Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions.

Science.gov (United States)

Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

2017-07-01

Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO 3 ) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO 3 -nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO 3 ) was produced in the flame. The HNO 3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO 3 showed the strongest affinity to histidine and formed (M histidine -H+HNO 3 ) - complex ions, whereas some amino acids did not react with HNO 3 at all. Reactions between HNO 3 and histidine residues in AI and AII resulted in the formation of dominant [M AI -H+(HNO 3 )] - and [M AII -H+(HNO 3 )] - ions. Results from analyses of AAs and insulin indicated that HNO 3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO 3 ) n ] 3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins. Graphical Abstract ᅟ.

Determination of low specific activity iodine-129 off-gas concentrations by GC separation and negative ionization mass spectrometry

International Nuclear Information System (INIS)

Fernandez, S.J.; Rankin, R.A.; McManus, G.J.; Nielsen, R.A.; Delmore, J.E.; Hohorst, F.A.; Murphy, L.P.

1983-09-01

This document is the final report of the laboratory development of a method for determining the specific activity of the 129 I emitted from a nuclear fuel reprocessing plant. The technique includes cryogenic sample collection, chemical form separation, quantitation by gas chromatography, and specific activity measurement of each chemical species by negative ionization mass spectrometry. The major conclusions were that both organic and elemental iodine can be quantitatively collected without fractionation and that specific activity measurements as low as one atom of 129 I per 10 5 atoms of 127 I are possible

Molecular Ionization-Desorption Analysis Source (MIDAS) for Mass Spectrometry: Thin-Layer Chromatography

Science.gov (United States)

Winter, Gregory T.; Wilhide, Joshua A.; LaCourse, William R.

2016-02-01

Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.

Derivatization reagents in liquid chromatography/electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Santa, Tomofumi

2011-01-01

Liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is one of the most prominent analytical techniques owing to its inherent selectivity and sensitivity. In LC/ESI-MS/MS, chemical derivatization is often used to enhance the detection sensitivity. Derivatization improves the chromatographic separation, and enhances the mass spectrometric ionization efficiency and MS/MS detectability. In this review, an overview of the derivatization reagents which have been applied to LC/ESI-MS/MS is presented, focusing on the applications to low molecular weight compounds. 2010 John Wiley & Sons, Ltd.

Determination of low specific activity iodine-129 off-gas concentrations by GC separation and negative ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Fernandez, S.J.; Rankin, R.A.; McManus, G.J.; Nielsen, R.A.; Delmore, J.E.; Hohorst, F.A.; Murphy, L.P.

1983-09-01

This document is the final report of the laboratory development of a method for determining the specific activity of the /sup 129/I emitted from a nuclear fuel reprocessing plant. The technique includes cryogenic sample collection, chemical form separation, quantitation by gas chromatography, and specific activity measurement of each chemical species by negative ionization mass spectrometry. The major conclusions were that both organic and elemental iodine can be quantitatively collected without fractionation and that specific activity measurements as low as one atom of /sup 129/I per 10/sup 5/ atoms of /sup 127/I are possible.

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...

A sensitive gas chromatography detector based on atmospheric pressure chemical ionization by a dielectric barrier discharge.

Science.gov (United States)

Kirk, Ansgar T; Last, Torben; Zimmermann, Stefan

2017-02-03

In this work, we present a novel concept for a gas chromatography detector utilizing an atmospheric pressure chemical ionization which is initialized by a dielectric barrier discharge. In general, such a detector can be simple and low-cost, while achieving extremely good limits of detection. However, it is non-selective apart from the use of chemical dopants. Here, a demonstrator manufactured entirely from fused silica capillaries and printed circuit boards is shown. It has a size of 75×60×25mm 3 and utilizes only 2W of power in total. Unlike other known discharge detectors, which require high-purity helium, this detector can theoretically be operated using any gas able to form stable ion species. Here, purified air is used. With this setup, limits of detection in the low parts-per-billion range have been obtained for acetone. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultra-high performance supercritical fluid chromatography hyphenated to atmospheric pressure chemical ionization high resolution mass spectrometry for the characterization of fast pyrolysis bio-oils.

Science.gov (United States)

Crepier, Julien; Le Masle, Agnès; Charon, Nadège; Albrieux, Florian; Duchene, Pascal; Heinisch, Sabine

2018-06-01

Extensive characterization of complex mixtures requires the combination of powerful analytical techniques. A Supercritical Fluid Chromatography (SFC) method was previously developed, for the specific case of fast pyrolysis bio oils, as an alternative to gas chromatography (GC and GC × GC) or liquid chromatography (LC and LC × LC), both separation methods being generally used prior to mass spectrometry (MS) for the characterization of such complex matrices. In this study we investigated the potential of SFC hyphenated to high resolution mass spectrometry (SFC-HRMS) for this characterization using Negative ion Atmospheric Pressure Chemical ionization ((-)APCI) for the ionization source. The interface between SFC and (-)APCI/HRMS was optimized from a mix of model compounds with the objective of maximizing the signal to noise ratio. The main studied parameters included both make-up flow-rate and make-up composition. A methodology for the treatment of APCI/HRMS data is proposed. This latter allowed for the identification of molecular formulae. Both SFC-APCI/HRMS method and data processing method were applied to a mixture of 36 model compounds, first analyzed alone and then spiked in a bio-oil. In both cases, 19 compounds could be detected. Among them 9 could be detected in a fast pyrolysis bio-oil by targeted analysis. The whole procedure was applied to the characterization of a bio-oil using helpful representations such as mass-plots, van Krevelen diagrams and heteroatom class distributions. Finally the results were compared with those obtained with a Fourier Transform ion-cyclotron resonance mass spectrometer (FT-ICR/MS). Copyright © 2018 Elsevier B.V. All rights reserved.

Polymer Analysis by Liquid Chromatography/Electrospray Ionization Time-of-Flight Mass Spectrometry.

Science.gov (United States)

Nielen, M W; Buijtenhuijs, F A

1999-05-01

Hyphenation of liquid chromatography (LC) techniques with electrospray ionization (ESI) orthogonal acceleration time-of-flight (oa-TOF) mass spectrometry (MS) provides both MS-based structural information and LC-based quantitative data in polymer analysis. In one experimental setup, three different LC modes are interfaced with MS:  size-exclusion chromatography (SEC/MS), gradient polymer elution chromatography (GPEC/MS), and liquid chromatography at the critical point of adsorption (LCCC/MS). In SEC/MS, both absolute mass calibration of the SEC column based on the polymer itself and determination of monomers and end groups from the mass spectra are achieved. GPEC/MS shows detailed chemical heterogeneity of the polymer and the chemical composition distribution within oligomer groups. In LCCC/MS, the retention behavior is primarily governed by chemical heterogeneities, such as different end group functionalities, and quantitative end group calculations can be easily made. The potential of these methods and the benefit of time-of-flight analyzers in polymer analysis are discussed using SEC/MS of a polydisperse poly(methyl methacrylate) sample, GPEC/MS of dipropoxylated bisphenol A/adipic acid polyester resin, LCCC/MS of alkylated poly(ethylene glycol), and LCCC/MS of terephthalic acid/neopentyl glycol polyester resin.

[Determination of acetanilide herbicide residues in tea by gas chromatography-mass spectrometry with two different ionization techniques].

Science.gov (United States)

Shen, Weijian; Xu, Jinzhong; Yang, Wenquan; Shen, Chongyu; Zhao, Zengyun; Ding, Tao; Wu, Bin

2007-09-01

An analytical method of solid phase extraction-gas chromatography-mass spectrometry with two different ionization techniques was established for simultaneous determination of 12 acetanilide herbicide residues in tea-leaves. Herbicides were extracted from tea-leaf samples with ethyl acetate. The extract was cleaned-up on an active carbon SPE column connected to a Florisil SPE column. Analytical screening was determined by the technique of gas chromatography (GC)-mass spectrometry (MS) in the selected ion monitoring (SIM) mode with either electron impact ionization (EI) or negative chemical ionization (NCI). It is reliable and stable that the recoveries of all herbicides were in the range from 50% to 110% at three spiked levels, 10 microg/kg, 20 microg/kg and 40 microg/kg, and the relative standard deviations (RSDs) were no more than 10.9%. The two different ionization techniques are complementary as more ion fragmentation information can be obtained from the EI mode while more molecular ion information from the NCI mode. By comparison of the two techniques, the selectivity of NCI-SIM was much better than that of EI-SIM method. The sensitivities of the both techniques were high, the limit of quantitative (LOQ) for each herbicide was no more than 2.0 microg/kg, and the limit of detection (LOD) with NCI-SIM technique was much lower than that of EI-SIM when analyzing herbicides with several halogen atoms in the molecule.

Analysis of acylcarnitines as their N-demethylated ester derivatives by gas chromatography-chemical ionization mass spectrometry.

Science.gov (United States)

Huang, Z H; Gage, D A; Bieber, L L; Sweeley, C C

1991-11-15

A novel approach to the analysis of acylcarnitines has been developed. It involves a direct esterification using propyl chloroformate in aqueous propanol followed by ion-pair extraction with potassium iodide into chloroform and subsequent on-column N-demethylation of the resulting acylcarnitine propyl ester iodides. The products, acyl N-demethylcarnitine propyl esters, are volatile and are easily analyzed by gas chromatography-chemical ionization mass spectrometry. For medium-chain-length (C4-C12) acylcarnitine standards, detection limits are demonstrated to be well below 1 ng starting material using selected ion monitoring. Well-separated gas chromatographic peaks and structure-specific mass spectra are obtained with samples of synthetic and biological origin. Seven acylcarnitines have been characterized in the urine of a patient suffering from medium-chain acyl-CoA dehydrogenase deficiency.

Quantitation of triacylglycerols in edible oils by off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column.

Science.gov (United States)

Wei, Fang; Hu, Na; Lv, Xin; Dong, Xu-Yan; Chen, Hong

2015-07-24

In this investigation, off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π-π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography-mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography-mass spectrometry data were analyzed

Ultra pressure liquid chromatography-negative electrospray ionization mass spectrometry determination of twelve halobenzoquinones at ng/L levels in drinking water.

Science.gov (United States)

Huang, Rongfu; Wang, Wei; Qian, Yichao; Boyd, Jessica M; Zhao, Yuli; Li, Xing-Fang

2013-05-07

We report here the characterization of twelve halobenzoquinones (HBQs) using electrospray ionization (ESI) high resolution quadrupole time-of-flight mass spectrometry. The high resolution negative ESI spectra of the twelve HBQs formed two parent ions, [M + H(+) + 2e(-)], and the radical M(-•). The intensities of these two parent ions are dependent on their chemical structures and on instrumental parameters such as the source temperature and flow rate. The characteristic ions of the HBQs were used to develop an ultra pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. At the UPLC flow rate (400 μL/min) and under the optimized ESI conditions, eleven HBQs showed the stable and abundant transitions [M + H(+) + 2e(-)] → X(-) (X(-) representing Cl(-), Br(-), or I(-)), while dibromo-dimethyl-benzoquinone (DBDMBQ) showed only the transition of M(-•) → Br(-). The UPLC efficiently separates all HBQs including some HBQ isomers, while the MS/MS offers exquisite limits of detection (LODs) at subng/mL levels for all HBQs except DBDMBQ. Combined with solid phase extraction (SPE), the method LOD is down to ng/L. The results from analysis of authentic samples demonstrated that the SPE-UPLC-MS/MS method is reliable, fast, and sensitive for the identification and quantification of the twelve HBQs in drinking water.

Negative chemical ionization gas chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry and automated accurate mass data processing for determination of pesticides in fruit and vegetables.

Science.gov (United States)

Besil, Natalia; Uclés, Samanta; Mezcúa, Milagros; Heinzen, Horacio; Fernández-Alba, Amadeo R

2015-08-01

Gas chromatography coupled to high resolution hybrid quadrupole time-of-flight mass spectrometry (GC-QTOF MS), operating in negative chemical ionization (NCI) mode and combining full scan with MSMS experiments using accurate mass analysis, has been explored for the automated determination of pesticide residues in fruit and vegetables. Seventy compounds were included in this approach where 50 % of them are not approved by the EU legislation. A global 76 % of the analytes could be identified at 1 μg kg(-1). Recovery studies were developed at three concentration levels (1, 5, and 10 μg kg(-1)). Seventy-seven percent of the detected pesticides at the lowest level yielded recoveries within the 70 %-120 % range, whereas 94 % could be quantified at 5 μg kg(-1), and the 100 % were determined at 10 μg kg(-1). Good repeatability, expressed as relative standard deviation (RSD home-made database was developed and applied to an automatic accurate mass data processing. Measured mass accuracies of the generated ions were mainly less than 5 ppm for at least one diagnostic ion. When only one ion was obtained in the single-stage NCI-MS, a representative product ion from MSMS experiments was used as identification criterion. A total of 30 real samples were analyzed and 67 % of the samples were positive for 12 different pesticides in the range 1.0-1321.3 μg kg(-1).

[Determination of naphthenic acids in distillates of crude oil by gas chromatography/chemical ionization-mass spectrometry].

Science.gov (United States)

Lü, Zhenbo; Tian, Songbai; Zhai, Yuchun; Sun, Yanwei; Zhuang, Lihong

2004-05-01

The petroleum carboxylic acids in 200-420 degrees C distillate of crude oil were separated by the extraction with column chromatography on an anion exchange resin. The effect of the composition and structure of naphthenic acids on separation were studied by the infra-red (IR) spectroscopic techniques. Naphthenic acids and iso-butane reagent gas were introduced into the ion source for chemical ionization, in which the ions represented by [M + C4H9]+ were used to calculate the relative molecular mass for each acid. Based on the mass spectra of pure fatty and naphthenic acids, in combination with the z-series formula CnH(2n + z)O2, the naphthenic acids can be classified into fatty, mono-, bi- ... hexa-cyclic types. The results indicated that the relative molecular mass range of naphthenic acids in this distillates was 170-510, and the carbon number range was C10-C35. The contents of bi-cyclic and tri-cyclic naphthenic acids were higher than others.

A rapid novel derivatization of amphetamine and methamphetamine using 2,2,2-trichloroethyl chloroformate for gas chromatography electron ionization and chemical ionization mass spectrometric analysis.

Science.gov (United States)

Dasgupta, A; Spies, J

1998-05-01

Amphetamine and methamphetamine are commonly abused central nervous system stimulants. We describe a rapid new derivatization of amphetamine and methamphetamine using 2,2,2-trichloroethyl chloroformate for gas chromatography-mass spectrometric analysis. Amphetamine and methamphetamine, along with N-propyl amphetamine (internal standard), were extracted from urine using 1-chlorobutane. The derivatization with 2,2,2-trichloroethyl chloroformate can be achieved at room temperature in 10 minutes. The electron ionization mass spectrum of amphetamine 2,2,2-trichloroethyl carbamate showed two weak molecular ions at m/z 309 and 311, but showed diagnostic strong peaks at m/z 218, 220, and 222. In contrast, chemical ionization of the mass spectrum of amphetamine 2,2,2-trichloroethyl carbamate showed strong (M + 1) ions at m/z 310 and 312 and other strong diagnostic peaks at m/z 274 and 276. The major advantages of this derivative are the presence of a diagnostic cluster of peaks due to the isotopic effect of three chlorine atoms (isotopes 35 and 37) in the derivatized molecule and the relative ease of its preparation. We also observed strong molecular ions for derivatized methamphetamine in the chemical ionization mass spectrum, but the molecular ions were very weak in the electron ionization mass spectrum. We used the scan mode of mass spectrometry in all analyses. When using a urine standard containing 1,000 ng/mL of amphetamine (a 7.4-micromol/L concentration) and methamphetamine (a 6.7-micromol/L concentration), the within-run precisions were 4.8% for amphetamine and 3.6% for methamphetamine. The corresponding between-run precisions were 5.3% for amphetamine and 6.7% for methamphetamine. The assay was linear for amphetamine and methamphetamine concentrations of 250 to 5,000 ng/mL (amphetamine, 1.9-37.0 micromol/L; methamphetamine, 1.7-33.6 micromol/L). The detection limit was 100 ng/mL (amphetamine, 0.74 micromol/L; methamphetamine, 0.67 micromol/L) using the scan mode

Schinus terebinthifolius scale-up countercurrent chromatography (Part I): High performance countercurrent chromatography fractionation of triterpene acids with off-line detection using atmospheric pressure chemical ionization mass spectrometry.

Science.gov (United States)

Vieira, Mariana Neves; Costa, Fernanda das Neves; Leitão, Gilda Guimarães; Garrard, Ian; Hewitson, Peter; Ignatova, Svetlana; Winterhalter, Peter; Jerz, Gerold

2015-04-10

'Countercurrent chromatography' (CCC) is an ideal technique for the recovery, purification and isolation of bioactive natural products, due to the liquid nature of the stationary phase, process predictability and the possibility of scale-up from analytical to preparative scale. In this work, a method developed for the fractionation of Schinus terebinthifolius Raddi berries dichloromethane extract was thoroughly optimized to achieve maximal throughput with minimal solvent and time consumption per gram of processed crude extract, using analytical, semi-preparative and preparative 'high performance countercurrent chromatography' (HPCCC) instruments. The method using the biphasic solvent system composed of n-heptane-ethyl acetate-methanol-water (6:1:6:1, v/v/v/v) was volumetrically scaled up to increase sample throughput up to 120 times, while maintaining separation efficiency and time. As a fast and specific detection alternative, the fractions collected from the CCC-separations were injected to an 'atmospheric pressure chemical ionization mass-spectrometer' (APCI-MS/MS) and reconstituted molecular weight MS-chromatograms of the APCI-ionizable compounds from S. terebinthifolius were obtained. This procedure led to the direct isolation of tirucallane type triterpenes such as masticadienonic and 3β-masticadienolic acids. Also oleanonic and moronic acids have been identified for the first time in the species. In summary, this approach can be used for other CCC scale-up processes, enabling MS-target-guided isolation procedures. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of gas chromatography-surface ionization organic mass spectrometry to forensic toxicology.

Science.gov (United States)

Ishii, Akira; Watanabe-Suzuki, Kanako; Seno, Hiroshi; Suzuki, Osamu; Katsumata, Yoshinao

2002-08-25

Surface ionization (SI), which consists in the formation of positive and negative ions along the course of thermal desorption of particles from a solid surface, was first applied as a detector for gas chromatography (GC), GC-surface ionization detection (SID); we developed many new sensitive methods for the determination of abused and other drugs by GC-SID. Recently, Fujii has devised a combination of SI and a quadrupole mass spectrometer and named this system a surface ionization organic mass spectrometer (SIOMS), which is highly selective and sensitive for organic compounds containing tertiary amino groups. We have tried to apply this mass spectrometer to forensic toxicological study; so far we have succeeded in determining important drugs-of-abuse and toxic compounds, such as phencyclidine (PCP), pethidine, pentazocine, MPTP and its derivatives from human body fluids with high sensitivity and selectivity. In this review, we describe our recent studies on the application of GC-SIOMS to forensic toxicology. Copyright 2002 Elsevier Science B.V.

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...... spectrometry with atmospheric pressure chemical ionization in selected reaction monitoring mode with deuterium-labeled vitamin K1 as an internal standard. The precision was estimated as the pooled estimate of three replicates performed on three different days for spinach, peas, apples, banana, and beetroot...

Chemical analysis of raw and processed Fructus arctii by high-performance liquid chromatography/diode array detection-electrospray ionization-mass spectrometry

Science.gov (United States)

Qin, Kunming; Liu, Qidi; Cai, Hao; Cao, Gang; Lu, Tulin; Shen, Baojia; Shu, Yachun; Cai, Baochang

2014-01-01

Background: In traditional Chinese medicine (TCM), raw and processed herbs are used to treat the different diseases. Fructus Arctii, the dried fruits of Arctium lappa l. (Compositae), is widely used in the TCM. Stir-frying is the most common processing method, which might modify the chemical compositions in Fructus Arctii. Materials and Methods: To test this hypothesis, we focused on analysis and identification of the main chemical constituents in raw and processed Fructus Arctii (PFA) by high-performance liquid chromatography/diode array detection-electrospray ionization-mass spectrometry. Results: The results indicated that there was less arctiin in stir-fried materials than in raw materials. however, there were higher levels of arctigenin in stir-fried materials than in raw materials. Conclusion: We suggest that arctiin reduced significantly following the thermal conversion of arctiin to arctigenin. In conclusion, this finding may shed some light on understanding the differences in the therapeutic values of raw versus PFA in TCM. PMID:25422559

Advantages of Atmospheric Pressure Chemical Ionization in Gas Chromatography Tandem Mass Spectrometry: Pyrethroid Insecticides as a Case Study

NARCIS (Netherlands)

Portolés, T.; Mol, J.G.J.; Sancho, J.V.; Hernández, F.

2012-01-01

Gas chromatography coupled to mass spectrometry (GC/MS) has been extensively applied for determination of volatile, nonpolar, compounds in many applied fields like food safety, environment, or toxicology. The wide majority of methods reported use electron ionization (EI), which may result in

Development and validation of a gas chromatography-negative chemical ionization tandem mass spectrometry method for the determination of ethyl glucuronide in hair and its application to forensic toxicology.

Science.gov (United States)

Kharbouche, Hicham; Sporkert, Frank; Troxler, Stéphanie; Augsburger, Marc; Mangin, Patrice; Staub, Christian

2009-08-01

Ethyl glucuronide (EtG) is a minor and direct metabolite of ethanol. EtG is incorporated into the growing hair allowing retrospective investigation of chronic alcohol abuse. In this study, we report the development and the validation of a method using gas chromatography-negative chemical ionization tandem mass spectrometry (GC-NCI-MS/MS) for the quantification of EtG in hair. EtG was extracted from about 30 mg of hair by aqueous incubation and purified by solid-phase extraction (SPE) using mixed mode extraction cartridges followed by derivation with perfluoropentanoic anhydride (PFPA). The analysis was performed in the selected reaction monitoring (SRM) mode using the transitions m/z 347-->163 (for the quantification) and m/z 347-->119 (for the identification) for EtG, and m/z 352-->163 for EtG-d(5) used as internal standard. For validation, we prepared quality controls (QC) using hair samples taken post mortem from 2 subjects with a known history of alcoholism. These samples were confirmed by a proficiency test with 7 participating laboratories. The assay linearity of EtG was confirmed over the range from 8.4 to 259.4 pg/mg hair, with a coefficient of determination (r(2)) above 0.999. The limit of detection (LOD) was estimated with 3.0 pg/mg. The lower limit of quantification (LLOQ) of the method was fixed at 8.4 pg/mg. Repeatability and intermediate precision (relative standard deviation, RSD%), tested at 4 QC levels, were less than 13.2%. The analytical method was applied to several hair samples obtained from autopsy cases with a history of alcoholism and/or lesions caused by alcohol. EtG concentrations in hair ranged from 60 to 820 pg/mg hair.

Fragmentation pathways and structural characterization of organophosphorus compounds related to the Chemical Weapons Convention by electron ionization and electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Hosseini, Seyed Esmaeil; Saeidian, Hamid; Amozadeh, Ali; Naseri, Mohammad Taghi; Babri, Mehran

2016-12-30

For unambiguous identification of Chemical Weapons Convention (CWC)-related chemicals in environmental samples, the availability of mass spectra, interpretation skills and rapid microsynthesis of suspected chemicals are essential requirements. For the first time, the electron ionization single quadrupole and electrospray ionization tandem mass spectra of a series of O-alkyl N-[bis(dimethylamino)methylidene]-P-methylphosphonamidates (Scheme 1, cpd 4) were studied for CWC verification purposes. O-Alkyl N-[bis(dimethylamino)methylidene]-P-methylphosphonamidates were prepared through a microsynthetic method and were analyzed using electron ionization and electrospray ionization mass spectrometry with gas and liquid chromatography, respectively, as MS-inlet systems. General EI and ESI fragmentation pathways were proposed and discussed, and collision-induced dissociation studies of the protonated derivatives of these compounds were performed to confirm proposed fragment ion structures by analyzing mass spectra of deuterated analogs. Mass spectrometric studies revealed some interesting fragmentation pathways during the ionization process, such as McLafferty rearrangement, hydrogen rearrangement and a previously unknown intramolecular electrophilic aromatic substitution reaction. The EI and ESI fragmentation routes of the synthesized compounds 4 were investigated with the aim of detecting and identifying CWC-related chemicals during on-site inspection and/or off-site analysis and toxic chemical destruction monitoring. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

High-throughput and simultaneous analysis of eight central-acting muscle relaxants in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry in the positive and negative ionization modes.

Science.gov (United States)

Ogawa, Tadashi; Hattori, Hideki; Kaneko, Rina; Ito, Kenjiro; Iwai, Masae; Mizutani, Yoko; Arinobu, Tetsuya; Ishii, Akira; Seno, Hiroshi

2011-06-01

In this report, a high-throughput and sensitive method for analysis of eight central-acting muscle relaxants in human plasma by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in the positive and negative ionization modes using tolbutamide as internal standard is presented. After pretreatment of a plasma sample by solid-phase extraction with an Oasis HLB cartridge, muscle relaxants were analyzed by UPLC with Acquity UPLC BEH C(18) column and Acquity TQD tandem quadrupole mass spectrometer equipped with an electrospray ionization interface. The calibration curves for muscle relaxants spiked into human plasma equally showed good linearities in the nanogram per milliliter order range. The detection limits (signal-to-noise ratio = 3) was as low as 0.1-2 ng/mL. The method gave satisfactory recovery rates, accuracy, and precision for quality control samples spiked with muscle relaxants. To further validate the present method, 250 mg of chlorphenesin carbamate was orally administered to a healthy male volunteer, and the concentrations of chlorphenesin carbamate in plasma were measured 0.5, 1, 2, 4, 6, and 8 h after dosing; their concentrations in human plasma were between 0.62 and 2.44 μg/mL. To our knowledge, this is the first report describing simultaneous analysis of over more than two central-acting muscle relaxants by liquid chromatography-tandem mass spectrometry. This has been realized by the capability of our instrument for simultaneous multiple reaction monitoring of the target compounds in both positive and negative ionization modes. Therefore, the present method seems very useful in forensic and clinical toxicology and pharmacokinetic studies.

Synthesis of trans-4,5-epoxy-(E)-2-decenal and its deuterated analog used for the development of a sensitive and selective quantification method based on isotope dilution assay with negative chemical ionization.

Science.gov (United States)

Lin, J; Fay, L B; Welti, D H; Blank, I

1999-10-01

The volatile compound trans-4,5-epoxy-(E)-2-decenal (1) was synthesized in two steps with good overall yields. The newly developed method is based on trans-epoxidation of (E)-2-octenal with alkaline hydrogen peroxide followed by a Wittig-type chain elongation with the ylide formylmethylene triphenylphosphorane. For the synthesis of [4,5-2H2]-trans-4,5-epoxy-(E)-2-decenal (d-1), [2,3-2H2]-(E)-2-octenal was prepared by reduction of 2-octyn-1-ol with lithium aluminum deuteride and subsequent oxidation of [2,3-2H2]-(E)-2-octen-1-ol with manganese oxide. Compound d1 was used as internal standard for the quantification of 1 by isotope dilution assay. Among various mass spectrometry (MS) ionization techniques tested, negative chemical ionization with ammonia as reagent gas gave best results with respect to both sensitivity and selectivity. The detection limit was found to be at about 1 pg of the analyte introduced into the gas chromatography-MS system.

Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids.

Science.gov (United States)

Raro, M; Portolés, T; Pitarch, E; Sancho, J V; Hernández, F; Garrostas, L; Marcos, J; Ventura, R; Segura, J; Pozo, O J

2016-02-04

The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid-liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H](+) or [M + H-2TMSOH](+) ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL(-1). Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. Copyright © 2015 Elsevier B.V. All rights reserved.

Analysis of insect triacylglycerols using liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

Czech Academy of Sciences Publication Activity Database

Kofroňová, Edita; Cvačka, Josef; Jiroš, Pavel; Sýkora, D.; Valterová, Irena

2009-01-01

Roč. 111, č. 5 (2009), s. 519-525 ISSN 1438-7697 R&D Projects: GA AV ČR IAA4055403; GA MŠk 2B06007 Institutional research plan: CEZ:AV0Z40550506 Keywords : atmospheric pressure chemical ionization * bumblebees * fat body * NARP-HPLC Subject RIV: CC - Organic Chemistry Impact factor: 1.831, year: 2009

An evaluation of liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization for the rapid and simultaneous measurement of carbamate pesticides and organophorus pesticides

International Nuclear Information System (INIS)

Kim, Byung Joo; So, Hun Young

2000-01-01

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface (LC/APCI/MS) is evaluated for the simultaneous determination of carbamate pesticides and organophosphorus pesticides in a single chromatographic analysis. APCI mass spectra of those compounds were obtained to study their ionization characteristics. APCI provided abundant ions such as protonated molecules and characteristic fragment ions for carbamate pesticides and organophosphorus pesticides. To evaluate the feasibility of the LC/APCI/MS for a routine quantitative analysis, the linearity and repeatability of LC/APCI/MS were examined by measuring standard solution mixtures of five carbamate pesticides and four organophosphorus pesticides over the range of 1 to 100 μg/mL. The peak areas in chromatograms of characteristic ions for those compounds showed less than 3% of variation from run to tun. The standard calibration curves for the nine pesticides show good linearity in the concentration range. The detection limits of the LC/APCI/MS system for those compounds range from 0.006 to 0.2 ng

An evaluation of liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization for the rapid and simultaneous measurement of carbamate pesticides and organophorus pesticides

Energy Technology Data Exchange (ETDEWEB)

Kim, Byung Joo; So, Hun Young [Korea Research Institute of Standards and Sceince, Taejon (Korea, Republic of)

2000-05-01

Liquid chromatography/mass spectrometry with an atmospheric pressure chemical ionization interface (LC/APCI/MS) is evaluated for the simultaneous determination of carbamate pesticides and organophosphorus pesticides in a single chromatographic analysis. APCI mass spectra of those compounds were obtained to study their ionization characteristics. APCI provided abundant ions such as protonated molecules and characteristic fragment ions for carbamate pesticides and organophosphorus pesticides. To evaluate the feasibility of the LC/APCI/MS for a routine quantitative analysis, the linearity and repeatability of LC/APCI/MS were examined by measuring standard solution mixtures of five carbamate pesticides and four organophosphorus pesticides over the range of 1 to 100 {mu}g/mL. The peak areas in chromatograms of characteristic ions for those compounds showed less than 3% of variation from run to tun. The standard calibration curves for the nine pesticides show good linearity in the concentration range. The detection limits of the LC/APCI/MS system for those compounds range from 0.006 to 0.2 ng.

Is ionizing radiation regulated more stringently than chemical carcinogens

International Nuclear Information System (INIS)

Travis, C.C.; Pack, S.R.; Hattemer-Frey, H.A.

1989-01-01

It is widely believed that United States government agencies regulate exposure to ionizing radiation more stringently than exposure to chemical carcinogens. It is difficult to verify this perception, however, because chemical carcinogens and ionizing radiation are regulated using vastly different strategies. Chemical carcinogens are generally regulated individually. Regulators consider the risk of exposure to one chemical rather than the cumulative radiation exposure from all sources. Moreover, standards for chemical carcinogens are generally set in terms of quantities released or resultant environmental concentrations, while standards for ionizing radiation are set in terms of dose to the human body. Since chemicals and ionizing radiation cannot be compared on the basis of equal dose to the exposed individual, standards regulating chemicals and ionizing radiation cannot be compared directly. It is feasible, however, to compare the two sets of standards on the basis of equal risk to the exposed individual, assuming that standards for chemicals and ionizing radiation are equivalent if estimated risk levels are equitable. This paper compares risk levels associated with current standards for ionizing radiation and chemical carcinogens. The authors do not attempt to determine whether either type of risk is regulated too stringently or not stringently enough but endeavor only to ascertain if ionizing radiation is actually regulated more strictly than chemical carcinogens

A positive (negative) surface ionization source concept for RIB generation

International Nuclear Information System (INIS)

Alton, G.D.; Mills, G.D.

1995-01-01

A novel, versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed and fabricated which will have the capability of generating both positive- and negative-ion beams without mechanical changes to the source. The source utilizes a highly permeable, high-work-function Ir ionizer (φ∼ = 5.29 eV) for ionizing highly electropositive atoms/molecules; while for negative-surface ionization, the work function is lowered to φ ∼ = 1.43 eV by continually feeding cesium vapor through the ionizer matrix. The use of Cs to effect low work function surfaces for negative ion beam generation has the potential of overcoming the chronic poisoning effects experienced with LaB 6 while enhancing the probability for negative ion formation of atomic and molecular species with low to intermediate electron affinities. The flexibility of operation in either mode makes it especially attractive for RIB applications and, therefore, the source will be used as a complementary replacement for the high-temperature electron impact ionization sources presently in use at the HRIBF The design features and operational principles of the source will be described in this report

Simultaneous testing of multiclass organic contaminants in food and environment by liquid chromatography/dielectric barrier discharge ionization-mass spectrometry.

Science.gov (United States)

Gilbert-López, Bienvenida; García-Reyes, Juan F; Meyer, Cordula; Michels, Antje; Franzke, Joachim; Molina-Díaz, Antonio; Hayen, Heiko

2012-11-21

A Dielectric Barrier Discharge Ionization (DBDI) LC/MS interface is based on the use of a low-temperature helium plasma, which features the possibility of simultaneous ionization of species with a wide variety of physicochemical properties. In this work, the performance of LC/DBDI-MS for trace analysis of highly relevant species in food and environment has been examined. Over 75 relevant species including multiclass priority organic contaminants and residues such as pesticides, polycyclic aromatic hydrocarbons, organochlorine species, pharmaceuticals, personal care products, and drugs of abuse were tested. LC/DBDI-MS performance for this application was assessed and compared with standard LC/MS sources (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)). The used benchtop Orbitrap mass spectrometer features a 10 Hz polarity switching mode, so that both positive and negative ion mode acquisitions are possible with acquisition cycles matching the requirements of fast liquid chromatography. Both polar and nonpolar species (including those typically analyzed by GC/electron ionization-MS) can be tested in a single run using polarity switching mode. The methodology was found to be effective in detecting a wide array of organic compounds at concentration levels in the low ng L(-1) to μg kg(-1) range in wastewater and food matrices, respectively. The linearity was evaluated in an olive oil extract, obtaining good correlation coefficients in the studied range. Additionally, minor matrix effects (≤15% of signal suppression or enhancement) were observed for most of the studied analytes in this complex fatty matrix. The results obtained were compared with data from both ESI and APCI sources, obtaining a merged coverage between ESI and APCI in terms of analyte ionization and higher overall sensitivity for the proposed ion source based on the DBD principle. The use of this approach further extends the coverage of current LC/MS methods towards

Chemical ionization mass spectrometry of indol-3yl-acetic acid and cis-abscisic acid: evaluation of negative ion detection and quantification of cis-abscisic acid in growing maize roots

International Nuclear Information System (INIS)

Rivier, L.; Saugy, M.

1986-01-01

Mass spectra of the derivatives of indol-3yl-acetic acid and cis-abscisic acid were obtained in electron impact and chemical ionization positive ion and negative ion modes. The respective merits of methane, isobutane, and ammonia as reagent gases for structure determination and sensitive detection were compared using the methyl esters. From one to 10 fluorine atoms were attached to IAA to improve the electron-capturing properties of the molecule. The best qualitative information was obtained when using positive ion chemical ionization with methane. However, the most sensitive detection, with at least two ions per molecule, was achieved by electron impact on the IAA-HFB-ME derivative and by negative ion chemical ionization with NH 3 on the ABA-methyl ester derivative. p ]Quantitative analyses of ABA in different parts of maize (Zea mays cv. LG 11) root tips were performed by the latter technique. It was found that the cap and apex contained less ABA than the physiologically older parts of the root such as the elongation zone and the more differentiated tissues. This technique was also used to show a relation between maize root growth and the endogenous ABA level of the elongation zone and root tip: there is more ABA in the slowly growing roots than in the rapidly growing ones. (author)

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.

Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids

International Nuclear Information System (INIS)

Raro, M.; Portolés, T.; Pitarch, E.; Sancho, J.V.; Hernández, F.; Garrostas, L.; Marcos, J.; Ventura, R.; Segura, J.; Pozo, O.J.

2016-01-01

The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid–liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H] + or [M + H-2TMSOH] + ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL −1 . Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. - Highlights: • APCI source has been evaluated for the screening of 16 exogenous AAS in urine. • Suitable precision was

Potential of atmospheric pressure chemical ionization source in gas chromatography tandem mass spectrometry for the screening of urinary exogenous androgenic anabolic steroids

Energy Technology Data Exchange (ETDEWEB)

Raro, M.; Portolés, T.; Pitarch, E.; Sancho, J.V.; Hernández, F. [Research Institute for Pesticides and Water, University Jaume I, E-12071 Castellón (Spain); Garrostas, L. [Bioanalysis Research Group, IMIM, Hospital del Mar Medical Research Institute, Doctor Aiguader 88, 08003 Barcelona (Spain); Marcos, J.; Ventura, R.; Segura, J. [Bioanalysis Research Group, IMIM, Hospital del Mar Medical Research Institute, Doctor Aiguader 88, 08003 Barcelona (Spain); Department of Experimental and Health Sciencies, Universitat Pompeu Fabra, Doctor Aiguader 88, 08003 Barcelona (Spain); Pozo, O.J., E-mail: opozo@imim.es [Bioanalysis Research Group, IMIM, Hospital del Mar Medical Research Institute, Doctor Aiguader 88, 08003 Barcelona (Spain)

2016-02-04

The atmospheric pressure chemical ionization (APCI) source for gas chromatography-mass spectrometry analysis has been evaluated for the screening of 16 exogenous androgenic anabolic steroids (AAS) in urine. The sample treatment is based on the strategy currently applied in doping control laboratories i.e. enzymatic hydrolysis, liquid–liquid extraction (LLE) and derivatization to form the trimethylsilyl ether-trimethylsilyl enol ether (TMS) derivatives. These TMS derivatives are then analyzed by gas chromatography tandem mass spectrometry using a triple quadrupole instrument (GC-QqQ MS/MS) under selected reaction monitoring (SRM) mode. The APCI promotes soft ionization with very little fragmentation resulting, in most cases, in abundant [M + H]{sup +} or [M + H-2TMSOH]{sup +} ions, which can be chosen as precursor ions for the SRM transitions, improving in this way the selectivity and sensitivity of the method. Specificity of the transitions is also of great relevance, as the presence of endogenous compounds can affect the measurements when using the most abundant ions. The method has been qualitatively validated by spiking six different urine samples at two concentration levels each. Precision was generally satisfactory with RSD values below 25 and 15% at the low and high concentration level, respectively. Most the limits of detection (LOD) were below 0.5 ng mL{sup −1}. Validation results were compared with the commonly used method based on the electron ionization (EI) source. EI analysis was found to be slightly more repeatable whereas lower LODs were found for APCI. In addition, the applicability of the developed method has been tested in samples collected after the administration of 4-chloromethandienone. The highest sensitivity of the APCI method for this compound, allowed to increase the period in which its administration can be detected. - Highlights: • APCI source has been evaluated for the screening of 16 exogenous AAS in urine. • Suitable

Unresolved issues in the analysis of F2-isoprostanes, F4-neuroprostanes, isofurans, neurofurans, and F2-dihomo-isoprostanes in body fluids and tissue using gas chromatography/negative-ion chemical-ionization mass spectrometry.

Science.gov (United States)

Yen, H-C; Wei, H-J; Lin, C-L

2015-01-01

F2-isoprostanes (F2-IsoPs) generated from arachidonic acid (AA) have been recognized as the most reliable marker of nonenzymatic lipid peroxidation in vivo. F2-IsoPs are initially produced in esterified form on phospholipids, and then released into body fluids in free form. The same mechanism can lead to generation of F4-neuroprostanes (F4-NPs) and F2-dihomo-IsoPs from docosahexaenoic acid (DHA) and adrenic acid, respectively. In addition, isofurans (IsoFs) and neurofurans (NFs) may be preferentially produced from AA and DHA, respectively, under high oxygen tension. The detection of F2-IsoPs using gas chromatography/negative-ion chemical-ionization mass spectrometry (GC/NICI-MS) has been widely employed, which is important for human body fluids containing low quantity of free-form F2-IsoPs. F4-NPs have also been detected using GC/NICI-MS, but multiple peaks need to be quantified. In this paper, we summarize the basic workflow of the GC/NICI-MS method for analyzing F2-IsoPs and F4-NPs, and various formats of assays conducted by different groups. We then discuss the feasibility of simultaneous analysis of IsoFs, NFs, and F2-dihomo-IsoPs with F2-IsoPs or F4-NPs. Representative GC chromatograms for analyzing these markers in human body fluids and rat brain tissue are demonstrated. Furthermore, we discuss several factors that may affect the performance of the analysis, such as those related to the sample processing steps, interference from specimens, types of GC liners used, and the addition of electron multiplier voltage in the method setting for the MS detector. Finally, we question the appropriateness of measuring total (free plus esterified) levels of these markers in body fluids.

Method for the elucidation of the elemental composition of low molecular mass chemicals using exact masses of product ions and neutral losses: application to environmental chemicals measured by liquid chromatography with hybrid quadrupole/time-of-flight mass spectrometry.

Science.gov (United States)

Suzuki, Shigeru; Ishii, Tetsuko; Yasuhara, Akio; Sakai, Shinichi

2005-01-01

A method for elucidating the elemental compositions of low molecular weight chemicals, based primarily on mass measurements made using liquid chromatography (LC) with time-of-flight mass spectrometry (TOFMS) and quadrupole/time-of-flight mass spectrometry (LC/QTOFMS), was developed and tested for 113 chemicals of environmental interest with molecular masses up to approximately 400 Da. As the algorithm incorporating the method is not affected by differences in the instrument used, or by the ionization method and other ionization conditions, the method is useful not only for LC/TOFMS, but also for all kinds of mass spectra measured with higher accuracy and precision (uncertainties of a few mDa) employing all ionization methods and on-line separation techniques. The method involves calculating candidate compositions for intact ionized molecules (ionized forms of the sample molecule that have lost or gained no more than a proton, i.e., [M+H](+) or [M-H](-)) as well as for fragment ions and corresponding neutral losses, and eliminating those atomic compositions for the molecules that are inconsistent with the corresponding candidate compositions of fragment ions and neutral losses. Candidate compositions were calculated for the measured masses of the intact ionized molecules and of the fragment ions and corresponding neutral losses, using mass uncertainties of 2 and 5 mDa, respectively. Compositions proposed for the ionized molecule that did not correspond to the sum of the compositions of a candidate fragment ion and its corresponding neutral loss were discarded. One, 2-5, 6-10, 11-20, and >20 candidate compositions were found for 65%, 39%, 1%, 1%, and 0%, respectively, for the 124 ionized molecules formed from the 113 chemicals tested (both positive and negative ions were obtained from 11 of the chemicals). However, no candidate composition was found for 2% of the test cases (i.e., 3 chemicals), for each of which the measured mass of one of the product ions was in

Supercritical fluid chromatography coupled with in-source atmospheric pressure ionization hydrogen/deuterium exchange mass spectrometry for compound speciation.

Science.gov (United States)

Cho, Yunju; Choi, Man-Ho; Kim, Byungjoo; Kim, Sunghwan

2016-04-29

An experimental setup for the speciation of compounds by hydrogen/deuterium exchange (HDX) with atmospheric pressure ionization while performing chromatographic separation is presented. The proposed experimental setup combines the high performance supercritical fluid chromatography (SFC) system that can be readily used as an inlet for mass spectrometry (MS) and atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI) HDX. This combination overcomes the limitation of an approach using conventional liquid chromatography (LC) by minimizing the amount of deuterium solvents used for separation. In the SFC separation, supercritical CO2 was used as a major component of the mobile phase, and methanol was used as a minor co-solvent. By using deuterated methanol (CH3OD), AP HDX was achieved during SFC separation. To prove the concept, thirty one nitrogen- and/or oxygen-containing standard compounds were analyzed by SFC-AP HDX MS. The compounds were successfully speciated from the obtained SFC-MS spectra. The exchange ions were observed with as low as 1% of CH3OD in the mobile phase, and separation could be performed within approximately 20min using approximately 0.24 mL of CH3OD. The results showed that SFC separation and APPI/APCI HDX could be successfully performed using the suggested method. Copyright © 2016 Elsevier B.V. All rights reserved.

Trace analysis of selected hormones and sterols in river sediments by liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

Science.gov (United States)

Matić, Ivana; Grujić, Svetlana; Jauković, Zorica; Laušević, Mila

2014-10-17

In this paper, development and optimization of new LC-MS method for determination of twenty selected hormones, human/animal and plant sterols in river sediments were described. Sediment samples were prepared using ultrasonic extraction and clean up with silica gel/anhydrous sodium sulphate cartridge. Extracts were analyzed by liquid chromatography-linear ion trap-tandem mass spectrometry, with atmospheric pressure chemical ionization. The optimized extraction parameters were extraction solvent (methanol), weight of the sediment (2 g) and time of ultrasonic extraction (3× 10 min). Successful chromatographic separation of hormones (estriol and estrone, 17α- and 17β-estradiol) and four human/animal sterols (epicoprostanol, coprostanol, α-cholestanol and β-cholestanol) that have identical fragmentation reactions was achieved. The developed and optimized method provided high recoveries (73-118%), low limits of detection (0.8-18 ng g(-1)) and quantification (2.5-60 ng g(-1)) with the RSDs generally lower than 20%. Applicability of the developed method was confirmed by analysis of six river sediment samples. A widespread occurrence of human/animal and plant sterols was found. The only detected hormone was mestranol in just one sediment sample. Copyright © 2014 Elsevier B.V. All rights reserved.

A positive (negative) surface ionization source concept for radioactive ion beam generation

International Nuclear Information System (INIS)

Alton, G.D.; Mills, G.D.

1996-01-01

A novel, versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed and fabricated which will have the capability of generating both positive- and negative-ion beams without mechanical changes to the source. The source utilizes a highly permeable, high-work-function Ir ionizer (φ ≅ 5.29 eV) for ionizing highly electropositive atoms/molecules; while for negative-surface ionization, the work function is lowered by continually feeding a highly electropositive vapor through the ionizer matrix. The use of this technique to effect low work function surfaces for negative ion beam generation has the potential of overcoming the chronic poisoning effects experienced with LaB 6 while enhancing the probability for negative ion formation of atomic and molecular species with low to intermediate electron affinities. The flexibility of operation in either mode makes it especially attractive for radioactive ion beam (RIB) applications and, therefore, the source will be used as a complementary replacement for the high-temperature electron impact ionization sources presently in the use at the Holifield radioactive ion beam facility (HRIBF). The design features and operational principles of the source are described in this report. (orig.)

Triacylglycerols profiling in plant oils important in food industry, dietetics and cosmetics using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Science.gov (United States)

Lísa, Miroslav; Holcapek, Michal

2008-07-11

Optimized non-aqueous reversed-phase high-performance liquid chromatography method using acetonitrile-2-propanol gradient elution and the column coupling in the total length of 45 cm has been applied for the high resolution separation of plant oils important in food industry, dietetics and cosmetics. Positive-ion atmospheric pressure chemical ionization mass spectrometry is used for the unambiguous identification and also the reliable quantitation with the response factors approach. Based on the precise determination of individual triacyglycerol concentrations, the calculation of average parameters important in the nutrition is performed, i.e. average carbon number, average double bond number, relative concentrations of essential, saturated, monounsaturated and polyunsaturated fatty acids. Results are reported in the form of both chromatographic fingerprints and tables containing relative concentrations for all triacylglycerols and fatty acids in individual samples. In total, 264 triacylglycerols consisting of 28 fatty acids with the alkyl chain length from 6 to 26 carbon atoms and 0 to 4 double bonds have been identified in 26 industrial important plant oils.

Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods

Science.gov (United States)

Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

2017-03-01

Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

Atmospheric Pressure Chemical Ionization Gas Chromatography Mass Spectrometry for the Analysis of Selected Emerging Brominated Flame Retardants in Foods.

Science.gov (United States)

Lv, Surong; Niu, Yumin; Zhang, Jing; Shao, Bing; Du, Zhenxia

2017-03-10

Emerging brominated flame retardants (eBFRs) other than polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs) and their derivatives in foods have been in focus in recent years due to their increasing production volumes, indefinite information on toxicities and the lack of data on occurrence in environments, foods as well as humans. In this study, gas chromatography was coupled to an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS) for the analysis of six eBFRs in pork, chicken, egg, milk and fish. A short section of unpacked capillary column coupled to the end of the analytical column was applied to improve the chromatographic behaviors of high boiling point compounds. The method was comprehensively validated with method limit of quantification (mLOQ) lower than 8 pg/g wet weight (w.w.). Samples from Chinese Total Diet study were quantified following the validated APGC-MS/MS method. 2,3,4,5-pentabromo-6-ethylbenzene (PBEB), hexabromobenzene (HBB), pentabromotoluene (PBT) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were most frequently detected in samples. The highest concentration was found in fish with 351.9 pg/g w.w. of PBT. This is the first report on the presence of PBT in food samples with non-ignorable concentrations and detection rate.

Chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Livesey, J.C.; Reed, D.J.

1987-01-01

Over 40 years have passed since the research of the Manhattan Project suggested the possibility of chemical protection against ionizing radiation. During that time, much has been learned about the nature of radiation-induced injury and the factors governing the expression of that injury. Thousands of compounds have been tested for radioprotective efficacy, and numerous theories have been proposed to account for these actions. The literature on chemical radioprotection is large. In this article, the authors consider several of the mechanisms by which chemicals may protect against radiation injury. They have chosen to accent this view of radioprotector research as opposed to that research geared toward developing specific molecules as protective agents because they feel that such an approach is more beneficial in stimulating research of general applicability. This paper describes the matrix of biological factors upon which an exogenous radioprotector is superimposed, and examines evidence for and against various mechanisms by which these agents may protect biological systems against ionizing radiation. It concludes with a brief outlook for research in chemical radioprotection

The Application of Resonance-Enhanced Multiphoton Ionization Technique in Gas Chromatography Mass Spectrometry

Directory of Open Access Journals (Sweden)

Adan Li

2014-01-01

Full Text Available Gas chromatography resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (GC/REMPI-TOFMS using a nanosecond laser has been applied to analyze the 16 polycyclic aromatic hydrocarbons (PAHs. The excited-state lifetime, absorption characters, and energy of electronic states of the 16 PAHs were investigated to optimize the ionization yield. A river water sample pretreated by means of solid phase extraction was analyzed to evaluate the performance of the analytical instrument. The results suggested that REMPI is superior to electron impact ionization method for soft ionization and suppresses the background signal due to aliphatic hydrocarbons. Thus, GC/REMPI-TOFMS is a more reliable method for the determination of PAHs present in the environment.

Ultra high performance liquid chromatography coupled with electrospray ionization/quadrupole time-of-flight mass spectrometry for the rapid analysis of constituents in the traditional Chinese medicine formula Wu Ji Bai Feng Pill.

Science.gov (United States)

Duan, Shengnan; Qi, Wen; Zhang, Siwen; Huang, Kunkun; Yuan, Dan

2017-10-01

An ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry method in both positive and negative ion modes was established in order to comprehensively investigate the major constituents in Wu Ji Bai Feng Pill. Briefly, a Waters ACQUITY UPLC HSS C 18 column was used to separate the aqueous extract of Wu Ji Bai Feng Pill. A total of 0.1% formic acid in acetonitrile and 0.1% aqueous formic acid v/v were used as the mobile phase. All analytes were determined using quadrupole time-of-flight mass spectrometry with electrospray ionization source in positive and negative ion modes. At length, a total of 173 components including flavones and their glycosides, monoterpene glycosides, triterpene saponins, phenethylalchohol glycosides, iridoid glycosides, phthalides, tanshinones, phenolic acids, sesquiterpenoids and cyclopeptides were identified or tentatively characterized in Wu Ji Bai Feng Pill in an analysis of 16.0 min based on the accurate mass and tandem mass spectrometry behaviors. The developed method is rapid and highly sensitive to characterize the chemical constituents of Wu Ji Bai Feng Pill, which could not only be used for chemical standardization and quality control of Wu Ji Bai Feng Pill, but also be helpful for further study in vivo metabolism of Wu Ji Bai Feng Pill. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Both gas chromatography and an electronic nose reflect chemical polymorphism of juniper shrubs browsed or avoided by sheep.

Science.gov (United States)

Markó, Gábor; Novák, Ildikó; Bernáth, Jeno; Altbäcker, Vilmos

2011-07-01

Chemical polymorphism may contribute to variation in browsing damage by mammalian herbivores. Earlier, we demonstrated that essential oil concentration in juniper, Juniperus communis, was negatively associated with herbivore browsing. The aim of the present study was to characterize the volatile chemical composition of browsed and non-browsed J. communis. By using either gas chromatography with flame ionization detection (GC-FID) or an electronic nose device, we could separate sheep-browsed or non-browsed juniper shrubs by their essential oil pattern and complex odor matrix. The main components of the essential oil from J. communis were monoterpenes. We distinguished three chemotypes, dominated either by α-pinene, sabinene, or δ-3-carene. Shrubs belonging to the α-pinene- or sabinene-dominated groups were browsed, whereas all individuals with the δ-3-carene chemotype were unused by the local herbivores. The electronic nose also separated the browsed and non-browsed shrubs indicating that their odor matrix could guide sheep browsing. Responses of sheep could integrate the post-ingestive effects of plant secondary metabolites with sensory experience that stems from odor-phytotoxin interactions. Chemotype diversity could increase the survival rate in the present population of J. communis as certain shrubs could benefit from relatively better chemical protection against the herbivores.

A high-efficiency positive (negative) surface ionization source for radioactive ion beam (abstract)a

International Nuclear Information System (INIS)

Alton, G.D.; Mills, G.D.

1996-01-01

A versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed and fabricated which will have the capability of generating both positive- and negative-ion beams without mechanical changes to the source. The source utilizes a highly permeable, high-work-function Ir ionizer (φ≡5.29 eV) for ionizing highly electropositive atoms/molecules; while for negative-surface ionization, the work function is lowered to φ≡1.43 eV by continually feeding cesium vapor through the ionizer matrix. The use of this technique for negative ion beam generation has the potential of overcoming the chronic poisoning effects experienced with LaB 6 while enhancing considerably the efficiency for negative surface ionization of atoms and molecules with intermediate electron affinities. The flexibility of operation in either mode makes it especially attractive for radioactive ion beam applications and, therefore, the source will be used as a complementary replacement for the high-temperature electron impact ionization sources presently in use at the Holifield radioactive beam facility. The design features and operational principles of the source will be described in this report. copyright 1996 American Institute of Physics

Simultaneous determination of thirteen flavonoids from Xiaobuxin-Tang extract using high-performance liquid chromatography coupled with electrospray ionization mass spectrometry.

Science.gov (United States)

Cen, Meifeng; Ruan, Jinxiu; Huang, Lihua; Zhang, Zhenqing; Yu, Nengjiang; Zhang, Youzhi; Cheng, Xuange; Xiong, Xiaohong; Wang, Guixiang; Zang, Linquan; Wang, Sujun

2015-11-10

A simple and reliable high performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis method was established to simultaneously determine thirteen flavonoids of Xiaobuxing-Tang in intestine perfusate, namely onpordin, 3'-O-methylorobol, glycitein, patuletin, genistein, luteolin, quercetin, nepitrin, quercimeritrin, daidzin, patulitrin, quercetagitrin and 3-glucosylisorhamnetin. Detection was performed on a quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source operating in negative ionization mode. Negative ion ESI was used to form deprotonated molecules at m/z 315 for onpordin, m/z 299 for 3'-O-methylorobol, m/z 283 for glycitein, m/z 331 for patuletin, m/z 269 for genistein, m/z 285 for luteolin, m/z 301 for quercetin, m/z 477 for nepitrin, m/z 463 for quercimeritrin, m/z 461 for daidzin, m/z 493 for patulitrin, m/z 479 for quercetagitrin, m/z 477 for 3-glucosylisorhamnetin and m/z 609.2 for rutin. The linearity, sensitivity, selectivity, repeatability, accuracy, precision, recovery and matrix effect of the assay were evaluated. The proposed method was successfully applied to simultaneous determination of these thirteen flavonoids, and using this method, the intestinal absorption profiles of thirteen flavonoids were preliminarily predicted. Copyright © 2015 Elsevier B.V. All rights reserved.

SFC-APLI-(TOF)MS: Hyphenation of Supercritical Fluid Chromatography to Atmospheric Pressure Laser Ionization Mass Spectrometry.

Science.gov (United States)

Klink, Dennis; Schmitz, Oliver Johannes

2016-01-05

Atmospheric-pressure laser ionization mass spectrometry (APLI-MS) is a powerful method for the analysis of polycyclic aromatic hydrocarbon (PAH) molecules, which are ionized in a selective and highly sensitive way via resonance-enhanced multiphoton ionization. APLI was presented in 2005 and has been hyphenated successfully to chromatographic separation techniques like high performance liquid chromatography (HPLC) and gas chromatography (GC). In order to expand the portfolio of chromatographic couplings to APLI, a new hyphenation setup of APLI and supercritical-fluid chromatography (SFC) was constructed and aim of this work. Here, we demonstrate the first hyphenation of SFC and APLI in a simple designed way with respect to different optimization steps to ensure a sensitive analysis. The new setup permits qualitative and quantitative determination of native and also more polar PAH molecules. As a result of the altered ambient characteristics within the source enclosure, the quantification of 1-hydroxypyrene (1-HP) in human urine is possible without prior derivatization. The limit of detection for 1-HP by SFC-APLI-TOF(MS) was found to be 0.5 μg L(-1), which is lower than the 1-HP concentrations found in exposed persons.

Liquid chromatography/negative electrospray ionization ion trap MS(2) mass spectrometry application for the determination of microcystins occurrence in Southern Portugal water reservoirs.

Science.gov (United States)

Rodrigues, M A; Reis, M P; Mateus, M C

2013-11-01

Microcystins (MCs) are toxins produced by cyanobacteria which are common organisms in the phytoplankton of eutrophic lakes, rivers and freshwater reservoirs. In the present work, a novel method of liquid chromatography-electrospray ion trap tandem mass spectrometry (LC/ESI/Ion trap-MS/MS), operated in the negative ionization mode, was developed for the analysis of these cyanotoxins. The method was applied to determine the amounts of total microcystins-LR, -YR and -RR in two water reservoirs in Southern Portugal, namely Alqueva and Beliche. A total of 30 water samples were analysed along 2011. Solid phase extraction (SPE) was used for sample cleaning-up and analyte enrichment. The extracted toxins were separated on a C18 column with a gradient of acetonitrile/water with 0.1% formic acid. Detection of microcystins was carried out using multiple reaction monitoring (MRM) in the negative polarity mode, as this method gave a higher selectivity. The MC-RR, YR and LR quantification limits were 17.9, 31.7 and 15.8 ng/L, respectively; quite below the limits recommended by WHO guidelines for drinking water (1 μg/L). Total MC highest concentrations were found in the warm months of June, July and September in Alqueva sampling sites, with concentrations of MC LR and RR ranging 17-344 and 25-212 ng/L, respectively, showing comparable results for MC-RR and LR and slightly lower concentration of MC-YR. Detected values for Beliche reservoir were below quantification limits. Copyright © 2013 Elsevier Ltd. All rights reserved.

Identification of the Related Substances in Ampicillin Capsule by Rapid Resolution Liquid Chromatography Coupled with Electrospray Ionization Tandem Mass Spectrometry

Directory of Open Access Journals (Sweden)

Lei Zhang

2014-01-01

Full Text Available Rapid Resolution Liquid Chromatography coupled with Electrospray Ionization Tandem Mass Spectrometry (RRLC-ESI-MSn was used to separate and identify related substances in ampicillin capsule. The fragmentation behaviors of related substances were used to identify their chemical structures. Finally, a total of 13 related substances in ampicillin capsule were identified, including four identified components for the first time and three groups of isomers on the basis of the exact mass, fragmentation behaviors, retention time, and chemical structures in the literature. This study avoided time-consuming and complex chemosynthesis of related substances of ampicillin and the results could be useful for the quality control of ampicillin capsule to guarantee its safety in clinic. In the meantime, it provided a good example for the rapid identification of chemical structures of related substances of drugs.

Sensitive and comprehensive detection of chemical warfare agents in air by atmospheric pressure chemical ionization ion trap tandem mass spectrometry with counterflow introduction.

Science.gov (United States)

Seto, Yasuo; Sekiguchi, Hiroshi; Maruko, Hisashi; Yamashiro, Shigeharu; Sano, Yasuhiro; Takayama, Yasuo; Sekioka, Ryoji; Yamaguchi, Shintaro; Kishi, Shintaro; Satoh, Takafumi; Sekiguchi, Hiroyuki; Iura, Kazumitsu; Nagashima, Hisayuki; Nagoya, Tomoki; Tsuge, Kouichiro; Ohsawa, Isaac; Okumura, Akihiko; Takada, Yasuaki; Ezawa, Naoya; Watanabe, Susumu; Hashimoto, Hiroaki

2014-05-06

A highly sensitive and specific real-time field-deployable detection technology, based on counterflow air introduction atmospheric pressure chemical ionization, has been developed for a wide range of chemical warfare agents (CWAs) comprising gaseous (two blood agents, three choking agents), volatile (six nerve gases and one precursor agent, five blister agents), and nonvolatile (three lachrymators, three vomiting agents) agents in air. The approach can afford effective chemical ionization, in both positive and negative ion modes, for ion trap multiple-stage mass spectrometry (MS(n)). The volatile and nonvolatile CWAs tested provided characteristic ions, which were fragmented into MS(3) product ions in positive and negative ion modes. Portions of the fragment ions were assigned by laboratory hybrid mass spectrometry (MS) composed of linear ion trap and high-resolution mass spectrometers. Gaseous agents were detected by MS or MS(2) in negative ion mode. The limits of detection for a 1 s measurement were typically at or below the microgram per cubic meter level except for chloropicrin (submilligram per cubic meter). Matrix effects by gasoline vapor resulted in minimal false-positive signals for all the CWAs and some signal suppression in the case of mustard gas. The moisture level did influence the measurement of the CWAs.

Separation and identification of corticosterone metabolites by liquid chromatography--electrospray ionization mass spectrometry.

Science.gov (United States)

Miksík, I; Vylitová, M; Pácha, J; Deyl, Z

1999-04-16

High-performance liquid chromatography coupled to atmospheric pressure ionization-electrospray ionization mass spectrometry (API-ESI-MS) was investigated for the analysis of corticosterone metabolites; their characterization was obtained by combining the separation on Zorbax Eclipse XDB C18 column (eluted with a methanol-water-acetic acid gradient) with identification using positive ion mode API-ESI-MS and selected ion analysis. The applicability of this method was verified by monitoring the activity of steroid converting enzymes (20beta-hydroxysteroid dehydrogenase and 11beta-hydroxysteroid dehydrogenase) in avian intestines.

Chemical effects of ionizing radiation and sonic energy in the context of chemical evolution

International Nuclear Information System (INIS)

Negron Mendoza, A.; Albarran, G.

1992-01-01

Ionizing radiation and sonic energy are considered as sources for chemical evolution processes. These sources have still a modest place in the interdisciplinary approach for the prebiological synthesis of organic compounds. Studies in Radiation Chemistry and Sonochemistry can provide a deeper insight into the chemical processes that may have importance for prebiotic chemistry. The present work concerns the analysis of some chemical reactions induced by ionizing radiation or cavitation in aqueous media that may be relevant to chemical evolution studies. (author)

Simultaneous determination of phentermine and topiramate in human plasma by liquid chromatography-tandem mass spectrometry with positive/negative ion-switching electrospray ionization and its application in pharmacokinetic study.

Science.gov (United States)

Ni, Yang; Zhou, Ying; Xu, Mingzhen; He, Xiaomeng; Li, Huqun; Haseeb, Satter; Chen, Hui; Li, Weiyong

2015-03-25

A new method for simultaneous determination of phentermine and topiramate by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching modes was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. Analyses were performed on a liquid chromatography system employing a Kromasil 60-5CN column (2.1 mm × 100 mm, 5 μm) and an isocratic elution with mixed solution of acetonitrile-20mM ammonium formate containing 0.3% formic acid (40:60, v/v), at a flow rate of 0.35 mL/min. Doxazosin mesylate and pioglitazone were used as the internal standard (IS) respectively for quantification. The determination was carried out on an API 4000 triple-quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 150.0/91.0 for phentermine, m/z 452.1/344.3 for doxazosin, and negative m/z 338.3/77.9 for topiramate, m/z 355.0/41.9 for pioglitazone. The method was validated to be linear over the concentration range of 1-800 ng mL(-1) for phentermine, 1-1000 ng mL(-1) for topiramate. Within- and between-day accuracy and precision of the validated method at three different concentration levels were within the acceptable limits of <15% at all concentrations. Blood samples were collected into heparinized tubes before and after administration. The simple and robust LC/MS/MS method was successfully applied for the simultaneous determination of phentermine and topiramate in a pharmacokinetic study in healthy male Chinese volunteers. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of Proanthocyanidins from Parkia biglobosa (Jacq. G. Don. (Fabaceae by Flow Injection Analysis — Electrospray Ionization Ion Trap Tandem Mass Spectrometry and Liquid Chromatography/Electrospray Ionization Mass Spectrometry

Directory of Open Access Journals (Sweden)

Wagner Vilegas

2013-03-01

Full Text Available The present study investigates the chemical composition of the African plant Parkia biglobosa (Fabaceae roots and barks by Liquid Chromatography - Electrospray Ionization and Direct Injection Tandem Mass Spectrometry analysis. Mass spectral data indicated that B-type oligomers are present, namely procyanidins and prodelphinidins, with their gallate and glucuronide derivatives, some of them in different isomeric forms. The analysis evidenced the presence of up to 40 proanthocyanidins, some of which are reported for the first time. In this study, the antiradical activity of extracts of roots and barks from Parkia biglobosa was evaluated using DPPH method and they showed satisfactory activities.

Comparison of derivatization/ionization techniques for liquid chromatography tandem mass spectrometry analysis of oxylipins.

Science.gov (United States)

Meckelmann, Sven W; Hellhake, Stefan; Steuck, Maryvonne; Krohn, Michael; Schebb, Nils Helge

2017-05-01

The performance of two derivatization and ionization techniques for the quantitative reversed phase liquid chromatography (LC)- mass spectrometry (MS) analysis of hydroxy fatty acids (OH-PUFA) in plasma was evaluated: One used AMPP (N-(4-aminomethylphenyl)pyridinium chloride) leading to a positive charged amid-derivate which can be detected by electrospray ionization (ESI)-MS. Second yielded penta fluorobenzyl bromide (PFB) ester derivates allowing detection in electron capture atmospheric pressure chemical ionization (ecAPCI)-MS. The sensitivity of detection of a comprehensive set of hydroxy fatty acids of n6- and n3- poly unsaturated fatty acids was investigated. On the SCIEX3200 MS the applied PFB derivatization led to poor limits of detection (LOD) of 10-100nM (0.1-1pmol/0.03-0.3ng on column). By contrast, AMPP derivatization led to a similar sensitivity compared to the standard ESI(-) of non derivatized analytes (LOD about 1nM (10fmol/3pg on column)). For several analytes, including 9-HETE, 11-HETE and 17-HDHA the AMPP derivatization improved sensitivity enabling their detection in human plasma. However, precision was reduced by AMPP derivatization and variation in IS recovery indicated a strong matrix influence on the MS-signal. In sum, with the instrumentation used, neither of these derivatization methods improves in our hands the LC-MS based quantification of oxylipins. Copyright © 2017 Elsevier Inc. All rights reserved.

Enhanced signal generation for use in the analysis of synthetic pyrethroids using chemical ionization tandem quadrupole ion trap mass spectrometry.

Science.gov (United States)

Sichilongo, Kwenga

2004-12-01

Synthetic pyrethroids fragment extensively under electron ionization (EI) conditions to give low mass ions, most of them with the same m/z ratios. This fragmentation is primarily due to the labile ester linkage found in these compounds. In this research we established the best gas chromatography (GC) conditions in the EI mode that served as a benchmark in the development of a chemical ionization (CI) protocol for ten selected synthetic pyrethroids. Based on proton affinity data, several reagent gases were evaluated in the positive CI ionization mode. Methanol was found to produce higher average ion counts relative to the other gases evaluated, which led to the development of an optimized method consisting of selective ejection chemical ionization (SECI) and MS/MS. Standard stainless steel ion trap electrodes produced significant degradation of chromatographic performance on late eluting compounds, which was attributed to electrode surface chemistry. A dramatic improvement in signal-to-noise (S/N) ratios was observed when the chromatographically inert Silcosteel coated electrodes were used. The resulting method, that has significant S/N ratio improvements resulting from a combination of septum programmable injections (SPI), optimized CI and inert Silcosteel-coated electrodes, was used to determine instrument detection limits.

Determination of torasemide in human plasma and its bioequivalence study by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry

Directory of Open Access Journals (Sweden)

Lin Zhang

2016-04-01

Full Text Available A sensitive and selective method using high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC–ESI–MS to determine the concentration of torasemide in human plasma samples was developed and validated. Tolbutamide was chosen as the internal standard (IS. The chromatography was performed on a Gl Sciences Inertsil ODS-3 column (100 mm×2.1 mm i.d., 5.0 µm within 5 min, using methanol with 10 mM ammonium formate (60:40, v/v as mobile phase at a flow rate of 0.2 mL/min. The targeted compound was detected in negative ionization at m/z 347.00 for torasemide and 269.00 for IS. The linearity range of this method was found to be within the concentration range of 1–2500 ng/mL (r=0.9984 for torasemide in human plasma. The accuracy of this measurement was between 94.05% and 103.86%. The extracted recovery efficiency was from 84.20% to 86.47% at three concentration levels. This method was also successfully applied in pharmacokinetics and bioequivalence studies in Chinese volunteers.

Simultaneous quantitative analysis of metabolites using ion-pair liquid chromatography-electrospray ionization mass spectrometry

NARCIS (Netherlands)

Coulier, L.; Bas, R.; Jespersen, S.; Verheij, E.; Werf, M.J. van der; Hankemeier, T.

2006-01-01

We have developed an analytical method, consisting of ion-pair liquid chromatography coupled to electrospray ionization mass spectrometry (IP-LC-ESI-MS), for the simultaneous quantitative analysis of several key classes of polar metabolites, like nucleotides, coenzyme A esters, sugar nucleotides,

Simultaneous determination of carboprost methylate and its active metabolite carboprost in dog plasma by liquid chromatography-tandem mass spectrometry with positive/negative ion-switching electrospray ionization and its application to a pharmacokinetic study.

Science.gov (United States)

Yin, Lei; Meng, Xiangjun; Zhou, Xiaotong; Zhang, Tinglan; Sun, Heping; Yang, Zhichao; Yang, Bo; Xiao, Ning; Fawcett, J Paul; Yang, Yan; Gu, Jingkai

2015-08-15

A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method using positive/negative electrospray ionization (ESI) switching for the simultaneous quantitation of carboprost methylate and carboprost in dog plasma has been developed and validated. After screening, the esterase inhibitor, dichlorvos was added to the whole blood at a ratio of 1:99 (v/v) to stabilize carboprost methylate during blood collection, sample storage and LLE. Indomethacin was added to plasma to inhibit prostaglandins synthesis after sampling. After liquid-liquid extraction of 500μL plasma with ethyl ether-dichloromethane (75:25, v/v), analytes and internal standard (IS), alprostadil-d4, were chromatographed on a CAPCELL PAK Phenyl column (150×2.0mm, 5μm) using acetonitrile-5mM ammonium acetate as mobile phase. Carboprost methylate was detected by positive ion electrospray ionization followed by multiple reaction monitoring (MRM) of the transition at m/z 400.5→329.3; the carboprost and IS were detected by negative ion electrospray ionization followed by MRM of the transitions at m/z 367.2→323.2, and 357.1→321.2, respectively. The method was linear for both analytes in the concentration range 0.05-30ng/mL with intra- and inter-day precisions (as relative standard deviation) of ≤6.75% and accuracy (as relative error) of ≤7.21% and limit of detection (LOD) values were 10 and 20pg/mL, respectively. The method was successfully applied to a pharmacokinetic study of the analytes in beagle dogs after intravaginal administration of a suppository containing 0.5mg carboprost methylate. Copyright © 2015 Elsevier B.V. All rights reserved.

[Determination of short chain chlorinated paraffins in polyvinyl chloride plastics by gas chromatography-negative chemical ion/mass spectrometry].

Science.gov (United States)

Xing, Yuanna; Lin, Zhihui; Feng, Anhong; Wang, Xin; Gong, Yemeng; Chen, Zeyong

2015-02-01

A novel method was established to determine short chain chlorinated paraffins (SC-CPs) in polyvinyl chloride (PVC) plastics by gas chromatography-negative chemical ion/mass spectrometry (GC-NCI/MS). Ultrasonic extraction was used to extract SCCPs from PVC plastics. The optimal extraction time was 1.5 h, and concentrated sulfuric acid was adopted to purify the extracted solution. Finally, SCCPs in a sample were detected by GC-NCI/MS at 160 C and with methane reagent gas at 1. 5 mL/min. This method was not influenced by medium chain chlorinated paraffins (MCCPs) in the sample, and accurate quantitation was made for SCCPs. Twelve batches of samples were analyzed and SCCPs were detected in each batch with the contents from 0. 3 x 10(2)mg/kg to 3. 5 x 10(4)mg/kg. With respect to European limitation of SC-CPs (1%), four batches of samples did not comply with the European regulation, and they accounted for 33. 3%. Obviously, high SCCPs risk was presented in PVC plastics.

A new concept positive (negative) surface ionization source for RIB applications

International Nuclear Information System (INIS)

Alton, G.D.; Welton, R.F.; Cui, B.

1996-01-01

A versatile, new concept, spherical-geometry, positive (negative) surface-ionization source has been designed. fabricated, and tests completed which can operate in either positive- or negative-ion beam generation modes without mechanical changes to the source. The highly permeable, composite Ir/C has an intrinsic work function of 0 = 5.29 eV and can be used directly for the generation of positive-ion beams of highly electropositive elements. For negative-surface ionization, the work function is lowered by dynamic flow of a highly electropositive adsorbate such as Cs through the ionizer matrix. The results of initial testing indicate that the source is reliable, stable and easy to operate, with efficiencies for Cs + estimated to exceed 60% and as high as ∼50% for F - generation. The design features, operational principles, and initial performance of the source for generating Cs + and F - , when operated with Cs, are discussed in this article

Chemical characterization of synthetic cannabinoids by electrospray ionization FT-ICR mass spectrometry.

Science.gov (United States)

Kill, Jade B; Oliveira, Izabela F; Tose, Lilian V; Costa, Helber B; Kuster, Ricardo M; Machado, Leandro F; Correia, Radigya M; Rodrigues, Rayza R T; Vasconcellos, Géssica A; Vaz, Boniek G; Romão, Wanderson

2016-09-01

The synthetic cannabinoids (SCs) represent the most recent advent of the new psychotropic substances (NPS) and has become popularly known to mitigate the effects of the Δ(9)-THC. The SCs are dissolved in organic solvents and sprayed in a dry herbal blend. However, little information is reported on active ingredients of SCs as well as the excipients or diluents added to the herbal blend. In this work, the direct infusion electrospray ionization Fourier transform ion cyclotron mass spectrometry technique (ESI-FT-ICR MS) was applied to explore the chemical composition of nine samples of herbal extract blends, where a total of 11 SCs (UR-144, JWH-073, XLR-11, JWH-250, JWH-122, AM-2201, AKB48, JWH-210, JWH-081, MAM-2201 and 5F-AKB48) were identified in the positive ionization mode, ESI(+), and other 44 chemical species (saturated and unsaturated fatty acids, sugars, flavonoids, etc.) were detected in the negative ionization mode, ESI(-). Additionally, CID experiments were performed, and fragmentation pathways were proposed to identify the connectivity of SCs. Thus, the direct infusion ESI-FT-ICR MS technique is a powerful tool in forensic chemistry that enables the rapid and unequivocal way for the determination of molecular formula, the degree of unsaturation (DBE-double bond equivalent) and exact mass (<1ppm) of a total of 55 chemical species without the prior separation step. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Comparison of the sensitivity of mass spectrometry atmospheric pressure ionization techniques in the analysis of porphyrinoids.

Science.gov (United States)

Swider, Paweł; Lewtak, Jan P; Gryko, Daniel T; Danikiewicz, Witold

2013-10-01

The porphyrinoids chemistry is greatly dependent on the data obtained in mass spectrometry. For this reason, it is essential to determine the range of applicability of mass spectrometry ionization methods. In this study, the sensitivity of three different atmospheric pressure ionization techniques, electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization, was tested for several porphyrinods and their metallocomplexes. Electrospray ionization method was shown to be the best ionization technique because of its high sensitivity for derivatives of cyanocobalamin, free-base corroles and porphyrins. In the case of metallocorroles and metalloporphyrins, atmospheric pressure photoionization with dopant proved to be the most sensitive ionization method. It was also shown that for relatively acidic compounds, particularly for corroles, the negative ion mode provides better sensitivity than the positive ion mode. The results supply a lot of relevant information on the methodology of porphyrinoids analysis carried out by mass spectrometry. The information can be useful in designing future MS or liquid chromatography-MS experiments. Copyright © 2013 John Wiley & Sons, Ltd.

Contribution to high-temperature chromatography and high-temperature-gas-chromatography-mass spectrometry of lipids

International Nuclear Information System (INIS)

Aichholz, R.

1998-04-01

This thesis describes the use of high temperature gas chromatography for the investigation of unusual triacylglycerols, cyanolipids and bees waxes. The used glass capillary columns were pretreated and coated with tailor made synthesized high temperature stable polysiloxane phases. The selective separation properties of the individual columns were tested with a synthetic lipid mixture. Suitable derivatization procedures for the gaschromatographic analyses of neutral lipids, containing multiple bonds as well as hydroxy-, epoxy-, and carboxyl groups, were developed and optimized. Therefore conjugated olefinic-, conjugated olefinic-acetylenic-, hydroxy-, epoxy-, and conjugated olefinic keto triacylglycerols in miscellaneous plant seed oils as well as hydroxy monoesters, diesters and hydroxy diesters in bees waxes could be analysed directly with high temperature gas chromatography for the first time. In order to elucidate the structures of separated lipid compounds, high temperature gas chromatography was coupled to mass spectrometry and tandem mass spectrometry, respectively. Comparable analytical systems are hitherto not commercial available. Therefore instrumental prerequisites for a comprehensive and detailed analysis of seed oils and bees waxes were established. In GC/MS commonly two ionization methods are used, electron impact ionization and chemical ionization. For the analysis of lipids the first is of limited use only. Due to intensive fragmentation only weak molecular ions are observed. In contrast, the chemical ionization yields in better results. Dominant quasi molecular ions enable an unambiguous determination of the molecular weight. Moreover, characteristic fragment ions provide important indications of certain structural features of the examined compounds. Nevertheless, in some cases the chromatographic resolution was insufficient in order to separate all compounds present in natural lipid mixtures. Owing to the selected detection with mass spectrometry

Identification and quantification of antitumor thioproline and methylthioproline in Korean traditional foods by a liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

Science.gov (United States)

Kim, Sun Hyo; Kim, Hyun-Ji; Shin, Ho-Sang

2014-11-01

A liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometric method (LC-APCI-MS/MS) has been developed for the sensitive determination of antitumor thioproline and methylthioproline from fermented foods. Thioproline and methylthioproline were derivatized in one step with ethyl chloroformate at room temperature. These compounds were identified and quantified in various traditional Korean fermented foods by LC-APCI-MS/MS. The concentration range of thioproline of each food was found for doenjang (0.011-0.032mg/kg), gochujang (0.010-0.038mg/kg), and ganjang (0.010-0.038mg/kg). Those of methylthioproline of each food was found for doenjang (0.098-0.632mg/kg), gochujang (0.015-0.112mg/kg), and ganjang (0.023-1.468mg/kg). A prolonged aging time leads to an increase in both the thioproline and methylthioproline contents, suggesting that the storage time plays a key role in the formation of thioproline and methylthioproline in Korean traditional foods. The results here suggest that thioproline and methylthioproline are related to the biological activities of traditional Korean fermented foods. Copyright © 2014 Elsevier B.V. All rights reserved.

Classical electron ionization mass spectra in gas chromatography/mass spectrometry with supersonic molecular beams.

Science.gov (United States)

Gordin, Alexander; Fialkov, Alexander B; Amirav, Aviv

2008-09-01

A major benefit of gas chromatography/mass spectrometry (GC/MS) with a supersonic molecular beam (SMB) interface and its fly-through ion source is the ability to obtain electron ionization of vibrationally cold molecules (cold EI), which show enhanced molecular ions. However, GC/MS with an SMB also has the flexibility to perform 'classical EI' mode of operation which provides mass spectra to mimic those in commercial 70 eV electron ionization MS libraries. Classical EI in SMB is obtained through simple reduction of the helium make-up gas flow rate, which reduces the SMB cooling efficiency; hence the vibrational temperatures of the molecules are similar to those in traditional EI ion sources. In classical EI-SMB mode, the relative abundance of the molecular ion can be tuned and, as a result, excellent identification probabilities and very good matching factors to the NIST MS library are obtained. Classical EI-SMB with the fly-through dual cage ion source has analyte sensitivity similar to that of the standard EI ion source of a basic GC/MS system. The fly-through EI ion source in combination with the SMB interface can serve for cold EI, classical EI-SMB, and cluster chemical ionization (CCI) modes of operation, all easily exchangeable through a simple and quick change (not involving hardware). Furthermore, the fly-through ion source eliminates sample scattering from the walls of the ion source, and thus it offers full sample inertness, tailing-free operation, and no ion-molecule reaction interferences. It is also robust and enables increased column flow rate capability without affecting the sensitivity.

Determination of oxygen and nitrogen derivatives of polycyclic aromatic hydrocarbons in fractions of asphalt mixtures using liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization.

Science.gov (United States)

Nascimento, Paulo Cicero; Gobo, Luciana Assis; Bohrer, Denise; Carvalho, Leandro Machado; Cravo, Margareth Coutinho; Leite, Leni Figueiredo Mathias

2015-12-01

Liquid chromatography coupled to mass spectrometry with atmospheric pressure chemical ionization was used for the determination of polycyclic aromatic hydrocarbon derivatives, the oxygenated polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons, formed in asphalt fractions. Two different methods have been developed for the determination of five oxygenated and seven nitrated polycyclic aromatic hydrocarbons that are characterized by having two or more condensed aromatic rings and present mutagenic and carcinogenic properties. The parameters of the atmospheric pressure chemical ionization interface were optimized to obtain the highest possible sensitivity for all compounds. The detection limits of the methods ranged from 0.1 to 57.3 μg/L for nitrated and from 0.1 to 6.6 μg/L for oxygenated derivatives. The limits of quantification were in the range of 4.6-191 μg/L for nitrated and 0.3-8.9 μg/L for oxygenated derivatives. The methods were validated against a diesel particulate extract standard reference material (National Institute of Standards and Technology SRM 1975), and the obtained concentrations (two nitrated derivatives) agreed with the certified values. The methods were applied in the analysis of asphalt samples after their fractionation into asphaltenes and maltenes, according to American Society for Testing and Material D4124, where the maltenic fraction was further separated into its basic, acidic, and neutral parts following the method of Green. Only two nitrated derivatives were found in the asphalt sample, quinoline and 2-nitrofluorene, with concentrations of 9.26 and 2146 mg/kg, respectively, whereas no oxygenated derivatives were detected. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[High-performance liquid-liquid chromatography in beverage analysis].

Science.gov (United States)

Bricout, J; Koziet, Y; de Carpentrie, B

1978-01-01

Liquid liquid chromatography was performed with columns packed with stationary phases chemically bonded to silica microparticules. These columns show a high efficiency and are used very easily. Flavouring compounds like aromatic aldehydes which have a low volatility were analyzed in brandy using a polar phase alkylnitrile. Sapid substances like amarogentin in Gentiana lutea or glyryrrhizin in Glycyrrhiza glabra were determined by reversed phase chromatography. Finally ionizable substances like synthetic dyes can be analyzed by paired ion chromatography witha non polar stationary phase.

Characterization of chemical constituents in Rhodiola Crenulate by high-performance liquid chromatography coupled with Fourier-transform ion cyclotron resonance mass spectrometer (HPLC-FT-ICR MS).

Science.gov (United States)

Han, Fei; Li, Yanting; Mao, Xinjuan; Xu, Rui; Yin, Ran

2016-05-01

In this work, an approach using high-performance liquid chromatography coupled with diode-array detection and Fourier-transform ion cyclotron resonance mass spectrometer (HPLC-FT-ICR MS) for the identification and profiling of chemical constituents in Rhodiola crenulata was developed for the first time. The chromatographic separation was achieved on an Inertsil ODS-3 column (150 mm × 4.6 mm,3 µm) using a gradient elution program, and the detection was performed on a Bruker Solarix 7.0 T mass spectrometer equipped with electrospray ionization source in both positive and negative modes. Under the optimized conditions, a total of 48 chemical compounds, including 26 alcohols and their glycosides, 12 flavonoids and their glycosides, 5 flavanols and gallic acid derivatives, 4 organic acids and 1 cyanogenic glycoside were identified or tentatively characterized. The results indicated that the developed HPLC-FT-ICR MS method with ultra-high sensitivity and resolution is suitable for identifying and characterizing the chemical constituents in R. crenulata. And it provides a helpful chemical basis for further research on R. crenulata. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Analysis of epoxyeicosatrienoic acids by chiral liquid chromatography/electron capture atmospheric pressure chemical ionization mass spectrometry using [13C]-analog internal standards

Science.gov (United States)

Mesaros, Clementina; Lee, Seon Hwa; Blair, Ian A.

2012-01-01

The metabolism of arachidonic acid (AA) to epoxyeicosatrienoic acids (EETs) is thought to be mediated primarily by the cytochromes P450 (P450s) from the 2 family (2C9, 2C19, 2D6, and 2J2). In contrast, P450s of the 4 family are primarily involved in omega oxidation of AA (4A11 and 4A22). The ability to determine enantioselective formation of the regioisomeric EETs is important in order to establish their potential biological activities and to asses which P450 isoforms are involved in their formation. It has been extremely difficult to analyze individual EET enantiomers in biological fluids because they are present in only trace amounts and they are extremely difficult to separate from each other. In addition, the deuterium-labeled internal standards that are commonly used for stable isotope dilution liquid chromatography/mass spectrometry (LC/MS) analyses have different LC retention times when compared with the corresponding protium forms. Therefore, quantification by LC/MS-based methodology can be compromised by differential suppression of ionization of the closely eluting isomers. We report the preparation of [13C20]-EET analog internal standards and the use of a validated high-sensitivity chiral LC/electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the trace analysis of endogenous EETs as their pentafluorobenzyl (PFB) ester derivatives. The assay was then used to show the exquisite enantioselectivity of P4502C19-, P4502D6-, P4501A1-, and P4501B1-mediated conversion of AA into EETs and to quantify the enantioselective formation of EETs produced by AA metabolism in a mouse epithelial hepatoma (Hepa) cell line. PMID:20972997

Cluster chemical ionization for improved confidence level in sample identification by gas chromatography/mass spectrometry.

Science.gov (United States)

Fialkov, Alexander B; Amirav, Aviv

2003-01-01

Upon the supersonic expansion of helium mixed with vapor from an organic solvent (e.g. methanol), various clusters of the solvent with the sample molecules can be formed. As a result of 70 eV electron ionization of these clusters, cluster chemical ionization (cluster CI) mass spectra are obtained. These spectra are characterized by the combination of EI mass spectra of vibrationally cold molecules in the supersonic molecular beam (cold EI) with CI-like appearance of abundant protonated molecules, together with satellite peaks corresponding to protonated or non-protonated clusters of sample compounds with 1-3 solvent molecules. Like CI, cluster CI preferably occurs for polar compounds with high proton affinity. However, in contrast to conventional CI, for non-polar compounds or those with reduced proton affinity the cluster CI mass spectrum converges to that of cold EI. The appearance of a protonated molecule and its solvent cluster peaks, plus the lack of protonation and cluster satellites for prominent EI fragments, enable the unambiguous identification of the molecular ion. In turn, the insertion of the proper molecular ion into the NIST library search of the cold EI mass spectra eliminates those candidates with incorrect molecular mass and thus significantly increases the confidence level in sample identification. Furthermore, molecular mass identification is of prime importance for the analysis of unknown compounds that are absent in the library. Examples are given with emphasis on the cluster CI analysis of carbamate pesticides, high explosives and unknown samples, to demonstrate the usefulness of Supersonic GC/MS (GC/MS with supersonic molecular beam) in the analysis of these thermally labile compounds. Cluster CI is shown to be a practical ionization method, due to its ease-of-use and fast instrumental conversion between EI and cluster CI, which involves the opening of only one valve located at the make-up gas path. The ease-of-use of cluster CI is analogous

Ionizing radiation effects in Acai oil analysed by gas chromatography coupled to mass spectrometry technique

International Nuclear Information System (INIS)

Valli, Felipe; Fernandes, Carlos Eduardo; Moura, Sergio; Machado, Ana Carolina; Furasawa, Helio Akira; Pires, Maria Aparecida Faustino; Bustillos, Oscar Vega

2007-01-01

The Acai fruit is a well know Brazilian seed plant used in large scale as a source of feed stock, specially in the Brazilian North-east region. The Acai oil is use in many purposes from fuel sources to medicine. The scope of this paper is to analyzed the chemical structures modification of the acai oil after the ionizing radiation. The radiation were set in the range of 10 to 25 kGy in the extracted Acai oil. The analyses were made by gas chromatography coupled to mass spectrometry techniques. A GC/MS Shimatzu QP-5000 equipped with 30 meters DB-5 capillary column with internal diameter of 0.25 mm and 0.25 μm film thickness was used. Helium was used as carried gas and gave a column head pressure of 12 p.s.i. (1 p.s.i. = 6894.76 Pa) and an average flux of 1 ml/min. The temperature program for the GC column consisted of a 4-minutes hold at 75 deg C, a 15 deg C /min ramp to 200 deg C, 8 minutes isothermal. 20 deg C/min ramp to 250 deg C, 2 minutes isothermal. The extraction of the fatty acids was based on liquid-liquid method using chloroform as solvent. The chromatograms resulted shows the presences of the oleic acid and others fatty acids identify by the mass spectra library (NIST-92). The ionization radiation deplete the fatty acids presents in the Acai oil. Details on the chemical qualitative analytical is present as well in this work. (author)

Annotation of the human serum metabolome by coupling three liquid chromatography methods to high-resolution mass spectrometry.

Science.gov (United States)

Boudah, Samia; Olivier, Marie-Françoise; Aros-Calt, Sandrine; Oliveira, Lydie; Fenaille, François; Tabet, Jean-Claude; Junot, Christophe

2014-09-01

This work aims at evaluating the relevance and versatility of liquid chromatography coupled to high resolution mass spectrometry (LC/HRMS) for performing a qualitative and comprehensive study of the human serum metabolome. To this end, three different chromatographic systems based on a reversed phase (RP), hydrophilic interaction chromatography (HILIC) and a pentafluorophenylpropyl (PFPP) stationary phase were used, with detection in both positive and negative electrospray modes. LC/HRMS platforms were first assessed for their ability to detect, retain and separate 657 metabolite standards representative of the chemical families occurring in biological fluids. More than 75% were efficiently retained in either one LC-condition and less than 5% were exclusively retained by the RP column. These three LC/HRMS systems were then evaluated for their coverage of serum metabolome. The combination of RP, HILIC and PFPP based LC/HRMS methods resulted in the annotation of about 1328 features in the negative ionization mode, and 1358 in the positive ionization mode on the basis of their accurate mass and precise retention time in at least one chromatographic condition. Less than 12% of these annotations were shared by the three LC systems, which highlights their complementarity. HILIC column ensured the greatest metabolome coverage in the negative ionization mode, whereas PFPP column was the most effective in the positive ionization mode. Altogether, 192 annotations were confirmed using our spectral database and 74 others by performing MS/MS experiments. This resulted in the formal or putative identification of 266 metabolites, among which 59 are reported for the first time in human serum. Copyright © 2014 Elsevier B.V. All rights reserved.

Identification and Quantification of the Major Constituents in Egyptian Carob Extract by Liquid Chromatography?Electrospray Ionization-Tandem Mass Spectrometry

OpenAIRE

Owis, Asmaa Ibrahim; El-Naggar, El-Motaz Bellah

2016-01-01

Background: Carob - Ceratonia siliqua L., commonly known as St John's-bread or locust bean, family Fabaceae - is one of the most useful native Mediterranean trees. There is no data about the chromatography methods performed by high performance liquid chromatography (HPLC) for determining polyphenols in Egyptian carob pods. Objective: To establish a sensitive and specific liquid chromatography?electrospray ionization (ESI)-tandem mass spectrometry (MSn) methodology for the identification of th...

Liquid Chromatography with Post-Column Reagent Addition of Ammonia in Methanol Coupled to Negative Ion Electrospray Ionization Tandem Mass Spectrometry for Determination of Phenoxyacid Herbicides and their Degradation Products in Surface Water

Directory of Open Access Journals (Sweden)

Michele L. Etter

2010-02-01

Full Text Available A new liquid chromatography (LC-negative ion electrospray ionization (ESI–tandem mass spectrometry (MS/MS method with post-column addition of ammonia in methanol has been developed for the analysis of acid herbicides: 2,4-dichlorophenoxy ace- tic acid, 4-chloro-o-tolyloxyacetic acid, 2-(2-methyl-4-chlorophenoxybutyric acid, mecoprop, dichlorprop, 4-(2,4-dichlorophenoxy butyric acid, 2,4,5-trichlorophenoxy propionic acid, dicamba and bromoxynil, along with their degradation products: 4-chloro-2- methylphenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and 3,5-dibromo-4-hydroxybenzoic acid. The samples were extracted from the surface water matrix using solid-phase extraction (SPE with a polymeric sorbent and analyzed with LC ESI- with selected reaction monitoring (SRM using a three-point confirmation approach. Chromatography was performed on a Zorbax Eclipse XDB-C18 (50 × 4.6 mm i.d., 1.8 µm with a gradient elution using water-methanol with 2 mM ammonium acetate mobile phase at a flow rate of 0.15 mL/min. Ammonia in methanol (0.8 M was added post-column at a flow rate of 0.05 mL/min to enhance ionization of the deg- radation products in the MS source. One SRM transition was used for quantitative analysis while the second SRM along with the ratio of SRM1/SRM2 within the relative standard deviation determined by standards for each individual pesticide and retention time match were used for confirmation. The standard deviation of ratio of SRM1/SRM2 obtained from standards run on the day of analysis for different phenoxyacid herbicides ranged from 3.9 to 18.5%. Limits of detection (LOD were between 1 and 15 ng L-1 and method detection limits (MDL with strict criteria requiring

Physico-chemical modifications of plastics by ionization

International Nuclear Information System (INIS)

Rouif, S.

2002-01-01

The industrial use of ionizing radiations (beta and gamma), initially for the sterilization of medico-surgical instruments and for the preservation of food products, has led to the development of the chemistry of polymers under radiations. Ionizing radiations can initiate chemical reactions (chain cutting, poly-additions, polymerization etc..) thanks to the formation of free radicals. The main applications concerns the degradation of plastics, the reticulation of plastics and of woods impregnated with resin, and the grafting of polymers. The processing of plastic materials was initially performed with low energy electron accelerators (0.1 to 3 MeV), allowing only surface treatments, while recent high energy accelerators (10 MeV) and gamma facilities allow the treatment in depth of materials (from few cm to 1 m). This article describes the industrial treatments performed with such high energy facilities: 1 - action of ionizing radiations on plastic materials: different types of ionizing radiations, action of beta and gamma radiations, chemical changes induced by beta and gamma radiations; 2 - reticulation of plastic materials submitted to beta and gamma radiations: radio-'reticulable' polymers and reticulation co-agents, modification of the properties of reticulated plastic materials under beta and gamma radiations; 3 - industrial aspects of reticulation under beta and gamma radiation: industrial irradiation facilities, dosimetry and radio-reticulation control, applications; 4 - conclusion. (J.S.)

Resonance Ionization Mass Spectrometry (RIMS): applications in spectroscopy and chemical dynamics

International Nuclear Information System (INIS)

Naik, P.D.; Kumar, Awadhesh; Upadhyaya, Hari; Bajaj, P.N.

2009-01-01

Resonance ionization is a photophysical process wherein electromagnetic radiation is used to ionize atoms, molecules, transient species, etc., by exciting them through their quantum states. The number of photons required to ionize depends on the species being investigated and energy of the photon. Once a charged particle is produced, it is easy to detect it with high efficiency. With the advent of narrow band high power pulsed and cw tunable dye lasers, it has blossomed into a powerful spectroscopic and analytical technique, commonly known as resonance ionization spectroscopy (RIS)/resonance enhanced multiphoton ionization (REMPI). The alliance of resonance ionization with mass spectrometry has grown into a still more powerful technique, known as resonance ionization mass spectrometry (RIMS), which has made significant contributions in a variety of frontier areas of research and development, such as spectroscopy, chemical dynamics, analytical chemistry, cluster science, surface science, radiochemistry, nuclear physics, biology, environmental science, material science, etc. In this article, we shall describe the application of resonance ionization mass spectrometry to spectroscopy of uranium and chemical dynamics of polyatomic molecules

The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

Science.gov (United States)

Rogers, Kevin; Milnes, John; Gormally, John

1993-02-01

Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

Quantification of short- and medium-chain chlorinated paraffins in environmental samples by gas chromatography quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Gao, Wei; Wu, Jing; Wang, Yawei; Jiang, Guibin

2016-06-24

Chlorinated paraffins (CPs) are technical products produced and used in bulk for a number of purposes. However, the analysis of CPs is challenging, as they are complex mixtures of compounds and isomers. We herein report the development of an analytical method for the analysis of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) using quadrupole time-of-flight high-resolution mass spectrometry (GC-NCI-qTOF-HRMS). This method employs gas chromatography with a chemical ionization source working in negative mode. The linear relationship between chlorination and the CP total response factors was applied to quantify the CP content and the congener group distribution patterns. In a single injection, 24 SCCP formula groups and 24 MCCP formula groups were quantified. Extraction of accurate masses using qTOF-HRMS allowed the SCCPs and MCCPs to be distinguished, with interference from other chemicals (e.g., PCBs) being largely avoided. The SCCP and MCCP detection limits were 24-81ng/mL and 27-170ng/mL, respectively. Comparison of the obtained results with analytical results from gas chromatography coupled with electron capture negative ionization low-resolution mass spectrometry (GC-ECNI-LRMS) indicate that the developed technique is a more accurate and convenient method for the analysis of CPs in samples from a range of matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of negative ions on current growth and ionizing wave propagation in air

International Nuclear Information System (INIS)

Kline, L.E.

1975-01-01

The spatiotemporal development of electron and ion densities, electric fields, and luminosity are calculated for electron pulse experiments in overvolted parallel-plane gaps by numerically solving continuity equations together with Poisson's equation. Experimental coefficients for primary ionization, cathode photoemission, photoionization, and luminosity are used. Unambiguous determination of the coefficients for attachment, detachment, and charge transfer is not possible from available experimental results. Therefore, the calculations are repeated for three sets of coefficients for these processes, corresponding to the following assumptions: unstable negative ions, stable negative ions, and no negative ions. The results of the calculations show, in each case, that the electron pulse initiates an avalanche which grows exponentially until the onset of space-charge effects. The calculated growth rate is strongly affected by the assumed attachment, detachment, and charge-transfer coefficients. When the total number of electrons in the avalanche reaches approx.10 8 , anode- and cathode-directed ionizing waves, or streamers, develop from the avalanche and produce a weakly ionized filamentary plasma. The calculated ionizing wave velocities are strongly increasing functions of the space-charge--enhanced electric field within the waves and are insensitive to the assumed attachment, detachment, and charge-transfer coefficients. The numerically calculated ionizing wave velocities are in approximate agreement with a simple analytical theory

Application of liquid chromatography-electrospray ionization mass spectrometry for study of steroid-converting enzymes.

Science.gov (United States)

Miksík, Ivan; Mikulíková, Katerina; Pácha, Jirí; Kucka, Marek; Deyl, Zdenek

2004-02-05

A high-performance liquid chromatography-atmospheric pressure ionization-electrospray ionization mass spectrometry (HPLC-API-ESI-MS) method was developed for the analysis of steroids in a study of steroid-converting enzymes. Separations ware done on a Zorbax Eclipse XDB-C18 column (eluted with a linear methanol-water-acetic acid gradient) and identification of the steroids involved was done by API-ESI-MS using positive ion mode and extracted ion analysis. The applicability of the present method for studying steroid metabolism was proven in assaying two steroid-converting enzymes (20beta-hydroxysteroid dehydrogenase and 11beta-hydroxysteroid dehydrogenase) in various biological samples (rat and chicken intestine, chicken oviduct).

Dissociative electron attachment negative ion mass spectrometry: a chlorine-specific detector for gas chromatography

Science.gov (United States)

Curtis, Jonathan M.; Boyd, Robert K.

1997-11-01

This work describes the application of negative ion chemical ionization, optimized for dissociative electron attachment (DEA), to location of unknown trace chlorinated compounds in complex gas chromatograms by selected ion recording (SIR) of m / z 35 and 37. The DEA-SIR technique is compared with other GC detectors, including the electron capture detector, electrolytic conductivity detector, the atomic emission detector and the chemical reaction interface mass spectrometry method, with respect to selectivity for chlorine, sensitivity, linear dynamic range, and general robustness and ease of use. When applied to quantitative analysis of target analytes such as polychlorobiphenyls, the DEA-SIR method has potential problems arising from the possibility of suppression effects due to abundant co-eluting components, and possible alleviating measures are discussed. In addition to these practical investigations, literature information on the fundamental physical and chemical phenomena underlying the DEA process is summarized in order to guide future work on extension to other compound types and on general improvements to the technique.

Stereoselective quantification of methadone and a d(6)-labeled isotopomer using high performance liquid chromatography-atmospheric pressure chemical ionization mass-spectrometry: application to a pharmacokinetic study in a methadone maintained subject.

Science.gov (United States)

Foster, David J R; Morton, Erin B; Heinkele, Georg; Mürdter, Thomas E; Somogyi, Andrew A

2006-08-01

There is evidence that the apparent oral clearance of rac-methadone is induced during the early phase of methadone maintenance treatment. However, it is not known if this is due to changes in bioavailability or if this phenomenon is stereoselective. This knowledge can be obtained by administering a dose of stable-labeled methadone at selected times during ongoing treatment. Therefore, the authors developed a stereoselective high performance liquid chromatography-atmospheric pressure chemical ionization mass-spectrometry assay for the quantification of the enantiomers of methadone and a d(6)-labeled isotopomer. The compounds were quantified in a single assay after liquid-liquid extraction and stereoselective high performance liquid chromatograph with atmospheric pressure chemical ionization-mass spectrometry detection. The following ions were monitored: m/z 310.15 for unlabeled methadone; m/z 316.15 for methadone-d(6); and m/z 313.15 for the methadone-d(3) (internal standard). Calibration curves ranged from 0.5 to 75 ng/mL for each compound. Extraction recovery was approximately 80% for all analytes, without evidence of differences between the unlabeled and stable-labeled compounds or concentration dependency. Minor ion promotion was observed (d(3)-labeled internal standard, with peak area ratios in extracted samples identical to control injections. The isotopomers did not alter each others' ionisation, even at 10:1 concentration ratios, and 10-fold diluted samples were within 10% of the nominal concentration. Assay performance was acceptable, with interassay and intra-assay bias and precision d(6) in a patient receiving chronic oral methadone maintenance therapy.

Application of Ni-63 photo and corona discharge ionization for the analysis of chemical warfare agents and toxic wastes

Science.gov (United States)

Stach, J.; Adler, J.; Brodacki, M.; Doring, H.-R.

1995-01-01

Over the past decade, advances in instrumental design and refinements in the understanding of ion molecule reactions at atmospheric pressure enabled the application of Ion Mobility Spectrometry (IMS) as a simple inexpensive and sensitive analytical method for the detection of organic trace compounds. Positive and negative gas-phase ions for ion mobility spectrometry have been produced by a variety of methods, including photo-ionization, laser multi photon ionization, surface ionization, corona discharge ionization. The most common ion source used in ion mobility spectrometry is a radioactive Ni-63 foil which is favored due to simplicity, stability, convenience, and high selectivity. If reactant ions like (H2O(n)H)(+) or (H2O(n)O2)(-) dominate in the reaction region, nearly all kinds of compounds with a given proton or electron affinity; are ionized. However, the radioactivity of the Ni-63 foil is one disadvantage of this ion source that stimulates the development and application of other ionization techniques. In this paper, we report analyses of old chemical warfare agents and toxic wastes using Bruker RAID ion mobility spectrometers. Due to the modular construction of the measuring cell, the spectrometers can be equipped with different ion sources. The combined use of Ni-63, photo- and corona discharge ionization allows the identification of different classes of chemical compounds and yields in most cases comparable results.

Decomposition of halogenated organic chemicals in ionic liquid by ionizing radiation

International Nuclear Information System (INIS)

Kimura, A.; Taguchi, M.; Kojima, T.; Nagaishi, R.; Hiratsuka, H.

2006-01-01

Introduction: Halogenated organic chemicals such as polychlorodibenzo-p-dioxin, polychlorobiphenyls and hexachlorobenzene are widely spread in water environment. These pollutants are persistent against advanced oxidation treatments such as ozone/UV, ozone/hydrogen peroxide, ionizing radiation and photocatalysts. The ionizing radiation, however, can also produce homogeneously and quantitatively reducing species in water. On the other hand, room temperature ionic liquids (RTILs) have unique properties such as nonflammable, high polarity, low melting point, hydrophobicity and wide electrochemical window. The combined method of reduction by ionizing radiation and RTILs is investigated as a new environmental conservation technology. Experimental: Chlorophenol (CP) is selected as model chemicals having the main frame of halogenated organic chemicals. Each o - , m - and p-CP were irradiated with 60 Co γ-ray in each diethylmethyl(2-methoxy-ethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEMMA- TFSI), diethylmethyl(2-methoxyethyl)-ammonium tetrafluoroborate (DEMMA-BF4), methanol and ethanol as solvent. Decomposition of CP and formation of irradiation products were studied using HPLC, LC-MS and ion chromatography. Results and discussion: Concentration of CP in each solution decreased as a function of dose. G-value was estimated from the slope at the primary stage of the decomposition curve. The G(-CP) and G(Phenol) were shown in Table 1. G(-CP) in the aliphatic alcohols was 0.21 to 0.37, which is lower than G-value of reducing species in the alcohols, e.g. G=1.0 to 1.5 for solvated electron. Since the rate constant for reaction of CP with hydrated electron is 1.3 x 10 9 mol -1 ·dm 3 ·s -1 , the reverse reaction is considered to attribute. G(-CP) in DEMMA-TFSI or DEMMA-BF4 was about 2 to 3 times higher than that in each alcohol. Lifetime of the reducing species in RTILs would be longer than that in each alcohol. G(-CP) in DEMMA-TFSI decreased by adding acetone or oxygen

The Use of Atmospheric Pressure Chemical Ionization Mass Spectrometry with High Performance Liquid Chromatography and Other Separation Techniques for Identification of Triacylglycerols

Czech Academy of Sciences Publication Activity Database

Řezanka, Tomáš; Sigler, Karel

2007-01-01

Roč. 3, - (2007), s. 252-271 ISSN 1573-4110 R&D Projects: GA ČR GA203/06/0219 Institutional research plan: CEZ:AV0Z50200510 Keywords : triacylglycerols * atmospheric presssure chemical ionization * mass spectrometry Subject RIV: EE - Microbiology, Virology Impact factor: 1.815, year: 2007

Determination of short chain carboxylic acids in vegetable oils and fats using ion exclusion chromatography electrospray ionization mass spectrometry.

Science.gov (United States)

Viidanoja, Jyrki

2015-02-27

A new method for quantification of short chain C1-C6 carboxylic acids in vegetable oils and fats by employing Liquid Chromatography Mass Spectrometry (LC-MS) has been developed. The method requires minor sample preparation and applies non-conventional Electrospray Ionization (ESI) liquid phase chemistry. Samples are first dissolved in chloroform and then extracted using water that has been spiked with stable isotope labeled internal standards that are used for signal normalization and absolute quantification of selected acids. The analytes are separated using Ion Exclusion Chromatography (IEC) and detected with Electrospray Ionization Mass Spectrometry (ESI-MS) as deprotonated molecules. Prior to ionization the eluent that contains hydrochloric acid is modified post-column to ensure good ionization efficiency of the analytes. The averaged within run precision and between run precision were generally lower than 8%. The accuracy was between 85 and 115% for most of the analytes. The Lower Limit of Quantification (LLOQ) ranged from 0.006 to 7mg/kg. It is shown that this method offers good selectivity in cases where UV detection fails to produce reliable results. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of a novel helium ionization detector within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography.

Science.gov (United States)

Franchina, Flavio A; Maimone, Mariarosa; Sciarrone, Danilo; Purcaro, Giorgia; Tranchida, Peter Q; Mondello, Luigi

2015-07-10

The present research is focused on the use and evaluation of a novel helium ionization detector, defined as barrier discharge ionization detector (BID), within the context of (low-)flow modulation comprehensive two-dimensional gas chromatography (FM GC×GC). The performance of the BID device was compared to that of a flame ionization detector (FID), under similar FM GC×GC conditions. Following development and optimization of the FM GC×GC method, the BID was subjected to fine tuning in relation to acquisition frequency and discharge flow. Moreover, the BID performance was measured and compared to that of the FID, in terms of extra-column band broadening, sensitivity and dynamic range. The comparative study was carried out by using standard compounds belonging to different chemical classes, along with a sample of diesel fuel. Advantages and disadvantages of the BID system, also within the context of FM GC×GC, are critically discussed. In general, the BID system was characterized by a more limited dynamic range and increased sensitivity, compared to the FID. Additionally, BID and FID contribution to band broadening was found to be similar under the operational conditions applied. Particular attention was devoted to the behaviour of the FM GC×GC-BID system toward saturated and aromatic hydrocarbons, for a possible future use in the field of mineral-oil food contamination research. Copyright © 2015 Elsevier B.V. All rights reserved.

DNA adducts of 2,3-epoxy-4-hydroxynonanal: detection of 7-(1', 2'-dihydroxyheptyl)-3H-imidazo[2,1-i]purine and 1,N6-ethenoadenine by gas chromatography/negative ion chemical ionization/mass spectrometry.

Science.gov (United States)

Chen, H J; Zhang, L; Cox, J; Cunningham, J A; Chung, F L

1998-12-01

2,3-Epoxy-4-hydroxynonanal (EH) is a bifunctional aldehyde formed by epoxidation of trans-4-hydroxy-2-nonenal, a peroxidation product of omega-6 polyunsaturated fatty acids. EH is mutagenic and tumorigenic and capable of modifying DNA bases forming etheno adducts in vitro. Recent studies showed that etheno adducts are present in tissue DNA of humans and untreated rodents, suggesting a potential endogenous role of EH in their formation. A sensitive assay is needed so we can determine whether EH is involved in etheno adduct formation in vivo and study the biological significance of the etheno adducts in DNA. In this study, we developed a gas chromatography/negative ion chemical ionization/mass spectrometry assay for the analysis of 1, N6-ethenoadenine (epsilonAde) and 7-(1', 2'-dihydroxyheptyl)-3H-imidazo[2,1-i]purine (DHH-epsilonAde) in DNA; both are products from the reaction of adenine with EH. The assay entails the following sequence of steps: (1) addition of [15N5]epsilonAde and [15N5]DHH-epsilonAde to DNA as internal standards, (2) acid hydrolysis of DNA, (3) adduct enrichment by C18 solid phase extraction (SPE), (4) derivatization by pentafluorobenzylation (PFB), (5) separation of PFB-epsilonAde and PFB-DHH-epsilonAde on a Si SPE column, (6) acetonide (ACT) formation of PFB-DHH-epsilonAde, and (7) GC/MS analysis with selective ion monitoring (SIM). The limit of detection by on-column injection for PFB-epsilonAde monitoring of the (M - PFB)- ion at m/z 158 was 30 amol and for ACT-PFB-DHH-epsilonAde monitoring of the (M - PFB)- ion at m/z 328 was 0.4 fmol; the detection limits for the entire assay were 6.3 fmol for epsilonAde and 36 fmol for DHH-epsilonAde. In calf thymus DNA modified with EH at 37 degreesC for 50 h, both epsilonAde and DHH-epsilonAde were detected at high levels by this method, 4.5 +/- 0.7 and 90.8 +/- 8.7 adducts/10(3) adenine, respectively. These levels were also verified by HPLC fluorescence analysis, indicating that EH extensively reacts

Effects of liquid post-column addition in electrospray ionization performance in supercritical fluid chromatography-mass spectrometry.

Science.gov (United States)

Akbal, Laura; Hopfgartner, Gérard

2017-09-29

In supercritical fluid chromatography coupled to atmospheric pressure ionization mass spectrometry (SFC-MS), the use of a make-up post-column is almost mandatory to avoid analyte precipitation, especially when using low percentage of modifier (supercritical conditions (1mL/min 40°C, 150bar) to gaseous state (room temperature, atmospheric pressure), the CO 2 expands around 430 times, contributing to almost 5% of the nebulizing process. In positive mode, the presence of ammonium ions either in the mobile phase or in the make-up did significantly increase the MS signal, even at basic apparent pH. The ionization performance of electrospray is influenced by the acidic buffer power of the carbon dioxide, and was found to be restricted in the apparent pH range of 3.8-7.2 in the various conditions investigated. This may challenge sensitive detection in negative mode, as illustrated for bosentan. The use of DMSO as make-up additive (up to 30%) showed a simplification of the full scan spectrum regarding the adducts. Finally, the optimization of make-up composition leads to an enhancement up to a factor of 69 on the electrospray MS response signal, for the SFC-SRM/MS analysis of HIV protease inhibitors in plasma extracted from Dried Plasma Spots. Copyright © 2017 Elsevier B.V. All rights reserved.

CHARACTERIZATION OF DANSYLATED CYSTEINE, GLUTATHIONE DISULFIDE, CYSTEINE AND CYSTINE BY NARROW BORE LIQUID CHROMATOGRAPHY/ELECTROSPRAY IONIZATION MASS SPECTROMETRY

Science.gov (United States)

A method using reversed phase high performance liquid chromatography/electrospray ionization-mass spectrometric (RP-LC/ESI-MS) method has been developed to confirm the identity of dansylated derivatives of cysteine and glutathione, and their respective dimers. Cysteine, GSH, CSSC...

Chemical Characteristics of Organic Aerosols in Shanghai: A Study by Ultrahigh-Performance Liquid Chromatography Coupled With Orbitrap Mass Spectrometry

Science.gov (United States)

Wang, Xinke; Hayeck, Nathalie; Brüggemann, Martin; Yao, Lei; Chen, Hangfei; Zhang, Ci; Emmelin, Corinne; Chen, Jianmin; George, Christian; Wang, Lin

2017-11-01

Particulate matter 2.5 (PM2.5) filter samples were collected in July and October 2014 and January and April 2015 in urban Shanghai and analyzed using ultrahigh-performance liquid chromatography coupled to Orbitrap mass spectrometry. The measured chromatogram-mass spectra were processed by a nontarget screening approach to identify significant signals. In total, 810-1,510 chemical formulas of organic compounds in the negative polarity (negative electrospray ionization (ESI-)) and 860-1,790 in the positive polarity (ESI+), respectively, were determined. The chemical characteristics of organic aerosols (OAs) in Shanghai varied among different months and between daytime and nighttime. In the January samples, organics were generally richer in terms of both number and abundance, whereas those in the July samples were far lower. More CHO- (compounds containing only carbon, hydrogen, and oxygen and detected in ESI-) and CHOS- (sulfur-containing organics) were found in the daytime samples, suggesting a photochemical source, whereas CHONS- (nitrogen- and sulfur-containing organics) were more abundant in the nighttime samples, due to nocturnal nitrate radical chemistry. A significant number of monocyclic and polycyclic aromatic compounds, and nitrogen- and sulfur-containing heterocyclic compounds, were detected in all samples, indicating that biomass burning and fossil fuel combustion made important contributions to the OAs in urban Shanghai. Additionally, precursor-product pair analysis indicates that the epoxide pathway is an important formation route for organosulfates observed in Shanghai. Moreover, a similar analysis suggests that 35-57% of nitrogen-containing compounds detected in ESI+ could be formed through reactions between ammonia and carbonyls. Our study presents a comprehensive overview of OAs in urban Shanghai, which helps to understand their characteristics and sources.

The use of isoprene as a novel dopant in negative ion atmospheric pressure photoionization mass spectrometry coupled to high-performance liquid chromatography.

Science.gov (United States)

Dousty, Faezeh; O'Brien, Rob

2015-06-15

As in the case with positive ion atmospheric pressure photoionization (PI-APPI), the addition of dopants significantly improves the sensitivity of negative ion APPI (NI-APPI). However, the research on dopant-assisted-NI-APPI has been quite limited compared to the studies on dopant-assisted PI-APPI. This work presents the potential of isoprene as a novel dopant for NI-APPI. Thirteen compounds, possessing suitable gas-phase ion energetic properties in order to make stable negative ions, were selected. Dopants were continuously introduced into a tee junction prior to the ion source through a fused-silica capillary, while analytes were directly injected into the same tee. Then both were mixed with the continuous solvent from high-performance liquid chromatography (HPLC), nebulized, and entered the source. The nebulized stream was analyzed by APPI tandem quadrupole mass spectrometry in the negative ion mode. The results obtained using isoprene were compared with those obtained by using toluene as a dopant and dopant-free NI-APPI. Isoprene enhanced the ionization intensities of the studied compounds, which were found to be comparable and, in some cases, more effective than toluene. The mechanisms leading to the observed set of negative analyte ions were also discussed. Because in NI-APPI, thermal electrons, which are produced during the photoionization of a dopant, are considered the main reagent ions, both isoprene and toluene promoted the ionization of analytes through the same mechanisms, as expected. Isoprene was shown to perform well as a novel dopant for NI-APPI. Isoprene has a high photoabsorption cross section in the VUV region; therefore, its photoionization leads to a highly effective production of thermal electrons, which further promotes the ionization of analytes. In addition, isoprene is environmentally benign and less toxic compared to currently used dopants. Copyright © 2015 John Wiley & Sons, Ltd.

Upper-room ultraviolet light and negative air ionization to prevent tuberculosis transmission.

Directory of Open Access Journals (Sweden)

A Roderick Escombe

2009-03-01

Full Text Available Institutional tuberculosis (TB transmission is an important public health problem highlighted by the HIV/AIDS pandemic and the emergence of multidrug- and extensively drug-resistant TB. Effective TB infection control measures are urgently needed. We evaluated the efficacy of upper-room ultraviolet (UV lights and negative air ionization for preventing airborne TB transmission using a guinea pig air-sampling model to measure the TB infectiousness of ward air.For 535 consecutive days, exhaust air from an HIV-TB ward in Lima, Perú, was passed through three guinea pig air-sampling enclosures each housing approximately 150 guinea pigs, using a 2-d cycle. On UV-off days, ward air passed in parallel through a control animal enclosure and a similar enclosure containing negative ionizers. On UV-on days, UV lights and mixing fans were turned on in the ward, and a third animal enclosure alone received ward air. TB infection in guinea pigs was defined by monthly tuberculin skin tests. All guinea pigs underwent autopsy to test for TB disease, defined by characteristic autopsy changes or by the culture of Mycobacterium tuberculosis from organs. 35% (106/304 of guinea pigs in the control group developed TB infection, and this was reduced to 14% (43/303 by ionizers, and to 9.5% (29/307 by UV lights (both p < 0.0001 compared with the control group. TB disease was confirmed in 8.6% (26/304 of control group animals, and this was reduced to 4.3% (13/303 by ionizers, and to 3.6% (11/307 by UV lights (both p < 0.03 compared with the control group. Time-to-event analysis demonstrated that TB infection was prevented by ionizers (log-rank 27; p < 0.0001 and by UV lights (log-rank 46; p < 0.0001. Time-to-event analysis also demonstrated that TB disease was prevented by ionizers (log-rank 3.7; p = 0.055 and by UV lights (log-rank 5.4; p = 0.02. An alternative analysis using an airborne infection model demonstrated that ionizers prevented 60% of TB infection and 51% of TB

Chemical protection against ionizing radiation. Final report

International Nuclear Information System (INIS)

Livesey, J.C.; Reed, D.J.; Adamson, L.F.

1984-08-01

The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references

Chemical protection against ionizing radiation. Final report

Energy Technology Data Exchange (ETDEWEB)

Livesey, J.C.; Reed, D.J.; Adamson, L.F.

1984-08-01

The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references.

Determination of Pesticides by Gas Chromatography Combined with Mass Spectrometry Using Femtosecond Lasers Emitting at 267, 400, and 800 nm as the Ionization Source.

Science.gov (United States)

Yang, Xixiang; Imasaka, Tomoko; Imasaka, Totaro

2018-04-03

A standard sample mixture containing 51 pesticides was separated by gas chromatography (GC), and the constituents were identified by mass spectrometry (MS) using femtosecond lasers emitting at 267, 400, and 800 nm as the ionization source. A two-dimensional display of the GC/MS was successfully used for the determination of these compounds. A molecular ion was observed for 38 of the compounds at 267 nm and for 30 of the compounds at 800 nm, in contrast to 27 among 50 compounds when electron ionization was used. These results suggest that the ultraviolet laser is superior to the near-infrared laser for molecular weight determinations and for a more reliable analysis of these compounds. In order to study the conditions for optimal ionization, the experimental data were examined using the spectral properties (i.e., the excitation and ionization energies and absorption spectra for the neutral and ionized species) obtained by quantum chemical calculations. A few molecules remained unexplained by the currently reported rules, requiring additional rules for developing a full understanding of the femtosecond ionization process. The pesticides in the homogenized matrix obtained from kabosu ( citrus sphaerocarpa) were measured using lasers emitting at 267 and 800 nm. The pesticides were clearly separated and measured on the two-dimensional display, especially for the data measured at 267 nm, suggesting that this technique would have potential for use in the practical trace analysis of the pesticides in the environment.

Quantification of isomerically summed hydrocarbon contributions to crude oil by carbon number, double bond equivalent, and aromaticity using gas chromatography with tunable vacuum ultraviolet ionization.

Science.gov (United States)

Nowak, Jeremy A; Weber, Robert J; Goldstein, Allen H

2018-03-12

The ability to structurally characterize and isomerically quantify crude oil hydrocarbons relevant to refined fuels such as motor oil, diesel, and gasoline represents an extreme challenge for chromatographic and mass spectrometric techniques. This work incorporates two-dimensional gas chromatography coupled to a tunable vacuum ultraviolet soft photoionization source, the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source at the Lawrence Berkeley National Laboratory, with a time-of-flight mass spectrometer (GC × GC-VUV-TOF) to directly characterize and isomerically sum the contributions of aromatic and aliphatic species to hydrocarbon classes of four crude oils. When the VUV beam is tuned to 10.5 ± 0.2 eV, both aromatic and aliphatic crude oil hydrocarbons are ionized to reveal the complete chemical abundance of C 9 -C 30 hydrocarbons. When the VUV beam is tuned to 9.0 ± 0.2 eV only aromatic hydrocarbons are ionized, allowing separation of the aliphatic and aromatic fractions of the crude oil hydrocarbon chemical classes in an efficient manner while maintaining isomeric quantification. This technique provides an effective tool to determine the isomerically summed aromatic and aliphatic hydrocarbon compositions of crude oil, providing information that goes beyond typical GC × GC separations of the most dominant hydrocarbon isomers.

Hydrocarbon analysis using desorption atmospheric pressure chemical ionization

KAUST Repository

Jjunju, Fred Paul Mark; Badu-Tawiah, Abraham K.; Li, Anyin; Soparawalla, Santosh; Roqan, Iman S.; Cooks, Robert Graham

2013-01-01

Characterization of the various petroleum constituents (hydronaphthalenes, thiophenes, alkyl substituted benzenes, pyridines, fluorenes, and polycyclic aromatic hydrocarbons) was achieved under ambient conditions without sample preparation by desorption atmospheric pressure chemical ionization (DAPCI). Conditions were chosen for the DAPCI experiments to control whether ionization was by proton or electron transfer. The protonated molecule [M+H]+ and the hydride abstracted [MH]+ form were observed when using an inert gas, typically nitrogen, to direct a lightly ionized plasma generated by corona discharge onto the sample surface in air. The abundant water cluster ions generated in this experiment react with condensed-phase functionalized hydrocarbon model compounds and their mixtures at or near the sample surface. On the other hand, when naphthalene was doped into the DAPCI gas stream, its radical cation served as a charge exchange reagent, yielding molecular radical cations (M+) of the hydrocarbons. This mode of sample ionization provided mass spectra with better signal/noise ratios and without unwanted side-products. It also extended the applicability of DAPCI to petroleum constituents which could not be analyzed through proton transfer (e.g., higher molecular PAHs such as chrysene). The thermochemistry governing the individual ionization processes is discussed and a desorption/ionization mechanism is inferred. © 2012 Elsevier B.V.

Hydrocarbon analysis using desorption atmospheric pressure chemical ionization

KAUST Repository

Jjunju, Fred Paul Mark

2013-07-01

Characterization of the various petroleum constituents (hydronaphthalenes, thiophenes, alkyl substituted benzenes, pyridines, fluorenes, and polycyclic aromatic hydrocarbons) was achieved under ambient conditions without sample preparation by desorption atmospheric pressure chemical ionization (DAPCI). Conditions were chosen for the DAPCI experiments to control whether ionization was by proton or electron transfer. The protonated molecule [M+H]+ and the hydride abstracted [MH]+ form were observed when using an inert gas, typically nitrogen, to direct a lightly ionized plasma generated by corona discharge onto the sample surface in air. The abundant water cluster ions generated in this experiment react with condensed-phase functionalized hydrocarbon model compounds and their mixtures at or near the sample surface. On the other hand, when naphthalene was doped into the DAPCI gas stream, its radical cation served as a charge exchange reagent, yielding molecular radical cations (M+) of the hydrocarbons. This mode of sample ionization provided mass spectra with better signal/noise ratios and without unwanted side-products. It also extended the applicability of DAPCI to petroleum constituents which could not be analyzed through proton transfer (e.g., higher molecular PAHs such as chrysene). The thermochemistry governing the individual ionization processes is discussed and a desorption/ionization mechanism is inferred. © 2012 Elsevier B.V.

Improving quantitative gas chromatography-electron ionization mass spectrometry results using a modified ion source: demonstration for a pharmaceutical application.

Science.gov (United States)

D'Autry, Ward; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Van Schepdael, Ann

2011-07-01

Gas chromatography-mass spectrometry is a well established analytical technique. However, mass spectrometers with electron ionization sources may suffer from signal drifts, hereby negatively influencing quantitative performance. To demonstrate this phenomenon for a real application, a static headspace-gas chromatography method in combination with electron ionization-quadrupole mass spectrometry was optimized for the determination of residual dichloromethane in coronary stent coatings. Validating the method, the quantitative performance of an original stainless steel ion source was compared to that of a modified ion source. Ion source modification included the application of a gold coating on the repeller and exit plate. Several validation aspects such as limit of detection, limit of quantification, linearity and precision were evaluated using both ion sources. It was found that, as expected, the stainless steel ion source suffered from signal drift. As a consequence, non-linearity and high RSD values for repeated analyses were obtained. An additional experiment was performed to check whether an internal standard compound would lead to better results. It was found that the signal drift patterns of the analyte and internal standard were different, consequently leading to high RSD values for the response factor. With the modified ion source however, a more stable signal was observed resulting in acceptable linearity and precision. Moreover, it was also found that sensitivity improved compared to the stainless steel ion source. Finally, the optimized method with the modified ion source was applied to determine residual dichloromethane in the coating of coronary stents. The solvent was detected but found to be below the limit of quantification. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterization of nitrated sugar alcohols by atmospheric-pressure chemical-ionization mass spectrometry.

Science.gov (United States)

Ostrinskaya, Alla; Kelley, Jude A; Kunz, Roderick R

2017-02-28

The nitrated sugar alcohols mannitol hexanitrate (MHN), sorbitol hexanitrate (SHN) and xylitol pentanitrate (XPN) are in the same class of compounds as the powerful military-grade explosive pentaerythritol tetranitrate (PETN) and the homemade explosive erythritol tetranitrate (ETN) but, unlike for PETN and ETN, ways to detect MHN, SHN and XPN by mass spectrometry (MS) have not been fully investigated. Atmospheric-pressure chemical-ionization mass spectrometry (APCI-MS) was used to detect ions characteristic of nitrated sugar alcohols. APCI time-of-flight mass spectrometry (APCI-TOF MS) and collision-induced dissociation tandem mass spectrometry (CID MS/MS) were used for confirmation of each ion assignment. In addition, the use of the chemical ionization reagent dichloromethane was investigated to improve sensitivity and selectivity for detection of MHN, SHN and XPN. All the nitrated sugar alcohols studied followed similar fragmentation pathways in the APCI source. MHN, SHN and XPN were detectable as fragment ions formed by the loss of NO 2 , HNO 2 , NO 3 , and CH 2 NO 2 groups, and in the presence of dichloromethane chlorinated adduct ions were observed. It was determined that in MS/MS mode, chlorinated adducts of MHN and SHN had the lowest limits of detection (LODs), while for XPN the lowest LOD was for the [XPN-NO 2 ] - fragment ion. Partially nitrated analogs of each of the three compounds were also present in the starting materials, and ions attributable to these compounds versus those formed from in-source fragmentation of MHN, SHN, and XPN were distinguished and assigned using liquid chromatography APCI-MS and ESI-MS. The APCI-MS technique provides a selective and sensitive method for the detection of nitrated sugar alcohols. The methods disclosed here will benefit the area of explosives trace detection for counterterrorism and forensics. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Characterization of Nitrated Sugar Alcohols by Atmospheric-Pressure Chemical-Ionization Mass Spectrometry

Science.gov (United States)

2016-07-27

Chemical, Microsystem, and Nanoscale Technology Group MIT-Lincoln Laboratory, Lexington, MA 02420 jude.kelley@ll.mit.edu RATIONALE: The...formed by the loss of NO2, HNO2, NO3, and CH2NO2 groups , and in the presence of dichloromethane chlorinated adduct ions were observed. It was determined...explosives trace detection, such as electrospray ionization ( ESI ) and atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) along

Preparative separation of polyphenols from artichoke by polyamide column chromatography and high-speed counter-current chromatography

International Nuclear Information System (INIS)

Shu, Xikai; Wang, Mei; Liu, Daicheng; Wang, Daijie; Lin, Xiaojing; Liu, Jianhua; Wang, Xiao; Huang, Luqi

2013-01-01

An efficient method for the rapid separation and purification of polyphenols from artichoke by polyamide column chromatography in combination with high-speed counter-current chromatography (HSCCC) was successfully built. The crude ethanol extracts from dry artichoke were first pre-separated by polyamide column chromatography and divided in two parts as sample 1 and sample 2. Then, the samples were further separated by HSCCC and yielded 7.8 mg of chlorogenic acid (compound I), 24.5 mg of luteolin-7-O-β-D-rutinoside (compound II), 18.4 mg of luteolin-7-O-β-D-glucoside (compound III), and 33.4 mg of cynarin (compound IV) with purity levels of 92.0%, 98.2%, 98.5%, and 98.0%, respectively, as determined by high-performance liquid chromatography (HPLC) method. The chemical structures of these compounds were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). (author)

Preparative separation of polyphenols from artichoke by polyamide column chromatography and high-speed counter-current chromatography

Energy Technology Data Exchange (ETDEWEB)

Shu, Xikai; Wang, Mei; Liu, Daicheng [College of Life Science, Shandong Normal University, Jinan, Shandong (China); Wang, Daijie; Lin, Xiaojing; Liu, Jianhua; Wang, Xiao; Huang, Luqi, E-mail: wxjn1998@126.com [Shandong Analysis and Test Center, Shandong Academy of Sciences, Jinan, Shandong (China)

2013-09-01

An efficient method for the rapid separation and purification of polyphenols from artichoke by polyamide column chromatography in combination with high-speed counter-current chromatography (HSCCC) was successfully built. The crude ethanol extracts from dry artichoke were first pre-separated by polyamide column chromatography and divided in two parts as sample 1 and sample 2. Then, the samples were further separated by HSCCC and yielded 7.8 mg of chlorogenic acid (compound I), 24.5 mg of luteolin-7-O-{beta}-D-rutinoside (compound II), 18.4 mg of luteolin-7-O-{beta}-D-glucoside (compound III), and 33.4 mg of cynarin (compound IV) with purity levels of 92.0%, 98.2%, 98.5%, and 98.0%, respectively, as determined by high-performance liquid chromatography (HPLC) method. The chemical structures of these compounds were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). (author)

Gas chromatography/atmospheric pressure chemical ionization/mass spectrometry for the analysis of organochlorine pesticides and polychlorinated biphenyls in human serum.

Science.gov (United States)

Geng, Dawei; Jogsten, Ingrid Ericson; Dunstan, Jody; Hagberg, Jessika; Wang, Thanh; Ruzzin, Jerome; Rabasa-Lhoret, Rémi; van Bavel, Bert

2016-07-01

A method using a novel atmospheric pressure chemical ionization source for coupling gas chromatography (GC/APCI) to triple quadrupole mass spectrometry (MS/MS) for the determination of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) regulated by the Stockholm Convention is presented. One microliter injection of a six-point calibration curve of native PCBs and OCPs, ranging from 0.04 to 300pg/μL, was performed. The relative standard deviation (RSD) of the relative response factors (RRFs) was less than 15% with a coefficient of determination (r(2))>0.995. Meanwhile, two calibration solutions (CS), CS 2 (0.4pg/μL) and CS 3 (4pg/μL) were analyzed to study the repeatability calculated for both area and RRFs. The RSD for RRF ranged from 3.1 to 16% and 3.6 to 5.5% for CS 2 and CS 3, respectively. The limits of detection (LOD) determined by peak-to-peak signal-to-noise ratio (S/N) of 3 were compared between the GC/APCI/MS/MS and a GC coupled to high resolution mass spectrometry (GC/HRMS) system. GC/APCI/MS/MS resulted in lower LOD for most of the compounds, except for PCB#74, cis-chlordane and trans-chlordane. GC/APCI/MS/MS and GC/HRMS were also compared by performing analysis on 75 human serum samples together with eight QA/QC serum samples. The comparison between GC/APCI/MS/MS system and GC/HRMS system for 16 of the targeted compounds was carried out. No statistically significant difference was discovered. Due to increased sensitivity and user friendly operation under atmospheric pressure, GC/APCI/MS/MS is a powerful alternative technique that can easily meet the specification of GC/HRMS. Copyright © 2016 Elsevier B.V. All rights reserved.

Insight into acid-base nucleation experiments by comparison of the chemical composition of positive, negative, and neutral clusters.

Science.gov (United States)

Bianchi, Federico; Praplan, Arnaud P; Sarnela, Nina; Dommen, Josef; Kürten, Andreas; Ortega, Ismael K; Schobesberger, Siegfried; Junninen, Heikki; Simon, Mario; Tröstl, Jasmin; Jokinen, Tuija; Sipilä, Mikko; Adamov, Alexey; Amorim, Antonio; Almeida, Joao; Breitenlechner, Martin; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Kangasluoma, Juha; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Laaksonen, Ari; Lawler, Michael J; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Riccobono, Francesco; Rissanen, Matti P; Rondo, Linda; Tomé, António; Virtanen, Annele; Viisanen, Yrjö; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M; Ye, Penglin; Curtius, Joachim; Kulmala, Markku; Worsnop, Douglas R; Donahue, Neil M; Baltensperger, Urs

2014-12-02

We investigated the nucleation of sulfuric acid together with two bases (ammonia and dimethylamine), at the CLOUD chamber at CERN. The chemical composition of positive, negative, and neutral clusters was studied using three Atmospheric Pressure interface-Time Of Flight (APi-TOF) mass spectrometers: two were operated in positive and negative mode to detect the chamber ions, while the third was equipped with a nitrate ion chemical ionization source allowing detection of neutral clusters. Taking into account the possible fragmentation that can happen during the charging of the ions or within the first stage of the mass spectrometer, the cluster formation proceeded via essentially one-to-one acid-base addition for all of the clusters, independent of the type of the base. For the positive clusters, the charge is carried by one excess protonated base, while for the negative clusters it is carried by a deprotonated acid; the same is true for the neutral clusters after these have been ionized. During the experiments involving sulfuric acid and dimethylamine, it was possible to study the appearance time for all the clusters (positive, negative, and neutral). It appeared that, after the formation of the clusters containing three molecules of sulfuric acid, the clusters grow at a similar speed, independent of their charge. The growth rate is then probably limited by the arrival rate of sulfuric acid or cluster-cluster collision.

Determination of flomoxef in human plasma by liquid chromatography/electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Kravtsova, Oxana Yu; Paramonov, Sergey A; Vasilevich, Natalya I; Kazyulkin, Denis N; Vlasova, Ekaterina; Engsig, Michael

2013-12-01

A specific, sensitive, rapid and reproducible method for the determination of flomoxef in human plasma using high-performance liquid chromatography-tandem mass spectrometry was developed and validated. Flomoxef was detected using an electrospay ionization method operated in negative-ion mode. Chromatographic separation was performed in gradient elution mode on a Luna® C18(2) column (3 μM, 20 × 4.0 mm) at a flow rate of 1 mL/min and runtime 3.5 min. The mobile phase consisted of acetonitrile and water containing 0.1% formic acid as additive. Extraction of flomoxef from plasma and precipitation of plasma proteins was performed with acetonitrile with an absolute recovery of 86.4 ± 1.6%. The calibration curve was linear with a correlation coefficient of 0.999 over the concentration range 10-5000 ng/mL and the lower limit of quantification was 10 ng/mL. The intra- and inter-day precisions were flomoxef revealed that it could be successfully analyzed at 4 ºС over 24 h, but it was unstable in solutions at room temperature during short-term storage (4 h) and several freeze-thaw cycles. Copyright © 2013 John Wiley & Sons, Ltd.

Identification of a tryptanthrin metabolite in rat liver microsomes by liquid chromatography/electrospray ionization-tandem mass spectrometry.

Science.gov (United States)

Lee, Sang Kyu; Kim, Ghee Hwan; Kim, Dong Hyeon; Kim, Dong Hyun; Jahng, Yurngdong; Jeong, Tae Cheon

2007-10-01

Tryptanthrin originally isolated from Isatis tinctoria L. has been characterized to have anti-inflammatory activities through the dual inhibition of cyclooxygenase-2 and 5-lipoxygenase mediated prostaglandin and leukotriene syntheses. To characterize phase I metabolite(s), tryptanthrin was incubated with rat liver microsomes in the presence of NADPH-generating system. One metabolite was identified by liquid chromatography/electrospray ionization-tandem mass spectrometry. M1 could be identified as a metabolite mono-hydroxylated on the aromatic ring of indole moiety from the MS(2) spectra of protonated tryptanthrin and M1. The structure of metabolite was confirmed as 8-hydroxytryptanthrin with a chemically synthesized authentic standard. The formation of M1 was NADPH-dependent and was inhibited by SKF-525A, a general CYP-inhibitor, indicating the cytochrome P450 (CYP)-mediated reaction. In addition, it was proposed that M1 might be formed by CYP 1A in rat liver microsomes from the experiments with enriched rat liver microsomes.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): review.

Science.gov (United States)

Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J

2015-09-03

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a "soft" ion source for preserving highly diagnostic molecular ion is desirable, as compared to the "hard" ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. Copyright © 2015. Published by Elsevier B.V.

Influence of ionization on the Gupta and on the Park chemical models

Science.gov (United States)

Morsa, Luigi; Zuppardi, Gennaro

2014-12-01

This study is an extension of former works by the present authors, in which the influence of the chemical models by Gupta and by Park was evaluated on thermo-fluid-dynamic parameters in the flow field, including transport coefficients, related characteristic numbers and heat flux on two current capsules (EXPERT and Orion) during the high altitude re-entry path. The results verified that the models, even computing different air compositions in the flow field, compute only slight different compositions on the capsule surface, therefore the difference in the heat flux is not very relevant. In the above mentioned studies, ionization was neglected because the velocities of the capsules (about 5000 m/s for EXPERT and about 7600 m/s for Orion) were not high enough to activate meaningful ionization. The aim of the present work is to evaluate the incidence of ionization, linked to the chemical models by Gupta and by Park, on both heat flux and thermo fluid-dynamic parameters. The present computer tests were carried out by a direct simulation Monte Carlo code (DS2V) in the velocity interval 7600-12000 m/s, considering only the Orion capsule at an altitude of 85 km. The results verified what already found namely when ionization is not considered, the chemical models compute only a slight different gas composition in the core of the shock wave and practically the same composition on the surface therefore the same heat flux. On the opposite, the results verified that when ionization is considered, the chemical models compute different compositions in the whole shock layer and on the surface therefore different heat flux. The analysis of the results relies on a qualitative and a quantitative evaluation of the effects of ionization on both chemical models. The main result of the study is that when ionization is taken into account, the Park model is more reactive than the Gupta model; consequently, the heat flux computed by Park is lower than the one computed by Gupta; using the

Combined Determination of Poly-β-Hydroxyalkanoic and Cellular Fatty Acids in Starved Marine Bacteria and Sewage Sludge by Gas Chromatography with Flame Ionization or Mass Spectrometry Detection

Science.gov (United States)

Odham, Göran; Tunlid, Anders; Westerdahl, Gunilla; Mårdén, Per

1986-01-01

Extraction of lipids from bacterial cells or sewage sludge samples followed by simple and rapid extraction procedures and room temperature esterification with pentafluorobenzylbromide allowed combined determinations of poly-β-hydroxyalkanoate constituents and fatty acids. Capillary gas chromatography and flame ionization or mass spectrometric detection was used. Flame ionization permitted determination with a coefficient of variation ranging from 10 to 27% at the picomolar level, whereas quantitative chemical ionization mass spectrometry afforded sensitivities for poly-β-hydroxyalkanoate constituuents in the attomolar range. The latter technique suggests the possibility of measuring such components in bacterial assemblies with as few as 102 cells. With the described technique using flame ionization detection, it was possible to study the rapid formation of poly-β-hydroxyalkanoate during feeding of a starved marine bacterium isolate with a complex medium or glucose and correlate the findings to changes in cell volumes. Mass spectrometric detection of short β-hydroxy acids in activated sewage sludge revealed the presence of 3-hydroxybutyric, 3-hydroxyhexanoic, and 3-hydroxyoctanoic acids in the relative proportions of 56, 5 and 39%, respectively. No odd-chain β-hydroxy acids were found. PMID:16347181

[Determination of endogenous agmatine in rat plasma by isotope dilution-gas chromatography-mass spectrometry].

Science.gov (United States)

Qiu, Zhongli; Lin, Ying; Xiong, Zhili; Xie, Jianwei

2014-07-01

A method for the determination of endogenous agmatine in rat plasma was developed by isotope dilution-gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The plasma samples were analyzed after protein precipitation, evaporation, derivatization by hexafluoroacetone (HFAA), and clean-up on a Florisil SPE column. The GC-MS analysis utilized stable isotope d8-agmatine as internal standard. The samples after treatme were tested by negative chemical ionization with selected ion monitoring (SIM) which was set at m/z 492 (molecular ion of agmatine) and m/z 500 (molecular ion of internal standard). The limit of detection (LOD) of agmatine standard solution was 0.005 7 ng/mL. The calibration curve of the agmatine spiked in rat plasma showed a good linear relationship at the range of 1.14-57.0 ng/mL (r = 0.997). The recoveries of agmatine spiked in rat plasma ranged from 92.3% to 109.8%. Inter-day and intra-day precisions were less than 15%. The average concentration level of agmatine in rat plasma was (22 +/- 9) ng/mL, and there was no significant difference between male and female SD rats (p > 0.05). The method is high sensitive and specific, and can be used for the determination of endogenous agmatine in plasma. It provides a strong support for the subsequent research of agmatine.

A comparison of chemical and ionization dosimetry for high-energy x-ray and electron beams

International Nuclear Information System (INIS)

Durocher, J.J.; Boese, H.; Cormack, D.V.; Holloway, A.F.

1981-01-01

A comparison was made of ferrous sulfate (Fricke) and ionometric methods for determining the absorbed dose in a phantom irradiated with 4-MV x-rays, 25-MV x-rays, or electron beams having various incident energies between 10 and 32 MeV. Both chemical and ionization instruments were calibrated in a 60 Co beam at a point in water where the absorbed dose had been previously determined. The chemical yield measurements were corrected for spatial variations in dose within the volume of the solution and used to obtain a value of the absorbed dose for each of the x-ray and electron beams. The ratios of G-values required for these determinations were taken from ICRU reports 14 and 21. Ionization instrument readings from three types of commercial ionization chambers were used to obtain alternate values of the absorbed dose for each radiation. C lambda and CE values used in determining these ionization values of dose were also taken from the above ICRU reports. For 4-MV x-rays the values of absorbed dose obtained from chemical measurements agreed to within 0.5% with values obtained from ionization measurements; for 25-MV x-rays the chemical values were about 1% higher than the ionization values; for the electron beams the chemical values were 1%-4% below the ionization values. These discrepancies suggest an inconsistency among the recommended G, C lambda, and CE values similar to that which has been noted by other workers

METHOD 332.0: DETERMINATION OF PERCHLORATE IN DRINKING WATER BY ION CHROMATOGRAPHY WITH SUPPRESSED CONDUCTIVITY AND ELECTROSPRAY IONIZATION MASS SPECTROMETRY

Science.gov (United States)

This method is applicable to the identification and quantitation of perchlorate in raw and finished drinking waters. The approach used is ion chromatography with suppressed conductivity and electrospray ionization mass spectrometry (IC-ESI/MS)

Microsynthesis and electron ionization mass spectral studies of O(S)-alkyl N,N-dimethyl alkylphosphono(thiolo)thionoamidates for Chemical Weapons Convention verification.

Science.gov (United States)

Saeidian, Hamdollah; Babri, Mehran; Abdoli, Morteza; Sarabadani, Mansour; Ashrafi, Davood; Naseri, Mohammad Taghi

2012-12-15

The availability of mass spectra and interpretation skills are essential for unambiguous identification of the Chemical Weapons Convention (CWC)-related chemicals. The O(S)-alkyl N,N-dimethyl alkylphosphono(thiolo)thionoamidates are included in the list of scheduled CWC-related compounds, but there are very few spectra from these compounds in the literature. This paper examines these spectra and their mass spectral fragmentation routes. The title chemicals were prepared through microsynthetic protocols and were analyzed using electron ionization mass spectrometry with gas chromatography as a MS-inlet system. Structures of fragments were confirmed using analysis of fragment ions of deuterated analogs, tandem mass spectrometry and density functional theory (DFT) calculations. Mass spectrometric studies revealed some interesting fragmentation pathways during the ionization process, such as alkene and amine elimination and McLafferty-type rearrangements. The most important fragmentation route of the chemicals is the thiono-thiolo rearrangement. DFT calculations are used to support MS results and to reveal relative preference formation of fragment ions. The retention indices (RIs) of all the studied compounds are also reported. Mass spectra of the synthesized compounds were investigated with the aim to enrich the Organization for the Prohibition of Chemical Weapons (OPCW) Central Analytical Database (OCAD) which may be used for detection and identification of CWC-related chemicals during on-site inspection and/or off-site analysis such as OPCW proficiency tests. Copyright © 2012 John Wiley & Sons, Ltd.

Chemical Profiling of Re-Du-Ning Injection by Ultra-Performance Liquid Chromatography Coupled with Electrospray Ionization Tandem Quadrupole Time-of-Flight Mass Spectrometry through the Screening of Diagnostic Ions in MSE Mode

Science.gov (United States)

Wang, Zhenzhong; Geng, Jianliang; Dai, Yi; Xiao, Wei; Yao, Xinsheng

2015-01-01

The broad applications and mechanism explorations of traditional Chinese medicine prescriptions (TCMPs) require a clear understanding of TCMP chemical constituents. In the present study, we describe an efficient and universally applicable analytical approach based on ultra-performance liquid chromatography coupled to electrospray ionization tandem quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q/TOF-MS) with the MSE (E denotes collision energy) data acquisition mode, which allowed the rapid separation and reliable determination of TCMP chemical constituents. By monitoring diagnostic ions in the high energy function of MSE, target peaks of analogous compounds in TCMPs could be rapidly screened and identified. “Re-Du-Ning” injection (RDN), a eutherapeutic traditional Chinese medicine injection (TCMI) that has been widely used to reduce fever caused by viral infections in clinical practice, was studied as an example. In total, 90 compounds, including five new iridoids and one new sesquiterpene, were identified or tentatively characterized by accurate mass measurements within 5 ppm error. This analysis was accompanied by MS fragmentation and reference standard comparison analyses. Furthermore, the herbal sources of these compounds were unambiguously confirmed by comparing the extracted ion chromatograms (EICs) of RDN and ingredient herbal extracts. Our work provides a certain foundation for further studies of RDN. Moreover, the analytical approach developed herein has proven to be generally applicable for profiling the chemical constituents in TCMPs and other complicated mixtures. PMID:25875968

Coupling of gas chromatography and electrospray ionization high resolution mass spectrometry for the analysis of anabolic steroids as trimethylsilyl derivatives in human urine.

Science.gov (United States)

Cha, Eunju; Jeong, Eun Sook; Cha, Sangwon; Lee, Jaeick

2017-04-29

In this study, gas chromatography (GC) was interfaced with high resolution mass spectrometry (HRMS) with electrospray ionization source (ESI) and the relevant parameters were investigated to enhance the ionization efficiency. In GC-ESI, the distances (x-, y- and z) and angle between the ESI needle, GC capillary column and MS orifice were set to 7 (x-distance), 4 (y-distance), and 1 mm (z-distance). The ESI spray solvent, acid modifier and nebulizer gas flow were methanol, 0.1% formic acid and 5 arbitrary units, respectively. Based on these results, analytical conditions for GC-ESI/HRMS were established. In particular, the results of spray solvent flow indicated a concentration-dependent mechanism (peak dilution effect), and other parameters also greatly influenced the ionization performance. The developed GC-ESI/HRMS was then applied to the analysis of anabolic steroids as trimethylsilyl (TMS) derivatives in human urine to demonstrate its application. The ionization profiles of TMS-derivatized steroids were investigated and compared with those of underivatized steroids obtained from gas chromatography-electrospray ionization/mass spectrometry (GC-ESI/MS) and liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS). The steroids exhibited ionization profiles based on their structural characteristics, regardless of the analyte phase or derivatization. Groups I and II with conjugated or unconjugated keto functional groups at C3 generated the [M+H] + and [M+H-TMS] + ions, respectively. On the other hand, Groups III and IV gave rise to the characteristic fragment ions [M+H-TMS-H 2 O] + and [M+H-2TMS-H 2 O] + , corresponding to loss of a neutral TMS·H 2 O moiety from the protonated molecular ion by in-source dissociation. To the best of our knowledge, this is the first study to successfully ionize and analyze steroids as TMS derivatives using ESI coupled with GC. The present system has enabled the ionization of TMS derivatives under ESI conditions

Mass Spectrometric Study of Some Fluoroquinolone Drugs Using Electron Ionization and Chemical Ionization Techniques in Combination With Semi-Empirical Calculations

International Nuclear Information System (INIS)

Abd EL Kareem, M.S.M.

2013-01-01

A mass spectrometer of the type QMS (SSQ710) is used to record the electron ionization mass spectra of some 6-fluoroquinolones molecules, namely: Norfloxacin, Pefloxacin, Ciprofloxacin and Levofloxacin.While the chemical ionization mass spectra of these compounds are recorded using Thermo Finnigan TRACE DSQ GC/MS system.In EI mass spectra, the relative intensities for the molecular ions [M] +. of the studied compounds and the prominent fragment ions are reported and discussed. Furthermore, fragmentation patterns for the four compounds have been suggested and discussed and the most important fragmentation processes such as [M-CO 2 ] +. , [M-C 2 H 4 N] + and [M-CO 2 -C 2 H 4 N] + are investigated.On the other hand, the chemical ionization (CI) mass spectra of the compounds have been recorded using methane as the reagent gas. These spectra are discussed in terms of the structure of the compounds, with particular reference to their conventional electron ionization mass spectra. The protonated molecules [M + H] + are more relatively intense than [M] +. ions in the recorded EI mass spectra indicating higher stability in the case of [M + H] + .Also, fragmentation patterns for the four compounds have been suggested and discussed (using chemical ionization technique) and the most important fragmentation processes such as [MH-CO 2 ] +. , [MH-C 2 H 4 N] + and [MH-H 2 O] + are investigated.

Negative chromatography of hepatitis B virus-like particle: Comparative study of different adsorbent designs.

Science.gov (United States)

Lee, Micky Fu Xiang; Chan, Eng Seng; Tan, Wen Siang; Tam, Kam Chiu; Tey, Beng Ti

2016-05-06

Purification of virus-like particles (VLPs) in bind-and-elute mode has reached a bottleneck. Negative chromatography has emerged as the alternative solution; however, benchmark of negative chromatography media and their respective optimized conditions are absent. Hence, this study was carried out to compare the performance of different negative chromatography media for the purification of hepatitis B VLPs (HB-VLPs) from clarified Escherichia coli feedstock. The modified anion exchange media, core-shell adsorbents (InertShell and InertLayer 1000) and polymer grafted adsorbents (SQ) were compared. The results of chromatography from packed bed column of core-shell adsorbents showed that there is a trade-off between the purity and recovery of HB-VLPs in the flowthrough fraction due to the shell thickness. Atomic force microscopic analysis revealed funnel-shaped pore channels in the shell layer which may contribute to the entrapment of HB-VLPs. A longer residence time at a lower feed flow rate (0.5ml/min) improved slightly the HB-VLPs purity in all modified adsorbents, but the recovery in InertShell reduced substantially. The preheat-treatment is not recommended for the negative chromatography as the thermal-induced co-aggregation of HCPs and HB-VLPs would flow along with HB-VLPs and thus reduced the HB-VLPs purity in the flowthrough. Further reduction in the feedstock concentration enhanced the purity of HB-VLPs especially in InertLayer 1000 but reduced substantially the recovery of HB-VLPs. In general, the polymer grafted adsorbent, SQ, performed better than the core-shell adsorbents in handling a higher feedstock concentration. Copyright © 2016 Elsevier B.V. All rights reserved.

Gas chromatography with simultaneous detection: Ultraviolet spectroscopy, flame ionization, and mass spectrometry.

Science.gov (United States)

Gras, Ronda; Luong, Jim; Haddad, Paul R; Shellie, Robert A

2018-05-08

An effective analytical strategy was developed and implemented to exploit the synergy derived from three different detector classes for gas chromatography, namely ultraviolet spectroscopy, flame ionization, and mass spectrometry for volatile compound analysis. This strategy was achieved by successfully hyphenating a user-selectable multi-wavelength diode array detector featuring a positive temperature coefficient thermistor as an isothermal heater to a gas chromatograph. By exploiting the non-destructive nature of the diode array detector, the effluent from the detector was split to two parallel detectors; namely a quadrupole mass spectrometer and a flame ionization detector. This multi-hyphenated configuration with the use of three detectors is a powerful approach not only for selective detection enhancement but also for improvement in structural elucidation of volatile compounds where fewer fragments can be obtained or for isomeric compound analysis. With the diode array detector capable of generating high resolution gas phase spectra, the information collected provides useful confirmatory information without a total dependence on the chromatographic separation process which is based on retention time. This information-rich approach to chromatography is achieved without incurring extra analytical time, resulting in improvements in compound identification accuracy, analytical productivity, and cost. Chromatographic performance obtained from model compounds was found to be acceptable with a relative standard deviation of the retention times of less than 0.01% RSD, and a repeatability at two levels of concentration of 100 and 1000 ppm (v/v) of less than 5% (n = 10). With this configuration, correlation of data between the three detectors was simplified by having near identical retention times for the analytes studied. Copyright © 2018 Elsevier B.V. All rights reserved.

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...

Degradation of chlorpyrifos by ionizing radiation

International Nuclear Information System (INIS)

Mori, M.N.; Oikawa, H.; Sampa, M.H.O.; Duarte, C.L.

2006-01-01

Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides. It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract. Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60 Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted from the radiolytic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography with flame ionization detector (GCFID). (author)

Liquid Chromatography with Post-Column Reagent Addition of Ammonia in Methanol Coupled to Negative Ion Electrospray Ionization Tandem Mass Spectrometry for Determination of Phenoxyacid Herbicides and their Degradation Products in Surface Water

Directory of Open Access Journals (Sweden)

Renata Raina

2010-01-01

Full Text Available A new liquid chromatography (LC-negative ion electrospray ionization (ESI − –tandem mass spectrometry (MS/MS method with post-column addition of ammonia in methanol has been developed for the analysis of acid herbicides: 2,4-dichlorophenoxy acetic acid, 4-chloro-o-tolyloxyacetic acid, 2-(2-methyl-4-chlorophenoxybutyric acid, mecoprop, dichlorprop, 4-(2,4-dichlorophenoxy butyric acid, 2,4,5-trichlorophenoxy propionic acid, dicamba and bromoxynil, along with their degradation products: 4-chloro-2-methylphenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and 3,5-dibromo-4-hydroxybenzoic acid. The samples were extracted from the surface water matrix using solid-phase extraction (SPE with a polymeric sorbent and analyzed with LC ESI − with selected reaction monitoring (SRM using a three-point confirmation approach. Chromatography was performed on a Zorbax Eclipse XDB-C18 (50 × 4.6 mm i.d., 1.8 μm with a gradient elution using water-methanol with 2 mM ammonium acetate mobile phase at a flow rate of 0.15 mL/min. Ammonia in methanol (0.8 M was added post-column at a flow rate of 0.05 mL/min to enhance ionization of the degradation products in the MS source. One SRM transition was used for quantitative analysis while the second SRM along with the ratio of SRM1/SRM2 within the relative standard deviation determined by standards for each individual pesticide and retention time match were used for confirmation. The standard deviation of ratio of SRM1/SRM2 obtained from standards run on the day of analysis for different phenoxyacid herbicides ranged from 3.9 to 18.5%. Limits of detection (LOD were between 1 and 15 ng L −1 and method detection limits (MDL with strict criteria requiring <25% deviation of peak area from best-fit line for both SRM1 and SRM2 ranged from 5 to 10 ng L −1 for acid ingredients (except dicamba at 30 ng L −1 and from 2 to 30 ng L −1 for degradation products. The SPE-LC-ESI − MS/MS method permitted low nanogram

Identification of major xanthones and steroidal saponins in rat urine by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry technology following oral administration of Rhizoma Anemarrhenae decoction.

Science.gov (United States)

Ma, Chunhui; Wang, Longxing; Tang, Yihong; Fan, Mingsong; Xiao, Hongbin; Huang, Chenggang

2008-10-01

Rhizoma Anemarrhenae (Zhimu in Chinese), the dried rhizome of Anemarrhena asphodeloides Bge. (Fam. Liliaceae), is a well-known traditional Chinese medicinal herb and has been used clinically in China for centuries to cure various diseases. However, like other traditional Chinese medicines, the effective constituents of this medicine, especially the assimilation and metabolites in vivo, which are very important to show their effects, have not been systematically studied. In this paper, solid-phase extraction and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry technologies were used to study the constituents absorbed into rat urine and their metabolites after oral administration of Rhizoma Anemarrhenae decoction. A total of 11 compounds, including two xanthones, three of their metabolites and six steroidal saponins, were identified in rat urine sample. They were neomangiferin (1), glucuronide and monomethyl conjugate of mangiferin (2), mangiferin (3), monomethyl conjugate of mangiferin (4), dimethyl conjugate of mangiferin (5), timosaponin N or timosaponin E1 (6), timosaponin BII (7), timosaponin BIII (8), anemarrhenasaponin I or anemarrhenasaponin II (9), timosaponin AII (10) and timosaponin AIII (11). The results would efficaciously narrow the potentially active compounds range in Rhizoma Anemarrhenae decoction, and pave a helpful way for follow-up mechanism of action research.

Analysis of abused drugs by selected ion monitoring: quantitative comparison of electron impact and chemical ionization

International Nuclear Information System (INIS)

Foltz, R.L.; Knowlton, D.A.; Lin, D.C.K.; Fentiman, A.F. Jr.

1975-01-01

A comparison was made of the relative sensitivities of electron impact and chemical ionization when used for selected ion monitoring analysis of commonly abused drugs. For most of the drugs examined chemical ionization using ammonia as the reactant gas gave the largest single m/e ion current response per unit weight of sample. However, if maximum sensitivity is desired it is important to evaluate electron impact and chemical ionization with respect to both maximum response and degree of interference from background and endogenous materials

Mechanism of Interaction between Ionizing Radiation and Chemicals

International Nuclear Information System (INIS)

Kim, Jin Kyu; Lee, B. H.; Shin, H. S.

2008-03-01

This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals . Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland

Mechanism of Interaction between Ionizing Radiation and Chemicals

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Kyu; Lee, B H; Shin, H S [and others

2008-03-15

This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals{sup .} Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland.

Mechanism of Interaction between Ionizing Radiation and Chemicals

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Kyu; Lee, B. H.; Shin, H. S. (and others)

2008-03-15

This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals{sup .} Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland.

Negative ion beam formation using thermal contact ionization type plasma source

Energy Technology Data Exchange (ETDEWEB)

Fukuura, Yoshiyuki; Murakami, Kazutugu; Masuoka, Toshio; Katsumata, Itsuo [Osaka City Univ. (Japan). Faculty of Engineering

1997-02-01

The small ion sources utilizing thermal ionization have been already developed, and at present, in order to increase ion yield, that being developed to the cylindrical plasma prototype having the inner surface of a Re foil cylinder as the ionization surface, and stably functioning at 3,000 K has been developed, and by using this plasma source, the research on the formation of various ions has been carried out. At present, the research on the formation of Li negative ion beam is carried out. The separation of negative ions from electrons is performed with the locally limited magnetic field using a small iron core electromagnet placed behind the electrostatic accelerating lens system. So for, the formation of about 2 {mu}A at maximum of negative ions was confirmed. It was decided to identify the kinds of ions by time of flight (TOF) process, and the various improvements for this purpose were carried out. The experimental setup, the structure of the plasma source, the circuits for TOF measurement and so on are explained. The experimental results are reported. The problems are the possibility of the formation of alkali metals, the resolution of the time axis of the TOF system and so on. (K.I.)

Plasma-chemical simulation of negative corona near the inception voltage

Science.gov (United States)

Pontiga, Francisco; Duran-Olivencia, Francisco J.; Castellanos, Antonio

2013-09-01

The spatiotemporal development of Trichel pulses in oxygen between a spherical electrode and a grounded plane has been simulated using a fluid approximation that incorporates the plasma chemistry of the electrical discharge. Elementary plasma processes, such as ionization, electron attachment, electron detachment, recombination between ions and chemical reactions between neutral species, are all included in a chemical model consisting of 55 reactions between 8 different species (electrons, O2+,O2-,O3-,O-, O2, O, O3). Secondary emission at the cathode by the impact of positive ions and photons is also considered. The spatial distribution of species is computed in three dimensions (2D-axysimmetrical) by solving Poisson's equation for the electric field and the continuity equations for the species, with the inclusion of the chemical gain/loss rate due to the particle interaction. The results of the simulation reveal the interplay between the different negative ions during the development of every Trichel pulse, and the rate of production of atomic oxygen and ozone by the corona discharge. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.

Isolation and identification of phenolic compounds from rum aged in oak barrels by high-speed countercurrent chromatography/high-performance liquid chromatography-diode array detection-electrospray ionization mass spectrometry and screening for antioxidant activity.

Science.gov (United States)

Regalado, Erik L; Tolle, Sebastian; Pino, Jorge A; Winterhalter, Peter; Menendez, Roberto; Morales, Ana R; Rodríguez, José L

2011-10-14

Beverages, especially wines are well-known to contain a variety of health-beneficial bioactive substances, mainly of phenolic nature which frequently exhibit antioxidant activity. Significant information is available about the separation and identification of polyphenols from some beverages by chromatographic and spectroscopic techniques, but considerably poor is chemical data related to the polyphenolic content in rums. In this paper, a method involving the all-liquid chromatographic technique of high-speed countercurrent chromatography (HSCCC) combined with high-performance liquid chromatography coupled with diode-array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS(n)) has been successfully applied for separation and identification of phenolic compounds in an aged rum. Besides, the phenolic fraction (PF) was assayed for its antioxidant effects using three different free radical in vitro assays (DPPH·, RO(2)· and spontaneous lipid peroxidation (LPO) on brain homogenates) and on ferric reducing antioxidant power (FRAP). Results showed that PF potently scavenged DPPH and strongly scavenged peroxyl radicals compared to ascorbic acid and butylated hydroxytoluene (BHT); and almost equally inhibited LPO on brain homogenates subjected to spontaneous LPO when compared to quercetin. Moreover, PF also exhibited strong reducing power. This chemical analysis illustrates the rich array of phenols in the aged rum and represents a rapid and suitable method for the isolation and identification of phenolic compounds from mixtures of considerable complexity, achieving high purity and reproducibility with the use of two separation steps. Copyright © 2011 Elsevier B.V. All rights reserved.

Enhancement of sensitivity in the determination of organic trace compounds in complex matrices with liquid chromatography-mass spectrometry (LC-MS)

International Nuclear Information System (INIS)

Mascher, D.G.

2002-05-01

The PhD-thesis deals with 'enhancement of sensitivity in the determination of organic trace compounds in complex matrices with liquid chromatography-mass spectrometry (LC-MS)'. Almost the most important factor is the enhancement of the ionization yield with Atmospheric Pressure Chemical Ionization (APCI) or Electrospray Ionization (ESI) in LC-MS. Ionization yields of different compounds can vary by a factor of 10000. Three ways to solve this problem of little ionization yield were tried: 1) Modification of the mobile phase in HPLC 2) Chemical modification of the analytes 3) A new type of ionization called Atmospheric Pressure Photo Ionization (APPI). ad 1) By using specific additives to mobile phases ion suppression that might derive from an ion pair reagent that was necessary for chromatography could be omitted. General remarks cannot be done. ad 2) Chemical modification or so called derivatization is well known for UV- and fluorescence-detection for a long period of time. As substances containing nitrogene (e.g. primary, secondary or tertiary amines) often have good ionization yields, poor or relatively poor ionizable substances like carboxylic acids, sugars and partially phenolic steroids were used as analytes for derivatization reactions. By using Dansyl as Dansylchlorid or Dansylhydrazine a basic derivatization agent could be found that ionizes very well. A 200 times more sensitive determination of estrogenes is possible after derivatization with Dansylchlorid. Using a tandem-mass-spectrometer a lower limit of quantification of 2 pg/mL plasma could be reached by using 1 mL of plasma. For ketones like carvon and campher an enhancement by a factor of 500 and 4000 could be reached by using Dansylhydrazine as the derivatization agent. For fatty acids DMEQ as derivatization agent enhanced the sensitivity by a factor of 20 to 100. ad 3) APPI as a new ionization mode showed really good results for specific molecules. Relatively unpolar substances as diphenylsulfide

Effect-directed analysis via hyphenated high-performance thin-layer chromatography for bioanalytical profiling of sunflower leaves.

Science.gov (United States)

Móricz, Ágnes M; Ott, Péter G; Yüce, Imanuel; Darcsi, András; Béni, Szabolcs; Morlock, Gertrud E

2018-01-19

High-performance thin-layer chromatography (HPTLC) coupled with effect-directed analysis was used for non-targeted screening of sunflower leaf extract for components exhibiting antioxidant, antibacterial and/or cholinesterase enzyme inhibitory effects. The active compounds were characterized by HPTLC-electrospray ionization-high resolution mass spectrometry (ESI-HRMS) and HPTLC-Direct Analysis in Real Time (DART)-MS/MS. The latter ambient ionization technique (less soft than ESI) resulted in oxidation and fragmentation products and characteristic fragment ions. NMR spectroscopy after targeted isolation via preparative normal phase flash chromatography and semi-preparative reversed phase high-performance liquid chromatography supported the identification of two diterpenes to be (-)-kaur-16-en-19-oic acid and 15-α-angeloyloxy-ent-kaur-16-en-19-oic acid. Both compounds found to be multi-potent as they inhibited acetylcholinesterase and butyrylcholinesterase and showed antibacterial effects against Gram-positive Bacillus subtilis and Gram-negative Aliivibrio fischeri bacteria. Kaurenoic acid was also active against the Gram-negative pepper pathogenic Xanthomonas euvesicatoria bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination of 14 active constituents of Shengjiang Xiexin decoction using ultrafast liquid chromatography coupled with electrospray ionization tandem mass spectrometry

Institute of Scientific and Technical Information of China (English)

Gang Peng; Huanyu Guan; Xiaoming Wang; Yue Shi

2017-01-01

An effective herbal medicinal prescription of Shengjiang Xiexin decoction (SXD) was used in treating the inflammatory bowel disease in clinic.In this study,an ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed to separate and to simultaneously determine 14 major active ingredients in SXD.Chromatographic separation was successfully accomplished on an Acquity BEH C18 (100 mm × 2.1 mm,1.7 μm) column using gradient elution with 0.1％ (v/v) formic acid water (A) and 0.1％ (v/v) formic acid in methanol (B).Negative and positive electrospray ionization tandem mass spectrometry was used to detect the 14 analytes using its selective reaction monitoring (SRM) mode.A good linear regression relationship for each analyte was obtained over the range from 3.88 ng/mL to 4080 ng/mL.The precision was evaluated by intra-and inter-day assays with a relative standard deviation (RSD) of less than 6.25％.The recovery measured at three concentration levels varied from 98.72％ to 103.47％.The overall limits of quantification (LOQ) ranged from 2.05 ng/mL to 4.72 ng/mL.The method was successfully implemented in the qualitative and quantitative analyses of the 14 chemical constituents in SXD.The results showed that the developed UFLC-MS/MS method was linear and accurate.The method could be used reliably as a quality control method for SXD.

Simultaneous determination of 14 active constituents of Shengjiang Xiexin decoction using ultrafast liquid chromatography coupled with electrospray ionization tandem mass spectrometry

Institute of Scientific and Technical Information of China (English)

Gang Peng; Huanyu Guan; Xiaoming Wang; Yue Shi

2017-01-01

An effective herbal medicinal prescription of Shengjiang Xiexin decoction(SXD) was used in treating the inflammatory bowel disease in clinic.In this study,an ultrafast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS) method was developed to separate and to simultaneously determine14 major active ingredients in SXD.Chromatographic separation was successfully accomplished on an Acquity BEH C18(100 mm × 2.1 mm,1.7 μm) column using gradient elution with 0.1%(v/v) formic acid water(A) and 0.1%(v/v) formic acid in methanol(B).Negative and positive electrospray ionization tandem mass spectrometry was used to detect the 14 analytes using its selective reaction monitoring(SRM) mode.A good linear regression relationship for each analyte was obtained over the range from3.88 ng/mL to 4080 ng/mL.The precision was evaluated by intra-and inter-day assays with a relative standard deviation(RSD) of less than 6.25%.The recovery measured at three concentration levels varied from 98.72%to 103.47%.The overall limits of quantification(LOQ) ranged from 2.05 ng/mL to4.72 ng/mL.The method was successfully implemented in the qualitative and quantitative analyses of the14 chemical constituents in SXD.The results showed that the developed UFLC-MS/MS method was linear and accurate.The method could be used reliably as a quality control method for SXD.

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Haehn, J.; Hannig, H.; Dlaske, R.; Martinek, K.

1977-01-01

Papers published in 1976 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in vitro and in vivo, the biochemical, pharmacological and toxic effects, the mechanisms of protection of radioprotective agents and the trends in this field of research are described. (author)

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Haehn, J.; Hannig, H.; Dlaske, R.

1976-03-01

Papers published in 1974 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in vitro and in vivo, the biochemical, pharmacological and toxic effects, the mechanisms of protection of radioprotective agents and the trends in this field of research are described. (author)

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Haehn, J.; Hannig, H.; Dlaske, R.; Martinek, K.

1977-01-01

Papers published in 1975 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in vitro and in vivo, the biochemical, pharmacological and toxic effects, the mechanisms of protection of radioprotective agents and the trends in this field of research are described. (author)

Numerical simulation of Trichel pulses of negative DC corona discharge based on a plasma chemical model

Science.gov (United States)

Chen, Xiaoyue; Lan, Lei; Lu, Hailiang; Wang, Yu; Wen, Xishan; Du, Xinyu; He, Wangling

2017-10-01

A numerical simulation method of negative direct current (DC) corona discharge based on a plasma chemical model is presented, and a coaxial cylindrical gap is adopted. There were 15 particle species and 61 kinds of collision reactions electrons involved, and 22 kinds of reactions between ions are considered in plasma chemical reactions. Based on this method, continuous Trichel pulses are calculated on about a 100 us timescale, and microcosmic physicochemical process of negative DC corona discharge in three different periods is discussed. The obtained results show that the amplitude of Trichel pulses is between 1-2 mA, and that pulse interval is in the order of 10-5 s. The positive ions produced by avalanche ionization enhanced the electric field near the cathode at the beginning of the pulse, then disappeared from the surface of cathode. The electric field decreases and the pulse ceases to develop. The negative ions produced by attachment slowly move away from the cathode, and the electric field increases gradually until the next pulse begins to develop. The positive and negative ions with the highest density during the corona discharge process are O4+ and O3- , respectively.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review

International Nuclear Information System (INIS)

Li, Du-Xin; Gan, Lin; Bronja, Amela; Schmitz, Oliver J.

2015-01-01

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a “soft” ion source for preserving highly diagnostic molecular ion is desirable, as compared to the “hard” ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. - Highlights: • Atmospheric pressure ion sources (APCI, ESI, APPI, APLC etc) enable the coupling of LC-based high-end MS to GC. • APIs show advantages in selectivity and sensitivity compared with EI in GC-MS. • Accurate mass database in GC-APCI/MS is emerging as an alternative to GC-EI/MS database.

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review

Energy Technology Data Exchange (ETDEWEB)

Li, Du-Xin; Gan, Lin; Bronja, Amela [University of Duisburg-Essen, Applied Analytical Chemistry, Universitaetsstr. 5-7, 45141 Essen (Germany); Schmitz, Oliver J., E-mail: oliver.schmitz@uni-due.de [University of Duisburg-Essen, Applied Analytical Chemistry, Universitaetsstr. 5-7, 45141 Essen (Germany)

2015-09-03

Although the coupling of GC/MS with atmospheric pressure ionization (API) has been reported in 1970s, the interest in coupling GC with atmospheric pressure ion source was expanded in the last decade. The demand of a “soft” ion source for preserving highly diagnostic molecular ion is desirable, as compared to the “hard” ionization technique such as electron ionization (EI) in traditional GC/MS, which fragments the molecule in an extensive way. These API sources include atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), atmospheric pressure laser ionization (APLI), electrospray ionization (ESI) and low temperature plasma (LTP). This review discusses the advantages and drawbacks of this analytical platform. After an introduction in atmospheric pressure ionization the review gives an overview about the history and explains the mechanisms of various atmospheric pressure ionization techniques used in combination with GC such as APCI, APPI, APLI, ESI and LTP. Also new developments made in ion source geometry, ion source miniaturization and multipurpose ion source constructions are discussed and a comparison between GC-FID, GC-EI-MS and GC-API-MS shows the advantages and drawbacks of these techniques. The review ends with an overview of applications realized with GC-API-MS. - Highlights: • Atmospheric pressure ion sources (APCI, ESI, APPI, APLC etc) enable the coupling of LC-based high-end MS to GC. • APIs show advantages in selectivity and sensitivity compared with EI in GC-MS. • Accurate mass database in GC-APCI/MS is emerging as an alternative to GC-EI/MS database.

Trace determination of 13 haloacetamides in drinking water using liquid chromatography triple quadrupole mass spectrometry with atmospheric pressure chemical ionization.

Science.gov (United States)

Chu, Wenhai; Gao, Naiyun; Yin, Daqiang; Krasner, Stuart W; Templeton, Michael R

2012-04-27

The haloacetamides (HAcAms) are disinfection by-products (DBPs) in drinking water which are currently receiving increased scientific attention due to their elevated toxicity relative to regulated disinfection by-products. A simultaneous determination method of 13 HAcAms, combining solid-phase extraction (SPE) enrichment, liquid chromatographic (LC) separation, and triple quadrupole mass spectrometry (tqMS) detection with atmospheric pressure chemical ionization (APCI) using selective reaction monitoring in positive mode, was developed to measure HAcAms, including chlorinated, brominated, and iodinated analogs. Ammonium chloride and Oasis HLB were selected as the dechlorinating reagent and polymeric SPE sorbent of HAcAm samples. The used tqMS apparatus showed higher sensitivity for the studied HAcAms in the APCI mode than electrospray ionization. 13 HAcAms were separated by LC in 9.0 min, and the detection limits ranged from 7.6 to 19.7 ng/L. The SPE-LC/tqMS method was successfully applied to quantify 13 HAcAms in drinking water samples for the first time, and first indentified tribromoacetamide and chloroiodoacetamide as DBPs in drinking water. Copyright © 2012 Elsevier B.V. All rights reserved.

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Hannig, H.; Dlaske, R.; Haehn, J.; Martinek, K.

1980-01-01

Papers published in 1978 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in in-vivo and model systems, the biochemical, pharmacological and toxic effects, and modes of action of radioprotective agents are described and the trends in this field of research appreciated. (author)

Acetonitrile Ion Suppression in Atmospheric Pressure Ionization Mass Spectrometry

Science.gov (United States)

Colizza, Kevin; Mahoney, Keira E.; Yevdokimov, Alexander V.; Smith, James L.; Oxley, Jimmie C.

2016-11-01

Efforts to analyze trace levels of cyclic peroxides by liquid chromatography/mass spectrometry gave evidence that acetonitrile suppressed ion formation. Further investigations extended this discovery to ketones, linear peroxides, esters, and possibly many other types of compounds, including triazole and menadione. Direct ionization suppression caused by acetonitrile was observed for multiple adduct types in both electrospray ionization and atmospheric pressure chemical ionization. The addition of only 2% acetonitrile significantly decreased the sensitivity of analyte response. Efforts to identify the mechanism were made using various nitriles. The ion suppression was reduced by substitution of an acetonitrile hydrogen with an electron-withdrawing group, but was exacerbated by electron-donating or steric groups adjacent to the nitrile. Although current theory does not explain this phenomenon, we propose that polar interactions between the various functionalities and the nitrile may be forming neutral aggregates that manifest as ionization suppression.

State and tendencies of chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Siegel, G.; Tapp, E.; Hannig, H.; Dlaske, R.; Papendieck, W.; Martinek, K.; Haehn, J.

1982-01-01

Papers published in 1979 and 1980 in the field of chemical protection against ionizing radiation are reviewed. Protection studies in in-vivo and model systems, the biochemical, pharmacological and toxic effects, and modes of action of radioprotective agents are described and the trends in this field of research estimated. (author)

Quantification of cardiolipin by liquid chromatography-electrospray ionization mass spectrometry.

Science.gov (United States)

Garrett, Teresa A; Kordestani, Reza; Raetz, Christian R H

2007-01-01

Cardiolipin (CL), a tetra-acylated glycerophospholipid composed of two phosphatidyl moieties linked by a bridging glycerol, plays an important role in mitochondrial function in eukaryotic cells. Alterations to the content and acylation state of CL cause mitochondrial dysfunction and may be associated with pathologies such as ischemia, hypothyrodism, aging, and heart failure. The structure of CL is very complex because of microheterogeneity among its four acyl chains. Here we have developed a method for the quantification of CL molecular species by liquid chromatography-electrospray ionization mass spectrometry. We quantify the [M-2H](2-) ion of a CL of a given molecular formula and identify the CLs by their total number of carbons and unsaturations in the acyl chains. This method, developed using mouse macrophage RAW 264.7 tumor cells, is broadly applicable to other cell lines, tissues, bacteria and yeast. Furthermore, this method could be used for the quantification of lyso-CLs and bis-lyso-CLs.

Physical and chemical changes in water pollutants caused by ionizing radiations

International Nuclear Information System (INIS)

Vacek, K.

1978-01-01

Ionization and excitation as primary effects of ionizing radiation form secondary activated intermediary products (H and OH radicals and hydrated electrons esub(aq) - ) in water systems, which act on all in substances present in water. Physical and chemical changes speeding the sludge sedimentation in waste-water show complex dependences. It is, however, possible to prove them even at low radiation doses (0.07 to 0.35 kJ/kg). Chemical effects can be observed at higher radiation doses (1 to 10 kJ/kg) and are based on oxidative destruction of pollutants. Some of these reactions may be based on chain mechanisms (phenol oxidizing in water), but there are limited chances for application of these chain mechanisms in waste-water systems. Slight damage of biologically important macromolecules leads to changes, or even stops biological processes. Therefore, biological effects of ionizing radiation have the most remarkable impact. The utilization of these reactions in water management may be possible in suppressing biological ochration (ochre sedimentation) in wells and for ensuring hygienic conditions of sludge in waste-water processing for agrotechnical purposes. (author)

Multiresidue analysis of pesticides in olive oil by gel permeation chromatography followed by gas chromatography-tandem mass-spectrometric determination

International Nuclear Information System (INIS)

Sanchez, Andres Garcia; Martos, Natividad Ramos; Ballesteros, Evaristo

2006-01-01

A method for the multiresidue analysis of olive oil samples for 26 pesticides is proposed. Residual pesticides are extracted from oil using an n-hexane/acetonitrile mixture, extracts being cleaned-up by gel permeation chromatography (GPC) for analysis by gas chromatography-tandem mass spectrometry (GC-MS/MS). Electron ionization and chemical ionization are employed in a single analysis for the determination of pesticides. Pesticide recoveries from virgin and refined olive oil spiked with 10, 100 and 250 μg/kg concentrations of the pesticides ranged from 83.8 to 110.3%. The proposed method features good sensitivity: its limits of quantification are low enough to allow pesticide residues to be determined at concentrations below the maximum residue levels legally accepted. The precision, expressed as relative standard deviation, ranges from 4.93 to 8.11%. Applicability was tested on 40 olive oil samples. Several pesticides were detected in most of the virgin olive oil samples. By contrast, refined olive samples contained few pesticides, and only endosulfan sulphate was detected in all

Application of gas chromatography/flame ionization detector-based metabolite fingerprinting for authentication of Asian palm civet coffee (Kopi Luwak).

Science.gov (United States)

Jumhawan, Udi; Putri, Sastia Prama; Yusianto; Bamba, Takeshi; Fukusaki, Eiichiro

2015-11-01

Development of authenticity screening for Asian palm civet coffee, the world-renowned priciest coffee, was previously reported using metabolite profiling through gas chromatography/mass spectrometry (GC/MS). However, a major drawback of this approach is the high cost of the instrument and maintenance. Therefore, an alternative method is needed for quality and authenticity evaluation of civet coffee. A rapid, reliable and cost-effective analysis employing a universal detector, GC coupled with flame ionization detector (FID), and metabolite fingerprinting has been established for discrimination analysis of 37 commercial and non-commercial coffee beans extracts. gas chromatography/flame ionization detector (GC/FID) provided higher sensitivity over a similar range of detected compounds than GC/MS. In combination with multivariate analysis, GC/FID could successfully reproduce quality prediction from GC/MS for differentiation of commercial civet coffee, regular coffee and coffee blend with 50 wt % civet coffee content without prior metabolite details. Our study demonstrated that GC/FID-based metabolite fingerprinting can be effectively actualized as an alternative method for coffee authenticity screening in industries. Copyright © 2015. Published by Elsevier B.V.

Chemical speciation analysis for bromine in tap water by ion chromatography/inductively coupled plasma-mass spectrometry and electrospray ionization-mass spectrometry

International Nuclear Information System (INIS)

Kurata, Keigo; Suzuki, Yoshinari; Furuta, Naoki

2010-01-01

Bromide compounds in tap water were measured by using a hyphenated technique of ion chromatography coupled with inductively coupled plasma - mass spectrometry (IC/ICP-MS) and electrospray ionization mass spectrometry (ESI-MS). We identified bromide ion (Br - ), bromate ion (BrO 3 - ), bromochloroacetic acid (BCAA), dibromoacetic acid (DBAA) and bromodichloroacetic acid (BDCAA) by standard addition methods with IC/ICP-MS. Moreover, we identified BCAA and BDCAA by ESI-MS after separation with IC. Br - , BrO 3 - , BCAA, DBAA and BDCAA in tap water collected from around Tokyo area were quantified by IC/ICP-MS. The maximum concentration of BrO 3 - (1.8 ng mL -1 ) was observed in tap water collected from Bunkyo-ku, although this concentration was lower than 10 ng mL -1 , which is the regulated concentration in Japan. DBAA, which is regulated by United States Environmental Protection Agency, was detected in tap water collected from all sites, except for Ome. However, since BrO 3 - and DBAA are toxic, it is necessary to continue monitoring bromide compounds in tap water. (author)

Identification of chemical warfare agents from vapor samples using a field-portable capillary gas chromatography/membrane-interfaced electron ionization quadrupole mass spectrometry instrument with Tri-Bed concentrator.

Science.gov (United States)

Nagashima, Hisayuki; Kondo, Tomohide; Nagoya, Tomoki; Ikeda, Toru; Kurimata, Naoko; Unoke, Shohei; Seto, Yasuo

2015-08-07

A field-portable gas chromatograph-mass spectrometer (Hapsite ER system) was evaluated for the detection of chemical warfare agents (CWAs) in the vapor phase. The system consisted of Tri-Bed concentrator gas sampler (trapping time: 3s(-1)min), a nonpolar low thermal-mass capillary gas chromatography column capable of raising temperatures up to 200°C, a hydrophobic membrane-interfaced electron ionization quadrupole mass spectrometer evacuated by a non-evaporative getter pump for data acquisition, and a personal computer for data analysis. Sample vapors containing as little as 22μg sarin (GB), 100μg soman (GD), 210μg tabun (GA), 55μg cyclohexylsarin (GF), 4.8μg sulfur mustard, 390μg nitrogen mustard 1, 140μg of nitrogen mustard 2, 130μg nitrogen mustard 3, 120μg of 2-chloroacetophenone and 990μg of chloropicrin per cubic meter could be confirmed after Tri-Bed micro-concentration (for 1min) and automated AMDIS search within 12min. Using manual deconvolution by background subtraction of neighboring regions on the extracted ion chromatograms, the above-mentioned CWAs could be confirmed at lower concentration levels. The memory effects were also examined and we found that blister agents showed significantly more carry-over than nerve agents. Gasoline vapor was found to interfere with the detection of GB and GD, raising the concentration limits for confirmation in the presence of gasoline by both AMDIS search and manual deconvolution; however, GA and GF were not subject to interference by gasoline. Lewisite 1, and o-chlorobenzylidene malononitrile could also be confirmed by gas chromatography, but it was hard to quantify them. Vapors of phosgene, chlorine, and cyanogen chloride could be confirmed by direct mass spectrometric detection at concentration levels higher than 2, 140, and 10mg/m(3) respectively, by bypassing the micro-concentration trap and gas chromatographic separation. Copyright © 2015 Elsevier B.V. All rights reserved.

Annotation of metabolites from gas chromatography/atmospheric pressure chemical ionization tandem mass spectrometry data using an in silico generated compound database and MetFrag.

Science.gov (United States)

Ruttkies, Christoph; Strehmel, Nadine; Scheel, Dierk; Neumann, Steffen

2015-08-30

Gas chromatography (GC) coupled to atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (APCI-QTOFMS) is an emerging technology in metabolomics. Reference spectra for GC/APCI-MS/MS barely exist; therefore, in silico fragmentation approaches and structure databases are prerequisites for annotation. To expand the limited coverage of derivatised structures in structure databases, in silico derivatisation procedures are required. A cheminformatics workflow has been developed for in silico derivatisation of compounds found in KEGG and PubChem, and validated on the Golm Metabolome Database (GMD). To demonstrate this workflow, these in silico generated databases were applied together with MetFrag to APCI-MS/MS spectra acquired from GC/APCI-MS/MS profiles of Arabidopsis thaliana and Solanum tuberosum. The Metabolite-Likeness of the original candidate structure was included as additional scoring term aiming at candidate structures of natural origin. The validation of our in silico derivatisation workflow on the GMD showed a true positive rate of 94%. MetFrag was applied to two datasets. In silico derivatisation of the KEGG and PubChem database served as a candidate source. For both datasets the Metabolite-Likeness score improved the identification performance. The derivatised data sources have been included into the MetFrag web application for the annotation of GC/APCI-MS/MS spectra. We demonstrated that MetFrag can support the identification of components from GC/APCI-MS/MS profiles, especially in the (common) case where reference spectra are not available. This workflow can be easily adapted to other types of derivatisation and is freely accessible together with the generated structure databases. Copyright © 2015 John Wiley & Sons, Ltd.

Mutagenic effect of ionizing radiation and chemical and environmental agents in Tradescantia

International Nuclear Information System (INIS)

Cebulska-Wasilewska, A.

1988-01-01

The studies covered the following problems: an influence of some environmental agents on the mutagenic effectiveness of ionizing radiation, interaction between ionizing radiation and chemical mutagens in the induction of somatic mutations and also an application of Tradescantia model system for biological monitoring. The studies showed that the pretreatment of Tradescantia plants with sodium fluoride or the modification of the soil composition with dolomite admixture, visibly influences plants radiosensitivity. The analysis of the changes in the dose-response curves suggested that the employed agents were influencing in different ways the repair processes of the DNA. The studies on the interaction between agents proved that the synergistic effect occurs in case of combined action of ionizing radiation with such chemical mutagens as ethyl methansulfonate or 1,2 dibromomethane. It was also discovered that in the range of low doses the effect was proportional to radiation dose and total exposition to chemical mutagen. The field application of Tradescantia method defined the mutagenicity of air pollution in the Cracow area. The highest frequencies of mutations were detected after the Chernobyl accident and after the damage of the filters in the Pharmaceutical Plant. The applied method was evaluated in respect of its usefulness for biological monitoring of environmental pollution. 163 refs. (author)

Quantitative Determination of Bioactive Constituents in Noni Juice by High-performance Liquid Chromatography with Electrospray Ionization Triple Quadrupole Mass Spectrometry.

Science.gov (United States)

Yan, Yongqiu; Lu, Yu; Jiang, Shiping; Jiang, Yu; Tong, Yingpeng; Zuo, Limin; Yang, Jun; Gong, Feng; Zhang, Ling; Wang, Ping

2018-01-01

Noni juice has been extensively used as folk medicine for the treatment of arthritis, infections, analgesic, colds, cancers, and diabetes by Polynesians for many years. Due to the lack of standard scientific evaluation methods, various kinds of commercial Noni juice with different quality and price were available on the market. To establish a sensitive, reliable, and accurate high-performance liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (HPLC-ESI-MS/MS) method for separation, identification, and simultaneous quantitative analysis of bioactive constituents in Noni juice. The analytes and eight batches of commercially available samples from different origins were separated and analyzed by the HPLC-ESI-MS/MS method on an Agilent ZORBAX SB-C 18 (150 mm × 4.6 mm i.d., 5 μm) column using a gradient elution of acetonitrile-methanol-0.05% glacial acetic acid in water (v/v) at a constant flow rate of 0.5 mL/min. Seven components were identification and all of the assay parameters were within the required limits. Components were within the correlation coefficient values ( R 2 ≥ 0.9993) at the concentration ranges tested. The precision of the assay method was high-performance liquid chromatography with electrospray ionization triple quadrupole mass spectrometryThe presented method was successfully applied to the quality control of eight batches of commercially available samples of Noni juiceThis method is simple, sensitive, reliable, accurate, and efficient method with strong specificity, good precision, and high recovery rate and provides a reliable basis for quality control of Noni juice. Abbreviations used: HPLC-ESI-MS/MS: High-performance liquid chromatography with electrospray ionization triple quadrupole mass spectrometry, LOD: Limit of detection, LOQ: Limit of quantitation, S/N: Signal-to-noise ratio, RSD: Relative standard deviations, DP: Declustering potential, CE: Collision energy, MRM: Multiple reaction monitoring, RT

Chemical Composition and Antifungal Properties of Essential Oil of ...

African Journals Online (AJOL)

Purpose: To evaluate the effect of the essential oil of Origanum vulgare Linnaeus (Lamiaceae) on the growth of Sporothrix schenckii and Sporothrix brasiliensis. Methods: The chemical composition of the essential oil was investigated by gas chromatography/flame ionization detector (GC-FID). The minimum inhibitory ...

Comparison of Atmospheric Pressure Chemical Ionization and Field Ionization Mass Spectrometry for the Analysis of Large Saturated Hydrocarbons.

Science.gov (United States)

Jin, Chunfen; Viidanoja, Jyrki; Li, Mingzhe; Zhang, Yuyang; Ikonen, Elias; Root, Andrew; Romanczyk, Mark; Manheim, Jeremy; Dziekonski, Eric; Kenttämaa, Hilkka I

2016-11-01

Direct infusion atmospheric pressure chemical ionization mass spectrometry (APCI-MS) was compared to field ionization mass spectrometry (FI-MS) for the determination of hydrocarbon class distributions in lubricant base oils. When positive ion mode APCI with oxygen as the ion source gas was employed to ionize saturated hydrocarbon model compounds (M) in hexane, only stable [M - H] + ions were produced. Ion-molecule reaction studies performed in a linear quadrupole ion trap suggested that fragment ions of ionized hexane can ionize saturated hydrocarbons via hydride abstraction with minimal fragmentation. Hence, APCI-MS shows potential as an alternative of FI-MS in lubricant base oil analysis. Indeed, the APCI-MS method gave similar average molecular weights and hydrocarbon class distributions as FI-MS for three lubricant base oils. However, the reproducibility of APCI-MS method was found to be substantially better than for FI-MS. The paraffinic content determined using the APCI-MS and FI-MS methods for the base oils was similar. The average number of carbons in paraffinic chains followed the same increasing trend from low viscosity to high viscosity base oils for the two methods.

Analysis of human plasma lipids by using comprehensive two-dimensional gas chromatography with dual detection and with the support of high-resolution time-of-flight mass spectrometry for structural elucidation.

Science.gov (United States)

Salivo, Simona; Beccaria, Marco; Sullini, Giuseppe; Tranchida, Peter Q; Dugo, Paola; Mondello, Luigi

2015-01-01

The main focus of the present research is the analysis of the unsaponifiable lipid fraction of human plasma by using data derived from comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection. This approach enabled us to attain both mass spectral information and analyte percentage data. Furthermore, gas chromatography coupled with high-resolution time-of-flight mass spectrometry was used to increase the reliability of identification of several unsaponifiable lipid constituents. The synergism between both the high-resolution gas chromatography and mass spectrometry processes enabled us to attain a more in-depth knowledge of the unsaponifiable fraction of human plasma. Additionally, information was attained on the fatty acid and triacylglycerol composition of the plasma samples, subjected to investigation by using comprehensive two-dimensional gas chromatography with dual quadrupole mass spectrometry and flame ionization detection and high-performance liquid chromatography with atmospheric pressure chemical ionization quadrupole mass spectrometry, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atmospheric pressure chemical ionization studies of non-polar isomeric hydrocarbons using ion mobility spectrometry and mass spectrometry with different ionization techniques

Science.gov (United States)

Borsdorf, H.; Nazarov, E. G.; Eiceman, G. A.

2002-01-01

The ionization pathways were determined for sets of isomeric non-polar hydrocarbons (structural isomers, cis/trans isomers) using ion mobility spectrometry and mass spectrometry with different techniques of atmospheric pressure chemical ionization to assess the influence of structural features on ion formation. Depending on the structural features, different ions were observed using mass spectrometry. Unsaturated hydrocarbons formed mostly [M - 1]+ and [(M - 1)2H]+ ions while mainly [M - 3]+ and [(M - 3)H2O]+ ions were found for saturated cis/trans isomers using photoionization and 63Ni ionization. These ionization methods and corona discharge ionization were used for ion mobility measurements of these compounds. Different ions were detected for compounds with different structural features. 63Ni ionization and photoionization provide comparable ions for every set of isomers. The product ions formed can be clearly attributed to the structures identified. However, differences in relative abundance of product ions were found. Although corona discharge ionization permits the most sensitive detection of non-polar hydrocarbons, the spectra detected are complex and differ from those obtained with 63Ni ionization and photoionization. c. 2002 American Society for Mass Spectrometry.

The experimental effect of artificial air ionizer (negative and positive on some hematological parameters at Wistar rats

Directory of Open Access Journals (Sweden)

Simionca Iuri

2011-02-01

Full Text Available The air near the ground, where the most organisms live, is characterized by physical-chemical and biological properties.All these factors (e.g. temperature, humidity, air ionization, etc perform certains roles and any quantitative and qualitative change, beyond certain limits, are felt on the body in one form or another.From the physical factors of the air, the electrical power includes, in turn, electrical conductivity, electric field, electrical potential gradient, thunderstorms, air ionization, atmospherical which manifests itself differently in beautiful weather (low cloud, little wind, no precipitation or the disturbed weather (storm.The most common electricity of beautiful weather, is characterized by a multitude of meanings with has direct or indirect effects on the living world, favorable or unfavorable, perceptible or not, depending on the intensity, duration or frequency of manifestation of that power factor.A special place of these biometeorological factors is occupied by the category natural air ionization. The first observations on the existence of gaseous ions in air have been made since the early twentieth century `30 (German physicist Panthenier Ladenburg and French, thorough research and then resumed after the 50s of various collective (including French physicist J. Bricard, University of Paris. They have highlighted the link between low ion content in the air and micropopulation atmosphere and that lack almost daily a minimum amount of negative ions of oxygen from small places of daily activities constitute a cause of a inevitable occurrence of disorders, often severe, health status.

Effect of pH and dissociation on the fate and exposure of ionizable chemicals

DEFF Research Database (Denmark)

Franco, Antonio; Trapp, Stefan

2010-01-01

Ionizable organic chemicals comprise an important fraction of pharmaceuticals, pesticides as well as industrial chemicals. It has been estimated that 33% of the preregistered REACH substances is mostly ionized at pH 7. To extend the appliccability of existing exposure models, a Multimedia Activity...... parameters. The sensitivity analysis showed that the parameters describing ionization, pH and the dissociation constant (pKa), are among the most sensitive model parameters. The uncertainty analysis, however, indicated that these parameters are not the major source of uncertainty, which statistically...... and sediments. In most cases, the uncertainty of PECs and of persistance is largely explained by the uncertainty of (bio)degradation rates, which may be caused by model assumptions, experimental or estimation errors or by the environmental variability, including the effect of pH....

Methods of uranium isotpic separation by chemical exchange chromatography

International Nuclear Information System (INIS)

Pena V, L.A.; Valle M, L.

1985-01-01

Chemical exchange chromatography as applied to isotope separation has undergone a constant development during the last few years. The results so far indicate that this method could eventually become commercially useful. This work presents a critical review of the experimental methods presently under study by principal research groups, and which have not get been compared. (Author)

A liquid chromatography-mass spectrometry method for the quantification of bioavailability and bioconversion of beta-carotene to retinol in humans

NARCIS (Netherlands)

Yan Wang,; Xiaoying Xu,; Lieshout, van M.; West, C.E.; Lugtenburg, J.; Verhoeven, M.A.; Creemers, A.F.L.

2000-01-01

A method based on high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (APCI LC-MS) was developed for the quantification of the bioavailability of retinyl palmitate and -carotene and the bioconversion of -carotene to retinol in humans. Following oral

Physical and chemical effects of ionizing radiation, application for conservation of food products

International Nuclear Information System (INIS)

Foos, J.

1986-01-01

The author sets about ''defining the parameters'' and ''describing the systems'' by means of which ionizing radiation can be used to conserve food products and make them more healthy. After defining the different types of radiation, he goes on to examine interactions between these types of radiation and the food to be processed, including the chemical reactions caused by the ionization and excitation processes [fr

Quantitation of tamsulosin in human plasma by liquid chromatography-electrospray ionization mass spectrometry.

Science.gov (United States)

Din, Li; Li, Limin; Tao, Ping; Yang, Jin; Zhang, Zhengxing

2002-02-05

A highly sensitive method for quantitation of tamsulosin in human plasma using 1-(2,6-dimethyl-3-hydroxylphenoxy)-2-(3,4-methoxyphenylethylamino)-propane hydrochloride as the internal standard (I.S.) was established using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). After alkalization with saturated sodium bicarbonate, plasma were extracted by ethyl acetate and separated by HPLC on a C18 reversed-phase column using a mobile phase of methanol-water-acetic acid-triethylamine (620:380:1.5:1.5, v/v). Analytes were quantitated using positive electrospray ionization in a quadrupole spectrometer. LC-ESI-MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 228 for tamsulosin and m/z 222 for the I.S. Calibration curves, which were linear over the range 0.2-30 ng/ml, were analyzed contemporaneously with each batch of samples, along with low (0.5 ng/ml), medium (3 ng/ml) and high (30 ng/ml) quality control samples. The intra- and inter-assay variability ranged from 2.14 to 8.87% for the low, medium and high quality control samples. The extraction recovery of tamsulosin from plasma was in the range of 84.2-94.5%. The method has been used successfully to study tamsulosin pharmacokinetics in adult humans.

High-Performance Liquid Chromatography in the Undergraduate Chemical Engineering Laboratory

Science.gov (United States)

Frey, Douglas D.; Guo, Hui; Karnik, Nikhila

2013-01-01

This article describes the assembly of a simple, low-cost, high-performance liquid chromatography (HPLC) system and its use in the undergraduate chemical engineering laboratory course to perform simple experiments. By interpreting the results from these experiments students are able to gain significant experience in the general method of…

Determination of benzothiazole and benzotriazole derivates in tire and clothing textile samples by high performance liquid chromatography-electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Avagyan, Rozanna; Sadiktsis, Ioannis; Thorsén, Gunnar; Östman, Conny; Westerholm, Roger

2013-09-13

A high performance liquid chromatography-tandem mass spectrometry method utilizing electrospray ionization in positive and negative mode has been developed for the separation and detection of benzothiazole and benzotriazole derivates. Ultra-sonication assisted solvent extraction of these compounds has also been developed and the overall method demonstrated on a selected clothing textile and an automobile tire sample. Matrix effects and extraction recoveries, as well as linearity and limits of detection have been evaluated. The calibration curves spanned over more than two orders of magnitude with coefficients of correlation R(2)>0.99 and the limits of detection and the limits of quantification were in the range 1.7-58pg injected and 18-140pg/g, respectively. The extraction recoveries ranged between 69% and 102% and the matrix effects between 75% and 101%. Benzothiazole and benzotriazole derivates were determined in the textile sample and benzothiazole derivatives determined in the tire sample with good analytical performance. Copyright © 2013 Elsevier B.V. All rights reserved.

Plasma chromatography

International Nuclear Information System (INIS)

Anon.

1984-01-01

This book examines the fundamental theory and various applications of ion mobility spectroscopy. Plasma chromatography developed from research on the diffusion and mobility of ions. Topics considered include instrument design and description (e.g., performance, spectral interpretation, sample handling, mass spectrometry), the role of ion mobility in plasma chromatography (e.g., kinetic theory of ion transport), atmospheric pressure ionization (e.g., rate equations), the characterization of isomers by plasma chromatography (e.g., molecular ion characteristics, polynuclear aromatics), plasma chromatography as a gas chromatographic detection method (e.g., qualitative analysis, continuous mobility monitoring, quantitative analysis), the analysis of toxic vapors by plasma chromatography (e.g., plasma chromatograph calibration, instrument control and data processing), the analysis of semiconductor devices and microelectronic packages by plasma chromatography/mass spectroscopy (e.g., analysis of organic surface contaminants, analysis of water in sealed electronic packages), and instrument design and automation (hardware, software)

Detection of methyl-, dimethyl- and diethylamine using a nitrate-based chemical ionization mass spectrometer

Science.gov (United States)

Jokinen, T.; Smith, J. N.

2016-12-01

New particle formation is one of the main sources of cloud condensation nuclei (CCN) contributing approximately half of the global CCN budget. The initial steps of nucleation have been studied for decades and it is widely accepted that in most places nucleation requires presence of sulphuric acid (SA) and cluster-stabilizing vapours. Recent results from the CLOUD chamber show that only a few pptv levels of dimethylamine (DMA) with SA forms stable clusters at boundary layer conditions. Ambient sulphuric acid is typically measured using nitrate-based chemical ionization mass spectrometers. Unfortunately, because of higher volatilities and stickiness of amines to surfaces, amine measurement techniques suffer from memory effects and high detection limits. Recently it was discovered that DMA can be detected by utilizing nitrate ionization, simultaneously with sulphuric acid measurements. Here we present results of detecting methylamine, dimethylamine and diethylamine using nitrate-based chemical ionization. We conducted a series of measurements with a home-built transverse chemical ionization inlet and a high resolution time-of-flight mass spectrometer (CI-HToF). Amine vapour was produced using permeation tubes. Three stages of dilution were applied at roughly one order-of-magnitude dilution per stage. The diluted flow of selected amine was then introduced to a sample flow rate of 7 slpm, thus achieving a final amine concentration of 10 pptv. All selected amines were detected as clusters with HNO3NO3- and showed linear response with increasing concentrations (0.5-minute integration time). Zero measurements were performed using clean nitrogen gas right after injection of a selected amine. Memory effects were only observed when using high amine concentrations (ppbv levels). Our results indicate that a variety of amines can be detected using nitrate-based chemical ionization mass spectrometers. However, more experiments are required to see if this presented method will be

Determination of La and Nd by thermal ionization mass spectrometry (TIMS) pre-separated by high performance liquid chromatography (HPLC)

International Nuclear Information System (INIS)

Jaison, P.G.; Raut, N.M.; Parab, A.R.; Khodade, P.S.; Govindan, R.; Aggarwal, S.K.

2003-01-01

Determination of La and Nd by TIMS is required for accurate determination of burn-up of nuclear fuels. During their thermal ionization mass spectrometric (TIMS) analysis, 138 Ce and 142 Ce show spectroscopic isobaric interferences at 138 La and 142 Nd, respectively. Hence, it is essential to remove Ce from La and Nd for their accurate isotopic composition determination. Reversed phase high performance liquid chromatography (HPLC) is a promising technique for rapid and effective separation

A method for simultaneous analysis of phytosterols and phytosterol esters in tobacco leaves using non aqueous reversed phase chromatography and atmospheric pressure chemical ionization mass spectrometry detector.

Science.gov (United States)

Ishida, Naoyuki

2014-05-02

While numerous analytical methods for phytosterols have been reported, the similar polarity and large molecules of phytosterol esters have made the methods lengthy and complicated. For this reason, an analytical method that could completely separate phytosterol esters including the higher fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid in addition to phytosterols without preliminary separation was developed. The separation was accomplished by non-aqueous reversed phase chromatography technique using only acetone and acetonitrile. An atmospheric pressure chemical ionization/mass spectrometry detector configured at selected ion monitoring mode was hyphenated with the separation system to detect phytosterols and phytosterol esters. Twenty-four types of these were consequently separated and then identified with their authentic components. The calibration curve was drawn in the range of about 5 to 25,000 ng/mL with a regression coefficient over 0.999. The limit of detection and limit of quantification, respectively, ranged from 0.9 to 3.0 ng/mL and from 3.0 to 11.0 ng/mL. Recovery rates ranged from 80 to 120%. The quantification results were subjected to statistical analysis and hierarchical clustering analysis, and were used to determine the differences in the amounts of phytosterols and phytosterol esters across tobacco leaves. The newly developed method succeeded in clarifying the whole composition of phytosterols and phytosterol esters in tobacco leaves and in explaining compositional differences across the variety of tobacco leaves. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of clarithromycin in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Jiang, Yao; Wang, Jiang; Li, Hao; Wang, Yingwu; Gu, Jingkai

2007-03-12

A rapid and sensitive method has been developed for the determination of clarithromycin in human plasma with liquid chromatography-tandem mass spectrometry. Clarithromycin and the internal standard, telmisartan were precipitated from the matrix (50 microl) with 200 microl acetonitrile and separated by HPLC using formic acid:10 mM ammonium acetate:methanol (1:99:400, v/v/v) as the mobile phase. The assay based on detection by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode was finished within 2.4 min. Linearity was over the concentration range 10-5000 ng/ml with a limit of detection of 0.50 ng/ml. Intra- and inter-day precision measured as relative standard deviation were bioequivalence study of two tablet formulations of clarithromycin.

A new liquid chromatography - tandem mass spectrometry method using atmospheric pressure photo ionization for the simultaneous determination of azaarenes and azaarones in Dutch river sediments

NARCIS (Netherlands)

Brulik, J.; Simek, Z.; de Voogt, P.

2013-01-01

A new method for the analysis of azaarenes and their degradation products (azaarones) was developed, optimized and validated using liquid chromatography coupled with atmospheric pressure photo ionization tandem mass spectrometric detection (LC-APPI/MS/MS). Seventeen compounds including 4 PAHs

Method development for the determination of 24S-hydroxycholesterol in human plasma without derivatization by high-performance liquid chromatography with tandem mass spectrometry in atmospheric pressure chemical ionization mode.

Science.gov (United States)

Sugimoto, Hiroshi; Kakehi, Masaaki; Satomi, Yoshinori; Kamiguchi, Hidenori; Jinno, Fumihiro

2015-10-01

We developed a highly sensitive and specific high-performance liquid chromatography with tandem mass spectrometry method with an atmospheric pressure chemical ionization interface to determine 24S-hydroxycholesterol, a major metabolite of cholesterol formed by cytochrome P450 family 46A1, in human plasma without any derivatization step. Phosphate buffered saline including 1% Tween 80 was used as the surrogate matrix for preparation of calibration curves and quality control samples. The saponification process to convert esterified 24S-hydroxycholesterol to free sterols was optimized, followed by liquid-liquid extraction using hexane. Chromatographic separation of 24S-hydroxycholesterol from other isobaric endogenous oxysterols was successfully achieved with gradient mobile phase comprised of 0.1% propionic acid and acetonitrile using L-column2 ODS (2 μm, 2.1 mm id × 150 mm). This assay was capable of determining 24S-hydroxycholesterol in human plasma (200 μL) ranging from 1 to 100 ng/mL with acceptable intra- and inter-day precision and accuracy. The potential risk of in vitro formation of 24S-hydroxycholesterol by oxidation from endogenous cholesterol in human plasma was found to be negligible. The stability of 24S-hydroxycholesterol in relevant solvents and human plasma was confirmed. This method was successfully applied to quantify the plasma concentrations of 24S-hydroxycholesterol in male and female volunteers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical data on ionizing and non-ionizing angiographic contrast materials

International Nuclear Information System (INIS)

Bonati, F.

1980-01-01

The cardiovascular effects of ionizing and non-ionizing contrast media are compared in experimental animals and in isolated heart preparations. The following parameters were recorded: peripheric arterial diastolic pressure, heart rate, duration of asystolic period, respiratory rate, contractility of the myocardium (dp/dt, LVSP, Vsub(max), EDV, ESV, SV). The observed changes are mainly due to the higher osmotic activity of the contrast media, as similar alterations were recorded after the injection of hyperosmotic glucose solution. It is concluded that administration of non-ionizing contrast media results in significantly less cardiovascular side effects. (L.E.)

Chemical protection and sensitization to ionizing radiation:molecular investigations

International Nuclear Information System (INIS)

Badiello, R.

1980-01-01

Chemical radioprotection and radiosensitization are induced by the presence of certain chemical compounds, which reduce or enhance the effect of ionizing radiation on living organisms. Such substances are either naturally present or may be artificially introduced in the living cells. Chemical radioprotectors are interesting for possible application in the health protection of both professionally exposed workers and patients treated by radiation for diagnostic and thereapeutic purposes. Interest in chemical radiosensitization has increased recently because of its potential application in the radiotherapy of tumours. Both radioprotection and radiosensitization occur by means of complicated mechanisms, which at first correspond to very fast reactions. The mechanism of the interaction between such substances and radiation-induced biological radicals has been investigated by means of pulse radiolysis and rapid mixing techniques. Examples of the application of these techniques are given to illustrate how information has been obtained on the molecular basis of radiation chemical modi-fication at the cellular level. In particular some interactions between model systems of biological interest (DNA, DNA components, enzymes, amino acids, etc.) and sulphur-containing radioprotectors (glutathione, cysteine, etc.) and/or electroaffinic radiosensitizers, are described. (H.K.)

Determination of telmisartan in human blood plasma: Part II: Liquid chromatography-tandem mass spectrometry method development, comparison to immunoassay and pharmacokinetic study

NARCIS (Netherlands)

Hempen, C.M.; Gläsle-Schwarz, Liane; Kunz, Ulrich; Karst, U.

2006-01-01

A new liquid chromatography/atmospheric pressure chemical ionization-tandem mass spectrometry (LC/APCI-MS/MS) method with on-line sample clean-up for the determination of telmisartan in human blood plasma is presented. This technique is compared to a previously introduced enzyme-linked immunosorbent

Negative Ion Formation of Pentaerythritol Tetranitrate in Atmospheric Pressure Chemical Ionization-Mass Spectrometry and in Corona Discharge Ionization-Ion Mobility Spectrometry

International Nuclear Information System (INIS)

Choi, Sung Seen; Kim, Ok Bae; Kim, Yun Ki; An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop

2011-01-01

Most organic explosives contain nitro groups and are subdivided into nitro-aromatic compounds, nitrate esters, and nitroamines. 1,3,5-Trinitrobenzene (TNB), 2,4,6-trinitrotoluene (TNT), and 2,4-dinitrotoluene (DNT) belong to the nitroaromatic compounds, pentaerythritol tetranitrate (PETN) is one of the nitrate esters, and the nitroamines include 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). Explosives are unstable compounds and their polarities vary from moderate to high due to their nitro groups. These properties impose certain limitations on techniques used for their analysis, since explosives may decompose during analysis or result in poor chromatographic retention. Gas chromatography (GC) is suitable for the analysis of nitroaromatic compounds, but not for nitrate esters and nitroamines, which undergo thermal decomposition under the high temperature conditions of injector and oven. High-performance liquid chromatography (HPLC) would be a better alternative for the more unstable and polar explosives Common analytical

Monitoring of monooctanoyl phosphatidylcholine synthesis by enzymatic acidolysis between soybean phosphatidylcholine and caprylic acid by thin-layer chromatography with a flame ionization detector

DEFF Research Database (Denmark)

Vikbjerg, Anders Falk; Mu, Huiling; Xu, Xuebing

2005-01-01

Thin-layer chromatography with flame ionization detector (TLC-FID) method was used for monitoring the production of structured phospholipids (ML-type: L-long chain fatty acids; M-medium chain fatty acids) by enzyme-catalyzed acidolysis between soybean phosphatidylcholine (PC) and caprylic acid....... It was found that the structured PC fractionated into 2-3 distinct bands on both plate thin layer chromatography (TLC) and Chromarod TLC. These 3 bands represented PC of LL-type, ML-type and MM-type, respectively. The TLC-FID method was applied in the present study to examine the influence of enzyme dosage...

Carbon Nanotube Fiber Ionization Mass Spectrometry: A Fundamental Study of a Multi-Walled Carbon Nanotube Functionalized Corona Discharge Pin for Polycyclic Aromatic Hydrocarbons Analysis

Science.gov (United States)

Nahan, Keaton S.; Alvarez, Noe; Shanov, Vesselin; Vonderheide, Anne

2017-09-01

Mass spectrometry continues to tackle many complicated tasks, and ongoing research seeks to simplify its instrumentation as well as sampling. The desorption electrospray ionization (DESI) source was the first ambient ionization source to function without extensive gas requirements and chromatography. Electrospray techniques generally have low efficiency for ionization of nonpolar analytes and some researchers have resorted to methods such as direct analysis in real time (DART) or desorption atmospheric pressure chemical ionization (DAPCI) for their analysis. In this work, a carbon nanotube fiber ionization (nanoCFI) source was developed and was found to be capable of solid phase microextraction (SPME) of nonpolar analytes as well as ionization and sampling similar to that of direct probe atmospheric pressure chemical ionization (DP-APCI). Conductivity and adsorption were maintained by utilizing a corona pin functionalized with a multi-walled carbon nanotube (MWCNT) thread. Quantitative work with the nanoCFI source with a designed corona discharge pin insert demonstrated linearity up to 0.97 (R2) of three target PAHs with phenanthrene internal standard. [Figure not available: see fulltext.

Specificity enhancement by electrospray ionization multistage mass spectrometry--a valuable tool for differentiation and identification of 'V'-type chemical warfare agents.

Science.gov (United States)

Weissberg, Avi; Tzanani, Nitzan; Dagan, Shai

2013-12-01

The use of chemical warfare agents has become an issue of emerging concern. One of the challenges in analytical monitoring of the extremely toxic 'V'-type chemical weapons [O-alkyl S-(2-dialkylamino)ethyl alkylphosphonothiolates] is to distinguish and identify compounds of similar structure. MS analysis of these compounds reveals mostly fragment/product ions representing the amine-containing residue. Hence, isomers or derivatives with the same amine residue exhibit similar mass spectral patterns in both classical EI/MS and electrospray ionization-MS, leading to unavoidable ambiguity in the identification of the phosphonate moiety. A set of five 'V'-type agents, including O-ethyl S-(2-diisopropylamino)ethyl methylphosphonothiolate (VX), O-isobutyl S-(2-diethylamino)ethyl methylphosphonothiolate (RVX) and O-ethyl S-(2-diethylamino)ethyl methylphosphonothiolate (VM) were studied by liquid chromatography/electrospray ionization/MS, utilizing a QTRAP mass detector. MS/MS enhanced product ion scans and multistage MS(3) experiments were carried out. Based on the results, possible fragmentation pathways were proposed, and a method for the differentiation and identification of structural isomers and derivatives of 'V'-type chemical warfare agents was obtained. MS/MS enhanced product ion scans at various collision energies provided information-rich spectra, although many of the product ions obtained were at low abundance. Employing MS(3) experiments enhanced the selectivity for those low abundance product ions and provided spectra indicative of the different phosphonate groups. Study of the fragmentation pathways, revealing some less expected structures, was carried out and allowed the formulation of mechanistic rules and the determination of sets of ions typical of specific groups, for example, methylphosphonothiolates versus ethylphosphonothiolates. The new group-specific ions elucidated in this work are also useful for screening unknown 'V'-type agents and related

Chemical systems in aqueous solutions for using in the holographic ionizing radiation

International Nuclear Information System (INIS)

Nicolau-Rebigan, S.

1979-01-01

Some types of chemical systems in aqueous solutions for utilization as active media in holographic ionizing radiation dosimeter are presented. One discussed some advantages of the holographic dosimeter comparatively with another existing types. It is outlined the advantages of using aqueousss solutions as active media in holographic dosimeter. (author)

Direct Laser Ablation and Ionization of Solids for Chemical Analysis by Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Holt, J K; Nelson, E J; Klunder, G L [Forensic Science Center, Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)

2007-04-15

A laser ablation/ionization mass spectrometer system is described for the direct chemical analysis of solids. An Nd:YAG laser is used for ablation and ionization of the sample in a quadrupole ion trap operated in an ion-storage (IS) mode that is coupled with a reflectron time-of-flight mass spectrometer (TOF-MS). Single pulse experiments have demonstrated simultaneous detection of up to 14 elements present in glasses in the ppm range. However, detection of the components has produced non-stoichiometric results due to difference in ionization potentials and fractionation effects. Time-of-flight secondary ionization mass spectrometry (TOF-SIMS) was used to spatially map elemental species on the surface and provide further evidence of fractionation effects. Resolution (m/{delta}m) of 1500 and detection limits of approximately 10 pg have been achieved with a single laser pulse. The system configuration and related operating principles for accurately measuring low concentrations of isotopes are described.

Reversed phase liquid chromatography hyphenated to continuous flow-extractive desorption electrospray ionization-mass spectrometry for analysis and charge state manipulation of undigested proteins

Czech Academy of Sciences Publication Activity Database

Li, L.; Yang, S.; Vidová, Veronika; Rice, E. M.; Wijeratne, A.; Havlíček, Vladimír; Schug, K. A.

2015-01-01

Roč. 21, č. 3 (2015), s. 361-368 ISSN 1469-0667 R&D Projects: GA ČR(CZ) GAP206/12/1150; GA MŠk(CZ) LH14064; GA MŠk LO1509 Institutional support: RVO:61388971 Keywords : protein chromatography * ambient ionization * charge-state manipulation Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.011, year: 2015

Composite glycerol/graphite/aromatic acid matrices for thin-layer chromatography/matrix-assisted laser desorption/ionization mass spectrometry of heterocyclic compounds.

Science.gov (United States)

Esparza, Cesar; Borisov, R S; Varlamov, A V; Zaikin, V G

2016-10-28

New composite matrices have been suggested for the analysis of mixtures of different synthetic organic compounds (N-containing heterocycles and erectile dysfunction drugs) by thin layer chromatography/matrix-assisted laser desorption ionization time-of-flight mass spectrometry (TLC/MALDI-TOF). Different mixtures of classical MALDI matrices and graphite particles dispersed in glycerol were used for the registration of MALDI mass spectra directly from TLC plates after analytes separation. In most of cases, the mass spectra possessed [M+H] + ions; however, for some analytes only [M+Na] + and [M+K] + ions were observed. These ions have been used to generate visualized TLC chromatograms. The described approach increases the desorption/ionization efficiencies of analytes separated by TLC, prevent spot blurring, simplifies and decrease time for sample preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

Antimicrobial Activity and Chemical Composition of the Essential Oils of Portuguese Foeniculum vulgare Fruits

OpenAIRE

Mota, Ana; Martins, M. Rosário; Arantes, Silvia; Lopes, Violeta; Bettencourt, Eliseu; Pombal, Sofia; Gomes, Arlindo; Silva, Lúcia

2015-01-01

The aim of this study was to investigate the chemical composition and antimicrobial activity of essential oils obtained by hydrodistillation from fruits of six fennel accessions collected from wild populations occurring in the centre and south of Portugal. Composition of essential oils was established by Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The obtained yields of the essential oils were found to vary greatly ...

Determination of eight nitrosamines in water at the ng L-1 levels by liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry

International Nuclear Information System (INIS)

Ripolles, Cristina; Pitarch, Elena; Sancho, Juan V.; Lopez, Francisco J.; Hernandez, Felix

2011-01-01

Highlights: · Eight N-nitrosamines in water by LC(APCI)MS/MS QqQ analysis. · Validation at two levels: 10 ng L -1 (LOQ) and 100 ng L -1 in drinking water. · Developed method applied to different types of water samples. · NDMA was the analyte more frequently detected and at the highest concentration levels. - Abstract: In this work, we have developed a sensitive method for detection and quantification of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMor), N-nitrosomethylethylamine (NMEA), N-nitrosopirrolidine (NPyr), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPip), N-nitroso-n-dipropylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA) in drinking water. The method is based on liquid chromatography coupled to tandem mass spectrometry, using atmospheric pressure chemical ionization (APCI) in positive mode with a triple quadrupole analyzer (QqQ). The simultaneous acquisition of two MS/MS transitions in selected reaction monitoring mode (SRM) for each compound, together with the evaluation of their relative intensity, allowed the simultaneous quantification and reliable identification in water at ppt levels. Empirical formula of the product ions selected was confirmed by UHPLC-(Q)TOF MS accurate mass measurements from reference standards. Prior to LC-MS/MS QqQ analysis, a preconcentration step by off-line SPE using coconut charcoal EPA 521 cartridges (by passing 500 mL of water sample) was necessary to improve the sensitivity and to meet regulation requirements. For accurate quantification, two isotope labelled nitrosamines (NDMA-d 6 and NDPA-d 14 ) were added as surrogate internal standards to the samples. The optimized method was validated at two concentration levels (10 and 100 ng L -1 ) in drinking water samples, obtaining satisfactory recoveries (between 90 and 120%) and precision (RSD -1 . The described methodology has been applied to different types of water samples: chlorinated from drinking water and wastewater treatment

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.

Fast screening of short-chain chlorinated paraffins in indoor dust samples by graphene-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Huang, Xiu; Liu, Qian; Gao, Wei; Wang, Yawei; Nie, Zhou; Yao, Shouzhuo; Jiang, Guibin

2018-03-01

As an important class of emerging chemical contaminants, short-chain chlorinated paraffins (SCCPs) are considered as one of the most challenging groups of compounds to analyze. In this paper, we report a new method for fast screening of SCCPs based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with graphene as a matrix and 2,5,6,9-tetrachlorodecane as an internal standard. We found that the use of graphene as MALDI matrix generated high peak intensities for SCCPs while producing few background noises. The ion fragmentation mechanisms of SCCPs in MALDI are discussed in detail. Under the optimized conditions, much lower detection limits of SCCP congeners (0.1-5ng/mL) than those reported previously were obtained. Other distinct advantages such as short analysis time and simplified sample preparation procedures are also demonstrated. The method was successfully applied in fast screening of SCCPs in indoor dust samples and monitoring of human exposure levels to SCCPs, and the results were verified by gas chromatography coupled to negative chemical ionization quadrupole time-of-flight high-resolution mass spectrometry. This work not only offers a new promising tool for SCCP studies, but also further demonstrates the promise of graphene as a new generation of MALDI matrix. Copyright © 2017 Elsevier B.V. All rights reserved.

[Separation and identification of bovine lactoferricin by high performance liquid chromatography-matrix-assisted laser desorption/ionization time of flight/ time of flight mass spectrometry].

Science.gov (United States)

An, Meichen; Liu, Ning

2010-02-01

A high performance liquid chromatography-matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (HPLC-MALDI-TOF/TOF MS) method was developed for the separation and identification of bovine lactoferricin (LfcinB). Bovine lactoferrin was hydrolyzed by pepsin and then separated by ion exchange chromatography and reversed-phase liquid chromatography (RP-LC). The antibacterial activities of the fractions from RP-LC separation were determined and the protein concentration of the fraction with the highest activity was measured, whose sequence was indentified by MALDI-TOF/TOF MS. The relative molecular mass of LfcinB was 3 124.89 and the protein concentration was 18.20 microg/mL. The method of producing LfcinB proposed in this study has fast speed, high accuracy and high resolution.

Comparative analysis of Ligusticum chuanxiong and related umbelliferous medicinal plants by high performance liquid chromatography-electrospray ionization mass spectrometry.

Science.gov (United States)

Yi, Tao; Leung, Kelvin Sze-Yin; Lu, Guang-Hua; Zhang, Hao

2007-04-01

A highly precise and accurate method, based on high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS), was developed for the qualitative and quantitative comparison of the main constituents in the rhizome of Ligusticum chuanxiong (LC) and three related umbelliferous medicinal plants. A comprehensive validation of the developed method was conducted, and the method was highly sensitive, reproducible and accurate. The unique properties of the present method were validated by analyzing 20 related herbal samples including 5 LC samples, 5 Cnidium officinale samples (CO), 5 Angelica sinensis samples (AS) and 5 Angelica acutiloba samples (AA). Twelve compounds including phenolic constituents, alkylphthalides and phthalide dimers were identified by online ESI-MS and by comparison with literature data and standard compounds, and six of them were quantified by HPLC-DAD simultaneously. The results demonstrated that identical compound types were identified as the main constituents of LC, CO, AS and AA herbs. The results also support the alternative application of these medicinal plants in Chinese and Japanese folk medicines. In the present study, it was found that the variation in the abundance of senkyunolide A was significant in these related herbs; it is therefore feasible to choose senkyunolide A as a characteristic compound for quality evaluation and chemical authentication of these herbs.

Rapid Screening and Characterization of Acetylcholinesterase Inhibitors from Yinhuang Oral Liquid Using Ultrafiltration-liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry.

Science.gov (United States)

Zhang, Haomin; Guo, Yinan; Meng, Lingwen; Sun, Hui; Yang, Yinping; Gao, Ying; Sun, Jiaming

2018-01-01

At present, approximately 17-25 million people in the world suffer from Alzheimer's disease (AD). The most efficacious and acceptable therapeutic drug clinically are the acetylcholinesterase inhibitors (AChEIs). Yinhuang oral liquid is a Chinese medicine preparation which contains AChEIs according to the literatures. However, no strategy has been presented for rapid screening and identification of AChEIs from Yinhuang oral liquid. To develop a method for rapid screening and identification of AChEIs from Yinhuang oral liquid using ultrafiltration-liquid chromatography-electrospray ionization tandem mass spectrometry (UF-LC-ESI-MS/MS). In this study, UF incubation conditions such as enzyme concentration, incubation time, and incubation temperature were optimized so as to get better screening results. The AChEIs from Yinhuang oral liquid were identified by high-performance liquid chromatography-ESI-MS and the improved Ellman method was used for the AChE inhibitory activity test in vitro . The results showed that Yinhuang oral liquid can inhibit the activity of AChE. We screened and identified seven compounds with potential AChE inhibitory activity from Yinhuang oral liquid, which provided experimental basis for the treatment and prevention of AD. The current technique was used to directly screen the active ingredients with acetylcholinesterase inhibition from complex traditional Chinese medicine, which was simple, rapid, accurate, and suitable for high-throughput screening of AChEI from complex systems. A UF-LC-ESI-MS/MS method for rapid screening and identification of AChEIs from Yinhuang oral liquid was developedSeven compounds were screened and identified with potential AChE inhibitory activity from Yinhuang oral liquidIt provided experimental basis of Yinhuang oral liquid for the treating and preventing AD. Abbreviations used: (AD): Alzheimer's disease; (UF-LC-ESI-MS/MS): ultrafiltration-liquid chromatography-electrospray ionization tandem mass spectrometry; (ACh

APCI as an innovative ionization mode compared with EI and CI for the analysis of a large range of organophosphate esters using GC-MS/MS.

Science.gov (United States)

Halloum, Wafaa; Cariou, Ronan; Dervilly-Pinel, Gaud; Jaber, Farouk; Le Bizec, Bruno

2017-01-01

Organophosphate esters (OPEs) are chemical compounds incorporated into materials as flame-proof and/or plasticizing agents. In this work, 13 non-halogenated and 5 halogenated OPEs were studied. Their mass spectra were interpreted and compared in terms of fragmentation patterns and dominant ions via various ionization techniques [electron ionization (EI) and chemical ionization (CI) under vacuum and corona discharge atmospheric pressure chemical ionization (APCI)] on gas chromatography coupled to mass spectrometry (GC-MS). The novelty of this paper relies on the investigation of APCI technique for the analysis of OPEs via favored protonation mechanism, where the mass spectra were mostly dominated by the quasi-molecular ion [M + H] + . The EI mass spectra were dominated by ions such as [H 4 PO 4 ] + , [M-R] + , [M-Cl] + , and [M-Br] + , and for some non-halogenated aryl OPEs, [M] +● was also observed. The CI mass spectra in positive mode were dominated by [M + H] + and sometimes by [M-R] + , while in negative mode, [M-R] - and more particularly [X] - and [X 2 ] -● were mainly observed for the halogenated OPEs. Both EI and APCI techniques showed promising results for further development of instrumental method operating in selective reaction monitoring mode. Instrumental detection limits by using APCI mode were 2.5 to 25 times lower than using EI mode for the non-brominated OPEs, while they were determined at 50-100 times lower by the APCI mode than by the EI mode, for the two brominated OPEs. The method was applied to fish samples, and monitored transitions by using APCI mode showed higher specificity but lower stability compared with EI mode. The sensitivity in terms of signal-to-noise ratio varying from one compound to another. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Chemical effects and their consequences for individuals occupationally exposed to ionizing radiation

International Nuclear Information System (INIS)

Salvador, C.; Kahl, G.G.; Kühn, P.; Zottis, A.D.; Flôr, R.C.

2017-01-01

By legal determination, workers exposed to ionizing radiation should use individual dosimeters in the most exposed region of the body, designed to estimate the effective dose, as well as radiation protective clothing to minimize occupational exposures. Regarding dosimetry, in most cases it is perceived that the monthly values of exposure are within the limits of normality, however, even being below the limit can not rule out the possibility of damage that the low dose of ionizing radiation can cause. The objective of this article is to highlight the main chemical effects caused by exposure to ionizing radiation, especially biochemical damage in DNA, chromosomal aberrations and the correlation with the exposure of occupationally exposed individuals, as well as individuals from the public. A bibliographic search was carried out in indexed databases from February to April 2017 with the following descriptors: Radiation Ionizing, DNA Damage and Occupational Exposure. In the 'Science Direct' database were found 1205 articles, in the 'Scopus' 19 articles, in the 'Web of Science' 83 articles, in the 'PubMed' 22 articles and in the 'VHL' 60 articles related to the theme. It was concluded that exposure to ionizing radiation can affect the DNA molecule despite its repair mechanisms, which may result in genotoxicity. It has been reported a correlation between occupationally exposed individuals and chromosomal aberrations, demonstrating that even low doses of ionizing radiation can compromise the genetic material integrity of exposed workers, leading to the need for a periodic cytogenetic study for this group of workers

Determination of polycyclic aromatic hydrocarbons in palm oil mill effluent by soxhlet extraction and gas chromatography-flame ionization detector

International Nuclear Information System (INIS)

Nor Fairolzukry Ahmad Rasdy; Mohd Marsin Sanagi; Wan Aini Wan Ibrahim; Ahmedy Abu Naim

2008-01-01

A method has been developed for the determination of polycyclic aromatic hydrocarbons (PAHs) from palm oil mill effluent based on gas chromatography-flame ionization detection. Extraction of spiked PAHs (napthalene, fluorene phenanthrene, fluoranthene and pyrene) in palm oil waste was carried out by Soxhlet extraction using hexane-dichloromethane (60:40 v/v) as the solvent. Excellent separations were achieved using temperature programmed GC on Ultra-1 fused-silica capillary column (30 m x 250 μm ID), carrier gas helium at a flow rate of 1 mL/ min. (author)

An Atmospheric Pressure Chemical Ionization MS/MS Assay Using Online Extraction for the Analysis of 11 Cannabinoids and Metabolites in Human Plasma and Urine.

Science.gov (United States)

Klawitter, Jelena; Sempio, Cristina; Mörlein, Sophie; De Bloois, Erik; Klepacki, Jacek; Henthorn, Thomas; Leehey, Maureen A; Hoffenberg, Edward J; Knupp, Kelly; Wang, George S; Hopfer, Christian; Kinney, Greg; Bowler, Russell; Foreman, Nicholas; Galinkin, Jeffrey; Christians, Uwe; Klawitter, Jost

2017-10-01

Although, especially in the United States, there has been a recent surge of legalized cannabis for either recreational or medicinal purposes, surprisingly little is known about clinical dose-response relationships, pharmacodynamic and toxicodynamic effects of cannabinoids such as Δ9-tetrahydrocannabinol (THC). Even less is known about other active cannabinoids. To address this knowledge gap, an online extraction, high-performance liquid chromatography coupled with tandem mass spectrometry method for simultaneous quantification of 11 cannabinoids and metabolites including THC, 11-hydroxy-Δ9-tetrahydrocannabinol, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide (THC-C-gluc), cannabinol, cannabidiol, cannabigerol, cannabidivarin, Δ9-tetrahydrocannabivarin (THCV), and 11-nor-9-carboxy-Δ9-tetrahydrocannabivarin (THCV-COOH) was developed and validated in human urine and plasma. In contrast to atmospheric pressure chemical ionization, electrospray ionization was associated with extensive ion suppression in plasma and urine samples. Thus, the atmospheric pressure chemical ionization assay was validated showing a lower limit of quantification ranging from 0.39 to 3.91 ng/mL depending on study compound and matrix. The upper limit of quantification was 400 ng/mL except for THC-C-gluc with an upper limit of quantification of 2000 ng/mL. The linearity was r > 0.99 for all analyzed calibration curves. Acceptance criteria for intrabatch and interbatch accuracy (85%-115%) and imprecision (<15%) were met for all compounds. In plasma, the only exceptions were THCV (75.3%-121.2% interbatch accuracy) and cannabidivarin (interbatch imprecision, 15.7%-17.2%). In urine, THCV did not meet predefined acceptance criteria for intrabatch accuracy. This assay allows for monitoring not only THC and its major metabolites but also major cannabinoids that are of interest for marijuana research and clinical practice.

Simultaneous quantification of reparixin and paclitaxel in plasma and urine using ultra performance liquid chromatography-tandem mass spectroscopy (UHPLC-MS/MS): Application to a preclinical pharmacokinetic study in rats.

Science.gov (United States)

Malhi, Sarandeep; Stesco, Nicholas; Alrushaid, Samaa; Lakowski, Ted M; Davies, Neal M; Gu, Xiaochen

2017-03-01

A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) assay was developed and validated to simultaneously quantify anticancer drugs reparixin and paclitaxel in this study. The compounds were extracted from plasma and urine samples by protein precipitation with acetone (supplemented with 0.1% formic acid). Chromatographic separation was achieved using a C18 column, and drug molecules were ionized using dual ion source electrospray and atmospheric pressure chemical ionization (DUIS: ESI-APCI). Reparixin and paclitaxel were quantified using negative and positive multiple reaction monitoring (MRM) mode, respectively. Stable isotope palcitaxel-D5 was used as the internal standard (IS). The assay was validated for specificity, recovery, carryover and sample stability under various storage conditions; it was also successfully applied to measure drug concentrations collected from a pharmacokinetic study in rats. The results confirmed that the assay was accurate and simple in quantifying both reparixin and paclitaxel in plasma and urine with minimal sample pretreatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Proof of cannabis administration by sensitive detection of 11-nor-Delta(9)-tetrahydrocannabinol-9-carboxylic acid in hair using selective methylation and application of liquid chromatography- tandem and multistage mass spectrometry.

Science.gov (United States)

Thieme, Detlef; Sachs, Hans; Uhl, Michael

2014-01-01

The identification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) in hair represents an exceptional forensic analytical challenge due to low target concentrations in a complex matrix. Several dedicated techniques [gas chromatography-negative chemical ionization-tandem mass spectrometry (GC-NCI-MS/MS) or GC-GC-MS couplings] were specifically introduced into forensic toxicology aiming to a selective and sensitive identification of THCCOOH in hair. The combination of liquid-chromatography (LC) and MS/MS gained an outstanding relevance in forensic toxicology (including the detection of cannabinoids). However, its application to hair matrix is characterized by a lack of specificity which is due to the unspecific decarboxylation as most abundant fragmentation reaction. Therefore, various chemical modifications of the carboxyl and/or phenolic hydroxyl groups were examined to improve the selectivity. The selective methylation of the 9-carboxyl-group proved to be the most efficient derivatization procedure. Hair extracts were redissolved in acetonitrile and after addition of few milligrams of solid sodium carbonate derivatized with 25 μL methyl iodide. The resulting THC-9-carboxymethylester was separated by conventional reverse phase LC and selectively detected using negative electrospray ionization by recording the fragmentation reactions 357➔325 and 357➔297. Resulting limits of quantification were below 100 fg/mg. A further significant improvement was achieved by application of the multistage MS3 fragmentation 357➔325➔297. To verify the validity of this procedure, a systematic quantitative comparison of THCCOOH concentrations in hair with data from a well established GC-NCI-MS/MS technique was performed. Both techniques proved to be in good accordance (R(2)=0.647, p = <0.001) and equally suitable for hair testing of THCCOOH. Copyright © 2013 John Wiley & Sons, Ltd.

Comparison of quantification methods for the analysis of polychlorinated alkanes using electron capture negative ionization mass spectrometry.

NARCIS (Netherlands)

Rusina, T.; Korytar, P.; de Boer, J.

2011-01-01

Four quantification methods for short-chain chlorinated paraffins (SCCPs) or polychlorinated alkanes (PCAs) using gas chromatography electron capture negative ionisation low resolution mass spectrometry (GC-ECNI-LRMS) were investigated. The method based on visual comparison of congener group

Determination of eight nitrosamines in water at the ng L{sup -1} levels by liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Ripolles, Cristina; Pitarch, Elena; Sancho, Juan V; Lopez, Francisco J [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellon (Spain); Hernandez, Felix [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellon (Spain)

2011-09-19

Highlights: {center_dot} Eight N-nitrosamines in water by LC(APCI)MS/MS QqQ analysis. {center_dot} Validation at two levels: 10 ng L{sup -1} (LOQ) and 100 ng L{sup -1} in drinking water. {center_dot} Developed method applied to different types of water samples. {center_dot} NDMA was the analyte more frequently detected and at the highest concentration levels. - Abstract: In this work, we have developed a sensitive method for detection and quantification of eight N-nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMor), N-nitrosomethylethylamine (NMEA), N-nitrosopirrolidine (NPyr), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPip), N-nitroso-n-dipropylamine (NDPA) and N-nitrosodi-n-butylamine (NDBA) in drinking water. The method is based on liquid chromatography coupled to tandem mass spectrometry, using atmospheric pressure chemical ionization (APCI) in positive mode with a triple quadrupole analyzer (QqQ). The simultaneous acquisition of two MS/MS transitions in selected reaction monitoring mode (SRM) for each compound, together with the evaluation of their relative intensity, allowed the simultaneous quantification and reliable identification in water at ppt levels. Empirical formula of the product ions selected was confirmed by UHPLC-(Q)TOF MS accurate mass measurements from reference standards. Prior to LC-MS/MS QqQ analysis, a preconcentration step by off-line SPE using coconut charcoal EPA 521 cartridges (by passing 500 mL of water sample) was necessary to improve the sensitivity and to meet regulation requirements. For accurate quantification, two isotope labelled nitrosamines (NDMA-d{sub 6} and NDPA-d{sub 14}) were added as surrogate internal standards to the samples. The optimized method was validated at two concentration levels (10 and 100 ng L{sup -1}) in drinking water samples, obtaining satisfactory recoveries (between 90 and 120%) and precision (RSD < 20%). Limits of detection were found to be in the range of 1-8 ng L{sup -1

Method and apparatus for analyzing ionizable materials

International Nuclear Information System (INIS)

Ehrlich, B.J.; Hall, R.C.; Thiede, P.W.

1979-01-01

An apparatus and method are described for analyzing a solution of ionizable compounds in a liquid. The solution is irradiated with electromagnetic radiation to ionize the compounds and the electrical conductivity of the solution is measured. The radiation may be X-rays, ultra-violet, infra-red or microwaves. The solution may be split into two streams, only one of which is irradiated, the other being used as a reference by comparing conductivities of the two streams. The liquid must be nonionizable and is preferably a polar solvent. The invention provides an analysis technique useful in liquid chromatography and in gas chromatography after dissolving the eluted gases in a suitable solvent. Electrical conductivity measurements performed on the irradiated eluent provide a quantitative indication of the ionizable materials existing within the eluent stream and a qualitative indication of the purity of the eluent stream. (author)

Liquid-chromatography mass spectrometry (LC-MS) of steroid hormone metabolites and its applications

Science.gov (United States)

Penning, Trevor M.; Lee, Seon-Hwa; Jin, Yi; Gutierrez, Alejandro; Blair, Ian A.

2010-01-01

Advances in liquid chromatography-mass spectrometry (LC-MS) can be used to measure steroid hormone metabolites in vitro and in vivo. We find that LC-Electrospray Ionization (ESI)-MS using a LCQ ion trap mass spectrometer in the negative ion mode can be used to monitor the product profile that results from 5α–dihydrotestosterone(DHT)-17β-glucuronide, DHT-17β-sulfate, and tibolone-17β-sulfate reduction catalyzed by human members of the aldo-keto reductase (AKR) 1C subfamily and assign kinetic constants to these reactions. We also developed a stable-isotope dilution LC-electron capture atmospheric pressure chemical ionization (ECAPCI)-MS method for the quantitative analysis of estrone (E1) and its metabolites as pentafluorobenzyl (PFB) derivatives in human plasma in the attomole range. The limit of detection for E1-PFB was 740 attomole on column. Separations can be performed using normal-phase LC because ionization takes place in the gas phase rather than in solution. This permits efficient separation of the regioisomeric 2- and 4-methoxy-E1. The method was validated for the simultaneous analysis of plasma E2 and its metabolites: 2-methoxy-E2, 4-methoxy-E2, 16α-hydroxy-E2, estrone (E1), 2-methoxy-E1, 4-methoxy-EI, and 16α-hydroxy-E1 from 5 pg/mL to 2,000 pg/mL. Our LC-MS methods have sufficient sensitivity to detect steroid hormone levels in prostate and breast tumors and should aid their molecular diagnosis and treatment. PMID:20083198

Comparison of the concepts used to develop and apply occupational exposure limits for ionizing radiation and hazardous chemical substances

International Nuclear Information System (INIS)

Halton, D.M.

1988-01-01

The rationales used by the American Conference of Governmental Industrial Hygienists (AC-GIH) to recommend exposure limits for 10 chemicals were reviewed. The 10 chemicals chosen were known to produce chronic disease after prolonged overexposure in the workplace. The chemicals were toluene diisocyanate, hydrogen fluoride, n-hexane, carbon disulfide, cadmium, inorganic mercury, cobalt, nitroglycerol, silica, and vinyl chloride. The rationales used by the International Commission on Radiological Protection (ICRP) to recommend limits for workplace exposure to ionizing radiation were reviewed. The rationales used in occupational health by ACGIH were then compared with those used by ICRP in health physics. The comparison revealed a significant divergence in the underlying concepts and philosophies of the two approaches. This divergence cannot be solely attributed to differences in scientific knowledge about toxicological and radiological effects. In areas of scientific uncertainty, exposure limits for ionizing radiation are based on worst case or conservative assumptions. This approach favors human safety. Parallel approaches could not be found for any of the 10 chemicals reviewed. Other factors such as the costs incurred by industry in meeting the proposed standards played a more significant role in establishing limits for workplace chemicals than for ionizing radiation

Identification of Three Kinds of Citri Reticulatae Pericarpium Based on Deoxyribonucleic Acid Barcoding and High-performance Liquid Chromatography-diode Array Detection-electrospray Ionization/Mass Spectrometry/Mass Spectrometry Combined with Chemometric Analysis

Science.gov (United States)

Yu, Xiaoxue; Zhang, Yafeng; Wang, Dongmei; Jiang, Lin; Xu, Xinjun

2018-01-01

Background: Citri Reticulatae Pericarpium is the dried mature pericarp of Citrus reticulata Blanco which can be divided into “Chenpi” and “Guangchenpi.” “Guangchenpi” is the genuine Chinese medicinal material in Xinhui, Guangdong province; based on the greatest quality and least amount, it is most expensive among others. Hesperidin is used as the marker to identify Citri Reticulatae Pericarpium described in the Chinese Pharmacopoeia 2010. However, both “Chenpi” and “Guangchenpi” contain hesperidin so that it is impossible to differentiate them by measuring hesperidin. Objective: Our study aims to develop an efficient and accurate method to separate and identify “Guangchenpi” from other Citri Reticulatae Pericarpium. Materials and Methods: The genomic deoxyribonucleic acid (DNA) of all the materials was extracted and then the internal transcribed spacer 2 was amplified, sequenced, aligned, and analyzed. The secondary structures were created in terms of the database and website established by Jörg Schultz et al. High-performance liquid chromatography-diode array detection-electrospray Ionization/mass spectrometry (HPLC-DAD-ESI-MS)/MS coupled with chemometric analysis was applied to compare the differences in chemical profiles of the three kinds of Citri Reticulatae Pericarpium. Results: A total of 22 samples were classified into three groups. The results of DNA barcoding were in accordance with principal component analysis and hierarchical cluster analysis. Eight compounds were deduced from HPLC-DAD-ESI-MS/MS. Conclusions: This method is a reliable and effective tool to differentiate the three Citri Reticulatae Pericarpium. SUMMARY The internal transcribed spacer 2 regions and the secondary structure among three kinds of Citri Reticulatae Pericarpium varied considerablyAll the 22 samples were analyzed by high-performance liquid chromatography (HPLC) to obtain the chemical profilesPrincipal component analysis and hierarchical cluster analysis

Radioimmunoassay and chemical ionization/mass spectrometry compared for plasma cortisol determination

International Nuclear Information System (INIS)

Lindberg, C.; Johnson, S.; Hedner, P.; Gustafsson, A.

1982-01-01

A method is described for determination of cortisol in plasma and urine, based on chemical ionization/mass spectrometry with deuterium-labeled cortisol as the internal standard. The within-run precision (CV) was 2.5-5.7%, the between-run precision 4.6%. Results by this method were compared with those by a radioimmunological method (RIANEN Cortisol, New England Nuclear) for 395 plasma samples. The latter method gave significantly higher (approx. 25%) cortisol values

Spatially resolved chemical analysis of cicada wings using laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS).

Science.gov (United States)

Román, Jessica K; Walsh, Callee M; Oh, Junho; Dana, Catherine E; Hong, Sungmin; Jo, Kyoo D; Alleyne, Marianne; Miljkovic, Nenad; Cropek, Donald M

2018-03-01

Laser-ablation electrospray ionization (LAESI) imaging mass spectrometry (IMS) is an emerging bioanalytical tool for direct imaging and analysis of biological tissues. Performing ionization in an ambient environment, this technique requires little sample preparation and no additional matrix, and can be performed on natural, uneven surfaces. When combined with optical microscopy, the investigation of biological samples by LAESI allows for spatially resolved compositional analysis. We demonstrate here the applicability of LAESI-IMS for the chemical analysis of thin, desiccated biological samples, specifically Neotibicen pruinosus cicada wings. Positive-ion LAESI-IMS accurate ion-map data was acquired from several wing cells and superimposed onto optical images allowing for compositional comparisons across areas of the wing. Various putative chemical identifications were made indicating the presence of hydrocarbons, lipids/esters, amines/amides, and sulfonated/phosphorylated compounds. With the spatial resolution capability, surprising chemical distribution patterns were observed across the cicada wing, which may assist in correlating trends in surface properties with chemical distribution. Observed ions were either (1) equally dispersed across the wing, (2) more concentrated closer to the body of the insect (proximal end), or (3) more concentrated toward the tip of the wing (distal end). These findings demonstrate LAESI-IMS as a tool for the acquisition of spatially resolved chemical information from fragile, dried insect wings. This LAESI-IMS technique has important implications for the study of functional biomaterials, where understanding the correlation between chemical composition, physical structure, and biological function is critical. Graphical abstract Positive-ion laser-ablation electrospray ionization mass spectrometry coupled with optical imaging provides a powerful tool for the spatially resolved chemical analysis of cicada wings.

Identification and quantification of flavonoids in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

DEFF Research Database (Denmark)

Nielsen, S. E.; Freese, R.; Cornett, Claus

2000-01-01

A rapid and sensitive high-performance liquid chromatographic mass spectrometric (HPLC-MS) method is described for the determination and quantification of 12 dietary flavonoid glycosides and aglycons in human urine samples. Chromatographic separation of the analytes of interest was achieved...... by column-switching, using the first column (a Zorbax 300SB C-3 column) for sample cleanup and eluting the heart-cut flavonoid fraction onto the second column (a Zorbax SE C-18 column) for separation and detection by ultraviolet and atmospheric pressure chemical ionization MS using single ion monitoring...... of variation for the analysis of the 12 different flavonoids in quality control urine samples were 12.3% on average (range 11.0-13.7%, n = 24, reproducibility) and the repeatability of the assay were 5.0% (mean, range 0.1-14.8%, it = 12). A subset of 10 urine samples from a human dietary intervention study...

Trace determination of the flame retardant tetrabromobisphenol A in the atmosphere by gas chromatography-mass spectrometry

International Nuclear Information System (INIS)

Xie Zhiyong; Ebinghaus, Ralf; Lohmann, Rainer; Heemken, Olaf; Caba, Armando; Puettmann, Wilhelm

2007-01-01

A simple and effective method has been developed for analysis of the flame retardant tetrabromobisphenol A (TBBPA) in environmental samples by using modified soxhlet extraction in combination with silica gel clean-up, derivatization with silylation reagent and gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Satisfactory recoveries were achieved for the large volume sampling, soxhlet extraction and silica gel clean-up. The overall recovery is 79 ± 1%. The derivatization procedure is simple and fast, and produces stable TBBPA derivative. GC-MS with electronic impact (EI) ionization mode shows better detection power than using negative chemical ionization (NCI) mode. EI gives a method detection limit of 0.04 pg m -3 and enables to determine trace TBBPA in ambient air in remote area. The method was successfully applied to the determination of TBBPA in atmospheric samples collected over land and coastal regions. The concentrations of TBBPA ranged from below the method detection limit (0.04 pg m -3 ) to 0.85 pg m -3 . A declining trend with increasing latitude was present from the Wadden Sea to the Arctic. The atmospheric occurrence of TBBPA in the Arctic is significant and might imply that TBBPA has long-range transport potential

Dosimetry of ionizing radiation

International Nuclear Information System (INIS)

Musilek, L.; Seda, J.; Trousil, J.

1992-01-01

The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

A Laboratory Experiment To Measure Henry's Law Constants of Volatile Organic Compounds with a Bubble Column and a Gas Chromatography Flame Ionization Detector (GC-FID)

Science.gov (United States)

Lee, Shan-Hu; Mukherjee, Souptik; Brewer, Brittany; Ryan, Raphael; Yu, Huan; Gangoda, Mahinda

2013-01-01

An undergraduate laboratory experiment is described to measure Henry's law constants of organic compounds using a bubble column and gas chromatography flame ionization detector (GC-FID). This experiment is designed for upper-division undergraduate laboratory courses and can be implemented in conjunction with physical chemistry, analytical…

Simultaneous determination of asperosaponin VI and its active metabolite hederagenin in rat plasma by liquid chromatography-tandem mass spectrometry with positive/negative ion-switching electrospray ionization and its application in pharmacokinetic study.

Science.gov (United States)

Zhu, He; Ding, Li; Shakya, Shailendra; Qi, Xiemin; Hu, Linlin; Yang, Xiaolin; Yang, Zhonglin

2011-11-15

A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method operated in the positive/negative electrospray ionization (ESI) switching mode has been developed and validated for the simultaneous determination of asperosaponin VI and its active metabolite hederagenin in rat plasma. After addition of internal standards diazepam (for asperosaponin VI) and glycyrrhetic acid (for hederagenin), the plasma sample was deproteinized with acetonitrile, and separated on a reversed phase C18 column with a mobile phase of methanol (solvent A)-0.05% glacial acetic acid containing 10 mM ammonium acetate and 30 μM sodium acetate (solvent B) using gradient elution. The detection of target compounds was done in multiple reaction monitoring (MRM) mode using a tandem mass spectrometry equipped with positive/negative ion-switching ESI source. At the first segment, the MRM detection was operated in the positive ESI mode using the transitions of m/z 951.5 ([M+Na](+))→347.1 for asperosaponin VI and m/z 285.1 ([M+H](+))→193.1 for diazepam for 4 min, then switched to the negative ESI mode using the transitions of m/z 471.3 ([M-H](-))→471.3 for hederagenin and m/z 469.4 ([M-H](-))→425.4 for glycyrrhetic acid, respectively. The sodiated molecular ion [M+Na](+) at m/z 951.5 was selected as the precursor ion for asperosaponin VI, since it provided better sensitivity compared to the deprotonated and protonated molecular ions. Sodium acetate was added to the mobile phase to make sure that abundant amount of the sodiated molecular ion of asperosaponin VI could be produced, and more stable and intensive mass response of the product ion could be obtained. For the detection of hederagenin, since all of the mass responses of the fragment ions were very weak, the deprotonated molecular ion [M-H](-)m/z 471.3 was employed as both the precursor ion and the product ion. But the collision energy was still used for the MRM, in order to eliminate the influences induced by the interference

Defence biochemical mechanisms of the organisms against chemical pollution and ionizing radiations

International Nuclear Information System (INIS)

Olinescu, Radu

2001-01-01

Acute exposure to high concentrations / doses of chemical pollutants and ionizing radiation usually kills giving no chance for survival, if not immediately, than later followed by specific diseases. Fortunately, this acute exposure is accidental, but chronic, low level exposure is also damaging. The involvement of pollution, especially of chemically produced, one in the etiology of several diseases is still under intensive research. Compared to other kinds of pollution (radioactive, microbiological), the chemical one seldom kills suddenly; it acts slowly, silently, by accumulation into the tissues, eventually inducing a failure of certain organ. The body is continuously adapting to low level concentrations of chemicals from environment until a certain threshold. All organisms, including humans, have a limited capacity of resisting the effects of various types of pollutants. Extensive laboratory research, demonstrated that most of damaging organic pollutants cause the formation of free radicals when they penetrate into the body and are metabolized. Free radicals are very reactive and are known to damage tissues with potentially fatal results. Substantial experimental evidence in recent years has demonstrated that all organisms are endowed with versatile, efficient antioxidant systems, that provide protection against the formation or effects of free radicals. However, the antioxidant systems are limited and when their capacity of protection is exceeded, injury resulting in illness or death occurs. In most cases, the harmful effects of chemicals on organisms depend on the biotransformation step, where free radicals are produced as byproducts of the metabolic reactions. The damaging effects of chemical pollutants are mostly restricted to an important organ depending on the way of penetration, nature of the compound and concentration. The organisms possess specific and nonspecific defense systems, which act from the exposure step, with attempt to block the entry of

Supercritical fluid chromatography-photodiode array detection-electrospray ionization mass spectrometry as a framework for impurity fate mapping in the development and manufacture of drug substances.

Science.gov (United States)

Pirrone, Gregory F; Mathew, Rose M; Makarov, Alexey A; Bernardoni, Frank; Klapars, Artis; Hartman, Robert; Limanto, John; Regalado, Erik L

2018-03-30

Impurity fate and purge studies are critical in order to establish an effective impurity control strategy for approval of the commercial filing application of new medicines. Reversed phase liquid chromatography-diode array-mass spectrometry (RPLC-DAD-MS) has traditionally been the preferred tool for impurity fate mapping. However, separation of some reaction mixtures by LC can be very problematic requiring combination LC-UV for area % analysis and a different LC-MS method for peak identification. In addition, some synthetic intermediates might be chemically susceptible to the aqueous conditions used in RPLC separations. In this study, the use of supercritical fluid chromatography-photodiode array-electrospray ionization mass spectrometry (SFC-PDA-ESIMS) for fate and purge of two specified impurities in the 1-uridine starting material from the synthesis of a bis-piv 2'keto-uridine, an intermediate in the synthesis of uprifosbuvir, a treatment under investigation for chronic hepatitis C infection. Readily available SFC instrumentation with a Chiralpak IC column (4.6 × 150 mm, 3 μm) and ethanol: carbon dioxide based mobile phase eluent enabled the separation of closely related components from complex reaction mixtures where RLPC failed to deliver optimal chromatographic performance. These results illustrate how SFC combined with PDA and ESI-MS detection can become a powerful tool for direct impurity fate mapping across multiple reaction steps. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of dimethylamine on the gas phase sulfuric acid concentration measured by Chemical Ionization Mass Spectrometry

CERN Document Server

Rondo, L.; Kürten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tomé, A.; Tröstl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J.

2016-01-01

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosolnucleation. Based on quantum chemical calculations it has been suggested that the quantitative detectionof gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased inthe presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was setup at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection ofH2SO4in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time inthe CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF(Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutralsulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presenceof dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS...

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.

Quantification of urinary 0,0'-dityrosine, a biomarker for oxidative damage to proteins, by high performance liquid chromatography with triple quadrupole tandem mas spectrometry. A comparison with ion-trap tandem mass spectrometry.

NARCIS (Netherlands)

Orhan, H.; Coolen, S.; Meerman, J.H.N.

2005-01-01

We recently described an isotope dilution reversed-phase liquid chromatography-atmospheric pressure chemical ionization-ion-trap-tandem mass spectrometry (HPLC-APCI-MS/MS) method for the quantitative determination of oxidized amino acids in human urine, including o,o′-dityrosine, a specific marker

Metabolic profiling of Vitex agnus castus leaves, fruits and sprouts: analysis by LC/ESI/(QqQ)MS and (HR) LC/ESI/(Orbitrap)/MS n.

Science.gov (United States)

Mari, Angela; Montoro, Paola; D'Urso, Gilda; Macchia, Mario; Pizza, Cosimo; Piacente, Sonia

2015-01-01

Food supplements based on Vitex agnus castus L. (Verbenaceae) fruits, also known as chasteberry, are routinely used by women against somatic and psychic premenstrual symptoms such as depression, sadness or irritability. With the aim of highlighting the differences in the chemical profiles of cultivated fruits and different parts of wild plants (fruits, leaves and sprouts) of V. agnus castus, a method concerning with the quali-quantitative study of the derived hydroalcoholic extracts was carried out by using high-performance liquid chromatography coupled to electrospray negative ionization Orbitrap multicollisional high resolution mass spectrometry (LC/ESI/(Orbitrap)MS(n)) and high-performance liquid chromatography coupled to electrospray negative ionization triple quadrupole tandem mass spectrometry (LC/ESI/(QqQ)MS) in multiple reaction monitoring (MRM) mode. Copyright © 2014 Elsevier B.V. All rights reserved.

The technique of negative ions in mass spectrometry. Application to aromatics

International Nuclear Information System (INIS)

George, G.

1984-01-01

The author examines the application of NCI (study of negative ions created by chemical ionization and particularly by a reacting negative ion) on a model popular at the present time: the passion fruit. The author stresses that this technique has its limitations and should be considered as auxiliary to electron impact. However, it seems destined for a promising future for the analysis of natural produce [fr

Identification of alkylated phosphates by gas chromatography-mass spectrometric investigations with different ionization principles of a thermally aged commercial lithium ion battery electrolyte.

Science.gov (United States)

Weber, Waldemar; Kraft, Vadim; Grützke, Martin; Wagner, Ralf; Winter, Martin; Nowak, Sascha

2015-05-15

The thermal aging process of a commercial LiPF6 based lithium ion battery electrolyte has been investigated in view of the formation of volatile phosphorus-containing degradation products. Aging products were analyzed by GC-MS. Structure determination of the products was performed by support of chemical ionization MS in positive and negative modes. A fraction of the discovered compounds belongs to the group of fluorophosphates (phosphorofluoridates) which are in suspect of potential toxicity. This is well known for relative derivatives, e.g. diisopropyl fluorophosphate. Another fraction of the identified compounds belongs to the group of trialkyl phosphates. These compounds may provide a positive impact on the thermal and electrochemical performance of Li-based batteries as repeatedly described in the literature. Copyright © 2015 Elsevier B.V. All rights reserved.

Qualitative and quantitative analysis of pyrolysis oil by gas chromatography with flame ionization detection and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry.

Science.gov (United States)

Sfetsas, Themistoklis; Michailof, Chrysa; Lappas, Angelos; Li, Qiangyi; Kneale, Brian

2011-05-27

Pyrolysis oils have attracted a lot of interest, as they are liquid energy carriers and general sources of chemicals. In this work, gas chromatography with flame ionization detector (GC-FID) and two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) techniques were used to provide both qualitative and quantitative results of the analysis of three different pyrolysis oils. The chromatographic methods and parameters were optimized and solvent choice and separation restrictions are discussed. Pyrolysis oil samples were diluted in suitable organic solvent and were analyzed by GC×GC-TOFMS. An average of 300 compounds were detected and identified in all three samples using the ChromaToF (Leco) software. The deconvoluted spectra were compared with the NIST software library for correct matching. Group type classification was performed by use of the ChromaToF software. The quantification of 11 selected compounds was performed by means of a multiple-point external calibration curve. Afterwards, the pyrolysis oils were extracted with water, and the aqueous phase was analyzed both by GC-FID and, after proper change of solvent, by GC×GC-TOFMS. As previously, the selected compounds were quantified by both techniques, by means of multiple point external calibration curves. The parameters of the calibration curves were calculated by weighted linear regression analysis. The limit of detection, limit of quantitation and linearity range for each standard compound with each method are presented. The potency of GC×GC-TOFMS for an efficient mapping of the pyrolysis oil is undisputable, and the possibility of using it for quantification as well has been demonstrated. On the other hand, the GC-FID analysis provides reliable results that allow for a rapid screening of the pyrolysis oil. To the best of our knowledge, very few papers have been reported with quantification attempts on pyrolysis oil samples using GC×GC-TOFMS most of which make use of the

Chemical profile of pineapple cv. Vitória in different maturation stages using electrospray ionization mass spectrometry.

Science.gov (United States)

Ogawa, Elizângela M; Costa, Helber B; Ventura, José A; Caetano, Luiz Cs; Pinto, Fernanda E; Oliveira, Bruno G; Barroso, Maria Eduarda S; Scherer, Rodrigo; Endringer, Denise C; Romão, Wanderson

2018-02-01

Pineapple is the fruit of Ananas comosus var. comosus plant, being cultivated in tropical areas and has high energy content and nutritional value. Herein, 30 samples of pineapple cv. Vitória were analyzed as a function of the maturation stage (0-5) and their physico-chemical parameters monitored. In addition, negative-ion mode electrospray ionization mass spectrometry [ESI(-)FT-ICR MS] was used to identify and semi-quantify primary and secondary metabolites present in the crude and phenolic extracts of pineapple, respectively. Physico-chemical tests show an increase in the total soluble solids (TSS) values and in the TSS/total titratable acidity ratio as a function of the maturity stage, where a maximum value was observed in stage 3 (¾ of the fruit is yellow, which corresponds to the color of the fruit peel). ESI(-)FT-ICR MS analysis for crude extracts showed the presence mainly of sugars as primary metabolites present in deprotonated molecule form ([M - H] - and [2 M - H] - ions) whereas, for phenolic fractions, 11 compounds were detected, being the most abundant in the third stage of maturation. This behavior was confirmed by quantitative analysis of total polyphenols. ESI-FT-ICR MS was efficient in identifying primary (carbohydrates and organic acids) and secondary metabolites (13 phenolic compounds) presents in the crude and phenolic extract of the samples, respectively. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Principles and applications of a research-oriented gas chromatography-mass spectrometry data system

International Nuclear Information System (INIS)

Campana, J.E.; Risby, T.H.; Jurs, P.C.

1979-01-01

A research-oriented gas chromatography-mass spectrometry data system for a quadrupole mass spectrometer has been developed based on a centrally located departmental computer facility. An overview of the hardware and software system is presented, emphasizing the important aspects of on-line computer data acquisition and control and the design philosophy used in the development of the system. The application of the system is demonstrated by the g.c.-m.s. analysis of a mixture of four transition metal β-diketonates (Al, Cr, Rh, and Ru tris-1,1,1-trifluoro-pentane-2,4-dionate). This anaysis involved vacuum gas chromatography with a support-coated open tubular column and detection of the eluent by chemical ionization mass spectrometry. The results demonstrate the data system capabilities and indicate the utility of the combined methodologies. (Auth.)

Chemical profile of Taxodium distichum winter cones

Directory of Open Access Journals (Sweden)

Đapić Nina M.

2017-01-01

Full Text Available This work is concerned with the chemical profile of Taxodium distichum winter cones. The extract obtained after maceration in absolute ethanol was subjected to qualitative analysis by gas chromatography/mass spectrometry and quantification was done by gas chromatography/ flame ionization detector. The chromatogram revealed the presence of 53 compounds, of which 33 compounds were identified. The extract contained oxygenated monoterpenes (12.42%, sesquiterpenes (5.18%, oxygenated sesquiterpenes (17.41%, diterpenes (1.15%, and oxygenated diterpenes (30.87%, while the amount of retinoic acid was 0.32%. Monoacylglycerols were detected in the amount of 4.32%. The most abundant compounds were: caryophyllene oxide (14.27%, 6,7-dehydro-ferruginol (12.49%, bornyl acetate (10.96%, 6- deoxy-taxodione (9.50% and trans-caryophyllene (4.20%.

Simultaneous ionization and analysis of 84 anabolic androgenic steroids in human urine using liquid chromatography-silver ion coordination ionspray/triple-quadrupole mass spectrometry.

Science.gov (United States)

Kim, So-Hee; Cha, Eun-Ju; Lee, Kang Mi; Kim, Ho Jun; Kwon, Oh-Seung; Lee, Jaeick

2014-01-01

Metal ion coordination ionspray (M(+) CIS) ionization is a powerful technique to enhance ionization efficiency and sensitivity. In this study, we developed and validated an analytical method for simultaneous ionization and analysis of 84 anabolic androgenic steroids (65 exogenous and 19 endogenous) using liquid chromatography-silver ion coordination ionspray/triple-quadrupole mass spectrometry (LC-Ag(+) CIS/MS/MS). The concentrations of silver ions and organic solvents have been optimized to increase the amount of silver ion coordinated complexes. A combination of 25 μM of silver ions and methanol showed the best sensitivity. The validation results showed the intra- (0.8-9.2%) and inter-day (2.5-14.9%) precisions, limits of detection (0.0005-5.0 ng/mL), and matrix effect (71.8-100.3%) for the screening analysis. No significant ion suppression was observed. In addition, this method was successfully applied to analysis of positive samples from suspected abusers and useful for the detection of the trace levels of anabolic steroids in human urine samples. Copyright © 2014 John Wiley & Sons, Ltd.

Identification and Quantification of Flavonoids and Phenolic Acids in Burr Parsley (Caucalis platycarpos L., Using High-Performance Liquid Chromatography with Diode Array Detection and Electrospray Ionization Mass Spectrometry

Directory of Open Access Journals (Sweden)

Ana Mornar

2009-07-01

Full Text Available A sensitive method coupling high-performance liquid chromatography (HPLC with diode-array detector (DAD and electrospray ionization mass spectrometry (MS was optimized for the separation and identification of phenolic acids, flavonoid glycosides and flavonoid aglycones in the extract of burr parsley (Caucalis platycarpos L.. Fragmentation behavior of flavonoid glycosides and phenolic acids were investigated using ion trap mass spectrometry in negative electrospray ionization. The MS, MSn and UV data together with HPLC retention time (TR of phenolic acids and flavonoids allowed structural characterization of these compounds. Caffeoylquinic acid (CQA isomers, p-coumaroyl-quinic acids (p-CoQA, feruloylquinic acids (FQA, dicaffeoylquinic acids (diCQA, luteolin-7-O-rutinoside, apigenin-7-O-rutinoside as well as isolated chrysoeriol-7-O-rutinoside have been identified as constituents of C. platycarpos for the first time. An accurate, precise and sensitive LC-DAD method for quantification of four phenolic acids (3-O-caffeoylquinic, caffeic, p-coumaric, o-coumaric acid, four flavonoid glycosides (luteolin-7-O-glucoside, apigenin-7-O-glucoside, quercetin-3-O-galactoside, quercetin-3-O-rhamnoside, and three flavonoid aglycones (luteolin, apigenin, chrysoeriol in C. platycarpos extract was validated in terms of linearity, limit of detection, limit of quantification, precision and accuracy. 3-O-caffeoylquinic acid was the predominant phenolic acid and luteolin-7-O-glucoside was the predominant flavonoid glycoside.

Lipids and Fatty Acids in Algae: Extraction, Fractionation into Lipid Classes, and Analysis by Gas Chromatography Coupled with Flame Ionization Detector (GC-FID).

Science.gov (United States)

Guihéneuf, Freddy; Schmid, Matthias; Stengel, Dagmar B

2015-01-01

Despite the number of biochemical studies exploring algal lipids and fatty acid biosynthesis pathways and profiles, analytical methods used by phycologists for this purpose are often diverse and incompletely described. Potential confusion and potential variability of the results between studies can therefore occur due to change of protocols for lipid extraction and fractionation, as well as fatty acid methyl esters (FAME) preparation before gas chromatography (GC) analyses. Here, we describe a step-by-step procedure for the profiling of neutral and polar lipids using techniques such as solid-liquid extraction (SLE), thin-layer chromatography (TLC), and gas chromatography coupled with flame ionization detector (GC-FID). As an example, in this protocol chapter, analyses of neutral and polar lipids from the marine microalga Pavlova lutheri (an EPA/DHA-rich haptophyte) will be outlined to describe the distribution of fatty acid residues within its major lipid classes. This method has been proven to be a reliable technique to assess changes in lipid and fatty acid profiles in several other microalgal species and seaweeds.

Photochemistry of limonene secondary organic aerosol studied with chemical ionization mass spectrometry

Science.gov (United States)

Pan, Xiang

Limonene is one of the most abundant monoterpenes in the atmosphere. Limonene easily reacts with gas-phase oxidants in air such as NO3, ozone and OH. Secondary organic aerosol (SOA) is formed when low vapor pressure products condense into particles. Chemicals in SOA particles can undergo further reactions with oxidants and with solar radiation that significantly change SOA composition over the course of several days. The goal of this work was to characterize radiation induced reaction in SOA. To perform experiments, we have designed and constructed an Atmospheric Pressure Chemical Ionization Mass Spectrometer (APCIMS) coupled to a photochemical cell containing SOA samples. In APCIMS, (H2O)nH 3O+ clusters are generated in a 63Ni source and react with gaseous organic analytes. Most organic chemicals are not fragmented by the ionization process. We have focused our attention on limonene SOA prepared in two different ways. The first type of SOA is produced by oxidation of limonene by ozone; and the second type of SOA is formed by the NO3-induced oxidation of limonene. They model the SOA formed under daytime and nighttime conditions, respectively. Ozone initiated oxidation is the most important chemical sink for limonene both indoors, where it is used for cleaning purposes, and outdoors. Terpenes are primarily oxidized by reactions with NO3 at night time. We generated limonene SOA under different ozone and limonene concentrations. The resulting SOA samples were exposed to wavelength-tunable radiation in the UV-Visible range between 270 nm and 630 nm. The results show that the photodegradation rates strongly depend on radiation wavelengths. Gas phase photodegradation products such as acetone, formaldehyde, acetaldehyde, and acetic acid were shown to have different production rates for SOA formed in different concentration conditions. Even for SOA prepared under the lowest concentrations, the SOA photodegradation was efficient. The conclusion is that exposure of SOA to

Influence of soil pH on the sorption of ionizable chemicals: modeling advances.

Science.gov (United States)

Franco, Antonio; Fu, Wenjing; Trapp, Stefan

2009-03-01

The soil-water distribution coefficient of ionizable chemicals (K(d)) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K(d) values normalized to organic carbon (K(OC)) from the literature, a method was developed to estimate the K(OC) of monovalent organic acids and bases. The regression considers pH-dependent speciation and species-specific partition coefficients, calculated from the dissociation constant (pK(a)) and the octanol-water partition coefficient of the neutral molecule (log P(n)). Probably because of the lower pH near the organic colloid-water interface, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of pH on the total sorption is contrasting. In fact, the shortcomings of the model assumptions affect the predictive power for acids and for bases differently. We evaluated accuracy and limitations of the regressions for their use in the environmental fate assessment of ionizable chemicals.

Integration of On-Column Chemical Reactions in Protein Characterization by Liquid Chromatography/Mass Spectrometry: Cross-Path Reactive Chromatography.

Science.gov (United States)

Pawlowski, Jake W; Carrick, Ian; Kaltashov, Igor A

2018-01-16

Profiling of complex proteins by means of mass spectrometry (MS) frequently requires that certain chemical modifications of their covalent structure (e.g., reduction of disulfide bonds), be carried out prior to the MS or MS/MS analysis. Traditionally, these chemical reactions take place in the off-line mode to allow the excess reagents (the majority of which interfere with the MS measurements and degrade the analytical signal) to be removed from the protein solution prior to MS measurements. In addition to a significant increase in the analysis time, chemical reactions may result in a partial or full loss of the protein if the modifications adversely affect its stability, e.g,, making it prone to aggregation. In this work we present a new approach to solving this problem by carrying out the chemical reactions online using the reactive chromatography scheme on a size exclusion chromatography (SEC) platform with MS detection. This is achieved by using a cross-path reaction scheme, i.e., by delaying the protein injection onto the SEC column (with respect to the injection of the reagent plug containing a disulfide-reducing agent), which allows the chemical reactions to be carried out inside the column for a limited (and precisely controlled) period of time, while the two plugs overlap inside the column. The reduced protein elutes separately from the unconsumed reagents, allowing the signal suppression in ESI to be avoided and enabling sensitive MS detection. The new method is used to measure fucosylation levels of a plasma protein haptoglobin at the whole protein level following online reduction of disulfide-linked tetrameric species to monomeric units. The feasibility of top-down fragmentation of disulfide-containing proteins is also demonstrated using β 2 -microglobulin and a monoclonal antibody (mAb). The new online technique is both robust and versatile, as the cross-path scheme can be readily expanded to include multiple reactions in a single experiment (as

Atmospheric Pressure Chemical Ionization Sources Used in The Detection of Explosives by Ion Mobility Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Waltman, Melanie J. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

2010-05-01

Explosives detection is a necessary and wide spread field of research. From large shipping containers to airline luggage, numerous items are tested for explosives every day. In the area of trace explosives detection, ion mobility spectrometry (IMS) is the technique employed most often because it is a quick, simple, and accurate way to test many items in a short amount of time. Detection by IMS is based on the difference in drift times of product ions through the drift region of an IMS instrument. The product ions are created when the explosive compounds, introduced to the instrument, are chemically ionized through interactions with the reactant ions. The identity of the reactant ions determines the outcomes of the ionization process. This research investigated the reactant ions created by various ionization sources and looked into ways to manipulate the chemistry occurring in the sources.

Ionization in matrix-assisted laser desorption/ionization: singly charged molecular ions are the lucky survivors.

Science.gov (United States)

Karas, M; Glückmann, M; Schäfer, J

2000-01-01

A new model for the ionization processes in UV matrix-assisted laser desorption/ionization (MALDI) which accounts for the major phenomena observed is presented and discussed. The model retains elements of earlier approaches, such as photoionization and photochemical reactions, but it redefines these in the light of new working questions, most importantly why only singly charged ions are detected. Based on experimental evidence, the formation of singly and multiply charged clusters by a deficiency/excess of ions and also by photoionization and subsequent photochemical processes is pointed out to be the major ionization processes, which typically occur in parallel. The generation of electrons and their partial loss into the surrounding vacuum and solid, on the one hand, results in a positively charged ion-neutral plume facilitating a high overall ionization yield. On the other hand, these electrons, and also the large excess of protonated matrix ions in the negative ion mode, induce effective ion reneutralization in the plume. These neutralization processes are most effective for the highly charged cluster ions initially formed. Their fragmentation behaviour is evidenced in fast metastable fragmentation characteristics and agrees well with an electron capture dissociation mechanism and the enthalpy transfer upon neutralization forms the rationale for the prominent fragmentation and intense chemical noise accompanying successful MALDI. Within the course of the paper, cross-correlations with other desorption/ionization techniques and with earlier discussions on their mechanisms are drawn. Copyright 2000 John Wiley & Sons, Ltd.

Analysis of pollutants in air and water using gas chromatography and headspace gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Stenner, H.

1980-01-01

The combination 'personal sampling' with headspace gas chromatography to determine traces of formaldehyde, phenol and benzene in air is investigated in this work, with the aim of developing maximum workplace concentration values (MWL values). Further possible applications of gas chromatography in trace analysis in the environmentally protected area. The analysis of chromium in waste waters (Cr III as acetyl acetonate complex) is investigated as further possible application, whereby optimum conditions are obtained. A modified flame ionization detector was used to increase the detection sensitivity.

Characterization and identification of iridoid glucosides, flavonoids and anthraquinones in Hedyotis diffusa by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Liu, E-Hu; Zhou, Ting; Li, Guo-Bin; Li, Jing; Huang, Xiu-Ning; Pan, Feng; Gao, Ning

2012-01-01

The multiple bioactive constituents in Hedyotis diffusa Willd. (H. diffusa) were extracted and characterized by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS(n)). The optimized separation condition was obtained using an Agilent ZorBax SB-C18 column (4.6×150 mm, 5 μm) and gradient elution with water (containing 0.1% formic acid) and acetonitrile (containing 0.1% formic acid), under which baseline separation for the majority of compounds was achieved. Among the compounds detected, 14 iridoid glucosides, 10 flavonoids, 7 anthraquinones, 1 coumarin and 1 triterpene were unambiguously identified or tentatively characterized based on their retention times and mass spectra in comparison with the data from standards or references. The fragmentation behavior for different types of constituents was also investigated, which could contribute to the elucidation of these constituents in H. diffusa. The present study reveals that even more iridoid glycosides were found in H. diffusa than hitherto assumed. The occurrence of two iridoid glucosides and five flavonoids in particular has not yet been described. This paper marks the first report on the structural characterization of chemical compounds in H. diffusa by a developed HPLC-ESI-MS(n) method. Copyright © 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrophilic interaction chromatography coupled matrix assisted laser desorption/ionization mass spectrometry for molecular analysis of organic compounds in medicines, tea, and coffee.

Science.gov (United States)

Wang, Ren-Qi; Bao, Kai; Croué, Jean-Philippe; Ng, Siu Choon

2013-11-21

Natural occurring organic compounds from food, natural organic matter, as well as metabolic products have received intense attention in current chemical and biological studies. Examination of unknown compounds in complex sample matrices is hampered by the limited choices for data readout and molecular elucidation. Herein, we report a generic method of hydrophilic interaction chromatography (HILIC) coupled with matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the rapid characterization of ingredients in pharmaceutical compounds, tea, and coffee. The analytes were first fractionated using a cationic HILIC column prior to MALDI-MS analyses. It was found that the retention times of a compound arising from different samples were consistent under the same conditions. Accordingly, molecules can be readily characterized by both the mass and chromatographic retention time. The retention behaviors of acidic and basic compounds on the cationic HILIC column were found to be significantly influenced by the pH of mobile phases, whereas neutral compounds depicted a constant retention time at different pH. The general HILIC-MALDI-MS method is feasible for fast screening of naturally occurring organic compounds. A series of homologs can be determined if they have the same retention behavior. Their structural features can be elucidated by considering their mass differences and hydrophilic properties as determined by HILIC chromatogram.

The coupling of supercritical fluid chromatography and field ionization time-of-flight high-resolution mass spectrometry for rapid and quantitative analysis of petroleum middle distillates.

Science.gov (United States)

Qian, Kuangnan; Diehl, John W; Dechert, Gary J; DiSanzo, Frank P

2004-01-01

We report the first coupling of supercritical fluid chromatography (SFC) with field ionization time-of-flight high-resolution mass spectrometry (FI-ToF HRMS), in parallel with ultraviolet (UV) detection and flame ionization detection (FID), for rapid and quantitative analysis of petroleum middle distillates. SFC separates petroleum middle distillates into saturates and 1- to 3-ring aromatics. FI generates molecular ions for hydrocarbon species eluted from the SFC. The high resolution and exact mass measurements by ToF mass spectrometry provide elemental compositions of the molecules in the petroleum product. The amounts of saturates and aromatic ring types were quantified using the parallel SFC-FID assisted by SFC-UV. With a proper carbon-number calibration, the detailed composition of the petroleum middle distillate was rapidly determined.

A fast and sensitive method for the separation of carotenoids using ultra-high performance supercritical fluid chromatography-mass spectrometry.

Science.gov (United States)

Jumaah, Firas; Plaza, Merichel; Abrahamsson, Victor; Turner, Charlotta; Sandahl, Margareta

2016-08-01

In this study, a rapid and sensitive ultra-high performance supercritical fluid chromatography-mass spectrometry (UHPSFC-MS) method has been developed and partially validated for the separation of carotenoids within less than 6 min. Six columns of orthogonal selectivity were examined, and the best separation was obtained by using a 1-aminoanthracene (1-AA) column. The length of polyene chain as well as the number of hydroxyl groups in the structure of the studied carotenoids determines their differences in the physiochemical properties and thus the separation that is achieved on this column. All of the investigated carotenoids were baseline separated with resolution values greater than 1.5. The effects of gradient program, back pressure, and column temperature were studied with respect to chromatographic properties such as retention and selectivity. Electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) were compared in both positive and negative mode, using both direct infusion and hyphenated with UHPSFC. The ESI in positive mode provided the highest response. The coefficient of determination (R (2)) for all calibration curves were greater than 0.998. Limit of detection (LOD) was in the range of 2.6 and 25.2 ng/mL for α-carotene and astaxanthin, respectively, whereas limit of quantification (LOQ) was in the range of 7.8 and 58.0 ng/mL for α-carotene and astaxanthin, respectively. Repeatability and intermediate precision of the developed UHPSFC-MS method were determined and found to be RSD supercritical fluid extracts of microalgae and rosehip. Graphical Abstract Ultra-high performance supercritical fluid chromatography-a rapid separation method for the analysis of carotenoids in rosehip and microalgae samples.

Fatty acid composition and its association with chemical and sensory analysis of boar taint.

Science.gov (United States)

Liu, Xiaoye; Trautmann, Johanna; Wigger, Ruth; Zhou, Guanghong; Mörlein, Daniel

2017-09-15

A certain level of disagreement between the chemical analysis of androstenone and skatole and the human perception of boar taint has been found in many studies. Here we analyze whether the fatty acid composition can explain such inconsistency between sensory evaluation and chemical analysis of boar taint compounds. Therefore, back fat samples (n=143) were selected according to their sensory evaluation by a 10-person sensory panel, and the chemical analysis (stable isotope dilution analysis with headspace solid-phase microextraction and gas chromatography-mass spectrometry) of androstenone and skatole. Subsequently a quantification of fatty acids using gas chromatography-flame ionization detection was conducted. The correlation analyses revealed that several fatty acids are significantly correlated with androstenone, skatole, and the sensory rating. However, multivariate analyses (principal component analysis) revealed no explanation of the fatty acid composition with respect to the (dis-)agreement between sensory and chemical analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cooperative biological effects between ionizing radiation and other physical and chemical agents.

Science.gov (United States)

Manti, Lorenzo; D'Arco, Annalisa

2010-01-01

Exposure to ionizing radiation (IR), at environmentally and therapeutically relevant doses or as a result of diagnostics or accidents, causes cyto- and genotoxic damage. However, exposure to IR alone is a rare event as it occurs in spatial and temporal combination with several physico-chemical agents. Some of these are of known noxiousness, as is the case with chemical compounds at high dose, hence additive/synergistic effects can be expected or have been demonstrated. Conversely, the cellular toxicity of other agents, such as non-ionizing electromagnetic fields (EMFs), is only presumed and their short- and long-term cooperation on IR-induced damage remains undetermined. In this review, we shall examine evidence in support of the interplay between spatially and/or temporally related environmentally relevant stressors. In vitro or animal-based studies as well as epidemiological surveys have generally examined the combined action of no more than a couple of known or potentially DNA-damaging agents. Moreover, most existing research mainly focused on short-term effects of combined exposures. Hence, it is important that quantitative research addresses the issue of the possible cooperation between chronic exposure to environmental trace contaminants and exposure to EMFs, examining not only the modulation of damage acutely induced by IR but also long-term genome stability. 2010 Elsevier B.V. All rights reserved.

Photoionization effects in ionization fronts

International Nuclear Information System (INIS)

Arrayas, Manuel; Fontelos, Marco A; Trueba, Jose L

2006-01-01

In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work

Photoionization effects in ionization fronts

Energy Technology Data Exchange (ETDEWEB)

Arrayas, Manuel [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Fontelos, Marco A [Departamento de Matematicas, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones CientIficas, C/Serrano 123, 28006 Madrid (Spain); Trueba, Jose L [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)

2006-12-21

In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work.

Fine structure and ionization energy of the 1s2s2p 4P state of the helium negative ion He-.

Science.gov (United States)

Wang, Liming; Li, Chun; Yan, Zong-Chao; Drake, G W F

2014-12-31

The fine structure and ionization energy of the 1s2s2p (4)P state of the helium negative ion He(-) are calculated in Hylleraas coordinates, including relativistic and QED corrections up to O(α(4)mc(2)), O((μ/M)α(4)mc(2)), O(α(5)mc(2)), and O((μ/M)α(5)mc(2)). Higher order corrections are estimated for the ionization energy. A comparison is made with other calculations and experiments. We find that the present results for the fine structure splittings agree with experiment very well. However, the calculated ionization energy deviates from the experimental result by about 1 standard deviation. The estimated theoretical uncertainty in the ionization energy is much less than the experimental accuracy.

Biological Effects of Ionizing Radiation

Science.gov (United States)

Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

1952-04-07

This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

Ambient ionization mass spectrometry: A tutorial

Energy Technology Data Exchange (ETDEWEB)

Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

2011-09-19

Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

Ambient ionization mass spectrometry: A tutorial

International Nuclear Information System (INIS)

Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu; Shiea, Jentaie

2011-01-01

Highlights: → Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. → We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. → The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

Improving washing strategies of human mesenchymal stem cells using negative mode expanded bed chromatography.

Science.gov (United States)

Cunha, Bárbara; Silva, Ricardo J S; Aguiar, Tiago; Serra, Margarida; Daicic, John; Maloisel, Jean-Luc; Clachan, John; Åkerblom, Anna; Carrondo, Manuel J T; Peixoto, Cristina; Alves, Paula M

2016-01-15

The use of human mesenchymal stem cells (hMSC) in clinical applications has been increasing over the last decade. However, to be applied in a clinical setting hMSC need to comply with specific requirements in terms of identity, potency and purity. This study reports the improvement of established tangential flow filtration (TFF)-based washing strategies, further increasing hMSC purity, using negative mode expanded bed adsorption (EBA) chromatography with a new multimodal prototype matrix based on core-shell bead technology. The matrix was characterized and a stable, expanded bed could be obtained using standard equipment adapted from what is used for conventional packed bed chromatography processes. The effect of different expansion rates on cell recovery yield and protein removal capacity was assessed. The best trade-off between cell recovery (89%) and protein clearance (67%) was achieved using an intermediate expansion bed rate (1.4). Furthermore, we also showed that EBA chromatography can be efficiently integrated on the already established process for the downstream processing (DSP) of hMSC, where it improved the washing efficiency more than 10-fold, recovering approximately 70% of cells after global processing. This strategy showed not to impact cell viability (>95%), neither hMSC's characteristics in terms of morphology, immunophenotype, proliferation, adhesion capacity and multipotent differentiation potential. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of water-soluble vitamins in selected food matrices by liquid chromatography/electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Gentili, Alessandra; Caretti, Fulvia; D'Ascenzo, Giuseppe; Marchese, Stefano; Perret, Daniela; Di Corcia, Daniele; Rocca, Lucia Mainero

2008-07-01

A rapid, simple and sensitive method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) with an electrospray ionization (ESI) source for the simultaneous analysis of fourteen water-soluble vitamins (B1, B2, two B3 vitamers, B5, five B6 vitamers, B8, B9, B12 and C) in various food matrices, i.e. maize flour, green and golden kiwi and tomato pulp, is presented here. Analytes were separated by ion-suppression reversed-phase liquid chromatography in less than 10 min and detected in positive ion mode. Sensitivity and specificity of this method allowed two important results to be achieved: (i) limits of detection of the analytes at ng g(-1) levels (except for vitamin C); (ii) development of a rapid sample treatment that minimizes analyte exposition to light, air and heat, eliminating any step of extract concentration. Analyte recovery depended on the type of matrix. In particular, recovery of the analytes in maize flour was > or =70%, with the exception of vitamin C, pyridoxal-5'-phosphate and vitamin B9 (ca 40%); with tomato pulp, recovery was > or =64%, except for vitamin C (41%); with kiwi, recovery was > or =73%, except for nicotinamide (ca. 30%).

A Comparison of Tissue Spray and Lipid Extract Direct Injection Electrospray Ionization Mass Spectrometry for the Differentiation of Eutopic and Ectopic Endometrial Tissues

Science.gov (United States)

Chagovets, Vitaliy; Wang, Zhihao; Kononikhin, Alexey; Starodubtseva, Natalia; Borisova, Anna; Salimova, Dinara; Popov, Igor; Kozachenko, Andrey; Chingin, Konstantin; Chen, Huanwen; Frankevich, Vladimir; Adamyan, Leila; Sukhikh, Gennady

2018-02-01

Recent research revealed that tissue spray mass spectrometry enables rapid molecular profiling of biological tissues, which is of great importance for the search of disease biomarkers as well as for online surgery control. However, the payback for the high speed of analysis in tissue spray analysis is the generally lower chemical sensitivity compared with the traditional approach based on the offline chemical extraction and electrospray ionization mass spectrometry detection. In this study, high resolution mass spectrometry analysis of endometrium tissues of different localizations obtained using direct tissue spray mass spectrometry in positive ion mode is compared with the results of electrospray ionization analysis of lipid extracts. Identified features in both cases belong to three lipid classes: phosphatidylcholines, phosphoethanolamines, and sphingomyelins. Lipids coverage is validated by hydrophilic interaction liquid chromatography with mass spectrometry of lipid extracts. Multivariate analysis of data from both methods reveals satisfactory differentiation of eutopic and ectopic endometrium tissues. Overall, our results indicate that the chemical information provided by tissue spray ionization is sufficient to allow differentiation of endometrial tissues by localization with similar reliability but higher speed than in the traditional approach relying on offline extraction.

Validation of a qualitative screening method for pesticides in fruits and vegetables by gas chromatography quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization

Energy Technology Data Exchange (ETDEWEB)

Portolés, T. [Research Institute for Pesticides and Water, University Jaume I, 12071 Castellón (Spain); RIKILT Institute of Food Safety, Wageningen University and Research Centre, Akkermaalsbos 2, 6708 WB Wageningen (Netherlands); Mol, J.G.J. [RIKILT Institute of Food Safety, Wageningen University and Research Centre, Akkermaalsbos 2, 6708 WB Wageningen (Netherlands); Sancho, J.V.; López, Francisco J. [Research Institute for Pesticides and Water, University Jaume I, 12071 Castellón (Spain); Hernández, F., E-mail: hernandf@uji.es [Research Institute for Pesticides and Water, University Jaume I, 12071 Castellón (Spain)

2014-08-01

Highlights: • Applicability of GC-(APCI)QTOF MS as new tool for wide-scope screening of pesticides in fruits and vegetables demonstrated. • Validation of screening method according to SANCO/12571/2013. • Detection of the pesticides based on the presence of M+·/MH+ in most cases. • Screening detection limit 0.01 mg kg{sup −1} for 77% of the pesticides investigated. • Successful identification at 0.01 mg kg{sup −1} for 70% of the pesticides/matrix combinations. - Abstract: A wide-scope screening method was developed for the detection of pesticides in fruit and vegetables. The method was based on gas chromatography coupled to a hybrid quadrupole time-of-flight mass spectrometer with an atmospheric pressure chemical ionization source (GC-(APCI)QTOF MS). A non-target acquisition was performed through two alternating scan events: one at low collision energy and another at a higher collision energy ramp (MS{sup E}). In this way, both protonated molecule and/or molecular ion together with fragment ions were obtained in a single run. Validation was performed according to SANCO/12571/2013 by analysing 20 samples (10 different commodities in duplicate), fortified with a test set of 132 pesticides at 0.01, 0.05 and 0.20 mg kg{sup −1}. For screening, the detection was based on one diagnostic ion (in most cases the protonated molecule). Overall, at the 0.01 mg kg{sup −1} level, 89% of the 2620 fortifications made were detected. The screening detection limit for individual pesticides was 0.01 mg kg{sup −1} for 77% of the pesticides investigated. The possibilities for identification according to the SANCO criteria, requiring two ions with a mass accuracy ≤±5 ppm and an ion-ratio deviation ≤±30%, were investigated. At the 0.01 mg kg{sup −1} level, identification was possible for 70% of the pesticides detected during screening. This increased to 87% and 93% at the 0.05 and 0.20 mg kg{sup −1} level, respectively. Insufficient sensitivity for the second

Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry of polychlorinated biphenyls

International Nuclear Information System (INIS)

Matsui, Taiki; Uchimura, Tomohiro; Imasaka, Totaro

2011-01-01

A sample mixture of polychlorinated biphenyls (PCBs) was measured by gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) using four types of laser sources. When a fourth harmonic emission (266 nm) of a picosecond Nd:YAG laser (1064 nm) was utilized, highly chlorinated PCBs larger than hepta-CBs were not observed. A fifth harmonic emission (213 nm) of the picosecond Nd:YAG laser allowed the measurement of PCBs from di-CBs to octa-CBs, and the limit of detection (LOD) was several pg for each component of PCBs. The LOD for the total amount of PCBs, which was calculated using the protocol provided by the Ministry of the Environment, Japan, was 1000 pg. The signal intensity of the congeners with chlorine atoms at the ortho positions (non-coplanar PCBs) was enhanced by using the fifth harmonic emission. When the fourth harmonic emission remaining after fifth harmonic generation was simultaneously used, the LOD for total PCBs was improved to 667 pg. The PCB sample was also measured using a third harmonic emission (267 nm) of a femtosecond Ti:sapphire laser (800 nm), providing an LOD of 677 pg. Thus, the two-color beam (266/213 nm) of a picosecond Nd:YAG laser had a comparable, or even slightly superior, performance to the more expensive femtosecond Ti:sapphire laser.

Dispersive liquid-liquid microextraction for the determination of vitamins D and K in foods by liquid chromatography with diode-array and atmospheric pressure chemical ionization-mass spectrometry detection.

Science.gov (United States)

Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Hernández-Córdoba, Manuel

2013-10-15

A simple and rapid method was developed using reversed-phase liquid chromatography (LC) with both diode array (DAD) and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of the vitamins ergocalciferol (D2), cholecalciferol (D3), phylloquinone (K1), menaquinone-4 (K2) and a synthetic form of vitamin K, menadione (K3). The Taguchi experimental method, an orthogonal array design (OAD), was used to optimize an efficient and clean preconcentration step based on dispersive liquid-liquid microextraction (DLLME). A factorial design was applied with six factors and three levels for each factor, namely, carbon tetrachloride volume, methanol volume, aqueous sample volume, pH of sample, sodium chloride concentration and time of the centrifugation step. The DLLME optimized procedure consisted of rapidly injecting 3 mL of acetonitrile (disperser solvent) containing 150 µL carbon tetrachloride (extraction solvent) into the aqueous sample, thereby forming a cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was evaporated with nitrogen, reconstituted with 50 µL of acetonitrile, and injected. The LC analyses were carried out using a mobile phase composed of acetonitrile, 2-propanol and water, under gradient elution. Quantification was carried out by the standard additions method. The APCI-MS spectra, in combination with UV spectra, permitted the correct identification of compounds in the food samples. The method was validated according to international guidelines and using a certified reference material. The validated method was applied for the analysis of vitamins D and K in infant foods and several green vegetables. There was little variability in the forms of vitamin K present in vegetables, with the most abundant vitamer in all the samples being phylloquinone, while menadione could not be detected. Conversely, cholecalciferol, which is present in food of animal origin, was

Induction of somatic mutations in ornamental plants by ionizing radiations and chemical mutagens

International Nuclear Information System (INIS)

Desai, B.M.; Abraham, V.

1980-01-01

Improvement in some ornamental plants through induction of somatic mutations by ionizing radiations and chemical mutagens viz. colchicine, EMS and DS has been attempted. Mutants of high ornamental value have been evolved, isolated and multiplied in canna, perennial portulaca, tuberose, bougainvillea, hibiscus, daisy, lilies. These pertain to changes in colour, shape and size of flower and foliage. Procedural details on induction, isolation, stabilisation of the mutants and description of the new characteristics are presented. (author)

High molecular weight non-polar hydrocarbons as pure model substances and in motor oil samples can be ionized without fragmentation by atmospheric pressure chemical ionization mass spectrometry.

Science.gov (United States)

Hourani, Nadim; Kuhnert, Nikolai

2012-10-15

High molecular weight non-polar hydrocarbons are still difficult to detect by mass spectrometry. Although several studies have targeted this problem, lack of good self-ionization has limited the ability of mass spectrometry to examine these hydrocarbons. Failure to control ion generation in the atmospheric pressure chemical ionization (APCI) source hampers the detection of intact stable gas-phase ions of non-polar hydrocarbon in mass spectrometry. Seventeen non-volatile non-polar hydrocarbons, reported to be difficult to ionize, were examined by an optimized APCI methodology using nitrogen as the reagent gas. All these analytes were successfully ionized as abundant and intact stable [M-H](+) ions without the use of any derivatization or adduct chemistry and without significant fragmentation. Application of the method to real-life hydrocarbon mixtures like light shredder waste and car motor oil was demonstrated. Despite numerous reports to the contrary, it is possible to ionize high molecular weight non-polar hydrocarbons by APCI, omitting the use of additives. This finding represents a significant step towards extending the applicability of mass spectrometry to non-polar hydrocarbon analyses in crude oil, petrochemical products, waste or food. Copyright © 2012 John Wiley & Sons, Ltd.

Quantum effects on the formation of negative hydrogen ion by polarization electron capture in partially ionized dense hydrogen plasmas

International Nuclear Information System (INIS)

Jung, Young-Dae; Kato, Daiji

2009-05-01

The quantum effects on the formation of the negative hydrogen ion (H - ) by the polarization electron capture process are investigated in partially ionized dense hydrogen plasmas. It is shown that the quantum effect strongly suppresses the electron capture radius as well as the cross section for the formation of the negative hydrogen ion. In addition, it has been found that the electron capture position is receded from the center of the projectile with decreasing the quantum effect of the plasma. (author)

A comprehensive high-resolution mass spectrometry approach for characterization of metabolites by combination of ambient ionization, chromatography and imaging methods.

Science.gov (United States)

Berisha, Arton; Dold, Sebastian; Guenther, Sabine; Desbenoit, Nicolas; Takats, Zoltan; Spengler, Bernhard; Römpp, Andreas

2014-08-30

An ideal method for bioanalytical applications would deliver spatially resolved quantitative information in real time and without sample preparation. In reality these requirements can typically not be met by a single analytical technique. Therefore, we combine different mass spectrometry approaches: chromatographic separation, ambient ionization and imaging techniques, in order to obtain comprehensive information about metabolites in complex biological samples. Samples were analyzed by laser desorption followed by electrospray ionization (LD-ESI) as an ambient ionization technique, by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging for spatial distribution analysis and by high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) for quantitation and validation of compound identification. All MS data were acquired with high mass resolution and accurate mass (using orbital trapping and ion cyclotron resonance mass spectrometers). Grape berries were analyzed and evaluated in detail, whereas wheat seeds and mouse brain tissue were analyzed in proof-of-concept experiments. In situ measurements by LD-ESI without any sample preparation allowed for fast screening of plant metabolites on the grape surface. MALDI imaging of grape cross sections at 20 µm pixel size revealed the detailed distribution of metabolites which were in accordance with their biological function. HPLC/ESI-MS was used to quantify 13 anthocyanin species as well as to separate and identify isomeric compounds. A total of 41 metabolites (amino acids, carbohydrates, anthocyanins) were identified with all three approaches. Mass accuracy for all MS measurements was better than 2 ppm (root mean square error). The combined approach provides fast screening capabilities, spatial distribution information and the possibility to quantify metabolites. Accurate mass measurements proved to be critical in order to reliably combine data from different MS

Odor and odorous chemical emissions from dairy and swine facilities: Part 5-Simultaneous chemical and sensory analysis with Gas Chromatography - Mass Spectrometry - Olfactometry

Science.gov (United States)

Simultaneous chemical and sensory analyses using gas chromatography-mass spectrometry-olfactometry (GC-MS-O) for air samples collected at barn exhaust fans were used for quantification and ranking of odor impact of target odorous gases. Fifteen target odorous VOCs (odorants) were selected. Air sampl...

Ionization effects in electronic inner-shells of ionized atoms

International Nuclear Information System (INIS)

Shchornak, G.

1983-01-01

A review of the atomic physics of ionization atoms has been presented. Interaction and structure effects in atomic shells, correlated to the occurrence of vacancies in several subshells of the atom have been considered. The methods of calculations of atomic states and wave functions have been reviewed. The energy shift of characteristic X-rays is discussed as a function of the ionization stage of the atom. The influence of inner and outer-shell vacancies on the energy of the X-rays is shown in detail. The influence of chemical effects on the parameters of X-rays is also taken into account. Further on, the change of transition probabilities in radiative and non-radiative transitions by changing stage of ionization is discussed; and among them the leading part of Auger and Coster-Kronig transitions by the arearrangement of the atomic states is shown. The influence of non-radiative electronic transitions on ionization cross-sections for multiple ionization is discussed. Using these results, ionization cross-sections for direct and indirect processes for several ionization stages are given

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.

GoAmazon 2014/15 Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) Field Campaign Report

Energy Technology Data Exchange (ETDEWEB)

Smith, JN [Univ. of California, Irvine, CA (United States)

2016-04-01

The Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) deployment to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility T3 site in Manacapuru, Brazil, was motivated by two main scientific objectives of the Green Ocean Amazon (GoAmazon) 2014/15 field campaign. 1) Study the interactions between anthropogenic and biogenic emissions by determining important molecular species in ambient nanoparticles. To address this, TDCIMS data will be combined with coincident measurements such as gas-phase sulfuric acid to determine the contribution of sulfuric acid condensation to nucleation and growth. We can then compare that result to TDCIMS-derived nanoparticle composition to determine the fraction of growth that can be attributed to the uptake of organic compounds. The molecular composition of sampled particles will also be used to attribute specific chemical species and mechanisms to growth, such as the condensation of low-volatility species or the oligomerization of α-dicarbonyl compounds. 2) Determine the source of new ambient nanoparticles in the Amazon. The hypothesis prior to measurements was that potassium salts formed from the evaporation of primary particles emitted by fungal spores can provide a unique and important pathway for new particle production in the Amazon basin. To explore this hypothesis, the TDCIMS recorded the mass spectra of sampled ambient particles using a protonated water cluster Chemical Ionization Mass Spectrometer (CIMS). Laboratory tests performed using potassium salts show that the TDCIMS can detect potassium with high sensitivity with this technique.

Modelling the Fate of Ionizable Trace Organic Chemicals from Consumption to Food Crops

DEFF Research Database (Denmark)

Polesel, Fabio; Plósz, Benedek G.; Trapp, Stefan

In this study, we developed and applied a simulation tool to comprehensively predict the fate of three ionizable trace chemicals (triclosan—TCS, furosemide—FUR, ciprofloxacin—CIP) from human consumption/excretion up to the accumulation in wheat, following application of sewage sludge or irrigation...... with river water. Highest translocation to wheat (4.3 μg kgDW-1 in grain) was calculated for FUR, being more significant with irrigation (>45% of emission to soil) than with sludge application (

Comparative experimental study of cancer induced by ionizing radiations or by chemical carcinogens

International Nuclear Information System (INIS)

Lafuma, J.

1983-01-01

Animal experiments have contributed to specify a number of parameters used in setting human safety limits for ionizing radiation. In the same way, comparisons have been made between cancers induced in man and in animals in well-defined conditions. In order to use the same experimental data for chemical carcinogens, the mechanisms of carcinogenesis should be the same, i.e. additivity of responses instead of synergy of effects, which requires the development of a new experimental method [fr

Analysis of benzene, toluene, ethylbenzene and xylenes in soils by headspace and gas chromatography/flame ionization detector

Directory of Open Access Journals (Sweden)

Jurandir Pereira Pinto

2006-02-01

Full Text Available The constituents of gasoline: benzene, toluene, ethylbenzene and xylenes (BTEX are frequently found in soils due to leaks in fuel storage tanks and they present chronic toxicity. In this work it was developed and validated a methodology of BTEX analysis in soil by gas chromatography/ flame ionization detector and static headspace. The recovery of BTEX in soil samples was evaluated using soils with different textures (sandy and loamy. The analysis method showed good resolution, in a low time of analysis (less than 30 minutes. Limits of quantification of 0.05 mg Kg¯¹ soil for benzene, toluene, ethylbenzene and xylenes are below the guiding values that range from 0.15 to 95 mg Kg¯¹ soil, established to determine soil quality. It was verified that the methodology enables the use of this method for BTEX analysis of soil samples for passive environmental identification of gas stations.

Evaluation of the capabilities of atmospheric pressure chemical ionization source coupled to tandem mass spectrometry for the determination of dioxin-like polychlorobiphenyls in complex-matrix food samples.

Science.gov (United States)

Portolés, T; Sales, C; Abalos, M; Sauló, J; Abad, E

2016-09-21

The use of the novel atmospheric pressure chemical ionization (APCI) source for gas chromatography (GC) coupled to triple quadrupole using tandem mass spectrometry (MS/MS) and its potential for the simultaneous determination of the 12 dioxin-like polychlorobiphenyls (DL-PCBs) in complex food and feed matrices has been evaluated. In first place, ionization and fragmentation behavior of DL-PCBs on the APCI source under charge transfer conditions has been studied followed by their fragmentation in the collision cell. Linearity, repeatability and sensitivity have been studied obtaining instrumental limits of detection and quantification of 0.0025 and 0.005 pg μL(-1) (2.5 and 5 fg on column) respectively for every DL-PCB. Finally, application to real samples has been carried out and DL-PCB congeners (PCB 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189) have been detected in the different samples in the range of 0.40-10000 pg g(-1). GC-(APCI)MS/MS has been proved as a suitable alternative to the traditionally accepted confirmation method based on the use of high resolution mass spectrometry and other triple quadrupole tandem mass spectrometry techniques operating with electron ionization. The development of MS/MS methodologies for the analysis of dioxins and DL-PCBs is nowadays particularly important, since this technique was included as a confirmatory method in the present European Union regulations that establish the requirements for the determination of these compounds in food and feed matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrapressure liquid chromatography-tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for quantification of 4-methoxydiphenylmethane in pharmacokinetic evaluation.

Science.gov (United States)

Farhan, Nashid; Fitzpatrick, Sean; Shim, Yun M; Paige, Mikell; Chow, Diana Shu-Lian

2016-09-05

4-Methoxydiphenylmethane (4-MDM), a selective augmenter of Leukotriene A4 Hydrolase (LTA4H), is a new anti-inflammatory compound for potential treatment of chronic obstructive pulmonary disease (COPD). Currently, there is no liquid chromatography tandem mass spectrometric (LC-MS/MS) method for the quantification of 4-MDM. A major barrier for developing the LC-MS/MS method is the inability of electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) to ionize 4-MDM due to its hydrophobicity and lack of any functional group for ionization. With the advent of atmospheric pressure photoionization (APPI) technique, many hydrophobic compounds have been demonstrated to ionize by charge transfer reactions. In this study, a highly sensitive ultrapressure liquid chromatography tandem mass spectrometry assay using atmospheric pressure photoionization (UPLC-APPI-MS/MS) for the quantifications of 4-MDM in rat plasma has been developed and validated. 4-MDM was extracted from the plasma by solid phase extraction (SPE) and separated chromatographically using a reverse phase C8 column. The photoionization (PI) was achieved by introducing anisole as a dopant to promote the reaction of charge transfer. The assay with a linear range of 5 (LLOQ)-400ngmL(-1) met the regulatory requirements for accuracy, precision and stability. The validated assay was employed to quantify the plasma concentrations of 4-MDM after an oral dosing in Sprague Dawley (SD) rats. Copyright © 2016 Elsevier B.V. All rights reserved.

The chemical basis of DNA damage by the direct pathway of ionizing radiation

International Nuclear Information System (INIS)

Sharma, Kiran Kumar K.

2013-01-01

Free radicals in living system has been implicated as playing a major role in the etiology of variety of diseases. The mechanism of free radicals in vivo involves predominantly the reaction with the DNA, producing different types of damage to the DNA. These lesions induced to the DNA could lead to mutation and even cell death. Radiolysis techniques, which uses ionizing radiation has proven to be one of the most advanced and excellent tool for studying the free radical reaction mechanisms as it can produce a host of well characterized free radicals. The effects of ionizing radiation on DNA have been studied for many years. Ionizing radiation interacts with DNA in vivo by two pathways, direct and indirect. The indirect accounts for 50-60% while the direct effect accounts for 40-50%. The chemical mechanism of the former reaction arising mainly from the reactive species produced by radiolysis of water has been extensively studied, however with respect to the later pathway, which creates holes and electrons to the DNA molecule using DNA films and crystals is an active area of research as both the pathways plays important roles in DNA damage in vivo particularly in chromosomal DNA which are tightly bound with histones and compartmentalized

Simultaneous Determination of Perfluorinated Compounds in Edible Oil by Gel-Permeation Chromatography Combined with Dispersive Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

Science.gov (United States)

Yang, Lili; Jin, Fen; Zhang, Peng; Zhang, Yanxin; Wang, Jian; Shao, Hua; Jin, Maojun; Wang, Shanshan; Zheng, Lufei; Wang, Jing

2015-09-30

A simple analytical method was developed for the simultaneous analysis of 18 perfluorinated compounds (PFCs) in edible oil. The target compounds were extracted by acetonitrile, purified by gel permeation chromatography (GPC) and dispersive solid-phase extraction (DSPE) using graphitized carbon black (GCB) and octadecyl (C18), and analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ES-MS/MS) in negative ion mode. Recovery studies were performed at three fortification levels. The average recoveries of all target PFCs ranged from 60 to 129%, with an acceptable relative standard deviation (RSD) (1-20%, n = 3). The method detection limits (MDLs) ranged from 0.004 to 0.4 μg/kg, which was significantly improved compared with the existing liquid-liquid extraction and cleanup method. The method was successfully applied for the analysis of all target PFCs in edible oil samples collected from markets in Beijing, China, and the results revealed that C6-C10 perfluorocarboxylic acid (PFCAs) and C7 perfluorosulfonic acid PFSAs were the major PFCs detected in oil samples.

Hydrophilic interaction chromatography coupled matrix assisted laser desorption/ionization mass spectrometry for molecular analysis of organic compounds in medicines, tea, and coffee

KAUST Repository

Wang, Renqi

2013-01-01

Natural occurring organic compounds from food, natural organic matter, as well as metabolic products have received intense attention in current chemical and biological studies. Examination of unknown compounds in complex sample matrices is hampered by the limited choices for data readout and molecular elucidation. Herein, we report a generic method of hydrophilic interaction chromatography (HILIC) coupled with matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the rapid characterization of ingredients in pharmaceutical compounds, tea, and coffee. The analytes were first fractionated using a cationic HILIC column prior to MALDI-MS analyses. It was found that the retention times of a compound arising from different samples were consistent under the same conditions. Accordingly, molecules can be readily characterized by both the mass and chromatographic retention time. The retention behaviors of acidic and basic compounds on the cationic HILIC column were found to be significantly influenced by the pH of mobile phases, whereas neutral compounds depicted a constant retention time at different pH. The general HILIC-MALDI-MS method is feasible for fast screening of naturally occurring organic compounds. A series of homologs can be determined if they have the same retention behavior. Their structural features can be elucidated by considering their mass differences and hydrophilic properties as determined by HILIC chromatogram. © 2013 The Royal Society of Chemistry.

Influence of soil pH on the sorption of ionizable chemicals

DEFF Research Database (Denmark)

Franco, Antonio; Fu, Wenjing; Trapp, Stefan

2009-01-01

, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of p......The soil-water distribution coefficient of ionizable chemicals (K-d) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K-d values normalized to organic carbon (K-OC) from the literature, a method was developed to estimate the K-OC of monovalent organic acids...

From consumption to harvest: Environmental fate prediction of excreted ionizable trace organic chemicals

DEFF Research Database (Denmark)

Polesel, Fabio; Plósz, Benedek G.; Trapp, Stefan

2015-01-01

Excreted trace organic chemicals, e.g., pharmaceuticals and biocides, typically undergo incomplete elimination in municipal wastewater treatment plants (WWTPs) and are released to surface water via treated effluents and to agricultural soils through sludge amendment and/or irrigation with freshwa......Excreted trace organic chemicals, e.g., pharmaceuticals and biocides, typically undergo incomplete elimination in municipal wastewater treatment plants (WWTPs) and are released to surface water via treated effluents and to agricultural soils through sludge amendment and/or irrigation...... with freshwater or reclaimed wastewater. Recent research has shown the tendency for these substances to accumulate in food crops. In this study, we developed and applied a simulation tool to predict the fate of three ionizable trace chemicals (triclosan-TCS, furosemide-FUR, ciprofloxacin-CIP) from human...... and a recently developed dynamic soil-plant uptake model. The simulation tool was tested using country-specific (e.g., consumption/emission rates, precipitation and temperature) input data. A Monte Carlo-based approach was adopted to account for the uncertainty associated to physico-chemical and biokinetic model...

Coupling an electrospray source and a solids probe/chemical ionization source to a selected ion flow tube apparatus

International Nuclear Information System (INIS)

Melko, Joshua J.; Ard, Shaun G.; Shuman, Nicholas S.; Viggiano, Albert A.; Pedder, Randall E.; Taormina, Christopher R.

2015-01-01

A new ion source region has been constructed and attached to a variable temperature selected ion flow tube. The source features the capabilities of electron impact, chemical ionization, a solids probe, and electrospray ionization. The performance of the instrument is demonstrated through a series of reactions from ions created in each of the new source regions. The chemical ionization source is able to create H 3 O + , but not as efficiently as similar sources with larger apertures. The ability of this source to support a solids probe, however, greatly expands our capabilities. A variety of rhenium cations and dications are created from the solids probe in sufficient abundance to study in the flow tube. The reaction of Re + with O 2 proceeds with a rate constant that agrees with the literature measurements, while the reaction of Re 2 2+ is found to charge transfer with O 2 at about 60% of the collision rate; we have also performed calculations that support the charge transfer pathway. The electrospray source is used to create Ba + , which is reacted with N 2 O to create BaO + , and we find a rate constant that agrees with the literature

Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization.

Science.gov (United States)

Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

2016-08-01

The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M(+.) decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques. Graphical Abstract ᅟ.

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.

Chemical fingerprint of Ganmaoling granule by double-wavelength ultra high performance liquid chromatography and ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Lou, Qiong; Ye, Xiaolan; Zhou, Yingyi; Li, Hua; Song, Fenyun

2015-06-01

A method incorporating double-wavelength ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry was developed for the investigation of the chemical fingerprint of Ganmaoling granule. The chromatographic separations were performed on an ACQUITY UPLC HSS C18 column (2.1 × 50 mm, 1.8 μm) at 30°C using gradient elution with water/formic acid (1%) and acetonitrile at a flow rate of 0.4 mL/min. A total of 11 chemical constituents of Ganmaoling granule were identified from their molecular weight, UV spectra, tandem mass spectrometry data, and retention behavior by comparing the results with those of the reference standards or literature. And 25 peaks were selected as the common peaks for fingerprint analysis to evaluate the similarities among 25 batches of Ganmaoling granule. The results of principal component analysis and orthogonal projection to latent structures discriminant analysis showed that the important chemical markers that could distinguish the different batches were revealed as 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 4-O-caffeoylquinic acid. This is the first report of the ultra high performance liquid chromatography chemical fingerprint and component identification of Ganmaoling granule, which could lay a foundation for further studies of Ganmaoling granule. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atmospheric pressure chemical ionization of fluorinated phenols in atmospheric pressure chemical ionization mass spectrometry, tandem mass spectrometry, and ion mobility spectrometry

Science.gov (United States)

Eiceman, G. A.; Bergloff, J. F.; Rodriguez, J. E.; Munro, W.; Karpas, Z.

1999-01-01

Atmospheric pressure chemical ionization (APCI)-mass spectrometry (MS) for fluorinated phenols (C6H5-xFxOH Where x = 0-5) in nitrogen with Cl- as the reagent ion yielded product ions of M Cl- through ion associations or (M-H)- through proton abstractions. Proton abstraction was controllable by potentials on the orifice and first lens, suggesting that some proton abstraction occurs through collision induced dissociation (CID) in the interface region. This was proven using CID of adduct ions (M Cl-) with Q2 studies where adduct ions were dissociated to Cl- or proton abstracted to (M-H)-. The extent of proton abstraction depended upon ion energy and structure in order of calculated acidities: pentafluorophenol > tetrafluorophenol > trifluorophenol > difluorophenol. Little or no proton abstraction occurred for fluorophenol, phenol, or benzyl alcohol analogs. Ion mobility spectrometry was used to determine if proton abstraction reactions passed through an adduct intermediate with thermalized ions and mobility spectra for all chemicals were obtained from 25 to 200 degrees C. Proton abstraction from M Cl- was not observed at any temperature for phenol, monofluorophenol, or difluorophenol. Mobility spectra for trifluorophenol revealed the kinetic transformations to (M-H)- either from M Cl- or from M2 Cl- directly. Proton abstraction was the predominant reaction for tetra- and penta-fluorophenols. Consequently, the evidence suggests that proton abstraction occurs from an adduct ion where the reaction barrier is reduced with increasing acidity of the O-H bond in C6H5-xFxOH.

Chemical synthesis of deuterated folate monoglutamate and in vivo assessment of urinary excretion of deuterated folates in man

International Nuclear Information System (INIS)

Gregory, J.F. III; Toth, J.P.

1988-01-01

The synthesis and in vivo application of stable-isotopically labeled folic acid was investigated to devise methods suitable for studies of folate metabolism in human subjects. Glutamate-labeled tetradeutero-pteroylglutamic acid (d4-folic acid) was prepared by mixed anhydride coupling of N10-trifluoroacetylpteroic acid and dimethyl L-[3,3,4,4-2H4]glutamic acid, saponification in sodium deuteroxide, and chromatographic purification. Retention of the isotopic label was verified by proton NMR and mass spectrometry of the para-aminobenzoylglutamic acid product of C9-N10 bond cleavage. A method was devised for determination of of isotopic enrichment of urinary d4-folates derived from orally administered d4-folic acid using affinity chromatographic purification, chemical cleavage of the C9-N10 bond, HPLC isolation of the p-[2H4]aminobenzoylglutamate product, followed by negative-ion chemical-ionization gas chromatography/mass spectrometry. Data concerning the urinary excretion of d4-folates derived from an oral dose of d4-folic acid in an adult human are presented

Regiospecific analysis of neutral ether lipids by liquid chromatography/electrospray ionization/single quadrupole mass spectrometry: validation with synthetic compounds

DEFF Research Database (Denmark)

Hartvigsen, Karsten; Ravandi, A.; Bukhave, Klaus

2001-01-01

A reversed-phase high-performance liquid chromatography (HPLC) method with on-line electrospray ionization/collision-induced dissociation/mass spectrometry (ESI/CID/MS) is presented for the regiospecific analysis of synthetic reference compounds of neutral ether lipids. The reference compounds were...... characterized by chromatographic retention times, full mass spectra, and fragmentation patterns as an aid to clarify the regiospecificity of ether lipids from natural sources. The results clearly show that single quadrupole mass spectroscopic analysis may elucidate the regiospecific structure of neutral ether...... + H - H2O](+), whereas the reverse situation characterized the sn-3 species. Furthermore, corresponding sn-2 and sn-3 species were separated by the chromatographic system. However, loss of water was promoted as fatty acid unsaturation was raised, which may complicate interpretation of the mass spectra...

Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

Science.gov (United States)

Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

2015-06-01

Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

Determination of reversed-phase high performance liquid chromatography based octanol-water partition coefficients for neutral and ionizable compounds: Methodology evaluation.

Science.gov (United States)

Liang, Chao; Qiao, Jun-Qin; Lian, Hong-Zhen

2017-12-15

Reversed-phase liquid chromatography (RPLC) based octanol-water partition coefficient (logP) or distribution coefficient (logD) determination methods were revisited and assessed comprehensively. Classic isocratic and some gradient RPLC methods were conducted and evaluated for neutral, weak acid and basic compounds. Different lipophilicity indexes in logP or logD determination were discussed in detail, including the retention factor logk w corresponding to neat water as mobile phase extrapolated via linear solvent strength (LSS) model from isocratic runs and calculated with software from gradient runs, the chromatographic hydrophobicity index (CHI), apparent gradient capacity factor (k g ') and gradient retention time (t g ). Among the lipophilicity indexes discussed, logk w from whether isocratic or gradient elution methods best correlated with logP or logD. Therefore logk w is recommended as the preferred lipophilicity index for logP or logD determination. logk w easily calculated from methanol gradient runs might be the main candidate to replace logk w calculated from classic isocratic run as the ideal lipophilicity index. These revisited RPLC methods were not applicable for strongly ionized compounds that are hardly ion-suppressed. A previously reported imperfect ion-pair RPLC method was attempted and further explored for studying distribution coefficients (logD) of sulfonic acids that totally ionized in the mobile phase. Notably, experimental logD values of sulfonic acids were given for the first time. The IP-RPLC method provided a distinct way to explore logD values of ionized compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

[Exposure to hazardous chemical substances in furniture industry].

Science.gov (United States)

Pośniak, Małgorzata; Kowalska, Joanna; Makhniashvili, Ivan

2005-01-01

The aim of the study was to assess the exposure to organic solvents in plants of the furniture industry. Studies were conducted in five furniture plants. Hazardous chemicals present in the air at workposts were determined by capillary gas chromatography with mass spectrometry and flame ionization detection. The analysis of air samples collected at the workposts allowed to identify the following chemicals occurring during varnishing and cleaning of furniture surface elements: acetone, butan-2-one, ethyl, isobutyl and methoxypropyl acetate, 4-methylpentan-2-on, toluene, ethylbenzene and xylenes. Indices characteristic of combined exposure ranged from 0.13 to 1.67 and exceeded the limit value at 21% of workposts. The results of the study indicate that chemicals present at representative workposts during the furniture production are harmful to health of workers, especially those involved in varnishing and cleaning of furniture elements.

Low-molecular weight protein profiling of genetically modified maize using fast liquid chromatography electrospray ionization and time-of-flight mass spectrometry.

Science.gov (United States)

Koc, Anna; Cañuelo, Ana; Garcia-Reyes, Juan F; Molina-Diaz, Antonio; Trojanowicz, Marek

2012-06-01

In this work, the use of liquid chromatography coupled to electrospray time-of-flight mass spectrometry (LC-TOFMS) has been evaluated for the profiling of relatively low-molecular weight protein species in both genetically modified (GM) and non-GM maize. The proposed approach consisted of a straightforward sample fractionation with different water and ethanol-based buffer solutions followed by separation and detection of the protein species using liquid chromatography with a small particle size (1.8 μm) C(18) column and electrospray-time-of-flight mass spectrometry detection in the positive ionization mode. The fractionation of maize reference material containing different content of transgenic material (from 0 to 5% GM) led to five different fractions (albumins, globulins, zeins, zein-like glutelins, and glutelins), all of them containing different protein species (from 2 to 52 different species in each fraction). Some relevant differences in the quantity and types of protein species were observed in the different fractions of the reference material (with different GM contents) tested, thus revealing the potential use of the proposed approach for fast protein profiling and to detect tentative GMO markers in maize. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance liquid chromatography (HPLC fingerprints and primary structure identification of corn peptides by HPLC-diode array detection and HPLC-electrospray ionization tandem mass spectrometry

Directory of Open Access Journals (Sweden)

Chi Wang

2016-01-01

Full Text Available Corn peptides (CPs are reported to have many biological functions, such as facilitating alcohol metabolism, antioxidation, antitumor, antihypertension, and hepatoprotection. To develop a method for quality control, the high-performance liquid chromatography (HPLC system was applied. Twenty-eight common peaks were found in all the CPs of corn samples from Enshi, China, based on which, a fingerprinting chromatogram was established for use in quality control in future research. Subsequently, the major chemical constituents of these common peaks were identified respectively using the HPLC-diode-array detection electrospray ionization tandem mass spectrometry (DAD-ESI-MS/MS system, and 48 peptide fractions were determined ultimately. This was the first time for the majority of these peptides to be reported, and many of them contained amino acids of glutamine (Q, L and A, which might play an important role in the exhibition of the bioactivities of CPs. Many peptides had a similar primary structure to the peptides which had been proven to be bioactive such as facilitating alcohol metabolism, scavenging free radicals, and inhibiting lipid peroxidation. This systematical analysis of the primary structure of CPs facilitated subsequent studies on the relationship between the structures and functions, and could accelerate holistic research on CPs.

Degradation of diazinon contaminated waters by ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.; Mohamed, K.A.; Al-Abduly, A.J.; Al-Kuraiji, T.S.; Al-Shahrani, A.A.

2007-01-01

Study of degradation of diazinon pesticide by 60 Co gamma irradiation in a single aqueous solution was conducted on a laboratory scale and the effect of ionizing radiation on the removal efficiency of diazinon residues was investigated. Distilled water solutions at three different concentrations of targeted compound (i.e. 0.329, 1.643 and 3.286 μmol dm -3 ) were irradiated over the range 0.1-6 kGy. The initial concentration of contaminant and irradiation doses play a significant role in the rate of destruction; this was evident from the calculated decay constants of diazinon residue. Gamma radiolysis showed that the absorbed doses from 1.5 to 5.6 kGy at a dose rate of 4.79 kGy h -1 achieved 90% destruction for diazinon with initial concentrations over the range 0.329-3.286 μmol dm -3 . The radiolytic degradation by-products and their mass balances were qualitative determined with good confidence by using GC/quadrupole mass spectrometry (GC/MS) with EI + or CI in positive and negative ionization mode and diazinon degradation pathways were proposed. Additionally, the final products of irradiation were identified by ion chromatography (IC) to be acetic and formic acid

K-shell ionization by antiprotons

International Nuclear Information System (INIS)

Mehler, G.; Mueller, B.; Greiner, W.; Soff, G.

1987-01-01

We present first calculations for the impact parameter dependence of K-shell ionization rates in anti pCu and in anti pAg collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the anti-binding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization cross-sections for proton and antiproton projectiles are compared with each other and with experimental ionization cross-sections for protons. (orig.)

Liquid Chromatography in 1982.

Science.gov (United States)

Freeman, David H.

1982-01-01

Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

Atmospheric pressure chemical ionization Fourier transform ion cyclotron resonance mass spectrometry for complex thiophenic mixture analysis

KAUST Repository

Hourani, Nadim

2013-10-01

Rationale Polycyclic aromatic sulfur heterocycles (PASHs) are detrimental species for refining processes in petroleum industry. Current mass spectrometric Methods that determine their composition are often preceded by derivatization and dopant addition approaches. Different ionization Methods have different impact on the molecular assignment of complex PASHs. The analysis of such species under atmospheric pressure chemical ionization (APCI) is still considered limited due to uncontrolled ion generation with low- and high-mass PASHs. Methods The ionization behavior of a model mixture of five selected PASH standards was investigated using an APCI source with nitrogen as the reagent gas. A complex thiophenic fraction was separated from a vacuum gas oil (VGO) and injected using the same method. The samples were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). RESULTS PASH model analytes were successfully ionized and mainly [M + H]+ ions were produced. The same ionization pattern was observed for the real thiophenic sample. It was found that S1 class species were the major sulfur-containing species found in the VGO sample. These species indicated the presence of alkylated benzothiophenic (BT), dibenzothiophenic (DBT) and benzonaphthothiophenic (BNT) series that were detected by APCI-FTICR MS. CONCLUSIONS This study provides an established APCI-FTICR MS method for the analysis of complex PASHs. PASHs were detected without using any derivatization and without fragmentation. The method can be used for the analysis of S-containing crude oil samples. © 2013 John Wiley & Sons, Ltd.

Robust automated mass spectra interpretation and chemical formula calculation using mixed integer linear programming.

Science.gov (United States)

Baran, Richard; Northen, Trent R

2013-10-15

Untargeted metabolite profiling using liquid chromatography and mass spectrometry coupled via electrospray ionization is a powerful tool for the discovery of novel natural products, metabolic capabilities, and biomarkers. However, the elucidation of the identities of uncharacterized metabolites from spectral features remains challenging. A critical step in the metabolite identification workflow is the assignment of redundant spectral features (adducts, fragments, multimers) and calculation of the underlying chemical formula. Inspection of the data by experts using computational tools solving partial problems (e.g., chemical formula calculation for individual ions) can be performed to disambiguate alternative solutions and provide reliable results. However, manual curation is tedious and not readily scalable or standardized. Here we describe an automated procedure for the robust automated mass spectra interpretation and chemical formula calculation using mixed integer linear programming optimization (RAMSI). Chemical rules among related ions are expressed as linear constraints and both the spectra interpretation and chemical formula calculation are performed in a single optimization step. This approach is unbiased in that it does not require predefined sets of neutral losses and positive and negative polarity spectra can be combined in a single optimization. The procedure was evaluated with 30 experimental mass spectra and was found to effectively identify the protonated or deprotonated molecule ([M + H](+) or [M - H](-)) while being robust to the presence of background ions. RAMSI provides a much-needed standardized tool for interpreting ions for subsequent identification in untargeted metabolomics workflows.

Evaluation and prevention of the negative matrix effect of terpenoids on pesticides in apples quantification by gas chromatography-tandem mass spectrometry.

Science.gov (United States)

Giacinti, Géraldine; Raynaud, Christine; Capblancq, Sophie; Simon, Valérie

2017-02-03

The sample matrix can enhance the gas chromatography signal of pesticide residues relative to that obtained with the same concentration of pesticide in solvent. This paper is related to negative matrix effects observed in coupled gas chromatography-mass spectrometry ion trap (GC/MS 2 ) quantification of pesticides in concentrated extracts of apple peel prepared by the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method. It is focused on the pesticides most frequently used on the apple varieties studied, throughout the crop cycle, right up to harvest, to combat pests and diseases and to improve fruit storage properties. Extracts from the fleshy receptacle (flesh), the epiderm (peel) and fruit of three apple varieties were studied by high-performance thin-layer chromatography hyphenated with UV-vis light detection (HPTLC/UV visible). The peel extracts had high concentrations of triterpenic acids (oleanolic and ursolic acids), reaching 25mgkg -1 , whereas these compounds were not detected in the flesh extracts (<0.05mgkg -1 ). A significant relationship has been found between the levels of these molecules and negative matrix effects in GC/MS 2 . The differences in the behavior of pesticides with respect to matrix effects can be accounted for by the physicochemical characteristics of the molecules (lone pairs, labile hydrogen, conjugation). The HPTLC/UV visible method developed here for the characterization of QuEChERS extracts acts as a complementary clean-up method, aimed to decrease the negative matrix effects of such extracts. Copyright © 2016 Elsevier B.V. All rights reserved.

Microfabrication, separations, and detection by mass spectrometry on ultrathin-layer chromatography plates prepared via the low-pressure chemical vapor deposition of silicon nitride onto carbon nanotube templates.

Science.gov (United States)

Kanyal, Supriya S; Häbe, Tim T; Cushman, Cody V; Dhunna, Manan; Roychowdhury, Tuhin; Farnsworth, Paul B; Morlock, Gertrud E; Linford, Matthew R

2015-07-24

Microfabrication of ultrathin-layer chromatography (UTLC) plates via conformal deposition of silicon nitride by low-pressure chemical vapor deposition onto patterned carbon nanotube (CNT) scaffolds was demonstrated. After removal of the CNTs and hydroxylation, the resulting UTLC phase showed no expansion or distortion of their microfeatures and the absence/reduction of remaining nitrogenic species. Developing time of a mixture of lipophilic dyes on this UTLC plates was 86% shorter than on high-performance thin-layer chromatography (HPTLC) plates. A water-soluble food dye mixture was also separated resulting in low band broadening and reduced developing time compared to HPTLC. For the latter example, mobile phase optimization on a single UTLC plate consisted of 14 developments with different mobile phases, each preceded by a plate prewashing step. The same plate was again reused for additional 11 separations under varying conditions resulting in a development procedure with a mean separation efficiency of 233,000theoretical plates/m and a reduced mobile phase consumption of only 400μL. This repeated use proved the physical robustness of the ultrathin layer and its resistance to damage. The layer was highly suited for hyphenation to ambient mass spectrometry, including desorption electrospray ionization (DESI) mass spectrometry imaging and direct analysis in real time (DART) mass spectrometry. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantification of abscisic acid in a single maize root

International Nuclear Information System (INIS)

Reymond, P.; Saugy, M.; Pilet, P.E.

1987-01-01

Quantitative analyses of abscisic acid in the elongating zone of a single maize root (Zea mays L. cv LG 11) were performed by gas chromatography-mass spectrometry using negative chemical ion ionization. Data showed that the more abscisic acid, the slower the growth, but a large dispersion of individual values was observed. We assume that abscisic acid is perhaps not correlated only to the growth rate. (author)

The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

Science.gov (United States)

Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

2014-11-01

A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

CHEMICAL ANALYSIS OF A DIFFUSE CLOUD ALONG A LINE OF SIGHT TOWARD W51: MOLECULAR FRACTION AND COSMIC-RAY IONIZATION RATE

Energy Technology Data Exchange (ETDEWEB)

Indriolo, Nick; Neufeld, D. A. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Gerin, M. [LERMA, CNRS, Observatoire de Paris and ENS, F-75231 Paris Cedex 05 (France); Geballe, T. R. [Gemini Observatory, Hilo, HI 96720 (United States); Black, J. H. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE-43992 Onsala (Sweden); Menten, K. M. [MPI fuer Radioastronomie, D-53121 Bonn (Germany); Goicoechea, J. R. [Departamento de Astrofisica, Centro de Astrobiologia (CSIC-INTA), E-28850 Madrid (Spain)

2012-10-20

Absorption lines from the molecules OH{sup +}, H{sub 2}O{sup +}, and H{sup +} {sub 3} have been observed in a diffuse molecular cloud along a line of sight near W51 IRS2. We present the first chemical analysis that combines the information provided by all three of these species. Together, OH{sup +} and H{sub 2}O{sup +} are used to determine the molecular hydrogen fraction in the outskirts of the observed cloud, as well as the cosmic-ray ionization rate of atomic hydrogen. H{sup +} {sub 3} is used to infer the cosmic-ray ionization rate of H{sub 2} in the molecular interior of the cloud, which we find to be {zeta}{sub 2} = (4.8 {+-} 3.4) Multiplication-Sign 10{sup -16} s{sup -1}. Combining the results from all three species we find an efficiency factor-defined as the ratio of the formation rate of OH{sup +} to the cosmic-ray ionization rate of H-of {epsilon} = 0.07 {+-} 0.04, much lower than predicted by chemical models. This is an important step in the future use of OH{sup +} and H{sub 2}O{sup +} on their own as tracers of the cosmic-ray ionization rate.

Chemical effects of ionizing radiation on the individual amino acids within intact and pure protein molecules. Final report

International Nuclear Information System (INIS)

Freidberg, F.

1977-01-01

Progress is reported on the following research projects: gamma radiation induced chemical and molecular weight changes in proteins; the free radical pattern for the irradiated protein; similarities in the mechanism of action of ionizing and of uv radiation; and spin trapping in the study of gamma radiolysis

Technical sheets of ionizing radiations. 2. Non-ionizing radiations

International Nuclear Information System (INIS)

Anon.

1975-01-01

The biological effects of different non-ionizing radiations are studied: ultra-violet radiation, visible radiation, infrared radiation, micrometric waves, ultrasonics. In spite of their apparent diversity these radiations are similar in their physico-chemical effects, but in view of their widely varying production methods and types of application each type is considered separately. It is pointed out that no organization resembling the CIPR exists in the field of non-ionizing radiations, the result being a great disparity amongst the different legislations in force [fr

Ionizing radiation and a wood-based biorefinery

International Nuclear Information System (INIS)

Driscoll, Mark S.; Stipanovic, Arthur J.; Cheng, Kun; Barber, Vincent A.; Manning, Mellony; Smith, Jennifer L.; Sundar, Smith

2014-01-01

Woody biomass is widely available around the world. Cellulose is the major structural component of woody biomass and is the most abundant polymer synthesized by nature, with hemicellulose and lignin being second and third. Despite this great abundance, woody biomass has seen limited application outside of the paper and lumber industries. Its use as a feedstock for fuels and chemicals has been limited because of its highly crystalline structure, inaccessible morphology, and limited solubility (recalcitrance). Any economic use of woody biomass for the production of fuels and chemicals requires a “pretreatment” process to enhance the accessibility of the biomass to enzymes and/or chemical reagents. Electron beams (EB), X-rays, and gamma rays produce ions in a material which can then initiate chemical reactions and cleavage of chemical bonds. Such ionizing radiation predominantly scissions and degrades or depolymerizes both cellulose and hemicelluloses, less is known about its effects on lignin. This paper discusses how ionizing radiation can be used to make a wood-based biorefinery more environmentally friendly and profitable for its operators. - Highlights: • Ionizing radiation reduces the crystallinity of cellulose. • Ionizing radiation reduces cellulose's degree of polymerization. • The amount and rate of enzymatic hydrolysis of lignocellulosic materials, including wood, are increased with increasing radiation dose. • Wood and other lignocellulosic materials have the potential to be a renewable material for the production of chemicals and fuels

Ionization chambers

International Nuclear Information System (INIS)

Boag, J.W.

1987-01-01

Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

Fast screening of analytes for chemical reactions by reactive low-temperature plasma ionization mass spectrometry.

Science.gov (United States)

Zhang, Wei; Huang, Guangming

2015-11-15

Approaches for analyte screening have been used to aid in the fine-tuning of chemical reactions. Herein, we present a simple and straightforward analyte screening method for chemical reactions via reactive low-temperature plasma ionization mass spectrometry (reactive LTP-MS). Solution-phase reagents deposited on sample substrates were desorbed into the vapor phase by action of the LTP and by thermal desorption. Treated with LTP, both reagents reacted through a vapor phase ion/molecule reaction to generate the product. Finally, protonated reagents and products were identified by LTP-MS. Reaction products from imine formation reaction, Eschweiler-Clarke methylation and the Eberlin reaction were detected via reactive LTP-MS. Products from the imine formation reaction with reagents substituted with different functional groups (26 out of 28 trials) were successfully screened in a time of 30 s each. Besides, two short-lived reactive intermediates of Eschweiler-Clarke methylation were also detected. LTP in this study serves both as an ambient ionization source for analyte identification (including reagents, intermediates and products) and as a means to produce reagent ions to assist gas-phase ion/molecule reactions. The present reactive LTP-MS method enables fast screening for several analytes from several chemical reactions, which possesses good reagent compatibility and the potential to perform high-throughput analyte screening. In addition, with the detection of various reactive intermediates (intermediates I and II of Eschweiler-Clarke methylation), the present method would also contribute to revealing and elucidating reaction mechanisms. Copyright © 2015 John Wiley & Sons, Ltd.

Seasonal variation of gastroprotective terpenoids in Maytenus robusta (Celastraceae) quantified by gas chromatography-flame ionization detection (GC-FID).

Science.gov (United States)

Zermiani, Tailyn; Junior, Antonio A S; Ferreira, Renê A; Wagner, Theodoro M; Machado, Marina S; Cechinel-Filho, Valdir; Niero, Rivaldo

2016-11-01

The triterpenes friedelin (1), β-friedelinol (2) and 3,15-dioxo-21α-hydroxyfriedelane (3) in the aerial parts of Maytenus robusta, a Brazilian medicinal plant with antiulcer potential, were seasonally quantified by gas chromatography flame-ionization detection (GC-FID) using an external standard. The method was found to be linear, precise and sensitive. Compounds 1 and 2 were found in M. robusta leaves and branches, with highest concentrations in the leaves collected in autumn, i.e. 3.21 ± 0.16 and 12.60 ± 1.49 mg g-1 dry weight of 1 and 2, respectively. On the other hand, compound 3 was found only in the branches, with the highest concentrations in winter and autumn (0.21 ± 0.01 and 0.20 ± 0.02 mg g-1). The results allow to define the optimal season and plant parts for the collection of M. robusta as a phytotherapeutic drug.

Soft ionization of saturated hydrocarbons, alcohols and nonpolar compounds by negative-ion direct analysis in real-time mass spectrometry.

Science.gov (United States)

Cody, Robert B; Dane, A John

2013-03-01

Large polarizable n-alkanes (approximately C18 and larger), alcohols, and other nonpolar compounds can be detected as negative ions when sample solutions are injected directly into the sampling orifice of the atmospheric pressure interface of the time-of-flight mass spectrometer with the direct analysis in real time (DART) ion source operating in negative-ion mode. The mass spectra are dominated by peaks corresponding to [M + O2]‾(•). No fragmentation is observed, making this a very soft ionization technique for samples that are otherwise difficult to analyze by DART. Detection limits for cholesterol were determined to be in the low nanogram range.

Amorphous silicon ionizing particle detectors

Science.gov (United States)

Street, Robert A.; Mendez, Victor P.; Kaplan, Selig N.

1988-01-01

Amorphous silicon ionizing particle detectors having a hydrogenated amorphous silicon (a--Si:H) thin film deposited via plasma assisted chemical vapor deposition techniques are utilized to detect the presence, position and counting of high energy ionizing particles, such as electrons, x-rays, alpha particles, beta particles and gamma radiation.

Comprehensive two-dimensional liquid chromatography and hyphenated liquid chromatography to study the degradation of poly(bisphenol A)carbonate

NARCIS (Netherlands)

Coulier, L.; Kaal, E.R.; Hankemeier, T.

2005-01-01

Size exclusion chromatography (SEC), gradient polymer elution chromatography (GPEC) and liquid chromatography at critical conditions (LC-CC) have been developed and applied to observe chemical changes in poly(bisphenol A)carbonate (PC) due to hydrolytic degradation. Especially LC-CC appeared to be

Chemical and biological effects of β-decay and inner shell ionization in biomolecules

International Nuclear Information System (INIS)

Stoecklin, G.

1979-01-01

Tritium and iodine-125, and the Auger effect either caused by the EC-decay of 125 I or by the inner shell vacancy created selectively by mono-energetic X-ray are reviewed in this paper. The specifically labelled precursors to bound 3 H large biomolecules were prepared by conventional syntheses, and then incorporated into the DNA of proliferating cells. The effects like DNA strand breaks or mutational changes are likely to be affected by the localization of the carbonium ions in biological molecules. In contrast to lethality, it was demonstrated that 3 H transmutation effect contributed to DNA strand breaks and played a key role in producing genetic effects. The decay of 3 H in uracil-5- 3 H in the DNA of E. coli was about 7 times as mutagenic as that in uracil-6- 3 H, and 500-fold greater in bacteriophage S13. Drastic chemical consequences are associated with the Auger effect occurring as a possible relaxation process whenever inner shell ionization is initiated. When the vacancy is filled by an electron from an outer shell, the bond energy difference between inner shell electron and outer shell electron is released either in the form of an X-ray fluorescence photon or it can be transmitted to another outer electron which is then ejected. The radioactive decay in specifically labelled biomolecules or the inner shell ionization in heavy constituent atoms caused by resonant X-ray are relevant to a) selective microsurgery in biological macromolecules for the correlation of biological and chemical functions, b) radiotoxicity estimation, and c) radiation therapy. (Yamashita, S.)

Use of a hand-portable gas chromatograph-toroidal ion trap mass spectrometer for self-chemical ionization identification of degradation products related to O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX)

Energy Technology Data Exchange (ETDEWEB)

Smith, Philip A., E-mail: Smith.Philip.A@dol.gov [Uniformed Services University of the Health Sciences, Department of Preventive Medicine and Biometrics, 4301 Jones Bridge Road, Bethesda, MD, 20814 (United States); Lepage, Carmela R. Jackson [Defence R and D Canada - Suffield, Box 400, Station Main, Medicine Hat, Alberta, T1A 8K6 (Canada); Savage, Paul B. [Brigham Young University, Department of Chemistry and Biochemistry, Provo, UT, 84602 (United States); Bowerbank, Christopher R.; Lee, Edgar D. [Torion Technologies Inc., 796 East Utah Valley Drive, Suite 200, American Fork, UT, 84003 (United States); Lukacs, Michael J. [Defence R and D Canada - Suffield, Box 400, Station Main, Medicine Hat, Alberta, T1A 8K6 (Canada)

2011-04-01

The chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX) and many related degradation products produce poorly diagnostic electron ionization (EI) mass spectra by transmission quadrupole mass spectrometry. Thus, chemical ionization (CI) is often used for these analytes. In this work, pseudomolecular ([M+H]{sup +}) ion formation from self-chemical ionization (self-CI) was examined for four VX degradation products containing the diisopropylamine functional group. A person-portable toroidal ion trap mass spectrometer with a gas chromatographic inlet was used with EI, and both fixed-duration and feedback-controlled ionization time. With feedback-controlled ionization, ion cooling (reaction) times and ion formation target values were varied. Evidence for protonation of analytes was observed under all conditions, except for the largest analyte, bis(diisopropylaminoethyl)disulfide which yielded [M+H]{sup +} ions only with increased fixed ionization or ion cooling times. Analysis of triethylamine-d{sub 15} provided evidence that [M+H]{sup +} production was likely due to self-CI. Analysis of a degraded VX sample where lengthened ion storage and feedback-controlled ionization time were used resulted in detection of [M+H]{sup +} ions for VX and several relevant degradation products. Dimer ions were also observed for two phosphonate compounds detected in this sample.

Use of a hand-portable gas chromatograph-toroidal ion trap mass spectrometer for self-chemical ionization identification of degradation products related to O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX)

International Nuclear Information System (INIS)

Smith, Philip A.; Lepage, Carmela R. Jackson; Savage, Paul B.; Bowerbank, Christopher R.; Lee, Edgar D.; Lukacs, Michael J.

2011-01-01

The chemical warfare agent O-ethyl S-(2-diisopropylaminoethyl) methyl phosphonothiolate (VX) and many related degradation products produce poorly diagnostic electron ionization (EI) mass spectra by transmission quadrupole mass spectrometry. Thus, chemical ionization (CI) is often used for these analytes. In this work, pseudomolecular ([M+H] + ) ion formation from self-chemical ionization (self-CI) was examined for four VX degradation products containing the diisopropylamine functional group. A person-portable toroidal ion trap mass spectrometer with a gas chromatographic inlet was used with EI, and both fixed-duration and feedback-controlled ionization time. With feedback-controlled ionization, ion cooling (reaction) times and ion formation target values were varied. Evidence for protonation of analytes was observed under all conditions, except for the largest analyte, bis(diisopropylaminoethyl)disulfide which yielded [M+H] + ions only with increased fixed ionization or ion cooling times. Analysis of triethylamine-d 15 provided evidence that [M+H] + production was likely due to self-CI. Analysis of a degraded VX sample where lengthened ion storage and feedback-controlled ionization time were used resulted in detection of [M+H] + ions for VX and several relevant degradation products. Dimer ions were also observed for two phosphonate compounds detected in this sample.

Hyphenation of ultra high performance supercritical fluid chromatography with atmospheric pressure chemical ionisation high resolution mass spectrometry: Part 1. Study of the coupling parameters for the analysis of natural non-polar compounds.

Science.gov (United States)

Duval, Johanna; Colas, Cyril; Pecher, Virginie; Poujol, Marion; Tranchant, Jean-François; Lesellier, Eric

2017-08-04

An analytical method based on Ultra-High-Performance Supercritical Fluid Chromatography (UHPSFC) coupled with Atmospheric Pressure Chemical Ionization - High-resolution mass spectrometry (APCI-Q-TOF-HRMS) was developed for compounds screening from oily samples. The hyphenation was made using a commercial UHPLC device coupled to a CO 2 pump in order to perform the chromatographic analysis. An adaptation of the injection system for compressible fluids was accomplished for this coupling: this modification of the injection sequence was achieved to prevent unusual variations of the injected volume related to the use of a compressible fluid. UHPSFC-HRMS hyphenation was optimized to enhance the response of the varied compounds from a seed extract (anthraquinones, free fatty acids, diacylglycerols, hydroxylated triacylglycerols and triacylglycerols). No split was used prior to the APCI ionization source, allowing introducing all the compounds in the spectrometer, ensuring a better sensitivity for minor compounds. The effects of a mechanical make-up (T-piece) added before this ionization source was discussed in terms of standard deviation of response, response intensity and fragmentation percentage. The location of the T-piece with regards to the backpressure regulator (BPR), the flow rate and the nature of the make-up solvent were studied. Results show that the effects of the studied parameters depend on the nature of the compounds, whereas the make-up addition favours the robustness of the mass response (quantitative aspect). Copyright © 2017 Elsevier B.V. All rights reserved.

The ionizing treatment of food

International Nuclear Information System (INIS)

1998-01-01

This book of proceedings contains the talks given by the members of the Society of chemical experts of France (SECF) and by various specialists of the ionizing treatment during the scientific days of September 25-26, 1997. The aim of this meeting was to reconsider the effects of ionization from a scientific point of view and apart from the polemics generated by this domain. The following topics were discussed successively: source and characterization of a ionizing treatment, biological effects of ionization on food and the expected consequences, the ionizing treatment and the reduction of the vitamin C content of fruits and vegetables, is it safe to eat irradiated food?, the organoleptic modifications of food after ionization, quality assurance of dosimetry measurements in an industrial installation of food ionization, the French and European regulations in food ionization, the detection of irradiated foodstuffs, processed food and complex lipid matrices, sterilization of dishes for immuno-depressed patients using ionization. (J.S.)

Metal-organic frameworks in chromatography.

Science.gov (United States)

Yusuf, Kareem; Aqel, Ahmad; ALOthman, Zeid

2014-06-27

Metal-organic frameworks (MOFs) emerged approximately two decades ago and are the youngest class of porous materials. Despite their short existence, MOFs are finding applications in a variety of fields because of their outstanding chemical and physical properties. This review article focuses on the applications of MOFs in chromatography, including high-performance liquid chromatography (HPLC), gas chromatography (GC), and other chromatographic techniques. The use of MOFs in chromatography has already had a significant impact; however, the utilisation of MOFs in chromatography is still less common than other applications, and the number of MOF materials explored in chromatography applications is limited. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of ionizing radiation in the physico-chemical characteristics of red wine Cabernet Sauvignon

International Nuclear Information System (INIS)

Silva, Fellipe Souza da; Leiras, Anderson; Wagner, Walsan

2014-01-01

The oenology in the current days is increasingly aimed obtain improvements on wine quality produced without there the deterioration of characteristics of the same, using new technologies for such order. The objective of present work will be the application of the radiation ionizing in wines Cabernet Sauvignon, with the interest of analyzing its effects on physic-chemical characteristics of this wines, such as quality, aging and etc. Were analyzed the following strands: degree alcoholic; dry extract; density and absorbance with spectrometer (420, 520 and 620 nm). (author)

Role of ionizing radiation in chemical evolution studies

International Nuclear Information System (INIS)

Albarran, G.; Negron-Mendoza, A.; Trevino, C.; Torres, J.L.

1988-01-01

The purpose of this paper is to emphasize the role of ionizing radiation in radiation-induced reactions in prebiotic chemistry. The use of ionizing radiation as an energy source is based on its unique qualities, its specific manner of energy deposition and its abundance in the Earth's crust. As an example of radiation-induced reactions, the radiolysis of malonic acid was investigated. Malonic acid is converted into other carboxylic acids. The results obtained have been correlated with the ready formation of this compound in prebiotic experiments. (author)

Magnetic covalent triazine framework for rapid extraction of phthalate esters in plastic packaging materials followed by gas chromatography-flame ionization detection.

Science.gov (United States)

Yan, Zijun; He, Man; Chen, Beibei; Gui, Bo; Wang, Cheng; Hu, Bin

2017-11-24

Covalent triazine frameworks (CTFs), featuring with high surface area, good thermal, chemical and mechanical stability, are good adsorbents in sample pretreatment. Herein, magnetic CTFs/Ni composite was prepared by in situ reduction of nickel ions on CTFs matrix with a solvothermal method. The prepared CTFs/Ni composite exhibited good preparation reproducibility, high chemical stability, and high extraction efficiency for targeted phthalate esters (PAEs) due to π-π interaction and hydrophobic effect. The porous structure of CTFs/Ni composite benefited the fast transfer of target PAEs from aqueous solution to the adsorbents, and the integrated magnetism contributed to the rapid separation of adsorbents from sample and elution solution. Based on it, a novel method of magnetic solid phase extraction (MSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the analysis of PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexl phthalate (DEHP), and di-n-octyl phthalate (DNOP) in plastic packaging materials. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) for six PAEs were found to be in the range of 0.024-0.085mg/kg. The linear range was 0.32-16mg/kg for DMP, DEP, 0.08-80mg/kg for DBP, 0.16-32mg/kg for BBP, DEHP, and 0.32-32mg/kg for DNOP, respectively. The enrichment factors ranged from 59 to 88-fold (theoretical enrichment factor was 133-fold). The proposed method was successfully applied to the analysis of PAEs in various plastic packaging materials with recoveries in the range of 70.6-119% for the spiked samples. This method is characterized with short operation time, high sensitivity, low consumption of harmful organic solvents and can be extended to the analysis of other trace aromatic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

A new ultrahigh performance liquid chromatography with diode array detection coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry analytical strategy for fast analysis and improved characterization of phenolic compounds in apple products.

Science.gov (United States)

Ramirez-Ambrosi, M; Abad-Garcia, B; Viloria-Bernal, M; Garmon-Lobato, S; Berrueta, L A; Gallo, B

2013-11-05

A new, rapid, selective and sensitive ultrahigh performance liquid chromatography with diode array detection coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-DAD-ESI-Q-ToF-MS) strategy using automatic and simultaneous acquisition of exact mass at high and low collision energy, MS(E), has been developed to obtain polyphenolic profile of apples, apple pomace and apple juice from Asturian cider apples in a single run injection of 22 min. MS(E) spectral data acquisition overcomes chromatographic co-elution problems, performing simultaneous collection of precursor ions as well as other ions produced as a result of their fragmentation, which allows resolving complex spectra from mixtures of precursor ions in an unsupervised way and eases their interpretation. Using this technique, 52 phenolic compounds of five different classes were readily characterized in these apple extracts in both positive and negative ionization modes. The spectral data for phenolic compounds obtained using this acquisition mode are comparable to those obtained by conventional LC-MS/MS as exemplified in this work. Among the 52 phenolic compounds identified in this work, 2 dihydrochalcones and 3 flavonols have been tentatively identified for the first time in apple products. Moreover, 2 flavanols, 4 dihydrochalcones, 9 hydroxycinnamic acids and 4 flavonols had not been previously reported in apple by ToF analysis to our knowledge. Copyright © 2013 Elsevier B.V. All rights reserved.

Gas chromatography-mass spectrometry with supersonic molecular beams.

Science.gov (United States)

Amirav, Aviv; Gordin, Alexander; Poliak, Marina; Fialkov, Alexander B

2008-02-01

Gas chromatography-mass spectrometry (GC-MS) with supersonic molecular beams (SMBs) (also named Supersonic GC-MS) is based on GC and MS interface with SMBs and on the electron ionization (EI) of vibrationally cold analytes in the SMBs (cold EI) in a fly-through ion source. This ion source is inherently inert and further characterized by fast response and vacuum background filtration capability. The same ion source offers three modes of ionization including cold EI, classical EI and cluster chemical ionization (CI). Cold EI, as a main mode, provides enhanced molecular ions combined with an effective library sample identification, which is supplemented and complemented by a powerful isotope abundance analysis method and software. The range of low-volatility and thermally labile compounds amenable for analysis is significantly increased owing to the use of the contact-free, fly-through ion source and the ability to lower sample elution temperatures through the use of high column carrier gas flow rates. Effective, fast GC-MS is enabled particularly owing to the possible use of high column flow rates and improved system selectivity in view of the enhancement of the molecular ion. This fast GC-MS with SMB can be further improved via the added selectivity of MS-MS, which by itself benefits from the enhancement of the molecular ion, the most suitable parent ion for MS-MS. Supersonic GC-MS is characterized by low limits of detection (LOD), and its sensitivity is superior to that of standard GC-MS, particularly for samples that are hard for analysis. The GC separation of the Supersonic GC-MS can be improved with pulsed flow modulation (PFM) GC x GC-MS. Electron ionization LC-MS with SMB can also be combined with the Supersonic GC-MS, with fast and easy switching between these two modes of operation. (c) 2008 John Wiley & Sons, Ltd.

Ion mobility spectrometric analysis of vaporous chemical warfare agents by the instrument with corona discharge ionization ammonia dopant ambient temperature operation.

Science.gov (United States)

Satoh, Takafumi; Kishi, Shintaro; Nagashima, Hisayuki; Tachikawa, Masumi; Kanamori-Kataoka, Mieko; Nakagawa, Takao; Kitagawa, Nobuyoshi; Tokita, Kenichi; Yamamoto, Soichiro; Seto, Yasuo

2015-03-20

The ion mobility behavior of nineteen chemical warfare agents (7 nerve gases, 5 blister agents, 2 lachrymators, 2 blood agents, 3 choking agents) and related compounds including simulants (8 agents) and organic solvents (39) was comparably investigated by the ion mobility spectrometry instrument utilizing weak electric field linear drift tube with corona discharge ionization, ammonia doping, purified inner air drift flow circulation operated at ambient temperature and pressure. Three alkyl methylphosphonofluoridates, tabun, and four organophosphorus simulants gave the intense characteristic positive monomer-derived ion peaks and small dimer-derived ion peaks, and the later ion peaks were increased with the vapor concentrations. VX, RVX and tabun gave both characteristic positive monomer-derived ions and degradation product ions. Nitrogen mustards gave the intense characteristic positive ion peaks, and in addition distinctive negative ion peak appeared from HN3. Mustard gas, lewisite 1, o-chlorobenzylidenemalononitrile and 2-mercaptoethanol gave the characteristic negative ion peaks. Methylphosphonyl difluoride, 2-chloroacetophenone and 1,4-thioxane gave the characteristic ion peaks both in the positive and negative ion mode. 2-Chloroethylethylsulfide and allylisothiocyanate gave weak ion peaks. The marker ion peaks derived from two blood agents and three choking agents were very close to the reactant ion peak in negative ion mode and the respective reduced ion mobility was fluctuated. The reduced ion mobility of the CWA monomer-derived peaks were positively correlated with molecular masses among structurally similar agents such as G-type nerve gases and organophosphorus simulants; V-type nerve gases and nitrogen mustards. The slope values of the calibration plots of the peak heights of the characteristic marker ions versus the vapor concentrations are related to the detection sensitivity, and within chemical warfare agents examined the slope values for sarin, soman

Chemical Composition of the Essential Oil and Antimicrobial Activity of Scaligeria DC. Taxa and Implications for Taxonomy

Directory of Open Access Journals (Sweden)

Ayşe Baldemir

2018-01-01

Full Text Available Six different Scaligeria DC. taxa (Apiaceae essential oils (EOs obtained by hydrodistillation from herba with the flowers collected from different sites from Turkey. The oils were analyzed and characterized by gas chromatography-flame ionization detector (GC-FID and gas chromatography–mass spectrometry (GC–MS simultaneously. A total of 133 different compounds were identified and relative qualitative and quantitative differences were observed among the evaluated samples. Analytical profiles of the Scaligeria EOs showed characteristic differences in terms of different main chemical constituents, between the two taxa S. lazica Boiss. and S. tripartita (Kalen. Tamamsch; and S. napiformis (Sprengel Grande, S. meifolia (Fenzl Boiss., S. capillifolia Post, S. hermonis Post, S. glaucescens (DC. Boiss. taxa, respectively. The main component germacrene D can be utilized as marker for the chemical discrimination of the Scaligeria genus. In addition, Scaligeria EOs were evaluated in vitro for their antimicrobial activity against pathogenic Gram positive (Staphylococcus aureus and Bacillus cereus, Gram negative (Pseudomonas aeruginosa and yeast (Candida albicans, C. parapsilosis, and C. krusei standard strains by using a micro-dilution assay. As a general result, the oils showed moderate inhibitory range when compared with standard antimicrobial agents.

Analysis of trichloroethylene-induced global DNA hypomethylation in hepatic L-02 cells by liquid chromatography-electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Zhang, Hang; Hong, Wen-Xu; Ye, Jinbo; Yang, Xifei; Ren, Xiaohu; Huang, Aibo; Yang, Linqing; Zhou, Li; Huang, Haiyan; Wu, Desheng; Huang, Xinfeng; Zhuang, Zhixiong; Liu, Jianjun

2014-04-04

Trichloroethylene (TCE), a major occupational and environmental pollutant, has been recently associated with aberrant epigenetic changes in experimental animals and cultured cells. TCE is known to cause severe hepatotoxicity; however, the association between epigenetic alterations and TCE-induced hepatotoxicity are not yet well explored. DNA methylation, catalyzed by enzymes known as DNA methyltransferases (DNMT), is a major epigenetic modification that plays a critical role in regulating many cellular processes. In this study, we analyzed the TCE-induced effect on global DNA methylation and DNMT enzymatic activity in human hepatic L-02 cells. A sensitive and quantitative method combined with liquid chromatography and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was validated and utilized for assessing the altered DNA methylation in TCE-induced L-02 cells. Quantification was accomplished in multiple reaction monitoring (MRM) mode by monitoring a transition pair of m/z 242.1 (molecular ion)/126.3 (fragment ion) for 5-mdC and m/z 268.1/152.3 for dG. The correlation coefficient of calibration curves between 5-mdC and dG was higher than 0.9990. The intra-day and inter-day relative standard derivation values (RSD) were on the range of 0.53-7.09% and 0.40-2.83%, respectively. We found that TCE exposure was able to significantly decrease the DNA methylation and inhibit DNMT activity in L-02 cells. Our results not only reveal the association between TCE exposure and epigenetic alterations, but also provide an alternative mass spectrometry-based method for rapid and accurate assessment of chemical-induced altered DNA methylation in mammal cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Chromatography and mass spectrometry of chemical warfare agents, toxins and related compounds: state of the art and future prospects

NARCIS (Netherlands)

Kientz, C.E.

1998-01-01

Methods for the identification of chemical warfare agents, toxins, bioregulators and related products are frequently reported in literature. These methods are often based on instrumental analysis using chromatography (gas and liquid) and mass spectrometry. Here, these instrumental techniques are

Separation Techniques for Uranium and Plutonium at Trace Levels for the Thermal Ionization Mass Spectrometric Determination

International Nuclear Information System (INIS)

Suh, M. Y.; Han, S. H.; Kim, J. G.; Park, Y. J.; Kim, W. H.

2005-12-01

This report describes the state of the art and the progress of the chemical separation and purification techniques required for the thermal ionization mass spectrometric determination of uranium and plutonium in environmental samples at trace or ultratrace levels. Various techniques, such as precipitation, solvent extraction, extraction chromatography, and ion exchange chromatography, for separation of uranium and plutonium were evaluated. Sample preparation methods and dissolution techniques for environmental samples were also discussed. Especially, both extraction chromatographic and anion exchange chromatographic procedures for uranium and plutonium in environmental samples, such as soil, sediment, plant, seawater, urine, and bone ash were reviewed in detail in order to propose some suitable methods for the separation and purification of uranium and plutonium from the safeguards environmental or swipe samples. A survey of the IAEA strengthened safeguards system, the clean room facility of IAEA's NWAL(Network of Analytical Laboratories), and the analytical techniques for safeguards environmental samples was also discussed here

Separation Techniques for Uranium and Plutonium at Trace Levels for the Thermal Ionization Mass Spectrometric Determination

Energy Technology Data Exchange (ETDEWEB)

Suh, M. Y.; Han, S. H.; Kim, J. G.; Park, Y. J.; Kim, W. H

2005-12-15

This report describes the state of the art and the progress of the chemical separation and purification techniques required for the thermal ionization mass spectrometric determination of uranium and plutonium in environmental samples at trace or ultratrace levels. Various techniques, such as precipitation, solvent extraction, extraction chromatography, and ion exchange chromatography, for separation of uranium and plutonium were evaluated. Sample preparation methods and dissolution techniques for environmental samples were also discussed. Especially, both extraction chromatographic and anion exchange chromatographic procedures for uranium and plutonium in environmental samples, such as soil, sediment, plant, seawater, urine, and bone ash were reviewed in detail in order to propose some suitable methods for the separation and purification of uranium and plutonium from the safeguards environmental or swipe samples. A survey of the IAEA strengthened safeguards system, the clean room facility of IAEA's NWAL(Network of Analytical Laboratories), and the analytical techniques for safeguards environmental samples was also discussed here.

A new temperature effect in ionized media in the presence of heavy negative electrical charges; Sur un nouvel effet de temperature dans des milieux ionises en presence de charges electriques negatives lourdes

Energy Technology Data Exchange (ETDEWEB)

Klein, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-12-01

A relatively large electromotive force appears between two electrodes having different temperatures in an atmosphere of ionized vapours. The theoretical interpretation of this phenomenon is based essentially on the one hand on the massive formation of heavy negative electrical charges near the 'cold' electrode and on the other hand, in the case of flames, on the existence of an electronic temperature much higher than that predicted by conventional theory. This temperature effect makes it possible to convert the ionizing energy directly into electricity. (author) [French] Une force electro-motrice relativement importante apparait dans des vapeurs ionisees entre deux electrodes maintenues a des temperatures differentes. L'interpretation theorique, de ce phenomene est essentiellement basee, d'une part sur la formation massive de charges electriques negatives lourdes pres de l'electrode ''froide'' et, d'autre part, dans le cas des flammes sur l'existence d'une temperature electronique beaucoup plus elevee que celle prevue par la theorie classique. Cet effet de temperature permet de convertir directement l'energie ionisante en electricite. (auteur)

Optimization of the combination micro-high-performance liquid-chromatography/mass spectrometry

International Nuclear Information System (INIS)

Haider, K.

1997-03-01

The coupling of liquid chromatography and mass spectrometry is still growing in significance. In this thesis, a particle beam interface has been investigated for combining ion chromatography with mass spectrometric detection. To introduce the eluent directly (without membrane suppressor) into the spectrometer, only methods with low flow rates like microcolumn chromatography can be used. For the preparation of the columns, reversed-phase and silica-based anion exchange materials were packed into PEEK, steel and fused-silica capillaries with i.d. from 130 to 1000 μm using different methods. The performance of the particle beam interface (modified with a new miniaturized aerosol generator) and the mass spectrometric detection has been studied for a series of inorganic anions as well as aminopolycarboxylic acids and the metal-EDTA complexes. Detection limits between 10 and 100 ng injected could be achieved in the multiple ion detection mode of the mass spectrometer for the investigated solutes. A second type of interface, the direct liquid introduction (DLI) has been used to analyze the priority pollutant phenols. This interface is based on a modified GC-interface into the MS. Separation columns used so far include packed fused-silica capillaries with inner diameter of 75 μm and polystyrene-divinylbenzene (functionalized with tert. butyl groups) as stationary phase. Aspects of instrumentation and effects of chemical ionization in the direct liquid introduction mode are discussed. (author)

Analysis of cocaine and its metabolites from biological specimens using solid-phase extraction and positive ion chemical ionization mass spectrometry.

Science.gov (United States)

Crouch, D J; Alburges, M E; Spanbauer, A C; Rollins, D E; Moody, D E

1995-10-01

An accurate and reliable gas chromatographic-mass spectrometric method was developed to analyze tissue, whole blood, plasma, and urine samples for cocaine (COC) and its major metabolites. COC, benzoylecgonine (BZE), and ecgonine methyl ester (EME) were isolated from the biological matrix using solid-phase extraction, and the tert-butyldimethylsilyl derivatives of BZE, EME, and their deuterium-labeled internal standards were formed. Separation of the compounds was performed by capillary chromatography, and analysis was performed by positive ion chemical ionization mass spectrometry using methane and ammonia as the reagent gases. The tert-butyldimethylsilyl derivatives of BZE and EME were stable and produced mass spectral ions with higher mass-to-charge ratios than trimethylsilyl derivatives. Recovery of COC and its metabolites exceeded 80% at all three concentrations tested. Linearity of the method was established from 2.5 to 2000 microg/L. Intra-assay precision had a coefficient of variation (CV) of less than 9% for all analytes when tested at 10, 25, 100, and 200 microg/L. Interassay precision also had a CV of less than 9% for COC, BZE, and EME at 25 and 100 microg/L. At 200 microg/L, %CVs for COC, BZE, and EME were 11.5, 12.0, and 12.7, respectively. In addition to the analysis of COC, BZE, and EME, the method was used to quantitate cocaethylene and to identify norcocaine.

Advancements in mass spectrometry for biological samples: Protein chemical cross-linking and metabolite analysis of plant tissues

Energy Technology Data Exchange (ETDEWEB)

Klein, Adam [Iowa State Univ., Ames, IA (United States)

2015-01-01

This thesis presents work on advancements and applications of methodology for the analysis of biological samples using mass spectrometry. Included in this work are improvements to chemical cross-linking mass spectrometry (CXMS) for the study of protein structures and mass spectrometry imaging and quantitative analysis to study plant metabolites. Applications include using matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to further explore metabolic heterogeneity in plant tissues and chemical interactions at the interface between plants and pests. Additional work was focused on developing liquid chromatography-mass spectrometry (LC-MS) methods to investigate metabolites associated with plant-pest interactions.

Investigation of Symphytum cordatum alkaloids by liquid-liquid partitioning, thin-layer chromatography and liquid chromatography-ion-trap mass spectrometry

International Nuclear Information System (INIS)

Mroczek, Tomasz; Ndjoko-Ioset, Karine; Glowniak, Kazimierz; Mietkiewicz-Capala, Agnieszka; Hostettmann, Kurt

2006-01-01

From the alkalised crude extract of Symphytum cordatum (L.) W.K. roots, pyrrolizidine alkaloids (PAs) were extracted as free tertiary bases and polar N-oxides in a merely one-step liquid-liquid partitioning (LLP) in separation funnel and subsequently pre-fractionated by preparative multiple-development (MD) thin-layer chromatography (TLC) on silica gel plates. In this way three alkaloid fractions of different polarities and retention on silica gel plates were obtained as: the most polar N-oxides of the highest retention, the tertiary bases of medium retention, and diesterified N-oxides of the lowest retention. The former fraction was reduced into free bases by sodium hydrosulfite and purified by LLP on Extrelut-NT3 cartridge. It was further analysed together with the two other fractions by high-performance liquid chromatography (HPLC)-ion-trap mass spectrometry with atmospheric pressure chemical ionization (APCI) interface on XTerra C 18 column using a gradient elution. Based on MS n spectra, 18 various alkaloids have been tentatively determined for the first time in this plant as the following types of structure: echimidine-N-oxide (three diasteroisomers), 7-sarracinyl-9-viridiflorylretronecine (two diasteroisomers), echimidine (two diasteroisomers), lycopsamine (two diasteroisomers), dihydroechinatine-N-oxide, dihydroheliospathuline-N-oxide, lycopsamine-N-oxide (three diasteroisomers), 7-acetyllycopsamine-N-oxide, symphytine-N-oxide (two diasteroisomers) and 2'',3''-epoxyechiumine-N-oxide

Investigation of Symphytum cordatum alkaloids by liquid-liquid partitioning, thin-layer chromatography and liquid chromatography-ion-trap mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Mroczek, Tomasz [Department of Pharmacognosy with Medicinal Plants Laboratory, Medical University, 1 Chodzki St., 20-093 Lublin (Poland)]. E-mail: tmroczek@pharmacognosy.org; Ndjoko-Ioset, Karine [Laboratoire de Pharmacognosie et Phytochimie, Ecole de Pharmacie Geneve-Lausanne, Universite de Geneve, Quai Ernest-Ansermet 30, CH-1211 Geneva 4 (Switzerland); Glowniak, Kazimierz [Department of Pharmacognosy with Medicinal Plants Laboratory, Medical University, 1 Chodzki St., 20-093 Lublin (Poland); Mietkiewicz-Capala, Agnieszka [Department of Pharmacognosy with Medicinal Plants Laboratory, Medical University, 1 Chodzki St., 20-093 Lublin (Poland); Hostettmann, Kurt [Laboratoire de Pharmacognosie et Phytochimie, Ecole de Pharmacie Geneve-Lausanne, Universite de Geneve, Quai Ernest-Ansermet 30, CH-1211 Geneva 4 (Switzerland)

2006-05-04

From the alkalised crude extract of Symphytum cordatum (L.) W.K. roots, pyrrolizidine alkaloids (PAs) were extracted as free tertiary bases and polar N-oxides in a merely one-step liquid-liquid partitioning (LLP) in separation funnel and subsequently pre-fractionated by preparative multiple-development (MD) thin-layer chromatography (TLC) on silica gel plates. In this way three alkaloid fractions of different polarities and retention on silica gel plates were obtained as: the most polar N-oxides of the highest retention, the tertiary bases of medium retention, and diesterified N-oxides of the lowest retention. The former fraction was reduced into free bases by sodium hydrosulfite and purified by LLP on Extrelut-NT3 cartridge. It was further analysed together with the two other fractions by high-performance liquid chromatography (HPLC)-ion-trap mass spectrometry with atmospheric pressure chemical ionization (APCI) interface on XTerra C{sub 18} column using a gradient elution. Based on MS {sup n} spectra, 18 various alkaloids have been tentatively determined for the first time in this plant as the following types of structure: echimidine-N-oxide (three diasteroisomers), 7-sarracinyl-9-viridiflorylretronecine (two diasteroisomers), echimidine (two diasteroisomers), lycopsamine (two diasteroisomers), dihydroechinatine-N-oxide, dihydroheliospathuline-N-oxide, lycopsamine-N-oxide (three diasteroisomers), 7-acetyllycopsamine-N-oxide, symphytine-N-oxide (two diasteroisomers) and 2'',3''-epoxyechiumine-N-oxide.

Pentafluorobenzyl bromide-A versatile derivatization agent in chromatography and mass spectrometry: I. Analysis of inorganic anions and organophosphates.

Science.gov (United States)

Tsikas, Dimitrios

2017-02-01

Pentafluorobenzyl bromide (PFB-Br) is a versatile derivatization agent. It is widely used in chromatography and mass spectrometry since several decades. The bromide atom is largely the single leaving group of PFB-Br. It is substituted by wide a spectrum of nucleophiles in aqueous and non-aqueous systems to form electrically neutral, in most organic solvents soluble, generally thermally stable, volatile, strongly electron-capturing and ultraviolet light-absorbing derivatives. Because of these greatly favoured physicochemical properties, PFB-Br emerged an ideal derivatization agent for highly sensitive analysis of endogenous and exogenous substances including various inorganic and organic anions by electron capture detection or after electron-capture negative-ion chemical ionization in GC-MS. The present article attempts an appraisal of the utility of PFB-Br in analytical chemistry. It reviews and discusses papers dealing with the use of PFB-Br as the derivatization reagent in the qualitative and quantitative analysis of endogenous and exogenous inorganic anions in various biological samples, notably plasma, urine and saliva. These analytes include nitrite, nitrate, cyanide and dialkyl organophosphates. Special emphasis is given to mass spectrometry-based approaches and stable-isotope dilution techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical characterisation of non-defective and defective green arabica and robusta coffees by electrospray ionization-mass spectrometry (ESI-MS).

Science.gov (United States)

Mendonça, Juliana C F; Franca, Adriana S; Oliveira, Leandro S; Nunes, Marcella

2008-11-15

The coffee roasted in Brazil is considered to be of low quality, due to the presence of defective coffee beans that depreciate the beverage quality. These beans, although being separated from the non-defective ones prior to roasting, are still commercialized in the coffee trading market. Thus, it was the aim of this work to verify the feasibility of employing ESI-MS to identify chemical characteristics that will allow the discrimination of Arabica and Robusta species and also of defective and non-defective coffees. Aqueous extracts of green (raw) defective and non-defective coffee beans were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS) and this technique provided characteristic fingerprinting mass spectra that not only allowed for discrimination of species but also between defective and non-defective coffee beans. ESI-MS profiles in the positive mode (ESI(+)-MS) provided separation between defective and non-defective coffees within a given species, whereas ESI-MS profiles in the negative mode (ESI(-)-MS) provided separation between Arabica and Robusta coffees. Copyright © 2008 Elsevier Ltd. All rights reserved.

Regioisomeric analysis of triacylglycerols using silver-ion liquid chromatography-atmospheric pressure chemical ionization mass spectrometry: Comparison of five different mass analyzers

Czech Academy of Sciences Publication Activity Database

Holčapek, M.; Dvořáková, H.; Lísa, M.; Girón, A. J.; Sandra, P.; Cvačka, Josef

2010-01-01

Roč. 1217, č. 52 (2010), s. 8186-8194 ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional research plan: CEZ:AV0Z40550506 Keywords : triacylglycerols * silver-ion liquid chromatography * regioisomer * HPLC/MS * APCI Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.194, year: 2010

Identification of chemical components in Baidianling Capsule based on gas chromatography-mass spectrometry and high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry.

Science.gov (United States)

Wu, Wenying; Chen, Yu; Wang, Binjie; Sun, Xiaoyang; Guo, Ping; Chen, Xiaohui

2017-08-01

Baidianling Capsule, which is made from 16 Chinese herbs, has been widely used for treating vitiligo clinically. In this study, the sensitive and rapid method has been developed for the analysis of chemical components in Baidianling Capsule by gas chromatography-mass spectrometry in combination with retention indices and high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry. Firstly, a total of 110 potential volatile compounds obtained from different extraction procedures including alkanes, alkenes, alkynes, ketones, ethers, aldehydes, alcohols, phenols, organic acids, esters, furans, pyrrole, acid amides, heterocycles, and oxides were detected from Baidianling Capsule by gas chromatography-mass spectrometry, of which 75 were identified by mass spectrometry in combination with the retention index. Then, a total of 124 components were tentatively identified by high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry. Fifteen constituents from Baidianling Capsule were accurately identified by comparing the retention times with those of reference compounds, others were identified by comparing the retention times and mass spectrometry data, as well as retrieving the reference literature. This study provides a practical strategy for rapidly screening and identifying the multiple constituents of a complex traditional Chinese medicine. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of Cocaine Detections in Corona Discharge Ionization-Ion Mobility Spectrometry and in Atmospheric Pressure Chemical Ionization-Mass Spectrometry

International Nuclear Information System (INIS)

Choi, Sung Seen; Kim, Yun Ki; Kim, Ok Bae; An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop

2010-01-01

In this study, we determined the detection limit and reproducibility of the new IMS equipped with corona discharge ionization source using cocaine. The sample was injected with liquid solution to compare the results of APCI-MS. Ion mobility spectrometry (IMS) was a technique originally applied for the detection of trace compounds. IMS has been widely used to detect chemical warfare agents, explosives, and illegal drugs since it combines both high sensitivity (detection limits down to the ng/L range to pg/L range, ppb range and ppt range) and relatively low technical expenditure with high-speed data acquisition. The time required to acquire a single spectrum is in the range of several tens ms. The working principle is based on the drift of ions at ambient pressure under the influence of an external electric field

Comparison of Cocaine Detections in Corona Discharge Ionization-Ion Mobility Spectrometry and in Atmospheric Pressure Chemical Ionization-Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Choi, Sung Seen; Kim, Yun Ki; Kim, Ok Bae [Sejong University, Seoul (Korea, Republic of); An, Seung Geon; Shin, Myung Won; Maeng, Seug Jin; Choi, Gyu Seop [Wooju Communication and Technology Co., Seoul (Korea, Republic of)

2010-08-15

In this study, we determined the detection limit and reproducibility of the new IMS equipped with corona discharge ionization source using cocaine. The sample was injected with liquid solution to compare the results of APCI-MS. Ion mobility spectrometry (IMS) was a technique originally applied for the detection of trace compounds. IMS has been widely used to detect chemical warfare agents, explosives, and illegal drugs since it combines both high sensitivity (detection limits down to the ng/L range to pg/L range, ppb range and ppt range) and relatively low technical expenditure with high-speed data acquisition. The time required to acquire a single spectrum is in the range of several tens ms. The working principle is based on the drift of ions at ambient pressure under the influence of an external electric field.

Virtual quantification of metabolites by capillary electrophoresis-electrospray ionization-mass spectrometry: predicting ionization efficiency without chemical standards.

Science.gov (United States)

Chalcraft, Kenneth R; Lee, Richard; Mills, Casandra; Britz-McKibbin, Philip

2009-04-01

A major obstacle in metabolomics remains the identification and quantification of a large fraction of unknown metabolites in complex biological samples when purified standards are unavailable. Herein we introduce a multivariate strategy for de novo quantification of cationic/zwitterionic metabolites using capillary electrophoresis-electrospray ionization-mass spectrometry (CE-ESI-MS) based on fundamental molecular, thermodynamic, and electrokinetic properties of an ion. Multivariate calibration was used to derive a quantitative relationship between the measured relative response factor (RRF) of polar metabolites with respect to four physicochemical properties associated with ion evaporation in ESI-MS, namely, molecular volume (MV), octanol-water distribution coefficient (log D), absolute mobility (mu(o)), and effective charge (z(eff)). Our studies revealed that a limited set of intrinsic solute properties can be used to predict the RRF of various classes of metabolites (e.g., amino acids, amines, peptides, acylcarnitines, nucleosides, etc.) with reasonable accuracy and robustness provided that an appropriate training set is validated and ion responses are normalized to an internal standard(s). The applicability of the multivariate model to quantify micromolar levels of metabolites spiked in red blood cell (RBC) lysates was also examined by CE-ESI-MS without significant matrix effects caused by involatile salts and/or major co-ion interferences. This work demonstrates the feasibility for virtual quantification of low-abundance metabolites and their isomers in real-world samples using physicochemical properties estimated by computer modeling, while providing deeper insight into the wide disparity of solute responses in ESI-MS. New strategies for predicting ionization efficiency in silico allow for rapid and semiquantitative analysis of newly discovered biomarkers and/or drug metabolites in metabolomics research when chemical standards do not exist.

Comparison of the Chemical Composition of “Cystoseira sedoides (Desfontaines C. Agardh” Volatile Compounds Obtained by Different Extraction Techniques

Directory of Open Access Journals (Sweden)

Naima Bouzidi

2016-01-01

Full Text Available The volatile fraction of the brown alga Cystoseira sedoides (Desfontaines C.Agardh is prepared from the crude extract through the following three extraction methods: Hydrodistillation (HD, focused microwave assisted hydrodistillation (FMAHD and supercritical fluid extraction (SFE. The volatile fractions are analyzed by gas chromatography-flame ionization detector-mass spectrometry (GC-FID-MS, the chemical components are identified on the basis of the comparison of their retention indices with literature and their mass spectra with those reported in commercial databases. The chemical composition of the volatile fractions obtained by different extraction techniques fall into three major chemical classes: fatty acids and derivatives, sesquiterpenes, and hydrocarbons and derivatives. Others Compounds belonging to different chemical classes are found in that chemical composition.

The characterization of petroleum and creosote-contaminated soils: Class component analysis by thin layer chromatography with flame ionization detection

International Nuclear Information System (INIS)

Pollard, S.J.T.; Hrudey, S.E.; Fuhr, B.J.; Alex, R.F.; Holloway, L.R.

1992-01-01

The assessment and reclamation of coal tar, creosote and petroleum-contaminated sites is emerging as a major challenge to industry and the federal and provincial Canadian governments. Contaminants frequently include polynuclear aromatic compounds (PAH), several high molecular weight analogues of which are documented carcinogens. Adaptation of thin layer chromatography with flame ionization detection for the analysis of hydrocarbon-contaminated soils is described. The method is directly applicable to the analysis of oily waste extracts from petroleum and creosote wood preservative site soils and is capable of distinguishing between the saturate, aromatic and polar components of waste residues. The method provides a rapid, low cost class component analysis of heavy hydrocarbon waste extracts and is particularly useful for estimating the extent of weathering experienced by chronically exposed hydrocarbon wastes in the soil environment. As such, it is useful as a screening tool for a preliminary assessment of the biotreatability or inherent recalcitrance of hydrocarbon waste mixtures. 11 refs., 5 figs

Recent advancements in sputter-type heavy negative ion sources

International Nuclear Information System (INIS)

Alton, G.D.

1989-01-01

Significant advancement have been made in sputter-type negative ion sources which utilize direct surface ionization, or a plasma to form the positive ion beam used to effect sputtering of samples containing the material of interest. Typically, such sources can be used to generate usable beam intensities of a few μA to several mA from all chemically active elements, depending on the particular source and the electron affinity of the element in question. The presentation will include an introduction to the fundamental processes underlying negative ion formation by sputtering from a low work function surface and several sources will be described which reflect the progress made in this technology. 21 refs., 9 figs., 1 tab

Low level ionizing radiation and human mortality: multi-regional epidemiological studies

International Nuclear Information System (INIS)

Hickey, R.J.; Bowers, E.J.; Spence, D.E.; Zemel, B.S.; Clelland, A.B.; Clelland, R.C.

1981-01-01

Analyses of relationships involving environmental chemicals, background radiation, and mortality rates for diseases of the heart and several cancer categories are presented. Bivariate correlation coefficients between radiation and mortality rate were significantly negative for cancer of the lung and respiratory organs, cancer of the buccal cavity and pharynx, cancer of the digestive organs and peritoneum, total cancer and diseases of the heart. Only the correlation coefficient between background radiation and leukemia-aleukemia was positive, and that not significantly positive. Initial multivariate statistical studies support the bivariate results in that all significant regression terms that represent background radiation have been negative. Background radiation level was not a significant predictor for leukemia-aleukemia mortality rate when examined without regard to age. This preliminary work suggests that any health effects of background radiation on the diseases studied do not exceed in magnitude those of environmental chemicals. It also suggests that models implying important long-term deleterious effects of low levels of ionizing radiation on humans may be invalid. (author)

Development of a liquid chromatography-electrospray chemical ionization tandem mass spectrometry analytical method for analysis of eleven hydroxylated polybrominated diphenyl ethers.

Science.gov (United States)

Feo, Maria Luisa; Barón, Enrique; Aga, Diana S; Eljarrat, Ethel; Barceló, Damià

2013-08-02

Recently, hydroxylated polybrominated diphenyl ethers (OH-PBDEs) have emerged as environmentally relevant pollutants due to recent reports of their natural production and metabolism. Recent mechanistic studies in human and rats have shown that some OH-PBDEs are more potent than parent compounds (PBDEs) and may contribute substantially to neurodevelopmental disorders by direct neurotoxicity, or indirectly through altered thyroid disruption. However, analytical methodologies for determination of OH-PBDEs are currently limited. In this study a robust liquid chromatography-electrospray tandem triple quadrupole-linear ion trap mass spectrometer (LC-ESI-QqLIT-MS-MS) in negative mode method was developed for the determination of eleven OH-tri- to OH-hexa-PBDEs. Two different columns were tested and compared for chromatographic separation: a C18 BetaBasic and a Purospher STAR RP 18, working at pH 8 and 10, respectively. Mobile phase (acetonitrile:water) was optimized by changing the pH of the aqueous phase and the concentration of the organic modifier (methanol). The MS-MS parameters (declustering potential (DP), collision energy (CE) and cell exit potential (CXP)) were optimized. Selected reaction monitoring (SRM) was used in order to increase sensitivity. Two SRM transitions ([M-H](-)>[Br](-)) were selected for each OH-PBDE, one for quantification and the second one for confirmation. Under the optimized conditions, the instrumental limits of detection were between 0.17 and 0.72injectedpg. The method provided good linearity (r>0.99 for a concentration range of 0.30-100ng/mL), accuracy and precision (%Dev and %RSD≤20% for intra- and inter-assays). Copyright © 2013 Elsevier B.V. All rights reserved.

Prediction of aged red wine aroma properties from aroma chemical composition. Partial least squares regression models.

Science.gov (United States)

Aznar, Margarita; López, Ricardo; Cacho, Juan; Ferreira, Vicente

2003-04-23

Partial least squares regression (PLSR) models able to predict some of the wine aroma nuances from its chemical composition have been developed. The aromatic sensory characteristics of 57 Spanish aged red wines were determined by 51 experts from the wine industry. The individual descriptions given by the experts were recorded, and the frequency with which a sensory term was used to define a given wine was taken as a measurement of its intensity. The aromatic chemical composition of the wines was determined by already published gas chromatography (GC)-flame ionization detector and GC-mass spectrometry methods. In the whole, 69 odorants were analyzed. Both matrixes, the sensory and chemical data, were simplified by grouping and rearranging correlated sensory terms or chemical compounds and by the exclusion of secondary aroma terms or of weak aroma chemicals. Finally, models were developed for 18 sensory terms and 27 chemicals or groups of chemicals. Satisfactory models, explaining more than 45% of the original variance, could be found for nine of the most important sensory terms (wood-vanillin-cinnamon, animal-leather-phenolic, toasted-coffee, old wood-reduction, vegetal-pepper, raisin-flowery, sweet-candy-cacao, fruity, and berry fruit). For this set of terms, the correlation coefficients between the measured and predicted Y (determined by cross-validation) ranged from 0.62 to 0.81. Models confirmed the existence of complex multivariate relationships between chemicals and odors. In general, pleasant descriptors were positively correlated to chemicals with pleasant aroma, such as vanillin, beta damascenone, or (E)-beta-methyl-gamma-octalactone, and negatively correlated to compounds showing less favorable odor properties, such as 4-ethyl and vinyl phenols, 3-(methylthio)-1-propanol, or phenylacetaldehyde.

Antimicrobial activity and chemical composition of the essential oils of Portuguese Foeniculum vulgare fruits.

Science.gov (United States)

Mota, Ana S; Martins, M Rosário; Arantes, Sílvia; Lopes, Violeta R; Bettencourt, Eliseu; Pombal, Sofia; Gomes, Arlindo C; Silva, Lúcia A

2015-04-01

The aim of this study was to investigate the chemical composition and antimicrobial activity of essential oils obtained by hydrodistillation from fruits of six fennel accessions collected from wild populations occurring in the centre and south of Portugal. Composition of essential oils was established by Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The obtained yields of the essential oils were found to vary greatly in the range of 1.1 to 2.9% (v/w) and the chemical composition varied with the region of collection. A total of 16 compounds were identified. The main compounds were fenchone (16.9 - 34.7%), estragole (2.5 - 66.0%) and trans-anethole (7.9 - 77.7%). The percentages of these three main compounds were used to determine the relationship between the different oil samples and to group them into four different chemotypes: anethole/fenchone; anethole; estragole and anethole/estragole. Antifungal activity of essential oils was evaluated against six food spoilage fungi: Aspergillus niger, A. japonicus, A. oryzae, Fusarium oxysporum, Rhizophus oryzae and R. stolonifer. Antibacterial activity was assessed against three Gram-positive strains: Enterococcus faecalis ATCC 29212, Staphylococcus epidermidis ATCC 12228 and S. aureus ATCC 28213; and against six Gram-negative strains: Escherichia coli ATCC 25922; Morganella morganii LFG 08; Proteus mirabilis LFG 04; Salmonella enteritidis LFG 05; S. entiritidis serovar typhimurium LFG 06 and Pseudomonas aeruginosa ATCC 27853 by the disc diffusion agar method; the minimal inhibitory concentration (MIC) was determined using the broth macro-dilution method. The MIC values varied from 62.5 (E. coli ATCC 25922) to 2000 µmL (P. aeruginosa ATCC 27853).

Liquid chromatography coupled to different atmospheric pressure ionization sources-quadrupole-time-of-flight mass spectrometry and post-column addition of metal salt solutions as a powerful tool for the metabolic profiling of Fusarium oxysporum.

Science.gov (United States)

Cirigliano, Adriana M; Rodriguez, M Alejandra; Gagliano, M Laura; Bertinetti, Brenda V; Godeas, Alicia M; Cabrera, Gabriela M

2016-03-25

Fusarium oxysporum L11 is a non-pathogenic soil-borne fungal strain that yielded an extract that showed antifungal activity against phytopathogens. In this study, reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to different atmospheric pressure ionization sources-quadrupole-time-of-flight mass spectrometry (API-QTOF-MS) was applied for the comprehensive profiling of the metabolites from the extract. The employed sources were electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). Post-column addition of metal solutions of Ca, Cu and Zn(II) was also tested using ESI. A total of 137 compounds were identified or tentatively identified by matching their accurate mass signals, suggested molecular formulae and MS/MS analysis with previously reported data. Some compounds were isolated and identified by NMR. The extract was rich in cyclic peptides like cyclosporins, diketopiperazines and sansalvamides, most of which were new, and are reported here for the first time. The use of post-column addition of metals resulted in a useful strategy for the discrimination of compound classes since specific adducts were observed for the different compound families. This technique also allowed the screening for compounds with metal binding properties. Thus, the applied methodology is a useful choice for the metabolic profiling of extracts and also for the selection of metabolites with potential biological activities related to interactions with metal ions. Copyright © 2015 Elsevier B.V. All rights reserved.

Explosives vapour identification in ion mobility spectrometry using a tunable laser ionization source: a comparison with conventional 63Ni ionization

International Nuclear Information System (INIS)

Clark, A.; Deas, R.M.; Kosmidis, C.; Ledingham, K.W.D.; Marshall, A.; Singhal, R.P.

1995-01-01

Laser multiphoton ionization (MPI) is used to produce ions from explosive vapours at atmospheric pressure in air for analysis by ion mobility spectrometry (IMS). In the positive ion mode of detection, NO + ions, generated directly by multiphoton dissociation/ionization of the explosive compounds, show strong variation with laser wavelength. This provides a means of identifying the presence of nitro-containing compounds. Moreover, electrons formed in the MPI of gaseous components in the air carrier stream, primarily O 2 , are transferred via neutral molecular oxygen (O 2 ) to trace explosive vapour, forming negative ions which give rise to characteristic and identifiable ion mobility spectra. Further, negative ion mobility spectra of several explosive vapours are presented using conventional 63 Ni ionization and are compared qualitatively with the laser ionization approach. (author)

Analysis of human plasma metabolites across different liquid chromatography/mass spectrometry platforms: Cross-platform transferable chemical signatures.

Science.gov (United States)

Telu, Kelly H; Yan, Xinjian; Wallace, William E; Stein, Stephen E; Simón-Manso, Yamil

2016-03-15

The metabolite profiling of a NIST plasma Standard Reference Material (SRM 1950) on different liquid chromatography/mass spectrometry (LC/MS) platforms showed significant differences. Although these findings suggest caution when interpreting metabolomics results, the degree of overlap of both profiles allowed us to use tandem mass spectral libraries of recurrent spectra to evaluate to what extent these results are transferable across platforms and to develop cross-platform chemical signatures. Non-targeted global metabolite profiles of SRM 1950 were obtained on different LC/MS platforms using reversed-phase chromatography and different chromatographic scales (conventional HPLC, UHPLC and nanoLC). The data processing and the metabolite differential analysis were carried out using publically available (XCMS), proprietary (Mass Profiler Professional) and in-house software (NIST pipeline). Repeatability and intermediate precision showed that the non-targeted SRM 1950 profiling was highly reproducible when working on the same platform (relative standard deviation (RSD) HPLC, UHPLC and nanoLC) on the same platform. A substantial degree of overlap (common molecular features) was also found. A procedure to generate consistent chemical signatures using tandem mass spectral libraries of recurrent spectra is proposed. Different platforms rendered significantly different metabolite profiles, but the results were highly reproducible when working within one platform. Tandem mass spectral libraries of recurrent spectra are proposed to evaluate the degree of transferability of chemical signatures generated on different platforms. Chemical signatures based on our procedure are most likely cross-platform transferable. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.

About particular use of ionizing radiations

International Nuclear Information System (INIS)

2001-01-01

Different uses of ionizing radiations are reviewed: tracers techniques, nuclear gauges, dating by carbon 14, silica doping, use of gamma irradiation for the density measurement in civil engineering, use of a electron capture detector to study by gas chromatography chlorinated contaminants in environment, neutron activation as environmental gauge, analysis of lead in paint and pollutants in ground and dusts, help for work of art valuation by x spectrometry. (N.C.)

Chemical characterization using gas chromatography/mass spectrometry of two extracts from Phyllanthus orbicularis HBK

International Nuclear Information System (INIS)

Gutierrez Gaiten, Yamilet Irene; Miranda Martinez, Migdalia; Bello Alarcon, Adonis

2011-01-01

The objective of this paper was the chemical characterization of two extracts from Phyllanthus orbicularis HBK through gas chromatography/mass spectrometry. To this end, maceration with N-hexane and ethyl acetate was used to obtain the respective extracts. The study of the hexane extract identified 17 components in which hydrocarbonate structures prevailed, mainly cyclooctacosane. In the ethyl acetate extract, 19 compounds were detected, being the terpenoids the predominant, although the most abundant was sterol g-sitosterol. For the first time, the identified compounds are reported for this species

Determination of acrylamide in Chinese traditional carbohydrate-rich foods using gas chromatography with micro-electron capture detector and isotope dilution liquid chromatography combined with electrospray ionization tandem mass spectrometry

International Nuclear Information System (INIS)

Zhang Yu; Ren Yiping; Zhao Hangmei; Zhang Ying

2007-01-01

The present study developed two analytical methods for quantification of acrylamide in complex food matrixes, such as Chinese traditional carbohydrate-rich foods. One is based on derivatization with potassium bromate and potassium bromide without clean-up prior to gas chromatography with micro-electron capture detector (GC-MECD). Alternatively, the underivatized acrylamide was detected by high-performance liquid chromatography coupled to quadrupole tandem mass spectrometry (HPLC-MS/MS) in the positive electrospray ionization mode. For both methods, the Chinese carbohydrate-rich samples were homogenized, defatted with petroleum ether and extracted with aqueous solution of sodium chloride. Recovery rates for acrylamide from spiked Chinese style foods with the spiking level of 50, 500 and 1000 μg kg -1 were in the range of 79-93% for the GC-MECD including derivatization and 84-97% for the HPLC-MS/MS method. Typical quantification limits of the HPLC-MSMS method were 4 μg kg -1 for acrylamide. The GC-MECD method achieved quantification limits of 10 μg kg -1 in Chinese style foods. Thirty-eight Chinese traditional foods purchased from different manufacturers were analyzed and compared with four Western style foods. Acrylamide contaminant was found in all of samples at the concentration up to 771.1 and 734.5 μg kg -1 detected by the GC and HPLC method, respectively. The concentrations determined with the two different quantitative methods corresponded well with each other. A convenient and fast pretreatment procedure will be optimized in order to satisfy further investigation of hundreds of samples

Ionization detectors, ch. 3

International Nuclear Information System (INIS)

Sevcik, J.

1976-01-01

Most measuring devices used in gas chromatography consist of detectors that measure the ionization current. The process is based on the collision of a moving high-energy particle with a target particle that is ionised while an electron is freed. The discussion of the conditions of the collision reaction, the properties of the colliding particles, and the intensity of the applied field point to a unified classification of ionisation detectors. Radioactive sources suitable for use in these detectors are surveyed. The slow-down mechanism, recombination and background current effect are discussed

Quantitative correlations between collision induced dissociation mass spectrometry coupled with electrospray ionization or atmospheric pressure chemical ionization mass spectrometry - Experiment and theory

Science.gov (United States)

Ivanova, Bojidarka; Spiteller, Michael

2018-04-01

The problematic that we consider in this paper treats the quantitative correlation model equations between experimental kinetic and thermodynamic parameters of coupled electrospray ionization (ESI) mass spectrometry (MS) or atmospheric pressure chemical ionization (APCI) mass spectrometry with collision induced dissociation mass spectrometry, accounting for the fact that the physical phenomena and mechanisms of ESI- and APCI-ion formation are completely different. There are described forty two fragment reactions of three analytes under independent ESI- and APCI-measurements. The developed new quantitative models allow us to study correlatively the reaction kinetics and thermodynamics using the methods of mass spectrometry, which complementary application with the methods of the quantum chemistry provide 3D structural information of the analytes. Both static and dynamic quantum chemical computations are carried out. The object of analyses are [2,3-dimethyl-4-(4-methyl-benzoyl)-2,3-di-p-tolyl-cyclobutyl]-p-tolyl-methanone (1) and the polycyclic aromatic hydrocarbons derivatives of dibenzoperylen (2) and tetrabenzo [a,c,fg,op]naphthacene (3), respectively. As far as (1) is known to be a product of [2π+2π] cycloaddition reactions of chalcone (1,3-di-p-tolyl-propenone), however producing cyclic derivatives with different stereo selectivity, so that the study provide crucial data about the capability of mass spectrometry to provide determine the stereo selectivity of the analytes. This work also first provides quantitative treatment of the relations '3D molecular/electronic structures'-'quantum chemical diffusion coefficient'-'mass spectrometric diffusion coefficient', thus extending the capability of the mass spectrometry for determination of the exact 3D structure of the analytes using independent measurements and computations of the diffusion coefficients. The determination of the experimental diffusion parameters is carried out within the 'current monitoring method

Urinary metabolomic profiling in rats exposed to dietary di(2-ethylhexyl) phthalate (DEHP) using ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS).

Science.gov (United States)

Dong, Xinwen; Zhang, Yunbo; Dong, Jin; Zhao, Yue; Guo, Jipeng; Wang, Zhanju; Liu, Mingqi; Na, Xiaolin; Wang, Cheng

2017-07-01

Di(2-ethylhexyl) phthalate (DEHP) is an omnipresent environmental chemical with widespread nonoccupational human exposure through multiple ways. Although considerable efforts have been invested to investigate mechanisms of DEHP toxicity, the key metabolic biomarkers of DEHP toxicity remain to be identified. The aim of this study was to assess the urinary metabonomics of dietary DEHP in rats using the technique of ultra-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UPLC/Q-TOF-MS). Fourteen female Wistar rats were divided into two groups and given increasing dietary doses of DEHP for 30 consecutive days. The urinary metabolite profile was studied using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) enabled clusters to be clearly separated. Eleven principal urinary metabolites were identified as contributing to the clusters. The clusters in the positive electrospray ionization (ESI) mode were xanthurenic acid, kynurenic acid, nonate, N6-methyladenosine, and L-isoleucyl-L-proline. The clusters in the negative ESI mode were hippuric acid, tetrahydrocortisol, citric acid, phenylpropionylglycine, cPA(18:2(9Z, 12Z)/0:0), and LysoPC(14:1(9Z)). The urinary metabonomic changes indicated that exposure to dietary DEHP can affect energy-related metabolism, liver and renal function, fatty acid metabolism, and cause DNA damage in rats. The findings of this study on the urinary metabolites and metabolic pathways of DEHP may form the basis for future studies on the mechanisms of toxicity of this commonly found environmental chemical.

Ion-Exchange Chromatography: Basic Principles and Application.

Science.gov (United States)

Cummins, Philip M; Rochfort, Keith D; O'Connor, Brendan F

2017-01-01

Ion-Exchange Chromatography (IEC) allows for the separation of ionizable molecules on the basis of differences in charge properties. Its large sample-handling capacity, broad applicability (particularly to proteins and enzymes), moderate cost, powerful resolving ability, and ease of scale-up and automation have led to it becoming one of the most versatile and widely used of all liquid chromatography (LC) techniques. In this chapter, we review the basic principles of IEC, as well as the broader criteria for selecting IEC conditions. By way of further illustration, we outline basic laboratory protocols to partially purify a soluble serine peptidase from bovine whole brain tissue, covering crude tissue extract preparation through to partial purification of the target enzyme using anion-exchange chromatography. Protocols for assaying total protein and enzyme activity in both pre- and post-IEC fractions are also described.

High-performance liquid chromatography on-line coupled to high-field NMR and mass spectrometry for structure elucidation of constituents of Hypericum perforatum L

DEFF Research Database (Denmark)

Hansen, S. H.; Jensen, A. G.; Cornett, Claus

1999-01-01

The on-line separation and structure elucidation of naphthodianthrones, flavonoids, and other constituents of an extract from Hypericum perforatum L, using high performance liquid chromatography (HPLC) coupled on-line with ultraviolet-visible, nuclear magnetic resonance (NMR), and mass spectrometry...... (MS) is described. A conventional reversed-phase HPLC system using ammonium acetate as the buffer substance in the eluent tvas used, and proton NMR spectra were obtained on a 500 MHz NMR instrument. The MS and MS/MS analyses were performed using negative electrospray ionization, In the present study...

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.

Rapid, simple, and highly sensitive analysis of drugs in biological samples using thin-layer chromatography coupled with matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Kuwayama, Kenji; Tsujikawa, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Iwata, Yuko T; Inoue, Hiroyuki

2012-01-01

Rapid and precise identification of toxic substances is necessary for urgent diagnosis and treatment of poisoning cases and for establishing the cause of death in postmortem examinations. However, identification of compounds in biological samples using gas chromatography and liquid chromatography coupled with mass spectrometry entails time-consuming and labor-intensive sample preparations. In this study, we examined a simple preparation and highly sensitive analysis of drugs in biological samples such as urine, plasma, and organs using thin-layer chromatography coupled with matrix-assisted laser desorption/ionization mass spectrometry (TLC/MALDI/MS). When the urine containing 3,4-methylenedioxymethamphetamine (MDMA) without sample dilution was spotted on a thin-layer chromatography (TLC) plate and was analyzed by TLC/MALDI/MS, the detection limit of the MDMA spot was 0.05 ng/spot. The value was the same as that in aqueous solution spotted on a stainless steel plate. All the 11 psychotropic compounds tested (MDMA, 4-hydroxy-3-methoxymethamphetamine, 3,4-methylenedioxyamphetamine, methamphetamine, p-hydroxymethamphetamine, amphetamine, ketamine, caffeine, chlorpromazine, triazolam, and morphine) on a TLC plate were detected at levels of 0.05-5 ng, and the type (layer thickness and fluorescence) of TLC plate did not affect detection sensitivity. In addition, when rat liver homogenate obtained after MDMA administration (10 mg/kg) was spotted on a TLC plate, MDMA and its main metabolites were identified using TLC/MALDI/MS, and the spots on a TLC plate were visualized by MALDI/imaging MS. The total analytical time from spotting of intact biological samples to the output of analytical results was within 30 min. TLC/MALDI/MS enabled rapid, simple, and highly sensitive analysis of drugs from intact biological samples and crude extracts. Accordingly, this method could be applied to rapid drug screening and precise identification of toxic substances in poisoning cases and

Effects of fires on the chemical and petrographic composition of peat in the Snuggedy Swamp, South Carolina

Energy Technology Data Exchange (ETDEWEB)

Rollins, M S; Cohen, A D; Durig, J R [South Carolina University, Columbia, SC (USA). Dept. of Chemistry

1993-04-01

Charcoal-rich zones in a peat core from the Snuggedy Swamp in South Carolina were investigated to determine the chemical and physical changes associated with fires. Petrographic analyses of microtome thin sections revealed that three charcoal zones were present in the core and that the fires causing such zones were severe enough to penetrate into the subsurface and burn some of the peat. Despite these severe fires, only minor changes in the botanical composition occurred throughout the history of the study site, suggesting that these fires were not extensive enough to retard recolonization of the site from nearby unburned areas. Pyrolysis gas chromatography/Fourier transform infrared/flame ionization detection and pyrolysis gas chromatography/mass spectrometry studies reveal distinct organic chemical changes in the peat that can be related to the fires. Decreases in aliphatic and cellulose compounds mirrored increases in charcoal abundance; while aromatic, lignin-related compounds increased as charcoal increased. 44 refs., 8 figs., 1 tab.

Measurement of the first ionization potential of astatine by laser ionization spectroscopy

Science.gov (United States)

Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.

2013-01-01

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620

Comprehensive Characterization of Extractable and Nonextractable Phenolic Compounds by High-Performance Liquid Chromatography-Electrospray Ionization-Quadrupole Time-of-Flight of a Grape/Pomegranate Pomace Dietary Supplement.

Science.gov (United States)

Pérez-Ramírez, Iza F; Reynoso-Camacho, Rosalía; Saura-Calixto, Fulgencio; Pérez-Jiménez, Jara

2018-01-24

Grape and pomegranate are rich sources of phenolic compounds, and their derived products could be used as ingredients for the development of functional foods and dietary supplements. However, the profile of nonextractable or macromolecular phenolic compounds in these samples has not been evaluated. Here, we show a comprehensive characterization of extractable and nonextractable phenolic compounds of a grape/pomegranate pomace dietary supplement using high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight (HPLC-ESI-QTOF) and matrix-assisted laser desorption/ionization (MALDI)-TOF techniques. The main extractable phenolic compounds were several anthocyanins (principally malvidin 3-O-glucoside) as well as gallotannins and gallagyl derivatives; some phenolic compounds were reported in grape or pomegranate for the first time. Additionally, there was a high proportion of nonextractable phenolic compounds, including vanillic acid, and dihydroxybenzoic acid. Unidentified polymeric structures were detected by MALDI-TOF MS analysis. This study shows that mixed grape and pomegranate pomaces are a source of different classes of phenolic compounds including a high proportion of nonextractable phenolic compounds.

Analysis of Essential Oil in Jerusalem Artichoke (Helianthus tuberosus L.) Leaves and Tubers by Gas Chromatography-Mass Spectrometry.

Science.gov (United States)

Helmi, Zead; Al Azzam, Khaldun Mohammad; Tsymbalista, Yuliya; Ghazleh, Refat Abo; Shaibah, Hassan; Aboul-Enein, Hassan

2014-12-01

To investigate, for the first time, the chemical composition of essential oil of the tubers and leaves of Jerusalem artichoke (Helianthus tuberosus L.), a species of sunflower native to eastern North America, growing in Ukraine. A hydrodistillation apparatus was used for the extraction of volatile components and then it was analysed by gas chromatography equipped with a split-splitless injector (split ratio, 1:50) and flame ionization detector (FID). The oil was analyzed under linear temperature programming applied at 4°C/min from 50°C - 340°C. Temperatures of the injector and FID detector were maintained at 280°C and 300°C, respectively. The chemical analysis of the oil was carried out using gas chromatography coupled to mass spectrometry (GC-MS), to determine the chemical composition of the volatile fraction. The essential oils content ranged from 0.00019 to 0.03486 and 0.00011 to 0.00205 (g/100g), in leaves and tubers, respectively. The qualitative and quantitative analysis led to the identification of 17 components in both species samples. The major component found in leaves and tubers was (-)-β-bisabolene with 70.7% and 63.1%, respectively. Essential oil profile of Jerusalem artichoke species showed significant differences between leaves and tubers species. Additionally, the leaves of Jerusalem artichoke are a promising source of natural β-bisabolene.

A quantitative assay of cortisol in human plasma by high performance liquid chromatography using a selective chemically bonded stationary phase

NARCIS (Netherlands)

van den Berg, J.H.M.; Mol, C.R.; Deelder, R.S.; Thijssen, J.H.H.

1977-01-01

The extraction and subsequent liquid chromatographic analysis of human plasma samples for cortisol is described. Extraction and chromatography are optimized, resulting in a recovery for cortisol of 96% and a detection limit of 1 microgram cortisol in 100 ml plasma. The application of two chemically

Accurate mass analysis of ethanesulfonic acid degradates of acetochlor and alachlor using high-performance liquid chromatography and time-of-flight mass spectrometry

Science.gov (United States)

Thurman, E.M.; Ferrer, I.; Parry, R.

2002-01-01

Degradates of acetochlor and alachlor (ethanesulfonic acids, ESAs) were analyzed in both standards and in a groundwater sample using high-performance liquid chromatography-time-of-flight mass spectrometry with electrospray ionization. The negative pseudomolecular ion of the secondary amide of acetochlor ESA and alachlor ESA gave average masses of 256.0750??0.0049 amu and 270.0786??0.0064 amu respectively. Acetochlor and alachlor ESA gave similar masses of 314.1098??0.0061 amu and 314.1153??0.0048 amu; however, they could not be distinguished by accurate mass because they have the same empirical formula. On the other hand, they may be distinguished using positive-ion electrospray because of different fragmentation spectra, which did not occur using negative-ion electrospray.

Profiling the triacylglyceride contents in bat integumentary lipids by preparative thin layer chromatography and MALDI-TOF mass spectrometry.

Science.gov (United States)

Pannkuk, Evan L; Risch, Thomas S; Savary, Brett J

2013-09-05

The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals.

Studies of nanosecond pulse surface ionization wave discharges over solid and liquid dielectric surfaces

International Nuclear Information System (INIS)

Petrishchev, Vitaly; Leonov, Sergey; Adamovich, Igor V

2014-01-01

Surface ionization wave discharges generated by high-voltage nanosecond pulses, propagating over a planar quartz surface and over liquid surfaces (distilled water and 1-butanol) have been studied in a rectangular cross section test cell. The discharge was initiated using a custom-made, alternating polarity, high-voltage nanosecond pulse plasma generator, operated at a pulse repetition rate of 100–500 Hz, with a pulse peak voltage and current of 10–15 kV and 7–20 A, respectively, a pulse FWHM of ∼100 ns, and a coupled pulse energy of 2–9 mJ/pulse. Wave speed was measured using a capacitive probe. ICCD camera images demonstrated that the ionization wave propagated predominantly over the quartz wall or over the liquid surface adjacent to the grounded waveguide placed along the bottom wall of the test cell. Under all experimental conditions tested, the surface plasma ‘sheet’ was diffuse and fairly uniform, both for positive and negative polarities. The parameters of ionization wave discharge propagating over distilled water and 1-butanol surfaces were close to those of the discharge over a quartz wall. No perturbation of the liquid surface by the discharge was detected. In most cases, the positive polarity surface ionization wave propagated at a higher speed and over a longer distance compared to the negative polarity wave. For all three sets of experiments (surface ionization wave discharge over quartz, water and 1-butanol), wave speed and travel distance decreased with pressure. Diffuse, highly reproducible surface ionization wave discharge was also observed over the liquid butanol–saturated butanol vapor interface, as well as over the distilled water–saturated water vapor interface, without buffer gas flow. No significant difference was detected between surface ionization discharges sustained using single-polarity (positive or negative), or alternating polarity high-voltage pulses. Plasma emission images yielded preliminary evidence of charge

An ultrahigh-performance liquid chromatography method with electrospray ionization tandem mass spectrometry for simultaneous quantification of five phytohormones in medicinal plant Glycyrrhiza uralensis under abscisic acid stress.

Science.gov (United States)

Xiang, Yu; Song, Xiaona; Qiao, Jing; Zang, Yimei; Li, Yanpeng; Liu, Yong; Liu, Chunsheng

2015-07-01

An efficient simplified method was developed to determine multiple classes of phytohormones simultaneously in the medicinal plant Glycyrrhiza uralensis. Ultrahigh-performance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS) with multiple reaction monitoring (MRM) in negative mode was used for quantification. The five studied phytohormones are gibberellic acid (GA3), abscisic acid (ABA), jasmonic acid (JA), indole-3-acetic acid, and salicylic acid (SA). Only 100 mg of fresh leaves was needed, with one purification step based on C18 solid-phase extraction. Cinnamic acid was chosen as the internal standard instead of isotope-labeled internal standards. Under the optimized conditions, the five phytohormones with internal standard were separated within 4 min, with good linearities and high sensitivity. The validated method was applied to monitor the spatial and temporal changes of the five phytohormones in G. uralensis under ABA stress. The levels of GA3, ABA, JA, and SA in leaves of G. uralensis were increased at different times and with different tendencies in the reported stress mode. These changes in phytohormone levels are discussed in the context of a possible feedback regulation mechanism. Understanding this mechanism will provide a good chance of revealing the mutual interplay between different biosynthetic routes, which could further help elucidate the mechanisms of effective composition accumulation in medicinal plants.

Improvement of ionizer and power supply of 860 A sputtering negative ion source

International Nuclear Information System (INIS)

An Kun; Yu Lingda; Wu Bingbing; Wang Guangfu

2014-01-01

A transmission surface type ionizer was developed with a φ2.5 mm stainless steel sheath core heating cable, and the ion source power supply was also improved. A continuous adjustable DC switching power supply was employed instead of the original AC power supply as the ionizer power supply, and a 0 - -20 kV DC power supply at the ground potential as the power of the immersion lens replaced the original 10 kV DC power supply suspended in -20 kV. The variation of the beam intensity of H"- in the front Faraday cup of the GIC4117 2 × 1.7 MV tandetron with the ionizer heating current was also shown. (authors)

Instrument platforms for nano liquid chromatography.

Science.gov (United States)

Šesták, Jozef; Moravcová, Dana; Kahle, Vladislav

2015-11-20

The history of liquid chromatography started more than a century ago and miniaturization and automation are two leading trends in this field. Nanocolumn liquid chromatography (nano LC) and largely synonymous capillary liquid chromatography (capillary LC) are the most recent results of this process where miniaturization of column dimensions and sorbent particle size play crucial role. Very interesting results achieved in the research of extremely miniaturized LC columns at the end of the last century lacked distinctive raison d'être and only advances in mass spectrometry brought a real breakthrough. Configuration of nano LC-electrospray ionization mass spectrometry (LC-ESI-MS) has become a basic tool in bioanalytical chemistry, especially in proteomics. This review discusses and summarizes past and current trends in the realization of nano liquid chromatography (nano LC) platforms. Special attention is given to the mobile phase delivery under nanoflow rates (isocratic, gradient) and sample injection to the nanocolumn. Available detection techniques applied in nano LC separations are also briefly discussed. We followed up the key themes from the original scientific reports over gradual improvements up to the contemporary commercial solutions. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of hydroxycinnamates and catechins in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

DEFF Research Database (Denmark)

Nielsen, Salka E.; Sandström, B.

2003-01-01

A quantitative liquid chromatography mass spectrometry (LC-MS) methodology with online sample clean up by column switching is described for the simultaneous determination of the hydroxycinnamates, caffeic acid and chlorogenic acid, and of the catechins, epicatechin and catechin in human urine...

Chiral separation and chemical profile of Dengzhan Shengmai by integrating comprehensive with multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Sheng, Ning; Zheng, Hao; Xiao, Yao; Wang, Zhe; Li, Menglin; Zhang, Jinlan

2017-09-29

Chemical profile for Chinese medicine formulas composed of several herbs is always a challenge due to a big array of small molecules with high chemical diversity so much as isomers. The present paper develops a feasible strategy to characterize and identify complex chemical constituents of a four-herb traditional Chinese medicine formula, Denzhan Shenmai (DZSM) by integrating comprehensive two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (LC×LC-qTOF-MS) with multiple heart-cutting two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (MHC-qTOF-MS). DZSM was separated by C8×C18 HPLC column system for comprehensive two-dimensional liquid chromatography system and 283 compounds most of which belonged to phenolic acid, flavonoid, saponin and lignan families were characterized and identified within 75min. Some isomers and compounds at low level were analyzed on C8×Chiral HPLC column system for multiple heart-cutting two-dimensional liquid chromatography system with 1D and 2D optimized gradient elution program. These 1D cutting fractions were successively separated on 2D chiral chromatographic column under extended the 2D gradient elution time from 30s to 5.0min. 12 pairs of isomer compounds were separated with good resolution. The combination of LC×LC and MHC system provides a powerful technique for global chemical profiling of DZSM and provided feasible strategy for other complex systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Solid-phase extraction combined with high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis of pesticides in water: method performance and application in a reconnaissance survey of residues in drinking water in Greater Cairo, Egypt.

Science.gov (United States)

Potter, Thomas L; Mohamed, Mahmoud A; Ali, Hannah

2007-01-24

Monitoring of water resources for pesticide residues is often needed to ensure that pesticide use does not adversely impact the quality of public water supplies or the environment. In many rural areas and throughout much of the developing world, monitoring is often constrained by lack of testing facilities; thus, collection of samples and shipment to centralized laboratories for analysis is required. The portability, ease of use, and potential to enhance analyte stability make solid-phase extraction (SPE) an attractive technique for handling water samples prior to their shipment. We describe performance of an SPE method targeting a structurally diverse mixture of 25 current-use pesticides and two common degradates in samples of raw and filtered drinking water collected in Greater Cairo, Egypt. SPE was completed in a field laboratory in Egypt, and cartridges were shipped to the United States for elution and high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis. Quantitative and reproducible recovery of 23 of 27 compounds (average = 96%; percent relative standard deviation = 21%) from matrix spikes (1 microg L-1 per component) prepared in the field and from deionized water fortified similarly in the analytical laboratory was obtained. Concurrent analysis of unspiked samples identified four parent compounds and one degradate in drinking water samples. No significant differences were observed between raw and filtered samples. Residue levels in all cases were below drinking water and "harm to aquatic-life" thresholds, indicating that human and ecological risks of pesticide contamination were relatively small; however, the study was limited in scale and scope. Further monitoring is needed to define spatial and temporal variation in residue concentrations. The study has demonstrated the feasibility of performing studies of this type using SPE to extract and preserve samples in the field. The approach should be broadly

Quantitative Analysis of Mixed Halogen Dioxins and Furans in Fire Debris Utilizing Atmospheric Pressure Ionization Gas Chromatography-Triple Quadrupole Mass Spectrometry.

Science.gov (United States)

Organtini, Kari L; Myers, Anne L; Jobst, Karl J; Reiner, Eric J; Ross, Brian; Ladak, Adam; Mullin, Lauren; Stevens, Douglas; Dorman, Frank L

2015-10-20

Residential and commercial fires generate a complex mixture of volatile, semivolatile, and nonvolatile compounds. This study focused on the semi/nonvolatile components of fire debris to better understand firefighter exposure risks. Using the enhanced sensitivity of gas chromatography coupled to atmospheric pressure ionization-tandem mass spectrometry (APGC-MS/MS), complex fire debris samples collected from simulation fires were analyzed for the presence of potentially toxic polyhalogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs and PBDD/Fs). Extensive method development was performed to create multiple reaction monitoring (MRM) methods for a wide range of PXDD/Fs from dihalogenated through hexa-halogenated homologue groups. Higher halogenated compounds were not observed due to difficulty eluting them off the long column used for analysis. This methodology was able to identify both polyhalogenated (mixed bromo-/chloro- and polybromo-) dibenzo-p-dioxins and dibenzofurans in the simulated burn study samples collected, with the dibenzofuran species being the dominant compounds in the samples. Levels of these compounds were quantified as total homologue groups due to the limitations of commercial congener availability. Concentration ranges in household simulation debris were observed at 0.01-5.32 ppb (PXDFs) and 0.18-82.11 ppb (PBDFs). Concentration ranges in electronics simulation debris were observed at 0.10-175.26 ppb (PXDFs) and 0.33-9254.41 ppb (PBDFs). Samples taken from the particulate matter coating the firefighters' helmets contained some of the highest levels of dibenzofurans, ranging from 4.10 ppb to 2.35 ppm. The data suggest that firefighters and first responders at fire scenes are exposed to a complex mixture of potentially hundreds to thousands of different polyhalogenated dibenzo-p-dioxins and dibenzofurans that could negatively impact their health.

IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

International Nuclear Information System (INIS)

Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

2013-01-01

Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10 –7 ) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10 –6 -1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H 2 , or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks

Airborne observations of formic acid using a chemical ionization mass spectrometer

Directory of Open Access Journals (Sweden)

M. Le Breton

2012-12-01

Full Text Available The first airborne measurements of formic acid mixing ratios over the United Kingdom were measured on the FAAM BAe-146 research aircraft on 16 March 2010 with a chemical ionization mass spectrometer using I⁻ reagent ions. The I⁻ ionization scheme was able to measure formic acid mixing ratios at 1 Hz in the boundary layer.

In-flight standard addition calibrations from a formic acid source were used to determine the instrument sensitivity of 35 ± 6 ion counts pptv⁻¹ s⁻¹ and a limit of detection of 25 pptv. Routine measurements were made through a scrubbed inlet to determine the instrumental background. Three plumes of formic acid were observed over the UK, originating from London, Humberside and Tyneside. The London plume had the highest formic acid mixing ratio throughout the flight, peaking at 358 pptv. No significant correlations of formic acid with NO_x and ozone were found, but a positive correlation was observed between CO and HCOOH within the two plumes where coincident data were recorded.

A trajectory model was employed to determine the sources of the plumes and compare modelled mixing ratios with measured values. The model underestimated formic acid concentrations by up to a factor of 2. This is explained by missing sources in the model, which were considered to be both primary emissions of formic acid of mainly anthropogenic origin and a lack of precursor emissions, such as isoprene, from biogenic sources, whose oxidation in situ would lead to formic acid formation.

Chemical modification of DNA: Molecular specificity studied by tandem mass spectrometry and liquid chromatography

International Nuclear Information System (INIS)

Chang, Ching-jer; Cooks, R.G.; Chae, Whi-Gun; Wood, J.M.

1989-01-01

Chemical modifications of DNA in vitro could be directly studied by C-13 NMR and P-31 NMR, which eliminated all degradation and separation processes. The prospects of utilized the NMR method in the in vitro experiments are limited because of the inherent low sensitivity of NMR and low level of DNA modification. We have developed a reverse-phase ion-paired HPLC method to study DNA modifications by methylating agents. The structural specificity of HPLC is significantly enhanced by conjunction with the specificity of enzymic transformations. The HPLC studies have also revealed the limitation of HPLC method for simultaneous determination of many minor modified nucleosides. This problem has been overcome by tandem mass spectrometry. In conjunction with the resolving power of HPLC in separating isomers, desorption chemical ionization tandem mass spectrometry has been utilized in the determination of the modified nucleosides at the picomole level using stable-isotope labeled compounds as internal references

Gas chromatography x gas chromatography-time-of-flight mass spectrometry analysis and antibacterial activity of essential oil from Amomum xanthophlebium

International Nuclear Information System (INIS)

Masila, A.; Aminah, I.; Yaakob, W.A.; Nazlina, I.

2011-01-01

Essential oils of fresh leaves, stem, rhizomes and whole aromatic plants of Amomum xanthophlebium (Zingiberaceae) were obtained by hydro distillation. Percentage yields of the leaf, stem and whole plant oils were 0.0032, 0.0074 and 0.0021 % whereas the rhizome oil obtained was very little. Chemical components of each oil and their percentages were determined by Gas Chromatography x Gas Chromatography-Time-of-Flight Mass Spectrometry (GCxGC-TOFMS). Analysis of A. xanthophlebium oils showed that they were dominated by terpenes. Main components in the leaves were allo-aromadendrene (3.41 %), (±)-globulol (2.58 %) and rosifoliol (2.55 %); stem, α-terpineol (4.25 %), rosifoliol (2.41 %) and bingpian (2.27 %); rhizomes, viridiflorol (5.72 %), (±)-globulol (5.23 %) and α-cadinol (4.81 %); whole plants, eucalyptol (4.11 %), l-α-terpineol (2.88 %) and rosifoliol (2.82 %). The stem oil of A. xanthophlebium showed antibacterial activity against Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) at the minimum inhibitory concentration of 80 mg/ ml. (author)

Evaluation of the capabilities of atmospheric pressure chemical ionization source coupled to tandem mass spectrometry for the determination of dioxin-like polychlorobiphenyls in complex-matrix food samples

International Nuclear Information System (INIS)

Portolés, T.; Sales, C.; Abalos, M.; Sauló, J.; Abad, E.

2016-01-01

The use of the novel atmospheric pressure chemical ionization (APCI) source for gas chromatography (GC) coupled to triple quadrupole using tandem mass spectrometry (MS/MS) and its potential for the simultaneous determination of the 12 dioxin-like polychlorobiphenyls (DL-PCBs) in complex food and feed matrices has been evaluated. In first place, ionization and fragmentation behavior of DL-PCBs on the APCI source under charge transfer conditions has been studied followed by their fragmentation in the collision cell. Linearity, repeatability and sensitivity have been studied obtaining instrumental limits of detection and quantification of 0.0025 and 0.005 pg μL"−"1 (2.5 and 5 fg on column) respectively for every DL-PCB. Finally, application to real samples has been carried out and DL-PCB congeners (PCB 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189) have been detected in the different samples in the range of 0.40–10000 pg g"−"1. GC-(APCI)MS/MS has been proved as a suitable alternative to the traditionally accepted confirmation method based on the use of high resolution mass spectrometry and other triple quadrupole tandem mass spectrometry techniques operating with electron ionization. The development of MS/MS methodologies for the analysis of dioxins and DL-PCBs is nowadays particularly important, since this technique was included as a confirmatory method in the present European Union regulations that establish the requirements for the determination of these compounds in food and feed matrices. - Highlights: • GC-(APCI)MS/MS with QqQ: a suitable alternative to GC-(EI)HRMS for DL-PCBs determination. • LODs and LOQs as low as 0.0025 and 0.005 pg μL"−"1 respectively achieved for each DL-PCB congener. • Enhanced sensitivity and specificity of APCI in comparison with EI source in QqQ instruments.

Evaluation of the capabilities of atmospheric pressure chemical ionization source coupled to tandem mass spectrometry for the determination of dioxin-like polychlorobiphenyls in complex-matrix food samples

Energy Technology Data Exchange (ETDEWEB)

Portolés, T., E-mail: tportole@uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón (Spain); Sales, C. [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellón (Spain); Abalos, M.; Sauló, J.; Abad, E. [Laboratory of Dioxins, IDAEA, CSIC, Jordi Girona 18-26, E-08034 Barcelona (Spain)

2016-09-21

The use of the novel atmospheric pressure chemical ionization (APCI) source for gas chromatography (GC) coupled to triple quadrupole using tandem mass spectrometry (MS/MS) and its potential for the simultaneous determination of the 12 dioxin-like polychlorobiphenyls (DL-PCBs) in complex food and feed matrices has been evaluated. In first place, ionization and fragmentation behavior of DL-PCBs on the APCI source under charge transfer conditions has been studied followed by their fragmentation in the collision cell. Linearity, repeatability and sensitivity have been studied obtaining instrumental limits of detection and quantification of 0.0025 and 0.005 pg μL{sup −1} (2.5 and 5 fg on column) respectively for every DL-PCB. Finally, application to real samples has been carried out and DL-PCB congeners (PCB 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189) have been detected in the different samples in the range of 0.40–10000 pg g{sup −1}. GC-(APCI)MS/MS has been proved as a suitable alternative to the traditionally accepted confirmation method based on the use of high resolution mass spectrometry and other triple quadrupole tandem mass spectrometry techniques operating with electron ionization. The development of MS/MS methodologies for the analysis of dioxins and DL-PCBs is nowadays particularly important, since this technique was included as a confirmatory method in the present European Union regulations that establish the requirements for the determination of these compounds in food and feed matrices. - Highlights: • GC-(APCI)MS/MS with QqQ: a suitable alternative to GC-(EI)HRMS for DL-PCBs determination. • LODs and LOQs as low as 0.0025 and 0.005 pg μL{sup −1} respectively achieved for each DL-PCB congener. • Enhanced sensitivity and specificity of APCI in comparison with EI source in QqQ instruments.

Multi-detection of corticosteroids in sports doping and veterinary control using high-resolution liquid chromatography/time-of-flight mass spectrometry

NARCIS (Netherlands)

Touber, M.E.; Engelen, M.C.; Georgakopoulus, C.; Rhijn, van J.A.; Nielen, M.W.F.

2007-01-01

A liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) method was developed using the latest high-resolution LC column technology, the ultra performance liquid chromatography (UPLC (TM)), and electrospray ionization (ESI) in the positive ion mode. Gradient UPLC separation conditions

A selective and sensitive method for quantitation of lysergic acid diethylamide (LSD) in whole blood by gas chromatography-ion trap tandem mass spectrometry.

Science.gov (United States)

Libong, Danielle; Bouchonnet, Stéphane; Ricordel, Ivan

2003-01-01

A gas chromatography-ion trap tandem mass spectrometry (GC-ion trap MS-MS) method for detection and quantitation of LSD in whole blood is presented. The sample preparation process, including a solid-phase extraction step with Bond Elut cartridges, was performed with 2 mL of whole blood. Eight microliters of the purified extract was injected with a cold on-column injection method. Positive chemical ionization was performed using acetonitrile as reagent gas; LSD was detected in the MS-MS mode. The chromatograms obtained from blood extracts showed the great selectivity of the method. GC-MS quantitation was performed using lysergic acid methylpropylamide as the internal standard. The response of the MS was linear for concentrations ranging from 0.02 ng/mL (detection threshold) to 10.0 ng/mL. Several parameters such as the choice of the capillary column, the choice of the internal standard and that of the ionization mode (positive CI vs. EI) were rationalized. Decomposition pathways under both ionization modes were studied. Within-day and between-day stability were evaluated.

Real time monitoring of accelerated chemical reactions by ultrasonication-assisted spray ionization mass spectrometry.

Science.gov (United States)

Lin, Shu-Hsuan; Lo, Ta-Ju; Kuo, Fang-Yin; Chen, Yu-Chie

2014-01-01

Ultrasonication has been used to accelerate chemical reactions. It would be ideal if ultrasonication-assisted chemical reactions could be monitored by suitable detection tools such as mass spectrometry in real time. It would be helpful to clarify reaction intermediates/products and to have a better understanding of reaction mechanism. In this work, we developed a system for ultrasonication-assisted spray ionization mass spectrometry (UASI-MS) with an ~1.7 MHz ultrasonic transducer to monitor chemical reactions in real time. We demonstrated that simply depositing a sample solution on the MHz-based ultrasonic transducer, which was placed in front of the orifice of a mass spectrometer, the analyte signals can be readily detected by the mass spectrometer. Singly and multiply charged ions from small and large molecules, respectively, can be observed in the UASI mass spectra. Furthermore, the ultrasonic transducer used in the UASI setup accelerates the chemical reactions while being monitored via UASI-MS. The feasibility of using this approach for real-time acceleration/monitoring of chemical reactions was demonstrated. The reactions of Girard T reagent and hydroxylamine with steroids were used as the model reactions. Upon the deposition of reactant solutions on the ultrasonic transducer, the intermediate/product ions are readily generated and instantaneously monitored using MS within 1 s. Additionally, we also showed the possibility of using this reactive UASI-MS approach to assist the confirmation of trace steroids from complex urine samples by monitoring the generation of the product ions. Copyright © 2014 John Wiley & Sons, Ltd.

Gas chromatography interfaced with atmospheric pressure ionization-quadrupole time-of-flight-mass spectrometry by low-temperature plasma ionization

DEFF Research Database (Denmark)

Norgaard, Asger W.; Kofoed-Sorensen, Vivi; Svensmark, Bo

2013-01-01

A low temperature plasma (LTP) ionization interface between a gas chromatograph (GC) and an atmospheric pressure inlet mass spectrometer, was constructed. This enabled time-of-flight mass spectrometric detection of GC-eluting compounds. The performance of the setup was evaluated by injection...

Ionizing Radiation Processing Technology

International Nuclear Information System (INIS)

Rida Tajau; Kamarudin Hashim; Jamaliah Sharif; Ratnam, C.T.; Keong, C.C.

2017-01-01

This book completely brief on the basic concept and theory of ionizing radiation in polymers material processing. Besides of that the basic concept of polymerization addition, cross-linking and radiation degradation also highlighted in this informative book. All of the information is from scientific writing based on comprehensive scientific research in polymerization industry which using the radiation ionizing. It is very useful to other researcher whose study in Nuclear Sciencea and Science of Chemical and Material to use this book as a guideline for them in future scientific esearch.

Atmospheric pressure photoionisation : An ionization method for liquid chromatography-mass spectrometry

NARCIS (Netherlands)

Robb, DB; Covey, TR; Bruins, AP

2000-01-01

Atmospheric pressure photoionization (APPI) has been successfully demonstrated to provide high sensitivity to LC-MS analysis. A vacuum-ultraviolet lamp designed for photoionization detection in gas chromatography is used as a source of 10-eV photons. The mixture of samples and solvent eluting from

Involvement of MAPK proteins in bystander effects induced by chemicals and ionizing radiation

International Nuclear Information System (INIS)

Asur, Rajalakshmi; Balasubramaniam, Mamtha; Marples, Brian; Thomas, Robert A.; Tucker, James D.

2010-01-01

Many studies have examined bystander effects induced by ionizing radiation, however few have evaluated the ability of chemicals to induce similar effects. We previously reported the ability of two chemicals, mitomycin C (MMC) and phleomycin (PHL) to induce bystander effects in normal human lymphoblastoid cell lines. The focus of the current study was to determine the involvement of the MAPK proteins in bystander effects induced by physical and chemical DNA damaging agents and to evaluate the effects of MAPK inhibition on bystander-induced caspase 3/7 activation. The phosphorylation levels of the MAPK proteins ERK1/2, JNK, and p38, were measured from 1 to 24 h following direct or bystander exposure to MMC, PHL or radiation. We observed transient phosphorylation, at early time points, of all 3 proteins in bystander cells. We also evaluated the effect of MAPK inhibition on bystander-induced caspase 3/7 activity to determine the role of MAPK proteins in bystander-induced apoptosis. We observed bystander-induced activation of caspase 3/7 in bystander cells. Inhibition of MAPK proteins resulted in a decrease in caspase 3/7 activity at the early time points, and the caspase activity increased (in the case of ERK inhibition) or returned to basal levels (in the case of JNK or p38 inhibition) between 12 and 24 h. PHL is considered to be a radiomimetic agent, however in the present study PHL behaved more like a chemical and not like radiation in terms of MAPK phosphorylation. These results point to the involvement of MAPK proteins in the bystander effect induced by radiation and chemicals and provide additional evidence that this response is not limited to radiation but is a generalized stress response in cells.

On-Site Detection as a Countermeasure to Chemical Warfare/Terrorism.

Science.gov (United States)

Seto, Y

2014-01-01

On-site monitoring and detection are necessary in the crisis and consequence management of wars and terrorism involving chemical warfare agents (CWAs) such as sarin. The analytical performance required for on-site detection is mainly determined by the fatal vapor concentration and volatility of the CWAs involved. The analytical performance for presently available on-site technologies and commercially available on-site equipment for detecting CWAs interpreted and compared in this review include: classical manual methods, photometric methods, ion mobile spectrometry, vibrational spectrometry, gas chromatography, mass spectrometry, sensors, and other methods. Some of the data evaluated were obtained from our experiments using authentic CWAs. We concluded that (a) no technologies perfectly fulfill all of the on-site detection requirements and (b) adequate on-site detection requires (i) a combination of the monitoring-tape method and ion-mobility spectrometry for point detection and (ii) a combination of the monitoring-tape method, atmospheric pressure chemical ionization mass spectrometry with counterflow introduction, and gas chromatography with a trap and special detectors for continuous monitoring. The basic properties of CWAs, the concept of on-site detection, and the sarin gas attacks in Japan as well as the forensic investigations thereof, are also explicated in this article. Copyright © 2014 Central Police University.

A Simultaneous Analytical Method to Profile Non-Volatile Components with Low Polarity Elucidating Differences Between Tobacco Leaves Using Atmospheric Pressure Chemical Ionization Mass Spectrometry Detection

Directory of Open Access Journals (Sweden)

Ishida Naoyuki

2016-04-01

Full Text Available A comprehensive analytical method using liquid chromatography atmospheric pressure chemical ionization mass spectrometry detector (LC/APCI-MSD was developed to determine key non-volatile components with low polarity elucidating holistic difference among tobacco leaves. Nonaqueous reversed-phase chromatography (NARPC using organic solvent ensured simultaneous separation of various components with low polarity in tobacco resin. Application of full-scan mode to APCI-MSD hyphenated with NARPC enabled simultaneous detection of numerous intense product ions given by APCI interface. Parameters for data processing to filter, feature and align peaks were adjusted in order to strike a balance between comprehensiveness and reproducibility in analysis. 63 types of components such as solanesols, chlorophylls, phytosterols, triacylglycerols, solanachromene and others were determined on total ion chromatograms according to authentic components, wavelength spectrum and mass spectrum. The whole area of identified entities among the ones detected on total ion chromatogram reached to over 60% and major entities among those identified showed favorable linearity of determination coefficient of over 0.99. The developed method and data processing procedure were therefore considered feasible for subsequent multivariate analysis. Data matrix consisting of a number of entities was then subjected to principal component analysis (PCA and hierarchical clustering analysis. Cultivars of tobacco leaves were distributed far from each cultivar on PCA score plot and each cluster seemed to be characterized by identified non-volatile components with low polarity. While fluecured Virginia (FCV was loaded by solanachromene, phytosterol esters and triacylglycerols, free phytosterols and chlorophylls loaded Burley (BLY and Oriental (ORI respectively. Consequently the whole methodology consisting of comprehensive method and data processing procedure proved useful to determine key

Critical assessment of ionization patterns and applications of ambient desorption/ionization mass spectrometry using FAPA-MS.

Science.gov (United States)

Brüggemann, Martin; Karu, Einar; Hoffmann, Thorsten

2016-02-01

Ambient desorption/ionization mass spectrometry (MS) has gained growing interest during the last decade due to its high analytical performance and yet simplicity. Here, one of the recently developed ambient desorption/ionization MS sources, the flowing atmospheric-pressure afterglow (FAPA) source, was investigated in detail regarding background ions and typical ionization patterns in the positive as well as the negative ion mode for a variety of compound classes, comprising alkanes, alcohols, aldehydes, ketones, carboxylic acids, organic peroxides and alkaloids. A broad range of signals for adducts and losses was found, besides the usually emphasized detection of quasimolecular ions, i.e. [M + H](+) and [M - H](-) in the positive and the negative mode, respectively. It was found that FAPA-MS is best suited for polar analytes containing nitrogen and/or oxygen functionalities, e.g. carboxylic acids, with low molecular weights and relatively high vapor pressures. In addition, the source was used in proof-of-principle studies, illustrating the capabilities and limitations of the technique: Firstly, traces of cocaine were detected and unambiguously identified on euro banknotes using FAPA ionization in combination with tandem MS, suggesting a correlation between cocaine abundance and age of the banknote. Secondly, FAPA-MS was used for the identification of acidic marker compounds in organic aerosol samples, indicating yet-undiscovered matrix and sample surface effects of ionization pathways in the afterglow region. Copyright © 2016 John Wiley & Sons, Ltd.

Developmental effects of magnetic field (50 Hz) in combination with ionizing radiation and chemical teratogens.

Science.gov (United States)

Pafková, H; Jerábek, J; Tejnorová, I; Bednár, V

1996-11-01

The influence of a 50 Hz magnetic field (MF) on avian and mammalian embryogenesis, the MF level and vector, as well as the effect of exposure to MF (50 Hz, 10 mT) in combination with X-rays has been recently reported [2,3]. No significant alterations of chick or rat embryogenesis were found after repeated exposures to 50 Hz MF at 10 mT or 6 microT or with different vectors. However, X-ray chick embryotoxicity was significantly affected by repeated exposures of developing organisms to MF. A strong dependence of effect on the type of interaction was revealed. A decrease of X-ray induced teratogenicity was observed when MF preceded X-ray exposure (indirect interaction), while MF exposure applied immediately after X-ray radiation (direct interaction) non-significantly potentiated adverse developmental effects of ionizing radiation. This study deals with the effects of MF in combination with insulin or tetracycline. Exposure of chick embryos to MF influenced the sensitivity of embryonic morphogenetic systems to the subsequently administered chemical teratogens, insulin and/or tetracycline. A protective effect of MF was detected similarly as in the case of indirect interaction with ionizing radiation.

Microparticle charging in dry air plasma created by an external ionization source

International Nuclear Information System (INIS)

Derbenev, I N; Filippov, A V

2015-01-01

In the present paper the dust particle charging is studied in a dry air plasma created by an external ionization source. The ionization rate is changed in the range 10 1 -10 20 cm -3 s -1 . It is found that the main positive ion of the plasma is O + 4 and the main negative ones are O − 2 and O − 4 . The point sink model based on the diffusion-drift approach shows that the screening potential distribution around a dust particle is a superposition of four Debye-like exponentials with four different spatial scales. The first scale almost coincides with the Debye radius. The second one is the distance, passed by positive and negative plasma components due to ambipolar diffusion in their recombination time. The third one is defined by the negative ion conversion and diffusion. The fourth scale is described by the electron attachment, recombination and diffusion at low gas ionization rates and by the recombination and diffusion of negative diatomic ions at high ionization rates. It is also shown that the electron flux defines the microparticle charge at high ionization rates, whereas the electron number density is much less than the ion one. (paper)

Liquid chromatography/mass spectrometric determination of patulin in apple juice using atmospheric pressure photoionization.

Science.gov (United States)

Takino, Masahiko; Daishima, Shigeki; Nakahara, Taketoshi

2003-01-01

This paper describes a comparison between atmospheric pressure chemical ionization (APCI) and the recently introduced atmospheric pressure photoionization (APPI) technique for the liquid chromatography/mass spectrometric (LC/MS) determination of patulin in clear apple juice. A column switching technique for on-line extraction of clear apple juice was developed. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for both APCI and APPI. The results indicated that APPI provides lower chemical noise and signal suppression in comparison with APCI. The linear range for patulin in apple juice (correlation coefficient >0.999) was 0.2-100 ng mL(-1). Mean recoveries of patulin in three apple juices ranged from 94.5 to 103.2%, and the limit of detection (S/N = 3), repeatability and reproducibility were 1.03-1.50 ng mL(-1), 3.9-5.1% and 7.3-8.2%, respectively. The total analysis time was 10.0 min. Copyright 2003 John Wiley & Sons, Ltd.

Ionizing and non-ionizing radiations

International Nuclear Information System (INIS)

1994-01-01

The monograph is a small manual to get a knowledge of ionizing and non-ionizing radiations. The main chapters are: - Electromagnetic radiations - Ionizing and non-ionizing radiations - Non-ionizing electromagnetic radiations - Ionizing electromagnetic radiation - Other ionizing radiations - Ionizing radiation effects - The Nuclear Safety Conseil

Unified pH values of liquid chromatography mobile phases.

Science.gov (United States)

Suu, Agnes; Jalukse, Lauri; Liigand, Jaanus; Kruve, Anneli; Himmel, Daniel; Krossing, Ingo; Rosés, Martí; Leito, Ivo

2015-03-03

This work introduces a conceptually new approach of measuring pH of mixed-solvent liquid chromatography (LC) mobile phases. Mobile phase pH is very important in LC, but its correct measurement is not straightforward, and all commonly used approaches have deficiencies. The new approach is based on the recently introduced unified pH (pH(abs)) scale, which enables direct comparison of acidities of solutions made in different solvents based on chemical potential of the proton in the solutions. This work represents the first experimental realization of the pH(abs) concept using differential potentiometric measurement for comparison of the chemical potentials of the proton in different solutions (connected by a salt bridge), together with earlier published reference points for obtaining the pH(abs) values (referenced to the gas phase) or pH(abs)(H₂O) values (referenced to the aqueous solution). The liquid junction potentials were estimated in the framework of Izutsu's three-component method. pH(abs) values for a number of common LC and LC-MS mobile phases have been determined. The pH(abs) scale enables for the first time direct comparison of acidities of any LC mobile phases, with different organic additives, different buffer components, etc. A possible experimental protocol of putting this new approach into chromatographic practice has been envisaged and its applicability tested. It has been demonstrated that the ionization behavior of bases (cationic acids) in the mobile phases can be better predicted by using the pH(abs)(H₂O) values and aqueous pKa values than by using the alternative means of expressing mobile phase acidity. Description of the ionization behavior of acids on the basis of pH(abs)(H₂O) values is possible if the change of their pKa values with solvent composition change is taken into account.

Simultaneous high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) analysis of cyanide and thiocyanate from swine plasma.

Science.gov (United States)

Bhandari, Raj K; Manandhar, Erica; Oda, Robert P; Rockwood, Gary A; Logue, Brian A

2014-01-01

An analytical procedure for the simultaneous determination of cyanide and thiocyanate in swine plasma was developed and validated. Cyanide and thiocyanate were simultaneously analyzed by high-performance liquid chromatography tandem mass spectrometry in negative ionization mode after rapid and simple sample preparation. Isotopically labeled internal standards, Na(13)C(15)N and NaS(13)C(15)N, were mixed with swine plasma (spiked and nonspiked), proteins were precipitated with acetone, the samples were centrifuged, and the supernatant was removed and dried. The dried samples were reconstituted in 10 mM ammonium formate. Cyanide was reacted with naphthalene-2,3-dicarboxaldehyde and taurine to form N-substituted 1-cyano[f]benzoisoindole, while thiocyanate was chemically modified with monobromobimane to form an SCN-bimane product. The method produced dynamic ranges of 0.1-50 and 0.2-50 μM for cyanide and thiocyanate, respectively, with limits of detection of 10 nM for cyanide and 50 nM for thiocyanate. For quality control standards, the precision, as measured by percent relative standard deviation, was below 8 %, and the accuracy was within ±10 % of the nominal concentration. Following validation, the analytical procedure successfully detected cyanide and thiocyanate simultaneously from the plasma of cyanide-exposed swine.

Analytical chromatography. Methods, instrumentation and applications

International Nuclear Information System (INIS)

Yashin, Ya I; Yashin, A Ya

2006-01-01

The state-of-the-art and the prospects in the development of main methods of analytical chromatography, viz., gas, high performance liquid and ion chromatographic techniques, are characterised. Achievements of the past 10-15 years in the theory and general methodology of chromatography and also in the development of new sorbents, columns and chromatographic instruments are outlined. The use of chromatography in the environmental control, biology, medicine, pharmaceutics, and also for monitoring the quality of foodstuffs and products of chemical, petrochemical and gas industries, etc. is considered.

Negative affect is associated with development and persistence of chemical intolerance

DEFF Research Database (Denmark)

Skovbjerg, Sine; Christensen, Karl Bang; Ebstrup, Jeanette Frost

2015-01-01

. METHODS: A general population sample aged 19 to 72years was examined in 2006-2008 and again in 2011-2012. Longitudinal data on CI were analysed with the purpose of examining baseline negative affect as a risk factor for having developed CI at 5-year follow-up and for reporting persistent CI. Participants.......4% of the participants who had reported CI at baseline also reported CI at follow-up. In participants with no baseline CI, 15.5% reported CI at follow-up and 18.1% reported symptoms related to chemicals but no daily life adjustments. Baseline negative affect was positively and statistically significantly associated...

Myrcia splendens (Sw. DC. (syn. M. fallax (Rich. DC. (Myrtaceae Essential Oil from Amazonian Ecuador: A Chemical Characterization and Bioactivity Profile

Directory of Open Access Journals (Sweden)

Laura Scalvenzi

2017-07-01

Full Text Available In this study, we performed the chemical characterization of Myrcia splendens (Sw. DC. (Myrtaceae essential oil from Amazonian Ecuador and the assessment of its bioactivity in terms of cytotoxic, antibacterial, and antioxidant activity as starting point for possible applicative uses. M. splendens essential oil, obtained by hydro-distillation, was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS and Gas Chromatography-Flame Ionization Detector (GC-FID: the major components were found to be trans-nerolidol (67.81% and α-bisabolol (17.51%. Furthermore, we assessed the cytotoxic activity against MCF-7 (breast, A549 (lung human tumor cell lines, and HaCaT (human keratinocytes non-tumor cell line through 3-(4,5-dimethyl-2-thiazolyl-2,5-diphenyl-2-H-tetrazolium bromide (MTT test: promising results in terms of selectivity and efficacy against the MCF-7 cell line (IC50 of 5.59 ± 0.13 μg/mL at 48 h were obtained, mainly due to α-bisabolol. Furthermore, antibacterial activity against Gram positive and negative bacteria were performed through High Performance Thin Layer Chromatography (HPTLC bioautographic assay and microdilution method: trans-nerolidol and β-cedren-9-one were the main molecules responsible for the low antibacterial effects against human pathogens. Nevertheless, interesting values of Minimum Inhibitory Concentration (MIC were noticeable against phytopathogen strains. Radical scavenging activity performed by HPTLC bioautographic and spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH approaches were negligible. In conclusion, the essential oil revealed a good potential for plant defense and anti-cancer applications.

Chromatography Analysis of Jatropha Curcas L Oil Raw and Refined

International Nuclear Information System (INIS)

Chitue de Assuncao Nascimento, Juliano; Lafargue Perez, Francisco; Diaz Velazquez, Manuel

2013-01-01

The chromatography of gases is one of the most versatile methods utilized in the chemical laboratory, which permits the determinations of the percentages and types of fatty acids present in vegetable oils. The objective of this work was to carry out a comparative study of the composition of the fatty acids, of the mechanically extracted oil from the seed of the Jatropha curcas L plant in the raw and refined state, using the data obtained by gas chromatography. The fatty acids of the oil were determined as methylic esteres. The analyst was carried out in a gas chromatographer, with a detector of ionization by way of flame (FID), Agilent 7890A (Agilent, USA) coupled to HP Pentium 4 computer, with a data processing program. The temperatures of the injector and of the detector were 250 °C and 260 °C respectively. The data obtained chromatographically of the oil of Jatropha curcas L, raw and refined indicates that the refinery process did not vary the composition of the fatty acid, because there are no significant differences between them. Also, the results obtained by other investigators, showed that the predominant fatty acids obtained from the oil of the Jatropha curcas L were palmitic and stearic in the saturated fatty acids, and oleic and linoleic in the unsaturated fatty acids

Chromatography analysis of Jatropha Curcas L oil raw and refined

International Nuclear Information System (INIS)

Chitue de Assuncao Nascimento, Juliano; Lafargue Perez, Francisco; Diaz Velazquez, Manuel

2013-01-01

The chromatography of gases is one of the most versatile methods utilized in the chemical laboratory, which permits the determinations of the percentages and types of fatty acids present in vegetable oils. The objective of this work was to carry out a comparative study of the composition of the fatty acids, of the mechanically extracted oil from the seed of the Jatropha curcas L plant in the raw and refined state, using the data obtained by gas chromatography. The fatty acids of the oil were determined as methylic esteres. The analyst was carried out in a gas chromatographer, with a detector of ionization by way of flame (FID), Agilent 7890A (Agilent, USA) coupled to HP Pentium 4 computer, with a data processing program. The temperatures of the injector and of the detector were 250℃ and 260℃ respectively. The data obtained chromatographically of the oil of Jatropha curcas L, raw and refined indicates that the refinery process did not vary the composition of the fatty acid, because there are no significant differences between them. Also, the results obtained by other investigators, showed that the predominant fatty acids obtained from the oil of the Jatropha curcas L were palmitic and stearic in the saturated fatty acids, and oleic and linoleic in the unsaturated fatty acids

Review of in situ derivatization techniques for enhanced bioanalysis using liquid chromatography with mass spectrometry.

Science.gov (United States)

Baghdady, Yehia Z; Schug, Kevin A

2016-01-01

Accurate and specific analysis of target molecules in complex biological matrices remains a significant challenge, especially when ultra-trace detection limits are required. Liquid chromatography with mass spectrometry is often the method of choice for bioanalysis. Conventional sample preparation and clean-up methods prior to the analysis of biological fluids such as liquid-liquid extraction, solid-phase extraction, or protein precipitation are time-consuming, tedious, and can negatively affect target recovery and detection sensitivity. An alternative or complementary strategy is the use of an off-line or on-line in situ derivatization technique. In situ derivatization can be incorporated to directly derivatize target analytes in their native biological matrices, without any prior sample clean-up methods, to substitute or even enhance the extraction and preconcentration efficiency of these traditional sample preparation methods. Designed appropriately, it can reduce the number of sample preparation steps necessary prior to analysis. Moreover, in situ derivatization can be used to enhance the performance of the developed liquid chromatography with mass spectrometry-based bioanalysis methods regarding stability, chromatographic separation, selectivity, and ionization efficiency. This review presents an overview of the commonly used in situ derivatization techniques coupled to liquid chromatography with mass spectrometry-based bioanalysis to guide and to stimulate future research. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of 62 synthetic cannabinoids by gas chromatography-mass spectrometry with photoionization.

Science.gov (United States)

Akutsu, Mamoru; Sugie, Ken-Ichi; Saito, Koichi

2017-01-01

Gas chromatography-mass spectrometry (GC-MS) in electron ionization (EI) mode is one of the most commonly used techniques for analysis of synthetic cannabinoids, because the GC-EI-MS spectra contain characteristic fragment ions for identification of a compound; however, the information on its molecular ions is frequently lacking. To obtain such molecular ion information, GC-MS in chemical ionization (CI) mode is frequently used. However, GC-CI-MS requires a relatively tedious process using reagent gas such as methane or isobutane. In this study, we show that GC-MS in photoionization (PI) mode provided molecular ions in all spectra of 62 synthetic cannabinoids, and 35 of the 62 compounds showed only the molecular radical cations. Except for the 35 compounds, the PI spectra showed very simple patterns with the molecular peak plus only a few fragment peak(s). An advantage is that the ion source for GC-PI-MS can easily be used for GC-EI-MS as well. Therefore, GC-EI/PI-MS will be a useful tool for the identification of synthetic cannabinoids contained in a dubious product. To the best of our knowledge, this is the first report to use GC-PI-MS for analysis of synthetic cannabinoids.

Determination of ribavirin in human serum using liquid chromatography tandem mass spectrometry

NARCIS (Netherlands)

van der Lijke, H.; Alffenaar, J.-W. C.; Kok, W.Th.; Greijdanus, B.; Uges, D.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

Decontamination of pesticide packing using ionizing radiation

International Nuclear Information System (INIS)

Duarte, C.L.; Mori, M.N.; Kodama, Yasko; Oikawa, H.; Sampa, M.H.O.

2007-01-01

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry-GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases

Decontamination of pesticide packing using ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Duarte, C.L. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP Av. Lineu Prestes 2.242, 05508-900, Sao Paulo, SP (Brazil)], E-mail: clduarte@ipen.br; Mori, M.N.; Kodama, Yasko; Oikawa, H.; Sampa, M.H.O. [Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/SP Av. Lineu Prestes 2.242, 05508-900, Sao Paulo, SP (Brazil)

2007-11-15

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry-GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.

A compact high resolution electrospray ionization ion mobility spectrometer.

Science.gov (United States)

Reinecke, T; Kirk, A T; Ahrens, A; Raddatz, C-R; Thoben, C; Zimmermann, S

2016-04-01

Electrospray is a commonly used ionization method for the analysis of liquids. An electrospray is a dispersed nebular of charged droplets produced under the influence of a strong electrical field. Subsequently, ions are produced in a complex process initiated by evaporation of neutral solvent molecules from these droplets. We coupled an electrospray ionization source to our previously described high resolution ion mobility spectrometer with 75 mm drift tube length and a drift voltage of 5 kV. When using a tritium source for chemical gas phase ionization, a resolving power of R=100 was reported for this setup. We replaced the tritium source and the field switching shutter by an electrospray needle, a desolvation region with variable length and a three-grid shutter for injecting ions into the drift region. Preliminary measurements with tetraalkylammonium halides show that the current configuration with the electrospray ionization source maintains the resolving power of R=100. In this work, we present the characterization of our setup. One major advantage of our setup is that the desolvation region can be heated separately from the drift region so that the temperature in the drift region stays at room temperature even up to desolvation region temperatures of 100 °C. We perform parametric studies for the investigation of the influence of temperature on solvent evaporation with different ratios of water and methanol in the solvent for different analyte substances. Furthermore, the setup is operated in negative mode and spectra of bentazon with different solvents are presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Production techniques for rare earth and other heavy negative ions

International Nuclear Information System (INIS)

McK Hyder, H.R.; Ashenfelter, J.; McGrath, R.

1998-01-01

Current nuclear structure studies demand a wide range of heavy negative ion beams for tandem acceleration. Some of the wanted isotopes have low natural abundances and many have low or negative electron affinities. For these, gas injection or the use of hydrides, oxides, or fluorides is required to achieve usable intensities. The chemical properties of the target materials, and of the additive gases used to form molecular ions, often have detrimental effects on ion source performance and life. These effects include insulator breakdown, ionizer poisoning, and the erosion or deposition of material on critical electrodes. Methods of controlling sputter source conditions are being studied on the Wright Nuclear Structure Laboratory ion source test bench with the object of extending source life, increasing target efficiency, and achieving consistent negative ion outputs. Results are reported for several heavy ions including tellurium, neodymium, and ytterbium. copyright 1998 American Institute of Physics

Liquid chromatography-electrospray ionization tandem mass spectrometry and dynamic multiple reaction monitoring method for determining multiple pesticide residues in tomato.

Science.gov (United States)

Andrade, G C R M; Monteiro, S H; Francisco, J G; Figueiredo, L A; Botelho, R G; Tornisielo, V L

2015-05-15

A quick and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method, using dynamic multiple reaction monitoring and a 1.8-μm particle size analytical column, was developed to determine 57 pesticides in tomato in a 13-min run. QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for samples preparations and validations was carried out in compliance with EU SANCO guidelines. The method was applied to 58 tomato samples. More than 84% of the compounds investigated showed limits of detection equal to or lower than 5 mg kg(-1). A mild (50%) matrix effect was observed for 72%, 25%, and 3% of the pesticides studied, respectively. Eighty-one percent of the pesticides showed recoveries ranging between 70% and 120%. Twelve pesticides were detected in 35 samples, all below the maximum residue levels permitted in the Brazilian legislation; 15 samples exceeded the maximum residue levels established by the EU legislation for methamidophos; and 10 exceeded limits for acephate and four for bromuconazole. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ultrahigh-performance liquid chromatography electrospray ionization Q-Orbitrap mass spectrometry for the analysis of 451 pesticide residues in fruits and vegetables: method development and validation.

Science.gov (United States)

Wang, Jian; Chow, Willis; Chang, James; Wong, Jon W

2014-10-22

This paper presents an application of ultrahigh-performance liquid chromatography electrospray ionization quadrupole Orbitrap high-resolution mass spectrometry (UHPLC/ESI Q-Orbitrap MS) for the determination of 451 pesticide residues in fruits and vegetables. Pesticides were extracted from samples using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure. UHPLC/ESI Q-Orbitrap MS in full MS scan mode acquired full MS data for quantification, and UHPLC/ESI Q-Orbitrap Full MS/dd-MS(2) (i.e., data-dependent scan mode) obtained product ion spectra for identification. UHPLC/ESI Q-Orbitrap MS quantification was achieved using matrix-matched standard calibration curves along with the use of isotopically labeled standards or a chemical analogue as internal standards to achieve optimal method accuracy. The method performance characteristics include overall recovery, intermediate precision, and measurement uncertainty evaluated according to a nested experimental design. For the 10 matrices studied, 94.5% of the pesticides in fruits and 90.7% in vegetables had recoveries between 81 and 110%; 99.3% of the pesticides in fruits and 99.1% of the pesticides in vegetables had an intermediate precision of ≤20%; and 97.8% of the pesticides in fruits and 96.4% of the pesticides in vegetables showed measurement uncertainty of ≤50%. Overall, the UHPLC/ESI Q-Orbitrap MS demonstrated acceptable performance for the quantification of pesticide residues in fruits and vegetables. The UHPLC/ESI Q-Orbitrap Full MS/dd-MS(2) along with library matching showed great potential for identification and is being investigated further for routine practice.

Phytochemical analysis of ethanolic extract of Dichrostachys Cinerea W and Arn leaves by a thin layer chromatography, high performance thin layer chromatography and column chromatography

OpenAIRE

M Vijayalakshmi; K Periyanayagam; K Kavitha; K Akilandeshwari

2013-01-01

Background: The leaves of Dichrostachys cinerea are used as laxative, diuretic, painkiller. It is also used in the treatment of gonorrhoea, boils, oedema, gout, veneral diseases and nasopharyngeal affections, etc. Materials and Methods: The Phytochemical investigation of ethanolic extract of D. cinerea leaves were performed by standard chemical tests, thin layer chromatography (TLC) by using various solvent systems, and by high performance liquid chromatography (HPTLC). Two compounds were...

Introduction to modern liquid chromatography

National Research Council Canada - National Science Library

Snyder, Lloyd R; Kirkland, J. J; Dolan, John W

2010-01-01

"High-performance liquid chromatography (HPLC) is today the leading technique for chemical analysis and related applications, with an ability to separate, analyze, and/or purify virtually any sample...

Mechanisms of chemical modification of neoplastic cell transformation by ionizing radiation

International Nuclear Information System (INIS)

Yang, T.C.; Tobias, C.A.

1985-01-01

During space travel, astronauts will be continuously exposed to ionizing radiation; therefore, it is necessary to minimize the radiation damage by all possible means. The authors' studies show that DMSO (when present during irradiation) can protect cells from being killed and transformed by X rays and that low concentration of DMSO can reduce the transformation frequency significantly when it is applied to cells, even many days after irradiation. The process of neoplastic cell transformation is a complicated one and includes at least two different stages: induction and expression. DMSO apparently can modify the radiation damage during both stages. There are several possible mechanisms for the DMSO effect: (1) changing the cell membrane structure and properties; (2) inducing cell differentiation by acting on DNA; and (3) scavanging free radicals in the cell. Recent studies with various chemical agents, e.g., 5-azacytidine, dexamethane, rhodamin-123, etc., indicate that the induction of cell differentiation by acting on DNA may be an important mechanism for the suppression of expression of neoplastic cell transformation by DMSO

Antimicrobial activity of Iranian propolis and its chemical composition

Directory of Open Access Journals (Sweden)

Yaghoubi M.J.

2007-04-01

Full Text Available The objective of this study was to investigate the antimicrobial activity of ethanol extract of Iranian propolis on some microorganisms using disc diffusion method. The chemical composition of the propolis was also investigated using thin layer chromatography and spectrophotometric methods. Ethanol extract of propolis showed activity only against Gram-positives and fungi, whereas no activity was observed against Gram-negatives. Thin layer chromatography screening revealed the presence of pinocembrine, caffeic acid, kaempferol, phenethyl caffeate, chrysin, and galangin in Iranian propolis. The total flavonoid and phenolic contents were 7.3% and 36%, respectively, which suggests that the strong antimicrobial activity of Iranian propolis may be due to high levels of phenolic and flavonoid compounds.

Analysis of solvent dyes in refined petroleum products by electrospray ionization mass spectrometry

Science.gov (United States)

Rostad, C.E.

2010-01-01

Solvent dyes are used to color refined petroleum products to enable differentiation between gasoline, diesel, and jet fuels. Analysis for these dyes in the hydrocarbon product is difficult due to their very low concentrations in such a complex matrix. Flow injection analysis/electrospray ionization/mass spectrometry in both negative and positive mode was used to optimize ionization of ten typical solvent dyes. Samples of hydrocarbon product were analyzed under similar conditions. Positive electrospray ionization produced very complex spectra, which were not suitably specific for targeting only the dyes. Negative electrospray ionization produced simple spectra because aliphatic and aromatic moieties were not ionized. This enabled screening for a target dye in samples of hydrocarbon product from a spill.

III. Penning ionization, associative ionization and chemi-ionization processes

International Nuclear Information System (INIS)

Cermak, V.

1975-01-01

Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)

Nanoscale control of reversible chemical reaction between fullerene C60 molecules using scanning tunneling microscope.

Science.gov (United States)

Nakaya, Masato; Kuwahara, Yuji; Aono, Masakazu; Nakayama, Tomonobu

2011-04-01

The nanoscale control of reversible chemical reactions, the polymerization and depolymerization between C60 molecules, has been investigated. Using a scanning tunneling microscope (STM), the polymerization and depolymerization can be controlled at designated positions in ultrathin films of C60 molecules. One of the two chemical reactions can be selectively induced by controlling the sample bias voltage (V(s)); the application of negative and positive values of V(s) results in polymerization and depolymerization, respectively. The selectivity between the two chemical reactions becomes extremely high when the thickness of the C60 film increases to more than three molecular layers. We conclude that STM-induced negative and positive electrostatic ionization are responsible for the control of the polymerization and depolymerization, respectively.

Development of an analytical strategy based on liquid chromatography-high resolution mass spectrometry for measuring perfluorinated compounds in human breast milk: application to the generation of preliminary data regarding perinatal exposure in France.

Science.gov (United States)

Kadar, Hanane; Veyrand, Bruno; Barbarossa, Andrea; Pagliuca, Giampiero; Legrand, Arnaud; Bosher, Cécile; Boquien, Clair-Yves; Durand, Sophie; Monteau, Fabrice; Antignac, Jean-Philippe; Le Bizec, Bruno

2011-10-01

Perfluorinated compounds (PFCs) are man-made chemicals for which endocrine disrupting properties and related possible side effects on human health have been reported, particularly in the case of an exposure during the early stages of development, (notably the perinatal period). Existing analytical methods dedicated to PFCs monitoring in food and/or human fluids are currently based on liquid chromatography coupled to tandem mass spectrometry, and were recently demonstrated to present some limitations in terms of sensitivity and/or specificity. An alternative strategy dedicated to the analysis of fourteen PFCs in human breast milk was proposed, based on an effective sample preparation followed by a liquid chromatography coupled to high resolution mass spectrometry measurement (LC-HRMS). This methodology confirmed the high interest for HRMS after negative ionization for such halogenated substances, and finally permitted to reach detection limits around the pg mL(-1) range with an outstanding signal specificity compared to LC-MS/MS. The proposed method was applied to a first set of 30 breast milk samples from French women. The main PFCs detected in all these samples were PFOS and PFOA with respective median values of 74 (range from 24 to 171) and 57 (range from 18 to 102) pg mL(-1), respectively. These exposure data appeared in the same range as other reported values for European countries. Copyright © 2011 Elsevier Ltd. All rights reserved.

Simultaneous detection of six urinary pteridines and creatinine by high-performance liquid chromatography-tandem mass spectrometry for clinical breast cancer detection.

Science.gov (United States)

Burton, Casey; Shi, Honglan; Ma, Yinfa

2013-11-19

Recent preliminary studies have implicated urinary pteridines as candidate biomarkers in a growing number of malignancies including breast cancer. While the developments of capillary electrophoresis-laser induced fluorescence (CE-LIF), high performance liquid chromatography (HPLC), and liquid chromatography-mass spectroscopy (LC-MS) pteridine urinalyses among others have helped to enable these findings, limitations including poor pteridine specificity, asynchronous or nonexistent renal dilution normalization, and a lack of information regarding adduct formation in mass spectrometry techniques utilizing electrospray ionization (ESI) have prevented application of these techniques to a larger clinical setting. In this study, a simple, rapid, specific, and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and optimized for simultaneous detection of six pteridines previously implicated in breast cancer and creatinine as a renal dilution factor in urine. In addition, this study reports cationic adduct formation of urinary pteridines under ESI-positive ionization for the first time. This newly developed technique separates and detects the following six urinary pteridines: 6-biopterin, 6-hydroxymethylpterin, d-neopterin, pterin, isoxanthopterin, and xanthopterin, as well as creatinine. The method detection limit for the pteridines is between 0.025 and 0.5 μg/L, and for creatinine, it is 0.15 μg/L. The method was also validated by spiked recoveries (81-105%), reproducibility (RSD: 1-6%), and application to 25 real urine samples from breast cancer positive and negative samples through a double-blind study. The proposed technique was finally compared directly with a previously reported CE-LIF technique, concluding that additional or alternative renal dilution factors are needed for proper investigation of urinary pteridines as breast cancer biomarkers.

Prototype inverted sputter source for negative heavy ions

International Nuclear Information System (INIS)

Minehara, Eisuke; Kobayashi, Chiaki; Kikuchi, Shiroh

1977-10-01

A sputter source from which negative heavy ion beam is extracted through a tungsten wire and disc ionizer was built and tested. An alkali metal surface ionization gun with the ionizer is described, and also performance of the surface ionization gun and of the sputter source for negative heavy ions using the gun is reported. The gun was tested for three alkali metals, i.e. sodium, potassium and cesium. Total potassium beam current of 1-2mA was obtained at entrance aperture of the magnet. Sputtering materials and gases for producing negative heavy ions are carbon, copper, aluminium, molybdenum, oxygen and air. With carbon and leakage air, the beam intensities analyzed are: 2-5μA (at Faraday cup) and 4.6-11μA (at exit slit) for C - , 3-5μA (at Faraday cup) and 6.8-11μA (at exit slit) for 2C - , and 11-15μA (at Faraday cup) and 25-34μA (at exit slit) for O - . Total beam current at the entrance aperture was 200-400μA. (auth.)

Analysis of biodiesel and biodiesel-petrodiesel blends by high performance thin layer chromatography combined with easy ambient sonic-spray ionization mass spectrometry.

Science.gov (United States)

Eberlin, Livia S; Abdelnur, Patricia V; Passero, Alan; de Sa, Gilberto F; Daroda, Romeu J; de Souza, Vanderlea; Eberlin, Marcos N

2009-08-01

High performance thin layer chromatography (HPTLC) combined with on-spot detection and characterization via easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is applied to the analysis of biodiesel (B100) and biodiesel-petrodiesel blends (BX). HPTLC provides chromatographic resolution of major components whereas EASI-MS allows on-spot characterization performed directly on the HPTLC surface at ambient conditions. Constituents (M) are detected by EASI-MS in a one component-one ion fashion as either [M + Na](+) or [M + H](+). For both B100 and BX samples, typical profiles of fatty acid methyl esters (FAME) detected as [FAME + Na](+) ions allow biodiesel typification. The spectrum of the petrodiesel spot displays a homologous series of protonated alkyl pyridines which are characteristic for petrofuels (natural markers). The spectrum for residual or admixture oil spots is characterized by sodiated triglycerides [TAG + Na](+). The application of HPTLC to analyze B100 and BX samples and its combination with EASI-MS for on-spot characterization and quality control is demonstrated.

Direct analysis of psychoactive tryptamine and harmala alkaloids in the Amazonian botanical medicine ayahuasca by liquid chromatography-electrospray ionization-tandem mass spectrometry.

Science.gov (United States)

McIlhenny, Ethan H; Pipkin, Kelly E; Standish, Leanna J; Wechkin, Hope A; Strassman, Rick; Barker, Steven A

2009-12-18

A direct injection/liquid chromatography-electrospray ionization-tandem mass spectrometry procedure has been developed for the simultaneous quantitation of 11 compounds potentially found in the increasingly popular Amazonian botanical medicine and religious sacrament ayahuasca. The method utilizes a deuterated internal standard for quantitation and affords rapid detection of the alkaloids by a simple dilution assay, requiring no extraction procedures. Further, the method demonstrates a high degree of specificity for the compounds in question, as well as low limits of detection and quantitation despite using samples for analysis that had been diluted up to 200:1. This approach also appears to eliminate potential matrix effects. Method bias for each compound, examined over a range of concentrations, was also determined as was inter- and intra-assay variation. Its application to the analysis of three different ayahuasca preparations is also described. This method should prove useful in the study of ayahuasca in clinical and ethnobotanical research as well as in forensic examinations of ayahuasca preparations.

Quantitative analysis of glycosaminoglycans, chondroitin/dermatan sulfate, hyaluronic acid, heparan sulfate, and keratan sulfate by liquid chromatography-electrospray ionization-tandem mass spectrometry.

Science.gov (United States)

Osago, Harumi; Shibata, Tomoko; Hara, Nobumasa; Kuwata, Suguru; Kono, Michihaya; Uchio, Yuji; Tsuchiya, Mikako

2014-12-15

We developed a method using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) with a selected reaction monitoring (SRM) mode for simultaneous quantitative analysis of glycosaminoglycans (GAGs). Using one-shot analysis with our MS/MS method, we demonstrated the simultaneous quantification of a total of 23 variously sulfated disaccharides of four GAG classes (8 chondroitin/dermatan sulfates, 1 hyaluronic acid, 12 heparan sulfates, and 2 keratan sulfates) with a sensitivity of less than 0.5 pmol within 20 min. We showed the differences in the composition of GAG classes and the sulfation patterns between porcine articular cartilage and yellow ligament. In addition to the internal disaccharides described above, some saccharides derived from the nonreducing terminal were detected simultaneously. The simultaneous quantification of both internal and nonreducing terminal saccharides could be useful to estimate the chain length of GAGs. This method would help to establish comprehensive "GAGomic" analysis of biological tissues. Copyright © 2014 Elsevier Inc. All rights reserved.

Simultaneous Determination of Fifteen Constituents of Jitai Tablet Using Ultra High-Performance Liquid Chromatography Coupled with Triple Quadrupole Electrospray Tandem Mass Spectrometry

Directory of Open Access Journals (Sweden)

Shuping Wang

2014-01-01

Full Text Available An ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS method was developed for simultaneous determination of fifteen constituents in Jitai tablet (JTT, a complex Traditional Chinese Medicine prescription (TCMP used in treating opiate addiction. Benefitting from a small particle size (1.8 µm C18 column, accelerated analysis with satisfactory resolution, sensitivity and selectivity were achieved in a single run within 7 min with linear gradient elution of acetonitrile-0.1% (v/v formic acid in water. The analytical signal was obtained by multiple reaction monitoring transitions via electrospray ionization source operating in both positive and negative ionization mode. The approach was validated for linearity, sensitivity, precision, repeatability, stability and recovery. All analytes showed good linearity over a wide concentration range (r > 0.99. The method limits ranged from 0.03 ng/mL to 19.35 ng/mL which are sensitive enough for quality control studies. The developed method was successfully applied to the simultaneous determination of fifteen constituents in JTT. In conclusion, our experimental results demonstrate that UHPLC-ESI-MS/MS is a useful approach for the overall quality assessment of complex TCMPs.

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

International Nuclear Information System (INIS)

Lu Jianghai; Wang San; Dong Ying; Wang Xiaobing; Yang Shuming; Zhang Jianli; Deng Jing; Qin Yang; Xu Youxuan; Wu Moutian; Ouyang Gangfeng

2010-01-01

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.

Determination of the n-octanol/water partition coefficients of weakly ionizable basic compounds by reversed-phase high-performance liquid chromatography with neutral model compounds.

Science.gov (United States)

Liang, Chao; Han, Shu-ying; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin

2014-11-01

A strategy to utilize neutral model compounds for lipophilicity measurement of ionizable basic compounds by reversed-phase high-performance liquid chromatography is proposed in this paper. The applicability of the novel protocol was justified by theoretical derivation. Meanwhile, the linear relationships between logarithm of apparent n-octanol/water partition coefficients (logKow '') and logarithm of retention factors corresponding to the 100% aqueous fraction of mobile phase (logkw ) were established for a basic training set, a neutral training set and a mixed training set of these two. As proved in theory, the good linearity and external validation results indicated that the logKow ''-logkw relationships obtained from a neutral model training set were always reliable regardless of mobile phase pH. Afterwards, the above relationships were adopted to determine the logKow of harmaline, a weakly dissociable alkaloid. As far as we know, this is the first report on experimental logKow data for harmaline (logKow = 2.28 ± 0.08). Introducing neutral compounds into a basic model training set or using neutral model compounds alone is recommended to measure the lipophilicity of weakly ionizable basic compounds especially those with high hydrophobicity for the advantages of more suitable model compound choices and convenient mobile phase pH control. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dansyl-peptides matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) and tandem mass spectrometric (MS/MS) features improve the liquid chromatography/MALDI-MS/MS analysis of the proteome.

Science.gov (United States)

Chiappetta, Giovanni; Ndiaye, Sega; Demey, Emmanuelle; Haddad, Iman; Marino, Gennaro; Amoresano, Angela; Vinh, Joëlle

2010-10-30

Peptide tagging is a useful tool to improve matrix-assisted laser desorption/ionization tandem mass spectrometric (MALDI-MS/MS) analysis. We present a new application of the use of the dansyl chloride (DNS-Cl). DNS-Cl is a specific primary amine reagent widely used in protein biochemistry. It adds a fluorescent dimethylaminonaphthalene moiety to the molecule. The evaluation of MALDI-MS and MS/MS analyses of dansylated peptides shows that dansylation raises the ionization efficiency of the most hydrophilic species compared with the most hydrophobic ones. Consequently, higher Mascot scores and protein sequence coverage are obtained by combining MS and MS/MS data of native and tagged samples. The N-terminal DNS-Cl sulfonation improves the peptide fragmentation and promotes the generation of b-fragments allowing better peptide sequencing. In addition, we set up a labeling protocol based on the microwave chemistry. Peptide dansylation proved to be a rapid and cheap method to improve the performance of liquid chromatography (LC)/MALDI-MS/MS analysis at the proteomic scale in terms of peptide detection and sequence coverage. Copyright © 2010 John Wiley & Sons, Ltd.

Development of a gas-cylinder-free plasma desorption/ionization system for on-site detection of chemical warfare agents.

Science.gov (United States)

Iwai, Takahiro; Kakegawa, Ken; Aida, Mari; Nagashima, Hisayuki; Nagoya, Tomoki; Kanamori-Kataoka, Mieko; Miyahara, Hidekazu; Seto, Yasuo; Okino, Akitoshi

2015-06-02

A gas-cylinder-free plasma desorption/ionization system was developed to realize a mobile on-site analytical device for detection of chemical warfare agents (CWAs). In this system, the plasma source was directly connected to the inlet of a mass spectrometer. The plasma can be generated with ambient air, which is drawn into the discharge region by negative pressure in the mass spectrometer. High-power density pulsed plasma of 100 kW could be generated by using a microhollow cathode and a laboratory-built high-intensity pulsed power supply (pulse width: 10-20 μs; repetition frequency: 50 Hz). CWAs were desorbed and protonated in the enclosed space adjacent to the plasma source. Protonated sample molecules were introduced to the mass spectrometer by airflow through the discharge region. To evaluate the analytical performance of this device, helium and air plasma were directly irradiated to CWAs in the gas-cylinder-free plasma desorption/ionization system and the protonated molecules were analyzed by using an ion-trap mass spectrometer. A blister agent (nitrogen mustard 3) and nerve gases [cyclohexylsarin (GF), tabun (GA), and O-ethyl S-2-N,N-diisopropylaminoethyl methylphosphonothiolate (VX)] in solution in n-hexane were applied to the Teflon rod and used as test samples, after solvent evaporation. As a result, protonated molecules of CWAs were successfully observed as the characteristic ion peaks at m/z 204, 181, 163, and 268, respectively. In air plasma, the limits of detection were estimated to be 22, 20, 4.8, and 1.0 pmol, respectively, which were lower than those obtained with helium plasma. To achieve quantitative analysis, calibration curves were made by using CWA stimulant dipinacolyl methylphosphonate as an internal standard; straight correlation lines (R(2) = 0.9998) of the peak intensity ratios (target per internal standard) were obtained. Remarkably, GA and GF gave protonated dimer ions, and the ratios of the protonated dimer ions to the protonated

ISOTOPE-DILUTION AMMONIA CHEMICAL-IONIZATION MASS FRAGMENTOGRAPHIC ANALYSIS OF URINARY 3-O-METHYLATED CATECHOLAMINE METABOLITES - RAPID SAMPLE CLEANUP BY DERIVATIZATION AND EXTRACTION OF LYOPHILIZED SAMPLES

NARCIS (Netherlands)

KEMA, IP; MEIBORG, G; NAGEL, GT; STOB, GJ; MUSKIET, FAJ

1993-01-01

We developed a method for simultaneous quantification of the urinary 3-O-methylated catecholamine metabolites 3-methoxytyramine, normetanephrine and metanephrine by stable isotope-dilution ammonia chemical ionization mass fragmentography. Prepurification of lyophilized samples was done by