ: 0.01-0.5 μg/L). Moreover, two LC separation mechanisms were evaluated: reversed-phase (RPLC) and hydrophilic interaction (HILIC), with RPLC providing better performance than HILIC. The final application of the method showed the presence of acesulfame, cyclamate, saccharin and sucralose in the wastewater and surface water samples analyzed at concentrations up to 54 μg/L. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Analysis of organochlorine pesticides in wine by solvent bar microextraction coupled with gas chromatography with tandem mass spectrometry detection.

    Science.gov (United States)

    Chia, Kan-Jung; Huang, Shang-Da

    2006-01-01

    A solvent bar microextraction (SBME) technique combined with gas chromatography/tandem mass spectrometry (GC/MS/MS), for the determination of selected organochlorine pesticides (OCPs) in wine samples, is described. In this work the OCPs were extracted and dissolved in a 2-microL aliquot of organic extraction solvent (n-tetradecane) confined within a 1.7-cm length of hollow fiber. Both ends of the hollow fiber (solvent bar) were sealed, and it was placed in an aqueous sample solution for extraction. The effects of solvent selection, sample agitation, extraction time, extraction temperature, and salt concentration on the SBME performance were optimized. The influence of aqueous sample/organic solvent phase ratio was further investigated in detail. High enrichments (1900-7100-fold) could be obtained at an aqueous sample/organic solvent volume ratio of 20 mL/2 microL in this study. Good extraction reproducibility was obtained with relative standard deviation (RSD) values below 12.6%. Comparisons of sensitivity and precision between SBME and dynamic hollow-fiber liquid-phase microextraction were also investigated.

  19. Simultaneous determination of plant growth regulator and pesticides in bean sprouts by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kim, Kwang-Gon; Park, Duck-Woong; Kang, Gyung-Ri; Kim, Tae-Sun; Yang, Yongshik; Moon, Su-Jin; Choi, Eun-Ah; Ha, Dong-Ryong; Kim, Eun-Sun; Cho, Bae-Sik

    2016-10-01

    A simple and sensitive analytical method based on QuEChERS approach using liquid chromatography tandem mass spectrometry was developed and validated for the determination of 6-benzylaminopurine, carbendazim and thiabendazole in bean sprouts. Sodium chloride and sodium acetate were used for salting-out step and magnesium sulfate for clean-up. The validation of optimized method was satisfactory with recoveries, between 89.5% and 103.2% for the three compounds, and relative standard deviation (RSD) values less than 3.3% at 20 and 40ng/g fortification levels (n=5). Limit of detection (LOD) and limit of quantification (LOQ) was 2.1-3.7ng/g and 6.3-11.1ng/g, respectively. Monitoring of 126 bean sprout samples collected from local markets was performed to verify the adaptability in real samples. No pesticides were detected but 6-benzylaminopurine was found in 3 samples at the level of 15-20ng/g. The optimized method should be applicable for monitoring of 6-benzylaminopurine, carbendazim and thiabendazole in bean sprouts in short time. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. [Determination of four plant growth regulator residues in amphisarcas by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Mou, Yanli; Guo, Dehua; Ding, Zhuoping

    2013-10-01

    A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of the plant growth regulator (PGR) (paclobutrazol, forchlorfenuron, isopentennyladenine and 6-benzylaminopurine) residues in amphisarcas. The sample was extracted with acetonitrile, then cleaned up by MCX solid phase extraction. The HPLC separation was performed on an Agilent XDB-C18 column with 5 mmol/L ammonium acetate solution and acetonitrile containing 0.1% (volume percentage) formic acid as the mobile phases in a gradient elution mode. The PGRs were determined by MS/MS in positive electrospray ionization mode, and quantified by matrix-matched external standard method. The calibration curves showed good linearity in each range with correlation coefficients greater than 0.999. The limits of quantification (LOQs, S/N > 10) were 0.04-1.35 g/kg and the limits of detection (LODs, S/N > 3) were 0. 01-0 41 microg/kg for the four PGRs spiked in cucumber and apple. The recoveries of the four PGRs spiked at three levels ranged from 81.0% to 93.%, with the relative standard deviations (RSDs) of 3.5%-9.5%. The sensitivity, accuracy and precision of the method meet the technical standards of the pesticide determination. Therefore the method can be applied to the determination of the four PGRs in amphisarcas.

  1. Determination of abamectin, doramectin, emamectin, eprinomectin, ivermectin, and moxidectin in milk by liquid chromatography electrospray tandem mass specrometry.

    Science.gov (United States)

    Sheridan, Robert; Desjardins, Lucille

    2006-01-01

    The avermectin and milbemycin families of compounds are derived from naturally occurring yeasts. They have proven to be potent preventatives against a variety of pests such as insects and parasites. Only eprinomectin and moxidectin are currently approved for use on lactating cattle with tolerances in milk of 12 microg/kg for eprinomectin and 40 microg/kg for moxidectin. Detection of misuse or inadvertent contamination in milk requires a sensitive and definitive analytical method. A method has been developed for the determination of 5 avermectins and 1 milbemycin in milk using a simple liquid-liquid extraction and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. Ivermectin (IVR), doramectin (DOR), abamectin (ABA), eprinomectin (EPR), emamectin (EMA), and moxidectin (MOX) were extracted from whole milk by partitioning into acetonitrile with a subsequent solvent exchange into methanol-water. Simultaneous confirmation and quantification were achieved with LC separation, positive electrospray ionization (ESI+), and MS/MS. The limits of detection ranged from 16 pg/g (ppt) for EMA to 1.7 microg/g (ppb) for MOX.

  2. Large-scale profiling of diterpenoid glycosides from Stevia rebaudiana using ultrahigh performance liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Shafii, Behnaz; Vismeh, Ramin; Beaudry, Randy; Warner, Ryan; Jones, A Daniel

    2012-07-01

    The plant Stevia rebaudiana accumulates a suite of diterpenoid metabolites that are natural sweeteners finding increased use as sugar substitutes. To guide breeding of stevia plants that accumulate substances with desirable flavor in high yield, rapid and accurate methods are needed to profile these substances in plant populations. This report describes an 8-min ultrahigh performance liquid chromatography-tandem mass spectrometry method for separation and quantification of seven stevia glycosides including steviolbioside; stevioside; rebaudiosides A, B, and C; rubusoside; and dulcoside as well as aglycones steviol and isosteviol. This negative mode electrospray ionization/multiple reaction monitoring method yielded low limits of detection stevia glycosides. Stevioside and Reb A, B, and C were quantified in more than 1,100 extracts from stevia leaves as part of a large-scale profiling exercise. Leaf tissue levels in this population spanned about two orders of magnitude for stevioside (2-125 mg/g dry weight), Reb A (2.5-164 mg/g), Reb B (0.5-50 mg/g), and Reb C (1.5-125 mg/g), but levels of individual metabolites exhibited independent variation. The wide spread of metabolite levels highlights the utility and importance of performing targeted metabolic profiling for large plant populations.

  3. A rapid liquid chromatography tandem mass spectrometry-based method for measuring propranolol on dried blood spots.

    Science.gov (United States)

    Della Bona, Maria Luisa; Malvagia, Sabrina; Villanelli, Fabio; Giocaliere, Elisa; Ombrone, Daniela; Funghini, Silvia; Filippi, Luca; Cavallaro, Giacomo; Bagnoli, Paola; Guerrini, Renzo; la Marca, Giancarlo

    2013-05-05

    Propranolol, a non-selective beta blocker drug, is used in young infants and newborns for treating several heart diseases; its pharmacokinetics has been extensively evaluated in adult patients using extrapolation to treat pediatric population. The purpose of the present study was to develop and validate a method to measure propranolol levels in dried blood spots. The analysis was performed by using liquid chromatography/tandem mass spectrometry operating in multiple reaction monitoring mode. The calibration curve in matrix was linear in the concentration range of 2.5-200 μg/L with correlation coefficient r=0.9996. Intra-day and inter-day precisions and biases were less than 8.0% (n=10) and 11.5% (n=10) respectively. The recoveries ranged from 94 to 100% and the matrix effect did not result in a severe signal suppression. Propranolol on dried blood spot showed a good stability at three different temperatures for one month. This paper describes a micromethod for measuring propranolol levels on dried blood spot, which determines a great advantage in neonates or young infants during pharmacokinetic studies because of less invasive sampling and small blood volume required. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. A novel method to detect seven microcystins in hard clam and corbicula fluminea by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Yang, Bo; Xu, Jin-Zhong; Ding, Tao; Wu, Bin; Jing, Su; Ding, Shu-jing; Chen, Hui-Lan; Sheng, Chong-Yu; Jiang, Yuan

    2009-11-01

    A simple and reliable method to detect seven microcystins in hard clam and corbicula fluminea, based on liquid chromatography with electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS), was developed and validated. The sample preparation procedure includes extraction of tissue by methanol, followed by cleanup on a reversed-phase solid phase extraction (SPE) cartridge. With the optimized method, recoveries were between 43.7% and 92.3% for hard clam, 54.3% and 93.8% for corbicula fluminea, the relative standard deviations (RSD) were less than or equal to 16.2% and 15.7% in hard clam and corbicula fluminea at spiking levels of 1 microg/kg, 2 microg/kg and 5 microg/kg for MC-RR, MC-YR, MC-LR, and MC-LY, and 2 microg/kg, 5 microg/kg and 10 microg/kg for MC-LA, MC-LW and MC-LF, respectively, the limits of quantitation (LOQ) of this method were ranged from 0.7 microg/kg to 2.0 microg/kg.

  5. Analysis of phospholipids in bio-oils and fats by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Viidanoja, Jyrki

    2015-09-15

    A new, sensitive and selective liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method was developed for the analysis of Phospholipids (PLs) in bio-oils and fats. This analysis employs hydrophilic interaction liquid chromatography-scheduled multiple reaction monitoring (HILIC-sMRM) with a ZIC-cHILIC column. Eight PL class selective internal standards (homologs) were used for the semi-quantification of 14 PL classes for the first time. More than 400 scheduled MRMs were used for the measurement of PLs with a run time of 34min. The method's performance was evaluated for vegetable oil, animal fat and algae oil. The averaged within-run precision and between-run precision were ≤10% for all of the PL classes that had a direct homologue as an internal standard. The method accuracy was generally within 80-120% for the tested PL analytes in all three sample matrices. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Determination of pesticides in soy-based infant formula using liquid chromatography with electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Wang, Jian; Cheung, Wendy

    2006-01-01

    A sensitive method using liquid chromatography with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was developed and validated to quantify and confirm 13 pesticides, including aldicarb sulfoxide, aldicarb sulfone, oxamyl, methomyl, formetanate, 3-hydroxycarbofuran, carbendazim, thiabendazole, aldicarb, propoxur, carbofuran, carbaryl, and methiocarb, in soy-based infant formula. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring of 2 fragment ion transitions to provide a high degree of sensitivity and selectivity for both quantitation and confirmation. Different approaches to constructing calibration curves were compared and discussed to address issues of the extraction efficiency or recovery, and matrix effects. Matrix-matched standard calibration curves with the use of isoprocarb as an internal standard were finally used to achieve the best accuracy of the method. Under most circumstances, recoveries of 13 pesticides, spiked at 5.0, 25.0, and 45.0 microg/kg, were close to 100%. The method detection limits (signal-to-noise ratio > or =3:1; microg/kg) of 13 pesticides were 0.2 for thiabendazole and methiocarb, 0.6 for aldicarb, and 0.1 for the others.

  7. Ultra-performance liquid chromatography-tandem mass spectrometry method for the analysis of amphetamines in plasma.

    Science.gov (United States)

    Fernández, María del Mar Ramírez; Samyn, Nele

    2011-10-01

    A fast and selective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) method for the determination of amphetamines (amphetamine, methamphetamine, methylenedioxymethamphetamine, methylenedioxyamphetamine, methylenedioxyethylamphetamine, ephedrine, and p-methoxyamphetamine) in plasma has been developed and validated. Sample preparation was performed by liquid-liquid extraction using ethyl acetate. For optimized chromatographic performance with repeatable retention times, narrow and symmetrical peaks, and focusing all analytes at the column inlet, a gradient start, with acid mobile phase consisting of 0.1% formic acid and methanol was chosen. Positive electrospray ionization MS-MS detection was performed with two multiple reaction monitoring transitions for each analyte. Deuteriumlabeled internal standards were used for five of the analytes. The limit of detection was in the range 0.25-1.25 ng/mL, and the limit of quantification was fixed at the lowest calibrator of 2.5 ng/mL for all of the compounds. The RSD values of the intra- and interassay precision and accuracy were lower than 11% at four concentration levels, including two external quality controls. No or only minor matrix effects were observed, and the extraction method presented recoveries higher than 93% for all the compounds. Total run time, including equilibration, was 12 min. The method is routinely used at the National Institute of Criminalistics and Criminology for quantitative determination of the main amphetamines in plasma from forensic and driving under the influence cases.

  8. Degradation and interconversion of plant pteridines during sample preparation and ultra-high performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Van Daele, Jeroen; Blancquaert, Dieter; Kiekens, Filip; Van Der Straeten, Dominique; Lambert, Willy E; Stove, Christophe P

    2016-03-01

    The degradation and interconversion of a selected set of pterins (dihydroneopterin, hydroxymethyldihydropterin, dihydroxanthopterin, neopterin, hydroxymethylpterin, xanthopterin, 6-formylpterin, 6-carboxypterin and pterin), spiked to charcoal-treated potato and Arabidopsis thaliana matrix was investigated, together with their relative recovery in potato and A. thaliana. As a result, a matrix-specific procedure for the ultra-high performance liquid chromatography-tandem mass spectrometry based determination of 6 aromatic pterins (neopterin, hydroxymethylpterin, xanthopterin, 6-formylpterin, 6-carboxypterin and pterin) is proposed: 1.5ml of an N2-flushed, alkaline (pH=10) extraction solvent is added to 200mg of plant sample. After boiling and homogenization, the samples are incubated: Arabidopsis samples for 30min at room temperature, while shaking, and potato samples for 2h at 37°C (applying a dienzyme treatment with α-amylase and protease). After a final boiling step, the samples are ultrafiltrated and resulting extracts are analyzed by UHPLC-MS/MS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Comprehensive characterization and identification of antioxidants in Folium Artemisiae Argyi using high-resolution tandem mass spectrometry.

    Science.gov (United States)

    Han, Binsong; Xin, Zhongquan; Ma, Shasha; Liu, Wenbin; Zhang, Bingyang; Ran, Lu; Yi, Lunzhao; Ren, Dabing

    2017-09-15

    Antioxidants from natural sources, such as vegetables and fruits, are attracting more and more interest. In this work, we evaluated the antioxidant potential of Folium Artemisia Argyi, a traditional Chinese herb medicine and food supplement. The total phenolic content, total flavonoid content, and antioxidant ability of the crude extracts and fractions obtained from consecutively partition of n-hexane, ethyl acetate, and n-butanol were measured and compared. Ethyl acetate fraction shows the highest total phenolic and flavonoid contents and highest antioxidant capability with regard to DPPH, ABTS, superoxide anion free radical scavenging ability, and ferric-reducing antioxidant power. In addition, the potential antioxidant components were screened by DPPH-UHPLC-MS experiments and subsequently characterized by using high-resolution tandem mass spectrometry. This work finally identified 45 antioxidants, including organic acids, phenolic compounds, flavonoids, and methoxylated flavonoids. The results suggested that Folium Artemisiae Argyi is a potential inexpensive resource of natural antioxidants. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. [Determination of 7 microcystins in Spirulina health food products by ultra performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Li, Bing; Liu, Wei; Fan, Sai; Zhao, Rong; Wu, Guohua

    2012-06-01

    Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) combined with solid phase extraction (SPE) has been developed for the determination of 7 microcystins (MCs) in Spirulina health food products. The sample was extracted by 70% (v/v) methanol. The lipid substances were isolated by centrifugation under freezing condition, and then followed by clean-up with a Waters Oasis HLB solid phase extraction cartridge. The separation was performed on a Waters ACQUITY UPLC BEH C18 column with gradient elution using acetonitrile and 0.2 mmol/L ammonium acetate. The electrospray ionization (ESI) source in positive ion mode was used for multiple reaction monitoring (MRM). The external standard method was used for the quantification. The linear ranges for 7 MCs were 20 - 400 microg/kg, and the correlation coefficients were not less than 0.995. The limits of detection were 6.7 - 33.3 microg/kg. The limits of quantification were 20.0 - 100.0 microg/kg. The recoveries of the 7 MCs spiked in blank Spirulina samples ranged from 87.5% to 97.9% with the relative standard deviations of 1.6% - 6.9%. The results demonstrated that the method is easy, fast, sensitive, and suitable for the confirmation and quantification of the 7 MCs in Spirulina samples.

  11. Simultaneous determination of buprenorphine, norbuprenorphine and naloxone in human plasma by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Liu, Yongzhen; Li, Xiaohua; Xu, Allan; Nasser, Azmi F; Heidbreder, Christian

    2016-02-20

    A simple, sensitive and rapid liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for simultaneous quantification of naloxone, buprenorphine and its metabolite norbuprenorphine in human plasma. Human plasma samples were extracted using a single step liquid-liquid extraction, and then separated on an Imtakt Unison UK-C18 column (2.1×50mm, 3μm) using alkaline mobile phases with gradient elution. All of the analytes were detected in positive ion mode using multiple reaction monitoring (MRM). The method was validated and the specificity, linearity, lower limit of quantitation, precision, accuracy, recoveries and stability were determined. The linear range was 20-10000pg/mL for buprenorphine and norbuprenorphine; and 1-500pg/mL for naloxone. The correlation coefficient (R(2)) values for all three analytes were ≥0.995. The precision and accuracy for intra-day and inter-day were 63% and matrix effects were tracked by the deuterated internal standards (IS) with the IS-normalized matrix factor ranging from 0.96 to 1.33 for all three analytes. The validated method was successfully applied in a clinical pharmacokinetic study with low dose administration of sublingual buprenorphine and naloxone. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Monolith immuno-affinity enrichment liquid chromatography tandem mass spectrometry for quantitative protein analysis of recombinant bovine somatotropin in serum.

    Science.gov (United States)

    Smits, Nathalie G E; Blokland, Marco H; Wubs, Klaas L; Nessen, Merel A; van Ginkel, Leen A; Nielen, Michel W F

    2015-08-01

    The use of recombinant bovine somatotropin (rbST) to enhance milk production is approved in several countries, but it is prohibited in the European Union. According to EU legislation, it is necessary to confirm positive screening results prior to enforcement. Although adequate screening assays are available nowadays, development of liquid chromatography tandem mass spectrometry (LC-MS/MS) confirmatory methods to detect low levels of rbST is still a challenge. Here, we present a novel approach using immuno-affinity enrichment on monolithic micro-columns in combination with state-of-the-art ultra-high pressure LC-MS/MS (UHPLC-MS/MS) detection. The developed approach enables detection and confirmation of rbST in serum at a decision limit (CCα) concentration of 0.8 ng mL(-1). Furthermore, the method is easy to handle, robust and reproducible. We successfully applied the confirmatory method to serum samples from rbST treated cows that were found suspect after immunoassay-based screening. The use of rbST could be confirmed over 1 week after treatment, and the developed method demonstrated the sensitivity needed for effective control. Graphical Abstract Graphical summary of the workflow, for serum preparation, enrichment with monolith microcolumns and LC-MS/MS measurement of rbST.

  13. Extraction and analysis of colourful eggshell pigments using HPLC and HPLC/electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Gorchein, A; Lim, C K; Cassey, P

    2009-06-01

    The literature on the pigments of avian eggshells is critically reviewed. Methods using methanolic sulfuric acid or hydrochloric acid to extract eggshell pigments are unsuitable to detect the occurrence of zinc protoporphyrin or zinc biliverdin because they demetallate these compounds. Extraction methods are described here using EDTA and acetonitrile-acetic acid or acetonitrile-dimethyl sulfoxide, which do not demetallate zinc protoporphyrin. Such extracts were prepared from eggshell of the common nighthawk, Chordeiles minor, and from another six bird species. Protoporphyrin and biliverdin were identified and fully characterized by HPLC/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) in all samples, but none contained zinc protoporphyrin. The zinc complex of biliverdin, claimed to be an additional pigment responsible for eggshell background colours, was labile to EDTA and acid pH and if occurring naturally could not be extracted intact by the published or the modified protocols. An explanation is advanced for the exceptional report that all porphyrins from uroporphyrin to protoporphyrin were found in eggshells of the fowl Gallus domesticus.

  14. Rapid Determination of L-carnitine in Infant and Toddler Formulas by Liquid Chromatography Tandem Mass Spectrometry.

    Science.gov (United States)

    Ahn, Jang-Hyuk; Kwak, Byung-Man; Park, Jung-Min; Kim, Na-Kyeoung; Kim, Jin-Man

    2014-01-01

    A rapid and simple analytical method for L-carnitine was developed for infant and toddler formulas by liquid chromatography tandem mass spectrometry (LC-MS/MS). A 0.3 g of infant formula and toddler formula sample was mixed in a 50 mL conical tube with 9 mL water and 1 mL 0.1 M hydrochloric acid (HCl) to chemical extraction. Then, chloroform was used for removing a lipid fraction. After centrifuged, L-carnitine was separated and quantified using LC-MS/MS with electrospray ionization (ESI) mode. The precursor ion for L-carnitine was m/z 162, and product ions were m/z 103 (quantitative) and m/z 85 (qualitative), respectively. The results for spiked recovery test were in the range of 93.18-95.64% and the result for certified reference material (SRM 1849a) was within the range of the certificated values. This method could be implemented in many laboratories that require time and labor saving.

  15. Differential mobility spectrometry followed by tandem mass spectrometry with multiple ion monitoring for bioanalysis of eptifibatide in rat plasma.

    Science.gov (United States)

    Ren, Tianming; Li, Runzhi; Meng, Xiangjun; Fawcett, J Paul; Sun, Dong; Gu, Jingkai

    2018-01-11

    Eptifibatide is a therapeutic cyclic peptide with poor collision-induced dissociation (CID) efficiency for multiple reaction monitoring (MRM), which limits the development of a traditional liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioassay with MRM. In this study, a method combining differential mobility spectrometry (DMS) with liquid chromatography-multiple ion monitoring (LC-DMS-MIM) was developed for the quantitation of eptifibatide in rat plasma. After solid phase extraction (SPE) of 100 μL plasma on an Oasis® HLB cartridge, the analyte and I.S. (octreotide) were analyzed using a SCIEX QTRAP 6500 operated in the positive ion mode and preceded by a DMS device. The lower limit of quantitation (LLOQ) for eptifibatide was 0.5 ng/mL using only 100 μL plasma. The method was linear in the concentration range 0.5-300 ng/mL with good precision and accuracy. Compared to regulated quantitative LC-MS/MS bioanalysis of eptifibatide, the LC-DMS-MIM method effectively overcomes the sensitivity challenge in the LC-MRM method and reduces the high background noise and matrix interference in LC-MIM method without DMS. The method was successfully applied to a pharmacokinetic study involving intravenous injection of eptifibatide to Wistar rats. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Screening for inherited metabolic diseases using gas chromatography-tandem mass spectrometry (GC-MS/MS) in Sichuan, China.

    Science.gov (United States)

    Wang, Hong; Wang, Xia; Li, Yingying; Dai, Wei; Jiang, Dongmei; Zhang, Xiaodong; Cui, Yali

    2017-04-01

    The aim of this study was to retrospectively diagnose and confirm inherited metabolic diseases (IMD), from a small population of IMD high-risk patients, with the aid of gas chromatography-tandem mass spectrometry (GC-MS/MS), technologies yet to be popularized in Sichuan, China. Using GC-MS/MS coupled with clinical diagnosis, we retrospectively analyzed samples of dried blood spots and urine specimen from 183 IMD high-risk infant patients, who visited the West China Second Hospital of Sichuan University between June 2013 and October 2015. Four out of 183 IMD high-risk infant patients were finally diagnosed to be IMD positive, among which two patients were identified with phenylketonuria, one with maple syrup urine disease, and 1 with methylmalonic academia. Restrictive diets and other symptomatic treatments were employed to treat the confirmed infant patients whose conditions are still under tracking and there are zero cases of death so far. GC-MS/MS was found to be an efficient and reliable way to detect IMD. It is necessary to apply GC-MS/MS, in addition to other clinical approaches, for diagnosing candidate IMD patients so that the confirmed patients can get medical intervention and timely treatment. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Determination of 20 synthetic dyes in chili powders and syrup-preserved fruits by liquid chromatography/tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Chia-Fen Tsai

    2015-09-01

    Full Text Available A liquid chromatography/tandem mass spectrometry (LC-MS/MS method is developed to simultaneously determine 20 synthetic dyes (New Coccine, Indigo Carmine, Erythrosine, Tartrazine, Sunset Yellow FCF, Fast Green FCF, Brilliant Blue FCF, Allura Red AC, Amaranth, Dimethyl Yellow, Fast Garnet GBC, Para Red, Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Orange G, Sudan Red 7B, Sudan Red B, and Sudan Red G in food samples. This method offers high sensitivity and selectivity through the selection of two fragment ion transitions under multiple reaction monitoring mode to satisfy the requirements of both quantitation and qualitation. Using LC-MS/MS, the newly developed extraction protocol used in this study is rapid and simple and does not require the use of solid-phase extraction cartridges. The linearities and recoveries of the method are observed at the concentration range of 0.10–200 μg/kg and more than 90% for all dyes, respectively. The method has been successfully applied to screen 18 commercial chili powders and six commercial syrup-preserved fruits purchased from retail establishments in Taipei City. The results show that three legal food dyes, Tartrazine, and/or Sunset Yellow FCF, and/or New Coccine, are present in some syrup-preserved fruits. Amaranth, an illegal food dye in certain countries but declared illegal in Taiwan, is found in an imported syrup-preserved fruit.

  18. Steroid and steroid glucuronide profiles in urine during pregnancy determined by liquid chromatography-electrospray ionization-tandem mass spectrometry.

    Science.gov (United States)

    Jäntti, Sirkku E; Hartonen, Minna; Hilvo, Mika; Nygren, Heli; Hyötyläinen, Tuulia; Ketola, Raimo A; Kostiainen, Risto

    2013-11-13

    An ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-MS/MS) method was developed for the analysis of steroids and their glucuronides in urine samples. The method provides high sensitivity and fast analysis, as both steroids and their glucuronides can be analyzed directly without hydrolysis or complex sample preparation. The method was applied in profiling of targeted and nontargeted steroids and steroid glucuronides during pregnancy. The concentrations of 11 of 27 targeted steroids and steroid glucuronides and the concentrations of 25 nontargeted steroid glucuronides increased about 10-400 fold during the pregnancy. The concentrations of most of these 36 compounds began to increase in the first days of the pregnancy, increased gradually during the pregnancy, achieved a maximum in late pregnancy, and decreased sharply after delivery. Exceptionally, the concentrations of allopregnanolone and 17-hydroxypregnenolone started to increase later than those of the other steroids. Moreover, the concentrations of E2 glucuronides began to decrease one week before the delivery, in contrast to most of the steroids and steroid glucuronides, whose concentrations dropped sharply during the delivery. Concentrations of 34 compounds decreased noticeably when the subject was on sick leave owing a series of painful contractions. The results suggest that steroids and especially steroid glucuronides may provide a valuable diagnostic tool to follow the course of pregnancy. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. [Determination of 11 ultraviolet absorbents in sun-screening cosmetics by liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Lin, Weixuan; Sun, Xingquan; Ma, Jie

    2013-05-01

    A method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been established for the simultaneous determination of eleven ultraviolet absorbents in sunscreening cosmetics. The cosmetic sample was extracted by methanol-ethanol-water (80: 10: 10, v/v/v). The extract was separated by reversed-phase high performance liquid chromatography on an Eclipse XDB-C18 chromatographic column (150 mm x 4.6 mm, 5 microm) with a gradient elution of acetonitrile and water containing 0.1% formic acid. The analyte was detected by MS/ MS with the multiple reaction monitoring (MRM) mode. The qualitative analysis was based on the retention time and the relative abundance ratio of the characteristic ions, and quantitative analysis on calibration curve method. The research results showed that the limits of quantification (LOQ, S/N = 10) of the eleven ultraviolet absorbents ranged from 200 to 500 mg/kg and the average recoveries ranged from 77. 17% to 98.32% with the relative standard deviations from 2.40% to 11.11%. The method is suitable to detect the eleven ultraviolet absorbents in cream and milky sun-screening cosmetics.

  20. Optimization of Analytical Conditions for a Rapid Determination of Aniline in Environmental Water by Liquid Chromatography/Tandem Mass Spectrometry.

    Science.gov (United States)

    Furukawa, Koji; Hashimoto, Makoto; Kaneco, Satoshi

    2017-01-01

    A rapid determination of aniline in environmental water was examined based on liquid chromatography/tandem mass spectrometry (LC/MS/MS). Environmental water samples were diluted 20-fold with Mill-Q water and measured by LC/MS/MS after adding a surrogate substance (aniline-d5). In the results of the present study, the calibration curve of aniline showed good linearity in the range of 0.05 - 2.0 μg/L. Since the RSD (repeatability) by measuring repeatedly an aniline standard solution (0.05 μg/L, n = 7) was 3.2%, the repeatability of this work was very excellent. In addition, the recovery rate of aniline in environmental water was in the range of 99.0 - 102% with RSD 3.4 - 7.7%, and very good recovery test results were obtained. From these results, this analytical method was confirmed to be effective for aniline measurements of environmental water samples. Also, it is possible to conduct rapid analyses of aniline in environmental water without any solid-phase extraction process, compared to the solid-phase extraction-GC/MS method.

  1. Simultaneous determination of rosuvastatin and amlodipine in human plasma using tandem mass spectrometry: Application to disposition kinetics

    Directory of Open Access Journals (Sweden)

    Anjaneyulu Narapusetti

    2015-11-01

    Full Text Available The liquid chromatography–tandem mass spectrometric assay method for the simultaneous determination of rosuvastatin and amlodipine in human plasma using deuterated analogs as internal standards has been developed and validated. The analytes were extracted from 100 μL aliquots of human plasma via liquid–liquid extraction using a mixture of ethyl acetate and n-hexane (80:20, v/v as an extraction solvent. The optimized mobile phase was composed of 0.1% formic acid in 5 mM ammonium acetate, methanol, and acetonitrile (20:20:60, v/v/v and delivered at a flow rate of 0.75 mL/min. The calibration curve obtained was linear (R2 ⩾ 0.999 over the concentration range of 0.52–51.77 ng/mL for rosuvastatin and 0.10–10.07 ng/mL for amlodipine. A sample turnover rate of less than 2.5 min makes it an attractive procedure in high-throughput bioanalysis of rosuvastatin and amlodipine. The present method was found to be applicable to clinical studies and the results were authenticated by incurred sample reanalysis.

  2. A Liquid Chromatography - Tandem Mass Spectrometry Approach for the Identification of Mebendazole Residue in Pork, Chicken, and Horse.

    Directory of Open Access Journals (Sweden)

    Ji Sun Lee

    Full Text Available A confirmatory and quantitative method of liquid chromatography-tandem mass spectrometry (LC-MS/MS for the determination of mebendazole and its hydrolyzed and reduced metabolites in pork, chicken, and horse muscles was developed and validated in this study. Anthelmintic compounds were extracted with ethyl acetate after sample mixture was made alkaline followed by liquid chromatographic separation using a reversed phase C18 column. Gradient elution was performed with a mobile phase consisting of water containing 10 mM ammonium formate and methanol. This confirmatory method was validated according to EU requirements. Evaluated validation parameters included specificity, accuracy, precision (repeatability and within-laboratory reproducibility, analytical limits (decision limit and detection limit, and applicability. Most parameters were proved to be conforming to the EU requirements. The decision limit (CCα and detection capability (CCβ for all analytes ranged from 15.84 to 17.96 μgkg-1. The limit of detection (LOD and the limit of quantification (LOQ for all analytes were 0.07 μgkg-1 and 0.2 μgkg-1, respectively. The developed method was successfully applied to monitoring samples collected from the markets in major cities and proven great potential to be used as a regulatory tool to determine mebendazole residues in animal based foods.

  3. High-throughput quantitative analysis of domoic acid directly from mussel tissue using Laser Ablation Electrospray Ionization - tandem mass spectrometry.

    Science.gov (United States)

    Beach, Daniel G; Walsh, Callee M; McCarron, Pearse

    2014-12-15

    Eliminating sample extraction or liquid chromatography steps from methods for analysis of the neurotoxin Domoic Acid (DA) in shellfish could greatly increase throughput in food safety testing laboratories worldwide. To this end, we have investigated the use of Laser Ablation Electrospray Ionization (LAESI) with tandem mass spectrometry (MS/MS) detection for DA analysis directly from mussel tissue homogenates without sample extraction, cleanup or separation. DA could be selectively detected directly from mussel tissue homogenates using MS/MS in selected reaction monitoring scan mode. The quantitative capabilities of LAESI-MS/MS for DA analysis from mussel tissue were evaluated by analysis of four mussel tissue reference materials using matrix-matched calibration. Linear response was observed from 1 mg/kg to 40 mg/kg and the method limit of detection was 1 mg/kg. Results for DA analysis in tissue within the linear range were in good agreement with two established methods, LC-UV and LC-MS/MS (recoveries from 103 to 125%). Beyond the linear range, extraction and clean-up were required to achieve good quantitation. Most notable is the extremely rapid analysis time of about 10 s per sample by LAESI-MS/MS, which corresponds to a significant increase in sample throughput compared with existing methodology for routine DA analysis. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  4. Simultaneous determination of tryptophan and 8 metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Boulet, Lysiane; Faure, Patrice; Flore, Patrice; Montérémal, Julien; Ducros, Véronique

    2017-06-01

    Tryptophan (Trp) is an essential amino-acid and the precursor of many biologically active substances such as kynurenine (KYN) and serotonin (5HT). Its metabolism is involved in different physiopathological states, such as cardiovascular diseases, cancer, immunomodulation or depression. Hence, the quantification of Trp catabolites, from both KYN and 5HT pathways, might be usefulfor the discovery of novel diagnostic and follow-up biomarkers. We have developed a simple method for quantification of Trp and 8 of its metabolites,involved in both KYN and 5HT pathways, using liquid chromatography coupled to tandem mass spectrometry. We also validated the methodin human plasma samples, according to NF EN ISO 15189 criteria. Our method shows acceptable intra- and inter-day coefficients of variation (CV) (<12% and <16% respectively). The linearity entirelycovers the human plasma range. Stabilities of whole blood and of residues weredetermined, as well as the use of 2 different types of collectiontube, enabling us to adapt our process. Matrix effects and reference values showed good agreement compared to the literature. We propose here a method allowing the simultaneous quantification of a panel of Trp catabolites, never used before to our knowledge. This method, witha quickchromatographic runtime (15min) and simple sample preparation, has beenvalidated according to NF EN ISO 15189 criteria. The method enables the detailed analysis of these metabolic pathways, which are thought to be involved in a number of pathological conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Negative Ion Mode Electrospray Tandem Mass Spectrometry of Hydroxy-Terminated Polydimethylsiloxanes Formed upon in situ Methanolysis.

    Science.gov (United States)

    Fouquet, Thierry; Charles, Laurence; Sato, Hiroaki

    2017-01-01

    Ethoxy-, methoxy- and hydroxy-terminated polydimethylsiloxanes (PDMS) are formed as the result of the methanolysis of diethoxy-ended PDMS during its infusion in electrospray ionization. The negative ion mode permits only hydroxy-ended products to be detected, and isomeric interference is avoided in single stage and tandem mass spectrometry. The routes for the fragmentation of (ethyl, hydroxy)-, (methyl, hydroxy)- and (hydro, hydroxy)-ended PDMS upon collision activated dissociation (CAD) were explored in the negative ion mode using either formate or acetate anion adduction. Symmetrical (hydro, hydroxy)-ended PDMS decomposed to product ions carrying one of the hydroxy terminations through the abstraction of an acidic hydrogen and depolymerization (expulsion of cyclic neutral species) regardless of the adducted anion. Asymmetric (ethyl, hydroxy)-ended (resp. (methyl, hydroxy)-ended) PDMS yielded both ethoxy-ended (resp. methoxy-ended) fragment ions through the abstraction of the only acidic hydrogens and linear product ions carrying both terminations still interacted with the anion. The production of information-rich ethoxy-ended (resp. methoxy-ended) fragment ions was limited by formate but favored when acetate (higher proton affinity) was used in a CAD fingerprint complementary to the positive ion mode.

  6. Surveillance study of novobiocin and phenylbutazone residues in raw bovine milk using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Thompson, T S; Noot, D K; Kendall, J D

    2010-08-01

    A simple method permitting the simultaneous determination of trace residues of novobiocin and phenylbutazone in raw milk samples using liquid chromatography-tandem mass spectrometry was developed. Raw milk samples were mixed with acetonitrile to facilitate the concurrent precipitation of milk proteins and extraction of both veterinary drugs. Without additional clean-up or concentration of the resulting extract, the analytes could be quantified at concentrations as low as 0.0025 and 0.001 microg ml(-1) for phenylbutazone and novobiocin, respectively. The analysis of a series of fortified raw milk samples at analyte concentrations ranging from 0.005 to 0.1 microg ml(-1) and from 0.01 to 0.2 microg ml(-1) for phenylbutazone and novobiocin, respectively, yielded average recoveries ranging from 89.2% to 104.3% with standard deviations below 7%. The analytical method was applied to the analysis of raw milk samples collected from transport trucks upon delivery at dairy-processing plants throughout Alberta, Canada. Novobiocin was detected in 13 of 1072 samples tested at concentrations ranging from 0.001 to 0.007 microg ml(-1). Phenylbutazone was not detected in any of the samples tested.

  7. Determination of ibuprofen, ketoprofen, diclofenac and phenylbutazone in bovine milk by gas chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Dowling, G; Gallo, P; Fabbrocino, S; Serpe, L; Regan, L

    2008-12-01

    A method has been developed to analyse for ibuprofen (IBP), ketoprofen (KPF), diclofenac (DCF) and phenylbutazone (PBZ) residues in bovine milk. Milk samples were extracted with acetonitrile and sample extracts were purified on Isolute C(18) solid-phase extraction cartridges. Aliquots were analysed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The method was validated in bovine milk, according to the criteria defined in Commission Decision 2002/657/EC. The decision limits (CCalpha were 0.59, 2.69, 0.90 and 0.70 ng ml(-1), respectively, for IBP, KPF, DCF and PBZ, and detection capabilities (CCbeta) of 1.01, 4.58, 1.54 and 1.19 ng ml(-1), respectively, were obtained. The measurement uncertainty of the method was 17.8%, 80.9%, 28.2% and 20.2% for IBP, KPF, DCF and PBZ, respectively. Fortifying bovine milk samples (n = 18) in three separate assays show the accuracy of the method to be between 104% and 112%. The precision of the method, expressed as relative standard deviations for the within-laboratory reproducibility at the three levels of fortification (5, 7.5 and 10 ng ml(-1)) was less than 8% for IBP, DCF and PBZ, respectively. Poor precision was obtained for KPF with a relative standard deviation of 28%.

  8. Determination of hepatotoxic indospicine in Australian camel meat by ultra-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Tan, Eddie T T; Fletcher, Mary T; Yong, Ken W L; D'Arcy, Bruce R; Al Jassim, Rafat

    2014-02-26

    Indospicine is a hepatotoxic amino acid found in Indigofera plant spp. and is unusual in that it is not incorporated into protein but accumulates as the free amino acid in the tissues (including muscle) of animals consuming these plants. Dogs are particularly sensitive to indospicine, and secondary poisoning of dogs has occurred from the ingestion of indospicine-contaminated horse meat and more recently camel meat. In central Australia, feral camels are known to consume native Indigofera species, but the prevalence of indospicine residues in their tissues has not previously been investigated. In this study, a method was developed and validated with the use of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine the level of indospicine in camel meat samples using isotopically labeled indospicine as an internal standard. UPLC-MS/MS analysis showed that the method is reproducible, with high recovery efficiency and a quantitation limit of 0.1 mg/kg. Camel meat samples from the Simpson Desert were largely contaminated (≈50%) by indospicine with levels up to 3.73 mg/kg (fresh weight) determined. However, the majority of samples (95%) contained less than 1 mg/kg indospicine.

  9. Reference values of amino acids, acylcarnitines and succinylacetone by tandem mass spectrometry for use in newborn screening in southwest Colombia.

    Science.gov (United States)

    Céspedes, Nora; Valencia, Angela; Echeverry, Carlos Alberto; Arce-Plata, Maria Isabel; Colón, Cristóbal; Castiñeiras, Daisy E; Hurtado, Paula Margarita; Cocho, Jose Angel; Herrera, Sócrates; Arévalo-Herrera, Myriam

    2017-09-30

    Inborn errors of metabolism (IEM) represent an important public health problem due to current diagnosis and treatment limitations, poor life quality of affected patients, and consequent untimely child death. In contrast to classical methods, tandem mass spectrometry (MS/MS) has allowed simultaneous evaluation of multiple metabolites associated with IEM offering higher sensitivity, low false positive rates and high throughput. Determine concentration levels for amino acids and acylcarnitines in blood of newborns from Colombia, to establish reference values for further use in diagnosis of IEM. Implementation of a method to determine amino acids, acylcarnitines and succinylacetone in newborn dried blood spots using MS/MS, and its application in a cross-sectional study conducted in 891 healthy neonates from Cali and Quibdo cities is described. fifty-seven analytes that allow the diagnosis of more than 40 different pathologies were tested. The method showed to be linear, precise and accurate. Healthy neonates 1-18 days of age were included, 523 from Cali and 368 from Quibdo; 52% male and 48% female. Age-related differences on the concentration levels of amino acids and acylcarnitines were observed whereas no significant differences by gender were found. The study has contributed to reveal the usual concentration levels of amino acids, acylcarnitines and succinylacetone that could be used as reference for the establishment of a newborn metabolic screening program in Colombia.

  10. Analysis of rocuronium in human plasma by liquid chromatography-tandem mass spectrometry with application in clinical pharmacokinetics.

    Science.gov (United States)

    de Moraes, Natália Valadares; Lauretti, Gabriela Rocha; Filgueira, Gabriela Campos de Oliveira; Lopes, Bruno Carvalho Portes; Lanchote, Vera Lucia

    2014-03-01

    Rocuronium (ROC) is a neuromuscular blocking agent used in surgical procedures which is eliminated primarily by biliary excretion. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for analysis of ROC in human plasma. Separation of ROC and IS (verapamil) was performed using an endcapped C-18 column and a mixture of water:acetonitrile:trifluoracetic acid (50:50:0.1, v/v) as mobile phase. Aliquots of 100 μL of human plasma were extracted at pH 3, using dichloromethane. The lower limit of quantification of 5 ng/mL shows the high sensitivity of this method. Intra- and inter-assay precision (as relative standard deviation) was all ≤14.2% and accuracy (as relative standard error) did not exceed 10.1%. The validated method was successfully applied to quantify ROC concentrations in patients under surgical procedures up to 6h after the administration of the 0.4-0.9 mg/kg ROC. The pharmacokinetic parameter estimations of ROC showed AUC/dose of 563 μg min/mL, total clearance of 2.5 mL/min/kg, volume of distribution at steady state of 190 mL/kg and mean residence time of 83 min. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Quantitative determination of 12-hydroxyeicosatetraenoic acids by chiral liquid chromatography tandem mass spectrometry in a murine atopic dermatitis model.

    Science.gov (United States)

    Hong, Seong-Ho; Han, Ji Eun; Ko, Ji-Seung; Do, Sun Hee; Lee, Eung Ho; Cho, Myung-Haing

    2015-01-01

    Atopic dermatitis, one of the most important skin diseases, is characterized by both skin barrier impairment and immunological abnormalities. Although several studies have demonstrated the significant relationship between atopic dermatitis and immunological abnormalities, the role of hydroxyeicosatetraenoic acids (HETE) in atopic dermatitis remains unknown. To develop chiral methods for characterization of 12-HETE enantiomers in a 1-chloro-2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis mouse model and evaluate the effects of 12-HETE on atopic dermatitis, BALB/c mice were treated with either DNCB or acetone/olive oil (AOO) to induce atopic dermatitis, after which 12(R)- and 12(S)-HETEs in the plasma, skin, spleen, and lymph nodes were quantified by chiral liquid chromatography-tandem mass spectrometry. 12(R)- and 12(S)-HETEs in biological samples of DNCB-induced atopic dermatitis mice increased significantly compared with the AOO group, reflecting the involvement of 12(R)- and 12(S)-HETEs in atopic dermatitis. These findings indicate that 12(R)- and 12(S)-HETEs could be a useful guide for understanding the pathogenesis of atopic dermatitis.

  12. Multiclass determination of phytochemicals in vegetables and fruits by ultra high performance liquid chromatography coupled to tandem mass spectrometry.

    Science.gov (United States)

    Alarcón-Flores, María Isabel; Romero-González, Roberto; Vidal, José Luis Martínez; Frenich, Antonia Garrido

    2013-11-15

    In this study a simultaneous determination of several classes of phytochemicals (isoflavones, glucosinolates, flavones, flavonols and phenolic acids) in tomato, broccoli, carrot, eggplant and grape has been carried out by ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Solid-liquid extraction assisted by rotary agitator was utilised, using a mixture of methanol:water (80:20, v/v) as solvent. The analytical procedure was validated in all the matrices, obtaining recoveries ranging from 60% to 120% with repeatability values (expressed as relative standard deviations, RSDs) lower than 25%. Limits of quantification (LOQs) were always equal or lower than 50μg/kg, except for some glucosinolates (125μg/kg). Finally the method was applied to different matrices such as tomato, broccoli, carrot, grape and eggplant, observing that chlorogenic acid was detected in most of the samples at higher concentrations in relation to the other compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Liquid chromatography – tandem mass spectrometry method for the determination of ten tetracycline residues in muscle samples

    Directory of Open Access Journals (Sweden)

    Gajda Anna

    2015-09-01

    Full Text Available A liquid chromatography – tandem mass spectrometry (LC-MS/MS method for the determination of oxytetracycline (OTC, 4-epi oxytetracycline (4-epi OTC, tetracycline (TC, 4-epi tetracycline (4-epi TC, chlortetracycline (CTC, 4-epi chlortetracycline (4-epi CTC, doxycycline (DC, minocycline (MINO, methacycline (META and rolitetracycline (ROLI residues in muscles was developed. The procedure consisted of an oxalic acid extraction followed by protein removal with trichloroacetic acid. Further solid phase clean-up on polymeric (Strata X reversed phase columns was performed to obtain an extract suitable for LC-MS/MS analysis. The tetracyclines were separated on a C 18 analytical column with mobile phase consisting of 0.01% formic acid in acetonitrile and 0.01% formic acid in water in gradient mode. The method was validated according to the Commission Decision 2002/657/EC. The recoveries of all target compounds were 91.8% – 103.6%. The decision limits were from 109.0 to 119.8 μg/kg and detection capability varied within the range of 122.2 to 137.6 μg/kg, depending on the analyte.

  14. Liquid Chromatography-Tandem Mass Spectrometry Analysis of Perfluorooctane Sulfonate and Perfluorooctanoic Acid in Fish Fillet Samples

    Directory of Open Access Journals (Sweden)

    Viviana Paiano

    2012-01-01

    Full Text Available Perfluorooctane sulfonate (PFOS and perfluorooctanoic (PFOA acid are persistent contaminants which can be found in environmental and biological samples. A new and fast analytical method is described here for the analysis of these compounds in the edible part of fish samples. The method uses a simple liquid extraction by sonication, followed by a direct determination using liquid chromatography-tandem mass spectrometry (LC-MS/MS. The linearity of the instrumental response was good, with average regression coefficients of 0.9971 and 0.9979 for PFOS and PFOA, respectively, and the coefficients of variation (CV of the method ranged from 8% to 20%. Limits of detection (LOD were 0.04 ng/g for both the analytes and recoveries were 90% for PFOS and 76% for PFOA. The method was applied to samples of homogenized fillets of wild and farmed fish from the Mediterranean Sea. Most of the samples showed little or no contamination by perfluorooctane sulfonate and perfluorooctanoic acid, and the highest concentrations detected among the fish species analyzed were, respectively, 5.96 ng/g and 1.89 ng/g. The developed analytical methodology can be used as a tool to monitor and to assess human exposure to perfluorinated compounds through sea food consumption.

  15. Multi-residue determination of plant growth regulators in apples and tomatoes by liquid chromatography/tandem mass spectrometry.

    Science.gov (United States)

    Xue, Jiaying; Wang, Suli; You, Xiangwei; Dong, Jiannan; Han, Lijun; Liu, Fengmao

    2011-11-15

    A sensitive and rapid multi-residue analytical method for plant growth regulators (PGRs) (i.e., chlormequat, mepiquat, paclobutrazol, uniconazole, ethephon and flumetralin) in apples and tomatoes was developed using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). A homogenised sample was extracted with a mixture of methanol/water (90:10, v/v) and adjusted to pH <3 with formic acid. Primary secondary amine (PSA) adsorbent was used to clean up the sample. The determination was performed using electrospray ionisation (ESI) and a triple quadrupole (QqQ) analyser. Under the optimised method, the results showed that, except for ethephon, the recoveries were 81.8-98.1% in apples and tomatoes at the spiked concentrations of 0.005 to 2 mg/kg, with relative standard deviations (RSDs) of less than 11.7%. The limits of quantification (LOQs) were lower than their maximum residue limits (MRLs). The procedure was concluded as a practical method to determine the PGR residues in fruit and vegetables and is also suitable for the simultaneous analysis of the amounts of samples for routine monitoring. The analytical method described herein demonstrates a strong potential for its application in the field of PGR multi-residue analysis to help assure food safety. Copyright © 2011 John Wiley & Sons, Ltd.

  16. Convenient expression, purification and quantitative liquid chromatography-tandem mass spectrometry-based analysis of TET2 5-methylcytosine demethylase.

    Science.gov (United States)

    Jaiswal, Mohit; Bhar, Subhradeep; Vemula, Harika; Prakash, Swami; Ponnaluri, V K Chaithanya; Gutheil, William G; Mukherji, Mridul

    2017-04-01

    5-Methylcytosine within CpG islands in DNA plays a crucial role in epigenetic transcriptional regulation during metazoan development. Recently, it has been established that the Ten-Eleven Translocation (TET) family, Fe(II)- and 2-oxoglutarate (2OG/αKG)-dependent oxygenases initiate 5-methylcytosine demethylation by iterative oxidation reactions. Mutations in the TET2 gene are frequently detected in patients with myeloid malignancies. Here, we describe the cloning of untagged human TET2 demethylase using Gateway technology and its efficient expression in E. coli. The untagged TET2 enzyme was purified using cation exchange and heparin sepharose chromatography. In addition, a reliable quantitative liquid chromatography-tandem mass spectrometry-based assay was utilized to analyze the activity of TET2 oxygenase. This assay was further used to analyze the activity of a number of clinical TET2 variants with mutations in the 2OG binding sites. Our results demonstrate that the activity of one TET2 mutant, TET2-R1896S, can be restored using an excess of 2OG in the reaction mixture. These studies suggest that dietary 2OG supplements, which are commonly used for several other conditions, may be used to treat some patients with myeloid malignancies harboring TET2-R1896S mutation. Results described in this paper serve as a foundation for better characterization of wild type as well as mutant TET2 demethylases. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. A liquid chromatography-tandem mass spectrometry assay for quantification of rilpivirine and dolutegravir in human plasma.

    Science.gov (United States)

    Grégoire, M; Deslandes, G; Renaud, C; Bouquié, R; Allavena, C; Raffi, F; Jolliet, P; Dailly, E

    2014-11-15

    A liquid chromatography-tandem mass spectrometry assay requiring a 100μL aliquot of human plasma for simultaneous determination of rilpivirine, a second generation non-nucleoside reverse transcriptase inhibitors of HIV and dolutegravir, a novel integrase stand transfer inhibitors of HIV concentrations has been developed. Sample pre-treatment is limited to protein precipitation with a mixture of methanol and zinc sulfate. After centrifugation the supernatant is injected in the chromatographic system, which consists of on-line solid phase extraction followed by separation on a phenyl-hexyl column. This 2.5min method, with its simple sample preparation provides sensitive (the limit of quantitation is 25ng/mL for each compound), accurate and precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%) quantification of the plasma concentration of these drugs and can be used for therapeutic drug monitoring in patients infected with HIV. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Detection and determination of reticuline and N-methylcoculaurine in the Annonaceae family using liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kotake, Yaichiro; Okuda, Katsuhiro; Kamizono, Machiko; Matsumoto, Naoki; Tanahashi, Takao; Hara, Hiroshi; Caparros-Lefebvre, Dominique; Ohta, Shigeru

    2004-06-25

    In Guadeloupe, the French West Indies, there is a high incidence of atypical parkinsonism or progressive supranuclear palsy, and all of the investigated patients had taken herbal tea or tropical fruits of the Annonaceae family. Local inhabitants consume the fruits, and also drink tea made from the leaves. In the present study, we used liquid chromatography-tandem mass spectrometry (LC/MS/MS) with multiple reaction monitoring (MRM) to detect low-molecular-weight neurotoxic benzylisoquinoline derivatives in the Annonaceae family. We detected reticuline and N-methylcoculaurine in every Annona muricata sample examined, except for pulp and seed. They were not detected in sweetsop fruits. Norreticuline was not detected in any sample. These three compounds were toxic to SH-SY5Y neuroblastoma cells and inhibited mitochondrial respiratory complex I. It is possible that uptake of the benzylisoquinoline derivatives reticuline and N-methylcoculaurine and their accumulation in the brain may be related to the pathogenesis of the local endemic disease.

  19. In vivo and in vitro metabolism of aspirin eugenol ester in dog by liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Shen, Youming; Liu, Xiwang; Yang, Yajun; Li, Jianyong; Ma, Ning; Li, Bing

    2015-01-01

    Aspirin eugenol ester (AEE) is a promising drug candidate for treatment of inflammation, pain and fever and prevention of cardiovascular diseases with fewer side effects than its precursor, aspirin. Investigation into its metabolic process in target animal species will help to illustrate its mechanism of action and to establish its residual mark compound to formulate its dosage. Six beagle dogs were orally given a dose of 20 mg kg(-1) of AEE and one dog was used to prepare blank liver microsomes. Their liver microsomes were prepared for in vitro study and their plasma and urine were collected for in vivo metabolic analysis using liquid chromatography tandem mass spectrometry. In this study we identified 10 metabolites, M1, M2, M3, M4, M5 in phase I and M6, M7, M8, M9, M10 in phase II. Based on the metabolites of AEE, the pathways of AEE metabolism in dog were demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Determination of pesticides and pesticide degradates in filtered water by direct aqueous-injection liquid chromatography-tandem mass spectrometry

    Science.gov (United States)

    Sandstrom, Mark W.; Kanagy, Leslie K.; Anderson, Cyrissa A.; Kanagy, Christopher J.

    2016-01-11

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for determination of 229 pesticides compounds (113 pesticides and 116 pesticide degradates) in filtered water samples from stream and groundwater sites. The pesticides represent a broad range of chemical classes and were selected based on criteria such as current-use intensity, probability of occurrence in streams and groundwater, and toxicity to humans or aquatic organisms. More than half of the analytes are pesticide degradates. The method involves direct injection of a 100-microliter (μL) sample onto the LC-MS/MS without any sample preparation other than filtration. Samples are analyzed with two injections, one in electrospray ionization (ESI) positive mode and one in ESI negative mode, using dynamic multiple reaction monitoring (MRM) conditions, with two MRM transitions for each analyte. The LC-MS/MS instrument parameters were optimized for highest sensitivity for the most analytes. This report describes the analytical method and presents characteristics of the method validation including bias and variability, detection levels, and holding-time studies.

  1. Determination of neonicotinoid insecticides and strobilurin fungicides in particle phase atmospheric samples by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Raina-Fulton, Renata

    2015-06-03

    A liquid chromatography-tandem mass spectrometry method has been developed for the determination of neonicotinoids and strobilurin fungicides in the particle phase fraction of atmosphere samples. Filter samples were extracted with pressurized solvent extraction, followed by a cleanup step with solid phase extraction. Method detection limits for the seven neonicotinoid insecticides and six strobilurin fungicides were in the range of 1.0-4.0 pg/m(3). Samples were collected from June to September 2013 at two locations (Osoyoos and Oliver) in the southern Okanagan Valley Agricultural Region of British Columbia, where these insecticides and fungicides are recommended for use on tree fruit crops (apples, pears, cherries, peaches, apricots) and vineyards. This work represents the first detection of acetamiprid, imidacloprid, clothianidin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin in particle phase atmospheric samples collected in the Okanagan Valley in Canada. The highest particle phase atmospheric concentrations were observed for imidacloprid, pyraclostrobin, and trifloxystrobin at 360.0, 655.6, and 1908.2 pg/m(3), respectively.

  2. Analysis of mononucleotides by tandem mass spectrometry: investigation of fragmentation pathways for phosphate- and ribose-modified nucleotide analogues.

    Science.gov (United States)

    Strzelecka, Dominika; Chmielinski, Sebastian; Bednarek, Sylwia; Jemielity, Jacek; Kowalska, Joanna

    2017-08-21

    Synthetic nucleotide and nucleic acid analogues are useful research tools and modern therapeutics. Hence, methods for the rapid and unambiguous identification of mononucleotides derived from organic syntheses or biological materials are of broad interest. Here, we analysed over 150 mononucleotides (mostly nucleoside 5'-mono-, 5'-di-, and 5'-triphosphates) and their structurally related nucleobase-, phosphate-, and ribose-modified analogues by electrospray tandem mass spectrometry (ESI/MS/MS), identifying characteristic fragmentation ions that may be helpful in structure determination. While positive-ion mode yielded fragments derived mainly from nucleobases, negative-ion mode provided insight into the structures of phosphoryl and phosphoribosyl moieties, enabling the determination of structural features such as the number of phosphate groups and the presence of ribose or phosphate substitutions. Based on these data, we proposed fragmentation pathways that were confirmed by experiments with [18O]-isotopologues. We demonstrated the utility of ESI(-)/MS/MS in the analysis of structurally related compounds by analysing isomeric and isobaric nucleotides and applying ESI(-)/MS/MS to rapid identification of nucleotide synthesis products. We formulated general rules regarding nucleotide structure-fragmentation pattern relationships and indicating characteristic fragmentation ions for the interpretation of ESI(-)/MS/MS spectra of nucleotides and their analogues. The ESI(-)/MS/MS spectra of all nucleotides are available in an on-line database, msTide, at www.msTide-db.com.

  3. Speeding up tandem mass spectrometry database search: metric embeddings and fast near neighbor search.

    Science.gov (United States)

    Dutta, Debojyoti; Chen, Ting

    2007-03-01

    Due to the recent advances in technology of mass spectrometry, there has been an exponential increase in the amount of data being generated in the past few years. Database searches have not been able to keep with this data explosion. Thus, speeding up the data searches becomes increasingly important in mass-spectrometry-based applications. Traditional database search methods use one-against-all comparisons of a query spectrum against a very large number of peptides generated from in silico digestion of protein sequences in a database, to filter potential candidates from this database followed by a detailed scoring and ranking of those filtered candidates. In this article, we show that we can avoid the one-against-all comparisons. The basic idea is to design a set of hash functions to pre-process peptides in the database such that for each query spectrum we can use the hash functions to find only a small subset of peptide sequences that are most likely to match the spectrum. The construction of each hash function is based on a random spectrum and the hash value of a peptide is the normalized shared peak counts score (cosine) between the random spectrum and the hypothetical spectrum of the peptide. To implement this idea, we first embed each peptide into a unit vector in a high-dimensional metric space. The random spectrum is represented by a random vector, and we use random vectors to construct a set of hash functions called locality sensitive hashing (LSH) for preprocessing. We demonstrate that our mapping is accurate. We show that our method can filter out >95.65% of the spectra without missing any correct sequences, or gain 111 times speedup by filtering out 99.64% of spectra while missing at most 0.19% (2 out of 1014) of the correct sequences. In addition, we show that our method can be effectively used for other mass spectra mining applications such as finding clusters of spectra efficiently and accurately. Supplementary data are available at Bioinformatics

  4. Tandem mass spectrometric investigation of acylpolyamines of spider venoms and their 15N-labeled derivatives.

    Science.gov (United States)

    Tzouros, Manuel; Manov, Nikolay; Bienz, Stefan; Bigler, Laurent

    2004-11-01

    The fragmentation mechanism of the acylpentamine toxins 1-4 found in the venom of the spider Agelenopsis aperta has been investigated in detail. To identify the origin of the two doublets of unexpected fragment ions at m/z 129/112 and m/z 115/98, three synthetic 15N-labeled analogs 5-7 have been prepared and subjected to CID fragmentation on a triple quadrupole mass spectrometer. It appears that the unexpected doublet of fragment ions arises from an internal portion of the polyamine backbone after either a transaminative Zip reaction or a sequential fragmentation of the quasi-molecular ion. The second option has been proven by in-source CID experiments. The detailed knowledge of acylpentamine fragmentation mechanisms is essential for the correct characterization of isomeric compounds, particularly for coeluting compounds within complex mixtures such as spider venoms.

  5. Sequencing Lys-N Proteolytic Peptides by ESI and MALDI Tandem Mass Spectrometry

    Science.gov (United States)

    Dupré, Mathieu; Cantel, Sonia; Verdié, Pascal; Martinez, Jean; Enjalbal, Christine

    2011-02-01

    In this study, we explored the MS/MS behavior of various synthetic peptides that possess a lysine residue at the N-terminal position. These peptides were designed to mimic peptides produced upon proteolysis by the Lys-N enzyme, a metalloendopeptidase issued from a Japanese fungus Grifola frondosa that was recently investigated in proteomic studies as an alternative to trypsin digestion, as a specific cleavage at the amide X-Lys chain is obtained that provides N-terminal lysine peptide fragments. In contrast to tryptic peptides exhibiting a lysine or arginine residue solely at the C-terminal position, and are thus devoid of such basic amino acids within the sequence, these Lys-N proteolytic peptides can contain the highly basic arginine residue anywhere within the peptide chain. The fragmentation patterns of such sequences with the ESI-QqTOF and MALDI-TOF/TOF mass spectrometers commonly used in proteomic bottom-up experiments were investigated.

  6. Saffron authentication based on liquid chromatography high resolution tandem mass spectrometry and multivariate data analysis.

    Science.gov (United States)

    Rubert, Josep; Lacina, Ondrej; Zachariasova, Milena; Hajslova, Jana

    2016-08-01

    Saffron is one of the oldest and most expensive spices, which is often target of fraudulent activities. In this research, a new strategy of saffron authentication based on metabolic fingerprinting was developed. In the first phase, a solid liquid extraction procedure was optimized, the main aim was to isolate as maximal representation of small molecules contained in saffron as possible. In the second step, a detection method based on liquid chromatography coupled with high-resolution mass spectrometry was developed. Initially, principal component analysis (PCA) revealed clear differences between saffron cultivated and packaged in Spain, protected designation of origin (PDO), and saffron packaged in Spain of unknown origin, labeled Spanish saffron. Afterwards, orthogonal partial least square discriminant analysis (OPLS-DA) was favorably used to discriminate between Spanish saffron. The tentative identification of markers showed glycerophospholipids and their oxidized lipids were significant markers according to their origin. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Differentiating samples and experimental protocols by direct comparison of tandem mass spectra

    DEFF Research Database (Denmark)

    van der Plas-Duivesteijn, Suzanne J.; Wulff, Tune; Klychnikov, Oleg

    2016-01-01

    , serendipitous uses. We used the existing compareMS2 algorithm without modification on a diverse set of experiments. First we conducted a small phylogenetic study, using (mammalian) bone samples to study old material, and human pathogens aiming to distinguish clinically important strains. Although...... not as straightforward as primate sera analysis, the method shows significant promise for all these applications. We also used the algorithm to compare 24 different protocols for extraction of proteins from muscle tissue. The results provided useful information in comparing protocols. Finally, we applied compareMS2...... protein digests in different types of experiments. There is no reason to assume that our instance of this method is optimal in any of these situations, as it makes limited or no use of accurate mass and chromatographic retention time. We propose that with further improvement and refinement, this type...

  8. Characterizing the effective density and primary particle diameter of airborne nanoparticles produced by spark discharge using mobility and mass measurements (tandem DMA/APM)

    Science.gov (United States)

    Charvet, Augustin; Bau, Sébastien; Paez Coy, Natalia Estefania; Bémer, Denis; Thomas, Dominique

    2014-05-01

    Nanoparticles are increasingly used in a wide variety of industries. As yet, their health effects are incompletely characterized. Effective density is among the key characteristics of airborne nanoparticles due to its role in particle deposition in the human respiratory tract and in the conversion of number distributions to mass distributions. Because it cannot be measured directly, different methods have been developed to accede to this parameter. The approach chosen in this study is based on the tandem measurement of airborne nanoparticles electrical mobility and mass (tandem differential mobility analyzer/aerosol particle mass analyzer), which major advantage lies in the absence of hypothesis contrary to the tandem differential mobility analyzer/electrical low pressure impactor (DMA/ELPI). The methodology was first applied to spherical model particles to validate the associated data treatment and protocol. In particular, the influence of APM rotational velocity and airflow rate were investigated with regards to the separation of multiply charged particles and electrometer signal. It emerged from experimental data that a compromise between separation efficiency and detection limit shall be found, depending on the nanoparticles to characterize. Accounting for their wide use in different domains, airborne nanoparticles of constantan®, copper, graphite, iron, silver and titanium, produced by spark discharge appear to be representative of ultrafine particles stemming from different industrial processes. In addition to their effective density, the mass-mobility exponents and primary particle diameters were determined for these particles, and found to agree well with published data.

  9. Structural Characterization of Anticancer Drug Paclitaxel and Its Metabolites Using Ion Mobility Mass Spectrometry and Tandem Mass Spectrometry

    Science.gov (United States)

    Lee, Hong Hee; Hong, Areum; Cho, Yunju; Kim, Sunghwan; Kim, Won Jong; Kim, Hugh I.

    2016-02-01

    Paclitaxel (PTX) is a popular anticancer drug used in the treatment of various types of cancers. PTX is metabolized in the human liver by cytochrome P450 to two structural isomers, 3'- p-hydroxypaclitaxel (3 p-OHP) and 6α-hydroxypaclitaxel (6α-OHP). Analyzing PTX and its two metabolites, 3 p-OHP and 6α-OHP, is crucial for understanding general pharmacokinetics, drug activity, and drug resistance. In this study, electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) and collision induced dissociation (CID) are utilized for the identification and characterization of PTX and its metabolites. Ion mobility distributions of 3 p-OHP and 6α-OHP indicate that hydroxylation of PTX at different sites yields distinct gas phase structures. Addition of monovalent alkali metal and silver metal cations enhances the distinct dissociation patterns of these structural isomers. The differences observed in the CID patterns of metalated PTX and its two metabolites are investigated further by evaluating their gas-phase structures. Density functional theory calculations suggest that the observed structural changes and dissociation pathways are the result of the interactions between the metal cation and the hydroxyl substituents in PTX metabolites.

  10. Tandem solid phase extraction followed by online trapping-hydrophilic interaction chromatography-tandem mass spectrometry for sensitive detection of endogenous cytokinins in plant tissues.

    Science.gov (United States)

    Liu, Zhao; Yuan, Bi-Feng; Feng, Yu-Qi

    2012-01-01

    Cytokinins (CKs) are a group of plant hormones that play pivotal roles at low concentration in plant growth, development and regulatory pathways. In order to study the function, metabolism and signal transduction of CKs, high performance analytical techniques are required for determination of their endogenous levels. To develop a highly sensitive, selective and reliable method for identification and quantification of CKs by employing a tandem solid phase extraction (SPE)-online trapping-hydrophilic interaction chromatography (HILIC)-MS/MS method. The extraction was performed firstly with tandem SPE containing a C(18) cartridge and a silica@C(8) /SO(3) H cartridge. After CKs were eluted from the silica@C(8)/SO(3) H cartridge, the desorption solvent was concentrated and redissolved in H(2)O and then injected into the online trapping-HILIC-MS/MS system with (Poly(MAA-co-EGDMA)) monolith as the trapping column. Subsequently, trapping, washing, desorption, separation and detection were accomplished automatically on the system. Good linearities were obtained for eight cytokinins with correlation coefficients (R(2)) > 0.9964. The limits of detection (LOD; S:N = 3) for the targets ranged from 0.042 to 1.6 pg/mL. Reproducibility of the method was evaluated with intraday and interday relative standard deviations (RSDs) less than 13.4% and the recoveries ranged from 77.3% to 116.3%. The results showed that the LOD of the analytical method were at least one order of magnitude lower compared with other previously reported methods. Furthermore, only 20 mg of plant tissues were required for the quantitative analysis of the major CKs, which is, to the best of our knowledge, the smallest amount reported so far for the determination of endogenous CKs in plant tissues. The tandem SPE-online trapping-HILIC-MS/MS method developed in current study provides a powerful tool for the convenient and highly sensitive quantification of the major CKs in plant tissue. Copyright © 2012 John

  11. Determination of serum glucose by isotope dilution liquid chromatography-tandem mass spectrometry: a candidate reference measurement procedure.

    Science.gov (United States)

    Zhang, Tianjiao; Zhang, Chuanbao; Zhao, Haijian; Zeng, Jie; Zhang, Jiangtao; Zhou, Weiyan; Yan, Ying; Wang, Yufei; Wang, Mo; Chen, Wenxiang

    2016-10-01

    Accurate and precise glucose measurements are requisite for ensuring appropriate diagnosis and management of diseases related to hyperglycemia or hypoglycemia. It is necessary to have a higher order method to provide an accuracy base to which routine methods can be compared. We developed and evaluated a highly reliable measurement procedure based on isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) with a simple one-step derivatization. An appropriate amount of serum was accurately weighed and spiked with an isotope-labeled internal standard. After protein precipitation, the supernatant was reacted with 1-phenyl-3-methyl-5-pyrazolone for chemical structural transformation. The glucose derivatives were analyzed with LC-MS/MS in positive electrospray ionization mode. The within-run and total CVs ranged from 0.28 to 0.42 % and from 0.42 to 0.76 %, respectively, for a concentration range of 1.691 to 15.676 mmol/L. A regression comparison of the presented method to an existing RMP based on ID GC-MS showed agreement with no statistical difference (Y = 0.9985X-0.008; 95 % CI for the slope, 0.9966 to 1.001; 95 % CI for the intercept, -0.012 to 0.019). The structural analogs of glucose with a molecular mass of 180 were tested, and no significant interference effect was found. The limit of quantification was estimated to 0.8 ng glucose in absolute amount. This method is accurate, simple, and can serve as a candidate reference measurement procedure (RMP) in the establishment of a serum glucose reference system.

  12. Simultaneous quantification of dabrafenib and trametinib in human plasma using high-performance liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Nijenhuis, C M; Haverkate, H; Rosing, H; Schellens, J H M; Beijnen, J H

    2016-06-05

    Dabrafenib (Tafinlar(®)) and trametinib (Mekinist(®)) are registered for the treatment of patients with BRAF V600 mutation positive unresectable or metastatic melanoma. To support therapeutic drug monitoring (TDM) and clinical pharmacological trials, an assay to simultaneously quantify dabrafenib and trametinib in human plasma using liquid chromatography tandem mass spectrometry was developed and validated. Human plasma samples were collected on an outpatient base and stored at nominally -20°C. Analytes and internal standards (stable isotope labeled compounds) were extracted with TBME. After snap freezing the samples in a dry ice-ethanol bath, the organic layer was transferred to a clean tube and evaporated under a gentle stream of nitrogen gas. The dry extract was then reconstituted with 100μL acetonitrile and 5μL of the final extract was injected and separated on a C18 column with gradient elution, and analyzed with triple quadrupole mass spectrometry in positive-ion mode. The validated assay ranges from 50 to 5000ng/mL for dabrafenib and 0.5-50ng/mL for trametinib were linear, and correlation coefficient (r(2)) of 0.996 or better. At all concentrations of both analytes the biases were within ±15% of the nominal concentrations and precisions were ≤15%. All results were within the acceptance criteria of the latest US FDA guidance and EMA guidelines on method validation. Dabrafenib was found to degrade under the influence of light in different organic solvents and at least seven degradation products were detected. In conclusion, the described method to simultaneously quantify dabrafenib and trametinib in human plasma was successfully validated and applied for therapeutic drug monitoring in cancer patients treated with dabrafenib and trametinib. Copyright © 2016 Elsevier B.V. All rights reserved.