Quality control for total evaporation technique by surface/thermal ionization mass spectrometer

International Nuclear Information System (INIS)

Kato, Seikou; Inoue, Sinichi; Yamaguchi, Katsuyuki; Tsutaki, Yasuhiro

2007-01-01

For the measurement of uranium and plutonium isotopic composition, the surface/thermal ionization mass spectrometry is widely used at the both nuclear facilities and safeguards verification laboratories. The progress of instrument specification makes higher sensitivity. The total evaporation technique is one of the latest measurement techniques by using this progress, in which all of uranium or plutonium on the filament would be evaporated by increasing the filament current. The accuracy and precision of this technique is normally checked by using the certified isotope reference materials measurement. But the fluctuation of ion beam is very different by each filament, depending on the chemical form of evaporation. So, it should be considered how to check the measurement quality of unknown samples which has no certified values. This presentation is focused on the monitoring of ion yields and pattern of isotope ratio fluctuation to attain the traceability between reference material and unknown sample as quality control approach of total evaporation technique. (author)

Inorganic trace analysis by laser ionization mass spectrometry

International Nuclear Information System (INIS)

Becker, S.; Dietze, H.J.

1991-01-01

Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytic method with a wide coverage. In the LIMS the sample material is evaporated and ionized by means of a focused pulsed laser beam in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The formed ions are separated according to mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments, and applications of laser ionization mass spectrometry in inorganic trace analysis are described. (orig.)

Laser ionization mass spectrometry in inorganic trace analysis

International Nuclear Information System (INIS)

Becker, J.S.; Dietze, H.J.

1992-01-01

Among the different spectrometric techniques for trace analysis Laser Ionization Mass Spectrometry (LIMS) is well established as a trace analytical method. With the LIMS technique the sample material is evaporated and ionized by means of a focused pulsed laser in a laser microplasma, which is formed in the spot area of the irradiated sample. All chemical elements in the sample materials are evaporated and ionized in the laser plasma. The ions formed are separated according to their mass and energy by a time-of-flight, quadrupole or double focusing mass spectrometer. In this review the characteristics and analytical features, some recent developments and applications of laser ionization mass spectrometry in inorganic trace analysis are described. (orig.)

Data acquisition and processing system for surface ionization mass spectrometers (types MS5 and R20)

International Nuclear Information System (INIS)

Dubois, J.-C.; Retali, G.; Grandcollot, P.; Hagemann, R.

1977-01-01

The data acquisition and processing system developed for surface ionization mass spectrometers is described. The main interest of the system is to shorten significantly the duration of isotopic analysis, the results of which are printed almost immediately after the end of the acquisition of the data. The quality of the results is also improved, particularly for isotopes at low concentration owing to an automatic range selection unit driven by the computer. The processing program, which includes several options, is adapted to all types of isotopic analysis. This system, in use for more than two years, has demonstrated its versatility and its safety [fr

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.

MPAI (mass probes aided ionization) method for total analysis of biomolecules by mass spectrometry.

Science.gov (United States)

Honda, Aki; Hayashi, Shinichiro; Hifumi, Hiroki; Honma, Yuya; Tanji, Noriyuki; Iwasawa, Naoko; Suzuki, Yoshio; Suzuki, Koji

2007-01-01

We have designed and synthesized various mass probes, which enable us to effectively ionize various molecules to be detected with mass spectrometry. We call the ionization method using mass probes the "MPAI (mass probes aided ionization)" method. We aim at the sensitive detection of various biological molecules, and also the detection of bio-molecules by a single mass spectrometry serially without changing the mechanical settings. Here, we review mass probes for small molecules with various functional groups and mass probes for proteins. Further, we introduce newly developed mass probes for proteins for highly sensitive detection.

A novel type of matrix for surface-assisted laser desorption-ionization mass spectrometric detection of biomolecules using metal-organic frameworks.

Science.gov (United States)

Fu, Chien-Ping; Lirio, Stephen; Liu, Wan-Ling; Lin, Chia-Her; Huang, Hsi-Ya

2015-08-12

A 3D metal-organic framework (MOF) nanomaterial as matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) and tandem mass spectrometry (MS/MS) was developed for the analysis of complex biomolecules. Unlike other nanoparticle matrices, this MOF nanomaterial does not need chemical modification prior to use. An exceptional signal reproducibility as well as very low background interferences in analyzing mono-/di-saccharides, peptides and complex starch digests demonstrate its high potential for biomolecule assays, especially for small molecules. Copyright © 2015 Elsevier B.V. All rights reserved.

Surface-MALDI mass spectrometry in biomaterials research

DEFF Research Database (Denmark)

Griesser, H.J.; Kingshott, P.; McArthur, S.L.

2004-01-01

Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) has been used for over a decade for the determination of purity and accurate molecular masses of macromolecular analytes, such as proteins, in solution. In the last few years the technique has been adapted to become a new...... surfaces and detecting their molecular ions with high mass resolution and at levels much below monolayer coverage. Thus, Surface-MALDI-MS offers unique means of addressing biomaterial surface analysis needs, such as identification of the proteins and lipids that adsorb from multicomponent biological...... solutions in vitro and in vivo, the study of interactions between biomaterial surfaces and biomolecules, and identification of surface-enriched additives and contaminants. Surface-MALDI-MS is rapid, experimentally convenient, overcomes limitations in mass resolution and sensitivity of established...

Peak quantification in surface-enhanced laser desorption/ionization by using mixture models

NARCIS (Netherlands)

Dijkstra, Martijn; Roelofsen, Han; Vonk, Roel J.; Jansen, Ritsert C.

2006-01-01

Surface-enhanced laser desorption/ionization (SELDI) time of flight (TOF) is a mass spectrometry technology for measuring the composition of a sampled protein mixture. A mass spectrum contains peaks corresponding to proteins in the sample. The peak areas are proportional to the measured

Ionization mechanisms in capillary supercritical fluid chromatography-chemical ionization mass spectrometry

NARCIS (Netherlands)

Houben, R.J.; Leclercq, P.A.; Cramers, C.A.M.G.

1991-01-01

Ionization mechanisms have been studied for supercritical fluid chromatography (SFC) with mass spectrometric (MS) detection. One of the problems associated with SFC-MS is the interference of mobile phase constituents in the ionization process, which complicates the interpretation of the resulting

Isotope dilution surface ionization mass spectrometry of silver in environmental materials

Energy Technology Data Exchange (ETDEWEB)

Murozumi, M; Nakamura, S; Suga, K [Muroran Inst. of Tech., Hokkaido (Japan)

1981-03-01

Surface ionization mass spectrometry has been developed to measure isotopic abundances and concentrations of silver in commercial high-purity metals, environmental materials such as rocks and plants, and /sup 109/Ag and /sup 107/Ag spikes. A minute amount of silver is extracted into a dithizone chloroform solution from a nitric acid solution of above samples. After the silver is back-extracted into 6.0 ml of a 7 mol/l HNO/sub 3/ solution, the solution is evaporated to dryness under the nitrogen atmosphere. Silver nitrate thus formed is dissolved in a mixture of 60 ..mu..l of an 0.003% silica gel suspended water and 5 ..mu..l of a 2% phosphoric acid. An aliquot of this solution is applied to the mass spectrometry using a rhenium single filament as an ion emitter. The proposed method can detect the presence of 10/sup -14/ g of silver on the ion emitter, and measure the /sup 109/Ag//sup 107/Ag isotopic ratio in environmental materials with the accuracy of 0.1 -- 0.2% in the coefficient of variation. Isotope dilution mass spectrometry using a /sup 107/Ag spike has revealed the silver concentration in the environmental standard materials, which were prepared by the National Bureau of Standards, U.S.A. and National Institute of Environmental Studies of Japan, as follows; 27.9 +- 0.2 ppb for the Orchard Leaves and 34.3 +- 0.3 ppb in the Pepper Bush. The determined values of silver in the Granodiorite, JG-1, and Basalt, JB-1 powders made by the Geological Survey of Japan are 25.4 +- 0.4 ppb and 41.3 +- 0.1 ppb respectively. Silver concentration in a coastal sea water sample is found to be at the level of 2.5 +- 0.4 ppt.

Modeling of Plutonium Ionization Probabilities for Use in Nuclear Forensic Analysis by Resonance Ionization Mass Spectrometry

Science.gov (United States)

2016-12-01

masses collide, they form a supercritical mass . Criticality refers to the neutron population within the system. A critical system is one that can...Spectrometry, no. 242, pp. 161–168, 2005. [9] S. Raeder, “Trace analysis of actinides in the environment by means of resonance ionization mass ...first ionization potential of actinide elements by resonance ionization mass spectrometry.” Spectrochimica Acta part B: Atomic Spectroscopy. vol. 52

Coffee-ring effects in laser desorption/ionization mass spectrometry.

Science.gov (United States)

Hu, Jie-Bi; Chen, Yu-Chie; Urban, Pawel L

2013-03-05

This report focuses on the heterogeneous distribution of small molecules (e.g. metabolites) within dry deposits of suspensions and solutions of inorganic and organic compounds with implications for chemical analysis of small molecules by laser desorption/ionization (LDI) mass spectrometry (MS). Taking advantage of the imaging capabilities of a modern mass spectrometer, we have investigated the occurrence of "coffee rings" in matrix-assisted laser desorption/ionization (MALDI) and surface-assisted laser desorption/ionization (SALDI) sample spots. It is seen that the "coffee-ring effect" in MALDI/SALDI samples can be both beneficial and disadvantageous. For example, formation of the coffee rings gives rise to heterogeneous distribution of analytes and matrices, thus compromising analytical performance and reproducibility of the mass spectrometric analysis. On the other hand, the coffee-ring effect can also be advantageous because it enables partial separation of analytes from some of the interfering molecules present in the sample. We report a "hidden coffee-ring effect" where under certain conditions the sample/matrix deposit appears relatively homogeneous when inspected by optical microscopy. Even in such cases, hidden coffee rings can still be found by implementing the MALDI-MS imaging technique. We have also found that to some extent, the coffee-ring effect can be suppressed during SALDI sample preparation. Copyright © 2013 Elsevier B.V. All rights reserved.

Characterization of foot- and mouth disease virus antigen by surface-enhanced laser desorption ionization-time of flight-mass spectrometry in aqueous and oil-emulsion formulations

NARCIS (Netherlands)

Harmsen, M.M.; Jansen, J.; Westra, D.F.; Coco-Martin, J.M.

2010-01-01

We have used a novel method, surface-enhanced laser desorption ionization-time of flight-mass spectrometry (SELDI-TOF-MS), to characterize foot-and-mouth disease virus (FMDV) vaccine antigens. Using specific capture with FMDV binding recombinant antibody fragments and tryptic digestion of FMDV

Inkjet-printed gold nanoparticle surfaces for the detection of low molecular weight biomolecules by laser desorption/ionization mass spectrometry.

Science.gov (United States)

Marsico, Alyssa L M; Creran, Brian; Duncan, Bradley; Elci, S Gokhan; Jiang, Ying; Onasch, Timothy B; Wormhoudt, Joda; Rotello, Vincent M; Vachet, Richard W

2015-11-01

Effective detection of low molecular weight compounds in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is often hindered by matrix interferences in the low m/z region of the mass spectrum. Here, we show that monolayer-protected gold nanoparticles (AuNPs) can serve as alternate matrices for the very sensitive detection of low molecular weight compounds such as amino acids. Amino acids can be detected at low fmol levels with minimal interferences by properly choosing the AuNP deposition method, density, size, and monolayer surface chemistry. By inkjet-printing AuNPs at various densities, we find that AuNP clusters are essential for obtaining the greatest sensitivity. Graphical Abstract ᅟ.

Electrospray ionization and matrix assisted laser desorption/ionization mass spectrometry: powerful analytical tools in recombinant protein chemistry

DEFF Research Database (Denmark)

Andersen, Jens S.; Svensson, B; Roepstorff, P

1996-01-01

Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is presen......Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy...... is presented encompassing protein characterization prior to and after cloning of the corresponding gene....

Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

International Nuclear Information System (INIS)

He, X.N.; Xie, Z.Q.; Gao, Y.; Hu, W.; Guo, L.B.; Jiang, L.; Lu, Y.F.

2012-01-01

Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

Identification of Fatty Acids, Phospholipids, and Their Oxidation Products Using Matrix-Assisted Laser Desorption Ionization Mass Spectrometry and Electrospray Ionization Mass Spectrometry

Science.gov (United States)

Harmon, Christopher W.; Mang, Stephen A.; Greaves, John; Finlayson-Pitts, Barbara J.

2010-01-01

Electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) have found increasing application in the analysis of biological samples. Using these techniques to solve problems in analytical chemistry should be an essential component of the training of undergraduate chemists. We…

Negative chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Smit, A.L.C.

1979-01-01

This thesis describes some aspects of Negative Chemical Ionization (NCI) mass spectrometry. The reasons for the growing interest in NCI are: (i) to extend the basic knowledge of negative ions and their reactions in the gas phase; (ii) to investigate whether or not this knowledge of negative ions can be used successfully to elucidate the structure of molecules by mass spectrometry. (Auth.)

Examination of Laser Microprobe Vacuum Ultraviolet Ionization Mass Spectrometry with Application to Mapping Mars Returned Samples

Science.gov (United States)

Burton, A. S.; Berger, E. L.; Locke, D. R.; Lewis, E. K.; Moore, J. F.

2018-04-01

Laser microprobe of surfaces utilizing a two laser setup whereby the desorption laser threshold is lowered below ionization, and the resulting neutral plume is examined using 157nm Vacuum Ultraviolet laser light for mass spec surface mapping.

Early Detection of Biofouling on Water Purification Membranes by Ambient Ionization Mass Spectrometry Imaging.

Science.gov (United States)

Jakka Ravindran, Swathy; Kumar, Ramesh; Srimany, Amitava; Philip, Ligy; Pradeep, Thalappil

2018-01-02

By direct analysis of water purification membranes using ambient ionization mass spectrometry, an attempt has been made to understand the molecular signatures of bacterial fouling. Membrane based purification methods are used extensively in water treatment, and a major challenge for them is biofouling. The buildup of microbes and their extracellular polymeric matrix clog the purification membranes and reduce their efficiency. To understand the early stages of bacterial fouling on water purification membranes, we have used desorption electrospray ionization mass spectrometry (DESI MS), where ion formation occurs in ambient conditions and the ionization event is surface sensitive. Biosurfactants at the air-water interface generated by microorganisms as a result of quorum sensing, influence the water-membrane interface and are important for the bacterial attachment. We show that these biosurfactants produced by bacteria can be indicator molecular species signifying initiation of biofilms on membrane surfaces, demonstrated by specific DESI MS signatures. In Pseudomonas aeruginosa, one of the best studied models for biofilm formation, this process is mediated by rhamnolipids forewarning bacterial fouling. Species dependent variation of such molecules can be used for the precise identification of the microorganisms, as revealed by studies on P. aeroginosa (ATCC 25619). The production of biosurfactants is tightly regulated at the transcriptional level by the quorum-sensing (QS) response. Thus, secretion of these extracellular molecules across the membrane surface allows rapid screening of the biofilm community. We show that, the ambient ionization mass spectrometry can detect certain toxic heavy metals present in water, using surfactant-metal complexes as analytes. We believe that such studies conducted on membranes in various input water streams will help design suitable membrane processes specific to the input streams.

Laser desorption/ionization mass spectrometry of lipids using etched silver substrates.

Science.gov (United States)

Schnapp, Andreas; Niehoff, Ann-Christin; Koch, Annika; Dreisewerd, Klaus

2016-07-15

Silver-assisted laser desorption/ionization mass spectrometry can be used for the analysis of small molecules. For example, adduct formation with silver cations enables the molecular analysis of long-chain hydrocarbons, which are difficult to ionize via conventional matrix-assisted laser desorption ionization (MALDI). Here we used highly porous silver foils, produced by etching with nitric acid, as sample substrates for LDI mass spectrometry. As model system for the analysis of complex lipid mixtures, cuticular extracts of fruit flies (Drosophila melanogaster) and worker bees (Apis mellifera) were investigated. The mass spectra obtained by spotting extract onto the etched silver substrates demonstrate the sensitive detection of numerous lipid classes such as long-chain saturated and unsaturated hydrocarbons, fatty acyl alcohols, wax esters, and triacylglycerols. MS imaging of cuticular surfaces with a lateral resolution of a few tens of micrometers became possible after blotting, i.e., after transferring lipids by physical contact with the substrate. The examples of pheromone-producing male hindwings of the squinting bush brown butterfly (Bicyclus anynana) and a fingermark are shown. Because the substrates are also easy to produce, they provide a viable alternative to colloidal silver nanoparticles and other so far described silver substrates. Copyright © 2016 Elsevier Inc. All rights reserved.

Examination and Manipulation of Protein Surface Charge in Solution with Electrospray Ionization Mass Spectrometry

Science.gov (United States)

Gross, Deborah S.; Van Ryswyk, Hal

2014-01-01

Electrospray ionization mass spectrometry (ESI-MS) is a powerful tool for examining the charge of proteins in solution. The charge can be manipulated through choice of solvent and pH. Furthermore, solution-accessible, protonated lysine side chains can be specifically tagged with 18-crown-6 ether to form noncovalent adducts. Chemical derivatization…

Analysis of chirality by femtosecond laser ionization mass spectrometry.

Science.gov (United States)

Horsch, Philipp; Urbasch, Gunter; Weitzel, Karl-Michael

2012-09-01

Recent progress in the field of chirality analysis employing laser ionization mass spectrometry is reviewed. Emphasis is given to femtosecond (fs) laser ionization work from the author's group. We begin by reviewing fundamental aspects of determining circular dichroism (CD) in fs-laser ionization mass spectrometry (fs-LIMS) discussing an example from the literature (resonant fs-LIMS of 3-methylcyclopentanone). Second, we present new data indicating CD in non-resonant fs-LIMS of propylene oxide. Copyright © 2012 Wiley Periodicals, Inc., A Wiley Company.

Chemical analysis of surfaces by resonance ionization mass spectroscopy associated to ionic pulverization

International Nuclear Information System (INIS)

Kern, P.

1995-01-01

This work shows that if resonance ionization mass spectroscopy was first applied in isotopic separation, it's also an analyzing method adapted to the study of semi-conductor materials and thin foils. We have improved this technic: a neodymium laser coupled with a dye laser, a new argon ions gun, a gallium ions gun and a new collection optic for the secondary ions quadrupole spectrometer to allow quantitative and selective measurements. (S.G.). 84 refs

Surface ionization ion source with high current

International Nuclear Information System (INIS)

Fang Jinqing; Lin Zhizhou; Yu Lihua; Zhan Rongan; Huang Guojun; Wu Jianhua

1986-04-01

The working principle and structure of a surface ionization ion source with high current is described systematically. Some technological keypoints of the ion source are given in more detail, mainly including: choosing and shaping of the material of the surface ionizer, heating of the ionizer, distributing of working vapour on the ionizer surface, the flow control, the cooling problem at the non-ionization surface and the ion optics, etc. This ion source has been used since 1972 in the electromagnetic isotope separator with 180 deg angle. It is suitable for separating isotopes of alkali metals and rare earth metals. For instance, in the case of separating Rubidium, the maximum ion current of Rbsup(+) extracted from the ion source is about 120 mA, the maximum ion current accepted by the receiver is about 66 mA, the average ion current is more than 25 mA. The results show that our ion source have advantages of high ion current, good characteristics of focusing ion beam, working stability and structure reliability etc. It may be extended to other fields. Finally, some interesting phenomena in the experiment are disccused briefly. Some problems which should be investigated are further pointed out

Rapid determination of trace nitrophenolic organics in water by combining solid-phase extraction with surface-assisted laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Chen, Y C; Shiea, J; Sunner, J

2000-01-01

A rapid technique for the screening of trace compounds in water by combining solid-phase extraction (SPE) with activated carbon surface-assisted laser desorption/ionization (SALDI) time-of-flight mass spectrometry is demonstrated. Activated carbon is used both as the sorbent in SPE and as the solid in the SALDI matrix system. This eliminates the need for an SPE elution process. After the analytes have been adsorbed on the surfaces of the activated carbon during SPE extraction, the activated carbon is directly mixed with the SALDI liquid and mass spectrometric analysis is performed. Trace phenolic compounds in water were used to demonstrate the effectiveness of the method. The detection limit for these compounds is in the ppb to ppt range. Copyright 2000 John Wiley & Sons, Ltd.

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.

Direct Surface and Droplet Microsampling for Electrospray Ionization Mass Spectrometry Analysis with an Integrated Dual-Probe Microfluidic Chip

Energy Technology Data Exchange (ETDEWEB)

Huang, Cong-Min [Institute of Microanalytical; Zhu, Ying [Institute of Microanalytical; Jin, Di-Qiong [Institute of Microanalytical; Kelly, Ryan T. [Environmental; Fang, Qun [Institute of Microanalytical

2017-08-15

Ambient mass spectrometry (MS) has revolutionized the way of MS analysis and broadened its application in various fields. This paper describes the use of microfluidic techniques to simplify the setup and improve the functions of ambient MS by integrating the sampling probe, electrospray emitter probe, and online mixer on a single glass microchip. Two types of sampling probes, including a parallel-channel probe and a U-shaped channel probe, were designed for dryspot and liquid-phase droplet samples, respectively. We demonstrated that the microfabrication techniques not only enhanced the capability of ambient MS methods in analysis of dry-spot samples on various surfaces, but also enabled new applications in the analysis of nanoliter-scale chemical reactions in an array of droplets. The versatility of the microchip-based ambient MS method was demonstrated in multiple different applications including evaluation of residual pesticide on fruit surfaces, sensitive analysis of low-ionizable analytes using postsampling derivatization, and high-throughput screening of Ugi-type multicomponent reactions.

Indigenously built resonance ionization mass spectrometer

International Nuclear Information System (INIS)

Razvi, M.A.N.; Jayasekharan, T.; Thankarajan, K.; Guhagarkar, M.B.; Dixit, M.N.; Bhale, G.L.

2000-04-01

Design, fabrication and performance testing of an indigenously built Resonance Ionization Mass Spectrometer (RIMS) is presented in this report. The instrument is totally indigenous, but for the laser components consisting of the excimer laser and tunable dye lasers. Constructional details of atomic beam source and linear time-of-flight mass spectrometer are included. Finally, commissioning and performance testing of the instrument is described. Mass resolving power of 400 and a detection limit of 100 atoms has been achieved using this RIMS set-up. (author)

Direct Analysis of Large Living Organism by Megavolt Electrostatic Ionization Mass Spectrometry

Science.gov (United States)

Ng, Kwan-Ming; Tang, Ho-Wai; Man, Sin-Heng; Mak, Pui-Yuk; Choi, Yi-Ching; Wong, Melody Yee-Man

2014-09-01

A new ambient ionization method allowing the direct chemical analysis of living human body by mass spectrometry (MS) was developed. This MS method, namely Megavolt Electrostatic Ionization Mass Spectrometry, is based on electrostatic charging of a living individual to megavolt (MV) potential, illicit drugs, and explosives on skin/glove, flammable solvent on cloth/tissue paper, and volatile food substances in breath were readily ionized and detected by a mass spectrometer.

Desorption and ionization processes in laser mass spectrometry

International Nuclear Information System (INIS)

Peyl, G.J.Q. van der.

1984-01-01

In this thesis results are reported from a study on the desorption- and ionization process initiated by infra-red laser irradiation (LDMS) or ion bombardment (SIMS) of thin organic sample layers. The study is especially focused on the formation of quasimolecular ions under these conditions. Results of these investigations can be used for a better optimization of the LDMS and SIMS techniques in organic mass spectrometry. First, an overview is given of laser desorption mass spectrometry. Next, the coupling of the laser energy into the organic sample layer is investigated. It is concluded that the laser energy is primarily absorbed by the substrate material and not by the organic overlayer. The formation of quasi-molecular ions, either in the gas phase or in the substrate surface is investigated. The final section reports kinetic energy distributions for ions sputtered from organic solids and liquids. (Auth.)

Laser post-ionization secondary neutral mass spectroscopy

International Nuclear Information System (INIS)

Gruen, D.M.; Pellin, M.J.; Calaway, W.F.; Young, C.E.

1987-01-01

Three different instruments using laser ionization techniques will be described. Results from the SARISA instrument with a demonstrated figure of merit of .05 (atoms detected/atoms sputtered) for resonance ionization; detection of Fe at the sub-part-per-billion level in ultrapure Si; and features of the instrument such as energy and angle refocusing time-of-flight (EARTOF) mass spectrometer and multiplexing for simultaneous detection of secondary ions and neutrals. 12 refs., 3 figs

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.

Desorption electro-spray ionization - orbitrap mass spectrometry of synthetic polymers and copolymers

International Nuclear Information System (INIS)

Friia, Manel; Legros, Veronique; Tortajada, Jeanine; Buchmann, William

2012-01-01

Desorption Electro-Spray Ionization (DESI) - Orbitrap Mass Spectrometry (MS) was evaluated as a new tool for the characterization of various industrial synthetic polymers (poly(ethylene glycol), poly(propylene glycol), poly(methylmethacrylate), poly(dimethylsiloxane)) and copolymers, with masses ranging from 500 g.mol -1 up to more than 20000 g.mol -1 . Satisfying results in terms of signal stability and sensitivity were obtained from hydrophobic surfaces (HTC Prosolia) with a mixture water/methanol (10/90) as spray solvent in the presence of sodium salt. Taking into account the formation of multiplied charged species by DESI-MS, a strategy based on the use of a deconvolution software followed by the automatic assignment of the ions was described allowing the rapid determination of Mn, Mw and PDI values. DESI-Orbitrap MS results were compared to those obtained from matrix-assisted laser desorption/ionization- time-of-flight MS and gel permeation chromatography. An application of DESI-Orbitrap MS for the detection and identification of polymers directly from cosmetics was described. (authors)

Silver nanostructures in laser desorption/ionization mass spectrometry and mass spectrometry imaging.

Science.gov (United States)

Sekuła, Justyna; Nizioł, Joanna; Rode, Wojciech; Ruman, Tomasz

2015-09-21

Silver nanoparticles have been successfully applied as a matrix replacement for the laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS). Nanoparticles, producing spectra with highly reduced chemical background in the low m/z region, are perfectly suited for low-molecular weight compound analysis and imaging. Silver nanoparticles (AgNPs) can efficiently absorb ultraviolet laser radiation, transfer energy to the analyte and promote analyte desorption, but also constitute a source of silver ions suitable for analyte cationisation. This review provides an overview of the literature on silver nanomaterials as non-conventional desorption and ionization promoters in LDI-MS and mass spectrometry imaging.

Laser desorption/ionization from nanostructured surfaces: nanowires, nanoparticle films and silicon microcolumn arrays

International Nuclear Information System (INIS)

Chen Yong; Luo Guanghong; Diao Jiajie; Chornoguz, Olesya; Reeves, Mark; Vertes, Akos

2007-01-01

Due to their optical properties and morphology, thin films formed of nanoparticles are potentially new platforms for soft laser desorption/ionization (SLDI) mass spectrometry. Thin films of gold nanoparticles (with 12±1 nm particle size) were prepared by evaporation-driven vertical colloidal deposition and used to analyze a series of directly deposited polypeptide samples. In this new SLDI method, the required laser fluence for ion detection was equal or less than what was needed for matrix-assisted laser desorption/ionization (MALDI) but the resulting spectra were free of matrix interferences. A silicon microcolumn array-based substrate (a.k.a. black silicon) was developed as a new matrix-free laser desorption ionization surface. When low-resistivity silicon wafers were processed with a 22 ps pulse length 3xω Nd:YAG laser in air, SF 6 or water environment, regularly arranged conical spikes emerged. The radii of the spike tips varied with the processing environment, ranging from approximately 500 nm in water, to ∼2 μm in SF 6 gas and to ∼5 μm in air. Peptide mass spectra directly induced by a nitrogen laser showed the formation of protonated ions of angiotensin I and II, substance P, bradykinin fragment 1-7, synthetic peptide, pro14-arg, and insulin from the processed silicon surfaces but not from the unprocessed areas. Threshold fluences for desorption/ionization were similar to those used in MALDI. Although compared to silicon nanowires the threshold laser pulse energy for ionization is significantly (∼10x) higher, the ease of production and robustness of microcolumn arrays offer complementary benefits

High-efficiency thermal ionization sources for mass spectrometry

International Nuclear Information System (INIS)

Olivares, Jose A.

1996-01-01

A version of the thermal ionization cavity (TIC) source developed specifically for use in mass spectrometry is presented. The performance of this ion source has been characterized extensively both with the use of an isotope separator and a quadrupole mass spectrometer. A detailed description of the TIC source for mass spectrometry is given along with the performance characteristics observed

Microplasma-based flowing atmospheric-pressure afterglow (FAPA) source for ambient desorption-ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Zeiri, Offer M.; Storey, Andrew P.; Ray, Steven J., E-mail: sjray2@buffalo.edu; Hieftje, Gary M.

2017-02-01

A new direct-current microplasma-based flowing atmospheric pressure afterglow (FAPA) source was developed for use in ambient desorption-ionization mass spectrometry. The annular-shaped microplasma is formed in helium between two concentric stainless-steel capillaries that are separated by an alumina tube. Current-voltage characterization of the source shows that this version of the FAPA operates in the normal glow-discharge regime. A glass surface placed in the path of the helium afterglow reaches temperatures of up to approximately 400 °C; the temperature varies with distance from the source and helium flow rate through the source. Solid, liquid, and vapor samples were examined by means of a time-of-flight mass spectrometer. Results suggest that ionization occurs mainly through protonation, with only a small amount of fragmentation and adduct formation. The mass range of the source was shown to extend up to at least m/z 2722 for singly charged species. Limits of detection for several small organic molecules were in the sub-picomole range. Examination of competitive ionization revealed that signal suppression occurs only at high (mM) concentrations of competing substances. - Highlights: • The first microplasma version of the FAPA source. • Current-voltage behavior reflects the behavior of a normal glow discharge. • Detection limits below 1 pmol for the classes of organic compounds studied over a wide mass range. • Mass spectra show limited fragmentation.

Fundamentals of Biomolecule Analysis by Electrospray Ionization Mass Spectrometry

Science.gov (United States)

Weinecke, Andrea; Ryzhov, Victor

2005-01-01

Electrospray ionization (ESI) is a soft ionization technique that allows transfer of fragile biomolecules directly from solution into the gas phase. An instrumental analysis laboratory experiment is designed that would introduce the students to the ESI technique, major parameters of the ion trap mass spectrometers and some caveats in…

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.

Ionization by a pulsed plasma surface water

International Nuclear Information System (INIS)

Bloyet, E.; Leprince, P.; Marec, J.; Llamas Blasco, M.

1981-01-01

The ionization mechanism is studied of a pulsed surface wave generating a microwave discharge. When the plasma is dominated by collisions, it is found that the velocity of the ionization front depends on the ponderomotive force due to the field gradient in the front. (orig.)

Optimization and evaluation of surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry for protein profiling of cerebrospinal fluid

Directory of Open Access Journals (Sweden)

Gomez-Mancilla Baltazar

2006-04-01

Full Text Available Abstract Cerebrospinal fluid (CSF potentially carries an archive of peptides and small proteins relevant to pathological processes in the central nervous system (CNS and surrounding brain tissue. Proteomics is especially well suited for the discovery of biomarkers of diagnostic potential in CSF for early diagnosis and discrimination of several neurodegenerative diseases. ProteinChip surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS is one such approach which offers a unique platform for high throughput profiling of peptides and small proteins in CSF. In this study, we evaluated methodologies for the retention of CSF proteins m/z we found a high degree of overlap between the tested array surfaces. The combination of CM10 and IMAC30 arrays was sufficient to represent between 80–90% of all assigned peaks when using either sinapinic acid or α-Cyano-4-hydroxycinnamic acid as the energy absorbing matrices. Moreover, arrays processed with SPA consistently showed better peak resolution and higher peak number across all surfaces within the measured mass range. We intend to use CM10 and IMAC30 arrays prepared in sinapinic acid as a fast and cost-effective approach to drive decisions on sample selection prior to more in-depth discovery of diagnostic biomarkers in CSF using alternative but complementary proteomic strategies.

Sensitivity enhancement for nitrophenols using cationic surfactant-modified activated carbon for solid-phase extraction surface-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Chen, Y C; Tsai, M F

2000-01-01

Previous work has demonstrated that a combination of solid-phase extraction with surface-assisted laser desorption/ionization (SPE-SALDI) mass spectrometry can be applied to the determination of trace nitrophenols in water. An improved method to lower the detection limit of this hyphenated technique is described in this present study. Activated carbon powder is used as both the SPE adsorbent and the SALDI solid in the analysis by SPE-SALDI. The surface of the activated carbon is modified by passing an aqueous solution of a cationic surfactant through the SPE cartridge. The results demonstrate that the sensitivity for nitrophenols in the analysis by SPE-SALDI can be improved by using cationic surfactants to modify the surface of the activated carbon. The detection limit for nitrophenols is about 25 ppt based on a signal-to-noise ratio of 3 by sampling from 100 mL of solution. Copyright 2000 John Wiley & Sons, Ltd.

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

Determination of trace quaternary ammonium surfactants in water by combining solid-phase extraction with surface-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Chen, Y C; Sun, M C

2001-01-01

This study demonstrates the feasibility of combining solid-phase extraction (SPE) with surface-assisted laser desorption/ionization (SALDI) mass spectrometry to determine trace quaternary ammonium surfactants in water. The trace surfactants in water were directly concentrated on the surface of activated carbon sorbent in SPE. The activated carbon sorbent was then mixed with the SALDI liquid for SALDI analysis. No SPE elution procedure was necessary. Experimental results indicate that the surfactants with longer chain alkyl groups exhibit higher sensitivities than those with shorter chain alkyl groups in SPE-SALDI analysis. The detection limit for hexadecyltrimethylammonium bromide is around 10 ppt in SPE-SALDI analysis by sampling 100 mL of aqueous solution, while that of tetradecyltrimethylammonium bromide is about 100 ppt. The detection limit for decyltrimethylammonium bromide and dodecyltrimethylammonium bromide is in the low-ppb range. Copyright 2001 John Wiley & Sons, Ltd.

Determination of Nerve Agent Metabolites by Ultraviolet Femtosecond Laser Ionization Mass Spectrometry.

Science.gov (United States)

Hamachi, Akifumi; Imasaka, Tomoko; Nakamura, Hiroshi; Li, Adan; Imasaka, Totaro

2017-05-02

Nerve agent metabolites, i.e., isopropyl methylphosphonic acid (IMPA) and pinacolyl methylphosphonic acid (PMPA), were derivatized by reacting them with 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr) and were determined by mass spectrometry using an ultraviolet femtosecond laser emitting at 267 and 200 nm as the ionization source. The analytes of the derivatized compounds, i.e., IMPA-PFB and PMPA-PFB, contain a large side-chain, and molecular ions are very weak or absent in electron ionization mass spectrometry. The use of ultraviolet femtosecond laser ionization mass spectrometry, however, resulted in the formation of a molecular ion, even for compounds such as these that contain a highly bulky functional group. The signal intensity was larger at 200 nm due to resonance-enhanced two-photon ionization. In contrast, fragmentation was suppressed at 267 nm (nonresonant two-photon ionization) especially for PMPA-PFB, thus resulting in a lower background signal. This favorable result can be explained by the small excess energy in ionization at 267 nm and by the low-frequency vibrational mode of a bulky trimethylpropyl group in PMPA.

Determination of ultra-low levels of uranium using resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Kiran Kumar, P.V.; Acharyulu, G.V.S.G.

2015-01-01

The determination of isotopic composition of actinides like U and Pu is important, due to their distribution in the environment as a result of nuclear weapons testing, fuel reprocessing, reactor operations and to a smaller extent from accidental releases. The analytical methods like fission track analysis (FTA), thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS) and resonance ionization mass spectrometry (RIMS) have evolved as sensitive techniques. Resonance Ionization Mass Spectrometry yields rapid isotopic signature data for material containing actinides without requiring time-consuming sample preparation and chemical separation procedures. In this paper, authors presented the details of the methodology and results for low-level detection of uranium using RIMS

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.

Development of a Portable Single Photon Ionization-Photoelectron Ionization Time-of-Flight Mass Spectrometer

Directory of Open Access Journals (Sweden)

Yunguang Huang

2015-01-01

Full Text Available A vacuum ultraviolet lamp based single photon ionization- (SPI- photoelectron ionization (PEI portable reflecting time-of-flight mass spectrometer (TOFMS was designed for online monitoring gas samples. It has a dual mode ionization source: SPI for analyte with ionization energy (IE below 10.6 eV and PEI for IE higher than 10.6 eV. Two kinds of sampling inlets, a capillary inlet and a membrane inlet, are utilized for high concentration and trace volatile organic compounds, respectively. A mass resolution of 1100 at m/z 64 has been obtained with a total size of 40 × 31 × 29 cm, the weight is 27 kg, and the power consumption is only 70 W. A mixture of benzene, toluene, and xylene (BTX, SO2, and discharging products of SF6 were used to test its performance, and the result showed that the limit of quantitation for BTX is as low as 5 ppbv (S/N = 10 : 1 with linear dynamic ranges greater than four orders of magnitude. The portable TOFMS was also evaluated by analyzing volatile organic compounds from wine and decomposition products of SF6 inside of a gas-insulated switchgear.

Identification of protein biomarkers in Dupuytren's contracture using surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS).

Science.gov (United States)

O'Gorman, David; Howard, Jeffrey C; Varallo, Vincenzo M; Cadieux, Peter; Bowley, Erin; McLean, Kris; Pak, Brian J; Gan, Bing Siang

2006-06-01

To study the protein expression profiles associated with Dupuytren's contracture (DC) to identify potential disease protein biomarkers (PBM) using a proteomic technology--Surface Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS). Normal and disease palmar fascia from DC patients were analyzed using Ciphergen's SELDI-TOF-MS Protein Biological System II (PBSII) ProteinChip reader. Analysis of the resulting SELDI-TOF spectra was carried out using the peak cluster analysis program (BioMarker Wizard, Ciphergen). Common peak clusters were then filtered using a bootstrap algorithm called SAM (Significant Analysis of Microarrays) for increased fidelity in our analysis. Several differentially expressed low molecular weight (mass standard deviation for both methods of biomarker-rich low molecular weight region of the human proteome. Application of such novel technology may help clinicians to focus on specific molecular abnormalities in diseases with no known molecular pathogenesis, and uncover therapeutic and/or diagnostic targets.

Stringent limits on the ionized mass loss from A and F dwarfs

International Nuclear Information System (INIS)

Brown, A.; Veale, A.; Judge, P.; Bookbinder, J.A.; Hubeny, I.

1990-01-01

Following the suggestion of Willson et al. (1987) that A- and F-type main-sequence stars might undergo significant mass loss due to pulsationally driven winds, upper limits to the ionized mass loss from A and F dwarfs have been obtained using VLA observations. These stringent upper limits show that the level of ionized mass loss would have at most only a small effect on stellar evolution. Radiative-equilibrium atmospheric and wind models for early A dwarfs indicate that it is highly likely that a wind flowing from such stars would be significantly ionized. In addition, late A and early F dwarfs exhibit chromospheric emission indicative of significant nonradiative heating. The present mass-loss limits are thus representative of the total mass-loss rates for these stars. It is concluded that A and F dwarfs are not losing sufficient mass to cause A dwarfs to evolve into G dwarfs. 24 refs

Determination of the Isotope Ratio for Metal Samples Using a Laser Ablation/Ionization Time-of-flight Mass Spectrometry

International Nuclear Information System (INIS)

Song, Kyu Seok; Cha, Hyung Ki; Kim, Duk Hyeon; Min, Ki Hyun

2004-01-01

The laser ablation/ionization time-of-flight mass spectrometry is applied to the isotopic analysis of solid samples using a home-made instrument. The technique is convenient for solid sample analysis due to the onestep process of vaporization and ionization of the samples. The analyzed samples were lead, cadmium, molybdenum, and ytterbium. To optimize the analytical conditions of the technique, several parameters, such as laser energy, laser wavelength, size of the laser beam on the samples surface, and high voltages applied on the ion source electrodes were varied. Low energy of laser light was necessary to obtain the optimal mass resolution of spectra. The 532 nm light generated mass spectra with the higher signal-to-noise ratio compared with the 355 nm light. The best mass resolution obtained in the present study is ∼1,500 for the ytterbium

Determination of trace elements by resonant ionization mass spectrometry (RIMS)

International Nuclear Information System (INIS)

Ruster, W.; Ames, F.; Rehklau, D.; Mang, M.; Muehleck, C.; Rimke, H.; Sattelberger, P.; Herrmann, G.; Trautmann, N.; Kluge, H.J.; Otten, E.W.

1988-01-01

A resonant ionization mass spectrometer has been developed as an analytical tool for the detection of trace elements, especially of plutonium and other radionuclides. The sample, deposited on a rhenium filament, is evaporated by electrical heating and the atoms of the element under investigation are selectively ionized by laser light delivered from three dye lasers pumped by a copper vapour laser. The resulting photoions are detected in a time-of-flight spectrometer with a channelplate detector. For plutonium a mass resolution of M/ΔM=1500 was obtained and an overall detection efficiency of 4x10 -6 was determined for stepwise excitation and ionization via autoionizing states. With a laser light bandwidth of 3-5 GHz neighbouring isotopes could be suppressed by a factor of 20 due to isotope shifts in the excitation transitions. The isotope composition of synthetic samples was measured and good agreement was found with mass spectroscopic results. The influence of the hyperfine structure on the isotope ratios is discussed. (orig.)

Determination of the first ionization potential of actinides by resonance ionization mass spectroscopy

International Nuclear Information System (INIS)

Koehler, S.; Albus, F.; Dibenberger, R.; Erdmann, N.; Funk, H.; Hasse, H.; Herrmann, G.; Huber, G.; Kluge, H.; Nunnemann, M.; Passler, G.; Rao, P.M.; Riegel, J.; Trautmann, N.; Urban, F.

1995-01-01

Resonance ionization mass spectroscopy (RIMS) is used for the precise determination of the first ionization potential of transuranium elements. The first ionization potentials (IP) of americium and curium have been measured for the first time to IP Am =5.9738(2) and IP Cm =5.9913(8) eV, respectively, using only 10 12 atoms of 243 Am and 248 Cm. The same technique was applied to thorium, neptunium, and plutonium yielding IP T H =6.3067(2), IP N P =6.2655(2), and IP Pu =6.0257(8) eV. The good agreement of our results with the literature data proves the precision of the method which was additionally confirmed by the analysis of Rydberg seris of americium measured by RIMS. copyright American Institute of Physics 1995

Instantaneous Characterization Of Vegetable Oils Via Tag And Ffa Profiles By Easy Ambient Sonic-spray Ionization Mass Spectrometry.

OpenAIRE

Simas, Rosineide C; Catharino, Rodrigo R; Cunha, Ildenize B S; Cabral, Elaine C; Barrera-Arellano, Daniel; Eberlin, Marcos N; Alberici, Rosana M

2015-01-01

A fast and reliable method is presented for the analysis of vegetable oils. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to efficiently desorb and ionize the main oil constituents from an inert surface under ambient conditions and to provide comprehensive triacylglyceride (TAG) and free fatty acid (FFA) profiles detected mainly as either [TAG + Na](+) or [FFA-H](-) ions. EASI(+/-)-MS analysis is simple, easily implemented, requires just a tiny droplet of the oil an...

Electrospray Ionization with High-Resolution Mass Spectrometry as a Tool for Lignomics: Lignin Mass Spectrum Deconvolution

Science.gov (United States)

Andrianova, Anastasia A.; DiProspero, Thomas; Geib, Clayton; Smoliakova, Irina P.; Kozliak, Evguenii I.; Kubátová, Alena

2018-05-01

The capability to characterize lignin, lignocellulose, and their degradation products is essential for the development of new renewable feedstocks. Electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR TOF-MS) method was developed expanding the lignomics toolkit while targeting the simultaneous detection of low and high molecular weight (MW) lignin species. The effect of a broad range of electrolytes and various ionization conditions on ion formation and ionization effectiveness was studied using a suite of mono-, di-, and triarene lignin model compounds as well as kraft alkali lignin. Contrary to the previous studies, the positive ionization mode was found to be more effective for methoxy-substituted arenes and polyphenols, i.e., species of a broadly varied MW structurally similar to the native lignin. For the first time, we report an effective formation of multiply charged species of lignin with the subsequent mass spectrum deconvolution in the presence of 100 mmol L-1 formic acid in the positive ESI mode. The developed method enabled the detection of lignin species with an MW between 150 and 9000 Da or higher, depending on the mass analyzer. The obtained M n and M w values of 1500 and 2500 Da, respectively, were in good agreement with those determined by gel permeation chromatography. Furthermore, the deconvoluted ESI mass spectrum was similar to that obtained with matrix-assisted laser desorption/ionization (MALDI)-HR TOF-MS, yet featuring a higher signal-to-noise ratio. The formation of multiply charged species was confirmed with ion mobility ESI-HR Q-TOF-MS. [Figure not available: see fulltext.

Resonance ionization mass spectrometry using tunable diode lasers

International Nuclear Information System (INIS)

Shaw, R.W.; Young, J.P.; Smith, D.H.

1990-01-01

Tunable semiconductor diode lasers will find many important applications in atomic spectroscopy. They exhibit the desirable attributes of lasers: narrow bandwidth, tunability, and spatial coherence. At the same time, they possess few of the disadvantages of other tunable lasers. They require no alignment, are simple to operate, and are inexpensive. Practical laser spectroscopic instruments can be envisioned. The authors have applied diode lasers to resonance ionization mass spectrometry (RIMS) of some of the lanthanide elements. Sub-Doppler resolution spectra have been recorded and have been used for atomic hyperfine structure analysis. Isotopically-selective ionization has been accomplished, even in cases where photons from a broadband dye laser are part of the overall ionization process and where the isotopic spectral shift is very small. A convenient RIMS instrument for isotope ratio measurements that employs only diode lasers, along with electric field ionization, should be possible

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.

On-surface Fenton and Fenton-like reactions appraised by paper spray ionization mass spectrometry.

Science.gov (United States)

Resende, S F; Oliveira, B S; Augusti, R

2018-06-21

On-surface degradation of sildenafil (an adequate substrate as it contains assorted functional groups in its structure) promoted by the Fenton (Fe 2+ / H 2 O 2 ) and Fenton-like (M n+ / H 2 O 2 ; M n+ = Fe 3+ , Co 2+ , Cu 2+ , Mn 2+ ) systems was investigated by using paper spray ionization mass spectrometry (PS-MS). The performance of each system was compared by measuring the ratio between the relative intensities of the ions of m/z 475 (protonated sildenafil) and m/z 235 (protonated lidocaine, used as a convenient internal standard and added to the paper just before the PS-MS analyzes). The results indicated the following order in the rates of such reactions: Fe 2+ /H 2 O 2 > H 2 O 2 > Cu 2+ /H 2 O 2 > M n+ / H 2 O 2 (M n+ = Fe 3+ , Co 2+ , Mn 2+ ) ~ M n+ (M n+ = Fe 2+ , Fe 3+ , Co 2+ , Cu 2+ , Mn 2 . The superior capability of Fe 2+ /H 2 O 2 in causing the degradation of sildenafil indicates that Fe 2+ efficiently decomposes H 2 O 2 to yield hydroxyl radicals, quite reactive species that cause the substrate oxidation. The results also indicate that H 2 O 2 can spontaneously decompose likely to yield hydroxyl radicals, although in a much smaller extension than the Fenton system. This effect, however, is strongly inhibited by the presence of the other cations, i. e. Fe 3+ , Co 2+ , Cu 2+ and Mn 2+ . A unique oxidation by-product was detected in the reaction between Fe 2+ /H 2 O 2 with sildenafil and a possible structure for it was proposed based on the MS/MS data. The on-surface reaction of other substrates (trimethoprim and tamoxifen) with the Fenton system was also investigated. In conclusion, PS-MS shown to be a convenient platform to promptly monitor on-surface oxidation reactions. This article is protected by copyright. All rights reserved.

Resonance ionization mass spectrometry system for measurement of environmental samples

International Nuclear Information System (INIS)

Pibida, L.; McMahon, C.A.; Noertershaeuser, W.; Bushaw, B.A.

2002-01-01

A resonance ionization mass spectrometry (RIMS) system has been developed at the National Institute of Standards and Technology (NIST) for sensitive and selective determination of radio-cesium in the environment. The overall efficiency was determined to be 4x10-7 with a combined (laser and mass spectrometer) selectivity of 108 for both 135Cs and 137Cs with respect to 133Cs. RIMS isotopic ratio measurements of 135Cs/ 137Cs were performed on a nuclear fuel burn-up sample and compared to measurements on a similar system at Pacific Northwest National Laboratory (PNNL) and to conventional thermal ionization mass spectrometry (TIMS). Results of preliminary RIMS investigations on a freshwater lake sediment sample are also discussed

Application of resonance ionization mass spectrometry for trace analysis and in fundamental research

International Nuclear Information System (INIS)

Passler, G.

1997-01-01

Resonance ionization mass spectrometry (RIMS) has been used for ultra-trace analysis on long-lived radioisotopes like Pu, Tc and 89,90 Sr in various environmental samples. The experimental approaches cover pulsed laser spectroscopy on a thermal atomic beam and subsequent time-of-flight mass analysis, a pulsed laser ion source combined with conventional mass spectrometry, and collinear resonance ionization on a mass-separated fast atomic beam. The high sensitivity of RIMS also enables atomic spectroscopy on rare isotopes. For the first time experimental values for the ionization potential of actinides up to Cf have been determined. The paper reviews the dependency of the different experimental approaches on the analytical problem. copyright 1997 American Institute of Physics

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.

Dehydrodimerization of pterostilbene during electrospray ionization mass spectrometry

KAUST Repository

Raji, Misjudeen; Amad, Maan H.; Emwas, Abdul-Hamid M.

2013-01-01

RATIONALE Pterostilbene is a member of the hydroxystilbene family of compounds commonly found in plants such as blueberry and grapes. During the analysis of this compound by electrospray ionization mass spectrometry (ESI-MS), an ion was observed

Exploring surface photoreaction dynamics using pixel imaging mass spectrometry (PImMS)

Science.gov (United States)

Kershis, Matthew D.; Wilson, Daniel P.; White, Michael G.; John, Jaya John; Nomerotski, Andrei; Brouard, Mark; Lee, Jason W. L.; Vallance, Claire; Turchetta, Renato

2013-08-01

A new technique for studying surface photochemistry has been developed using an ion imaging time-of-flight mass spectrometer in conjunction with a fast camera capable of multimass imaging. This technique, called pixel imaging mass spectrometry (PImMS), has been applied to the study of butanone photooxidation on TiO2(110). In agreement with previous studies of this system, it was observed that the main photooxidation pathway for butanone involves ejection of an ethyl radical into vacuum which, as confirmed by our imaging experiment, undergoes fragmentation after ionization in the mass spectrometer. This proof-of-principle experiment illustrates the usefulness and applicability of PImMS technology to problems of interest within the surface science community.

Quantification of captopril in urine through surface-assisted laser desorption/ionization mass spectrometry using 4-mercaptobenzoic acid-capped gold nanoparticles as an internal standard.

Science.gov (United States)

Chen, Wen-Tsen; Chiang, Cheng-Kang; Lin, Yang-Wei; Chang, Huan-Tsung

2010-05-01

We have developed a new internal standard method for the determination of the concentration of captopril (CAP) through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using gold nanoparticles (Au NPs). This approach provided linearity for CAP over the concentration range 2.5-25 microM (R(2) = 0.987), with a limit of detection (signal-to-noise ratio = 3) of 1.0 microM. The spot-to-spot variations in the concentration of CAP through SALDI-MS analyses performed in the absence and presence of the internal standard were 26% and 9%, respectively (15 measurements). This approach provides simplicity, accuracy, precision, and great reproducibility to the determination of the levels of CAP in human urine samples. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

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

Selective laser ionization for mass-spectral isotopic analysis

International Nuclear Information System (INIS)

Miller, C.M.; Nogar, N.S.; Downey, S.W.

1983-01-01

Resonant enhancement of the ionization process can provide a high degree of elemental selectivity, thus eliminating or drastically reducing the interference problem. In addition, extension of this method to isotopically selective ionization has the potential for greatly increasing the range of isotope ratios that can be determined experimentally. This gain can be realized by reducing or eliminating the tailing of the signal from the high-abundance isotope into that of the low-abundance isotope, augmenting the dispersion of the mass spectrometer. We briefly discuss the hardware and techniques used in both our pulsed and cw RIMS experiments. Results are presented for both cw ionization experiments on Lu/Yb mixtures, and spectroscopic studies of multicolor RIMS of Tc. Lastly, we discuss practical limits of cw RIMS analysis in terms of detection limits and measurable isotope ratios

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.

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

Analysis of Nitro-aromatic and Nitramine Explosives by Atmospheric Pressure Chemical Ionization / High Performance Liquid Chromatography / Mass Spectrometry / Mass Spectrometry

International Nuclear Information System (INIS)

Hicks, B.J.; Han, W.; Robben, J.R.

2009-01-01

This procedure is capable of separating and quantifying twenty-nine high explosives and internal surrogates with a single injection. After the initial preparation step, the sample is introduced to the high performance liquid chromatograph for target separation, ionized by atmospheric pressure chemical ionization and the explosives of interest are isolated / quantified by mass spectrometry / mass spectrometry. Concentrations of the target explosives are measured relative to the response of both internal and external standard concentrations. A C-18 reverse phase high performance liquid chromatograph column is used for separation. Ionization is performed using both positive and negative atmospheric pressure chemical ionization resulting in a molecular ion with little fragmentation. These ions are isolated at the first quadrupole of the mass spectrometer, dissociated by collision with argon in the collision cell and the resulting daughter ions are isolated at the second quadrupole. These daughter ions then reach the detector where they are quantified. To date this procedure represents the most thorough high performance liquid chromatography / mass spectrometry / mass spectrometry explosives analysis available in the environmental chemistry market. (authors)

Imaging of plant materials using indirect desorption electrospray ionization mass spectrometry

DEFF Research Database (Denmark)

Janfelt, Christian

2015-01-01

Indirect desorption electrospray ionization mass spectrometry (DESI-MS) imaging is a method for imaging distributions of metabolites in plant materials, in particular leaves and petals. The challenge in direct imaging of such plant materials with DESI-MS is particularly the protective layer of cu...... of interest from parts of their matrix while preserving the spatial information in the two dimensions. The imprint can then easily be imaged by DESI-MS. The method delivers simple and robust mass spectrometry imaging of plant material with very high success ratios....... of cuticular wax present in leaves and petals. The cuticle protects the plant from drying out, but also makes it difficult for the DESI sprayer to reach the analytes of interest inside the plant material. A solution to this problem is to imprint the plant material onto a surface, thus releasing the analytes...

Direct olive oil analysis by mass spectrometry: A comparison of different ambient ionization methods.

Science.gov (United States)

Lara-Ortega, Felipe J; Beneito-Cambra, Miriam; Robles-Molina, José; García-Reyes, Juan F; Gilbert-López, Bienvenida; Molina-Díaz, Antonio

2018-04-01

Analytical methods based on ambient ionization mass spectrometry (AIMS) combine the classic outstanding performance of mass spectrometry in terms of sensitivity and selectivity along with convenient features related to the lack of sample workup required. In this work, the performance of different mass spectrometry-based methods has been assessed for the direct analyses of virgin olive oil for quality purposes. Two sets of experiments have been setup: (1) direct analysis of untreated olive oil using AIMS methods such as Low-Temperature Plasma Mass Spectrometry (LTP-MS) or paper spray mass spectrometry (PS-MS); or alternatively (2) the use of atmospheric pressure ionization (API) mass spectrometry by direct infusion of a diluted sample through either atmospheric pressure chemical ionization (APCI) or electrospray (ESI) ionization sources. The second strategy involved a minimum sample work-up consisting of a simple olive oil dilution (from 1:10 to 1:1000) with appropriate solvents, which originated critical carry over effects in ESI, making unreliable its use in routine; thus, ESI required the use of a liquid-liquid extraction to shift the measurement towards a specific part of the composition of the edible oil (i.e. polyphenol rich fraction or lipid/fatty acid profile). On the other hand, LTP-MS enabled direct undiluted mass analysis of olive oil. The use of PS-MS provided additional advantages such as an extended ionization coverage/molecular weight range (compared to LTP-MS) and the possibility to increase the ionization efficiency towards nonpolar compounds such as squalene through the formation of Ag + adducts with carbon-carbon double bounds, an attractive feature to discriminate between oils with different degree of unsaturation. Copyright © 2017 Elsevier B.V. All rights reserved.

Resonantly-enhanced two-photon ionization and mass-analyzed threshold ionization (MATI) spectroscopy of 2-hydroxypyridine

CERN Document Server

Lee, D H; Choi, K W; Choi, Y S; Kim, S K

2002-01-01

Mass-analyzed threshold ionization (MATI) spectra of 2-hydroxypyridines existing as lactims (2-pyridionl) in a molecular beam are obtained via (1+1') two-photon process to give accurate ionization energies of 8.9344 +- 0.0005 and 8.9284 +- 0.0005 eV for 2-pyridinol (2Py-OH) and its deuterated analogue (2Py-OD), respectively. Resonantly-enhanced two-photon ionization spectra of these compounds are also presented to give vibrational structures of their S sub 1 states. Vibrational frequencies of 2Py-OH and 2Py-OD in ionic ground states are accurately determined from MATI spectra taken via various S sub 1 intermediate states, and associated vibrational modes are assigned with the aid of ab initio calculations.

Two-step Laser Time-of-Flight Mass Spectrometry to Elucidate Organic Diversity in Planetary Surface Materials.

Science.gov (United States)

Getty, Stephanie A.; Brinckerhoff, William B.; Cornish, Timothy; Li, Xiang; Floyd, Melissa; Arevalo, Ricardo Jr.; Cook, Jamie Elsila; Callahan, Michael P.

2013-01-01

Laser desorption/ionization time-of-flight mass spectrometry (LD-TOF-MS) holds promise to be a low-mass, compact in situ analytical capability for future landed missions to planetary surfaces. The ability to analyze a solid sample for both mineralogical and preserved organic content with laser ionization could be compelling as part of a scientific mission pay-load that must be prepared for unanticipated discoveries. Targeted missions for this instrument capability include Mars, Europa, Enceladus, and small icy bodies, such as asteroids and comets.

Iron oxide nanomatrix facilitating metal ionization in matrix-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Obena, Rofeamor P; Lin, Po-Chiao; Lu, Ying-Wei; Li, I-Che; del Mundo, Florian; Arco, Susan dR; Nuesca, Guillermo M; Lin, Chung-Chen; Chen, Yu-Ju

2011-12-15

The significance and epidemiological effects of metals to life necessitate the development of direct, efficient, and rapid method of analysis. Taking advantage of its simple, fast, and high-throughput features, we present a novel approach to metal ion detection by matrix-functionalized magnetic nanoparticle (matrix@MNP)-assisted MALDI-MS. Utilizing 21 biologically and environmentally relevant metal ion solutions, the performance of core and matrix@MNP against conventional matrixes in MALDI-MS and laser desorption ionization (LDI) MS were systemically tested to evaluate the versatility of matrix@MNP as ionization element. The matrix@MNPs provided 20- to >100-fold enhancement on detection sensitivity of metal ions and unambiguous identification through characteristic isotope patterns and accurate mass (<5 ppm), which may be attributed to its multifunctional role as metal chelator, preconcentrator, absorber, and reservoir of energy. Together with the comparison on the ionization behaviors of various metals having different ionization potentials (IP), we formulated a metal ionization mechanism model, alluding to the role of exciton pooling in matrix@MNP-assisted MALDI-MS. Moreover, the detection of Cu in spiked tap water demonstrated the practicability of this new approach as an efficient and direct alternative tool for fast, sensitive, and accurate determination of trace metal ions in real samples.

Super-atmospheric pressure ionization mass spectrometry and its application to ultrafast online protein digestion analysis.

Science.gov (United States)

Chen, Lee Chuin; Ninomiya, Satoshi; Hiraoka, Kenzo

2016-06-01

Ion source pressure plays a significant role in the process of ionization and the subsequent ion transmission inside a mass spectrometer. Pressurizing the ion source to a gas pressure greater than atmospheric pressure is a relatively new approach that aims to further improve the performance of atmospheric pressure ionization sources. For example, under a super-atmospheric pressure environment, a stable electrospray can be sustained for liquid with high surface tension such as pure water, because of the suppression of electric discharge. Even for nano-electrospray ionization (nano-ESI), which is known to work with aqueous solution, its stability and sensitivity can also be enhanced, particularly in the negative mode when the ion source is pressurized. A brief review on the development of super-atmospheric pressure ion sources, including high-pressure electrospray, field desorption and superheated ESI, and the strategies to interface these ion sources to a mass spectrometer will be given. Using a recent ESI prototype with an operating temperature at 220 °C under 27 atm, we also demonstrate that it is possible to achieve an online Asp-specific protein digestion analysis in which the whole processes of digestion, ionization and MS acquisition could be completed on the order of a few seconds. This method is fast, and the reaction can even be monitored on a near-real-time basis. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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.

Surface acoustic wave nebulization facilitating lipid mass spectrometric analysis.

Science.gov (United States)

Yoon, Sung Hwan; Huang, Yue; Edgar, J Scott; Ting, Ying S; Heron, Scott R; Kao, Yuchieh; Li, Yanyan; Masselon, Christophe D; Ernst, Robert K; Goodlett, David R

2012-08-07

Surface acoustic wave nebulization (SAWN) is a novel method to transfer nonvolatile analytes directly from the aqueous phase to the gas phase for mass spectrometric analysis. The lower ion energetics of SAWN and its planar nature make it appealing for analytically challenging lipid samples. This challenge is a result of their amphipathic nature, labile nature, and tendency to form aggregates, which readily precipitate clogging capillaries used for electrospray ionization (ESI). Here, we report the use of SAWN to characterize the complex glycolipid, lipid A, which serves as the membrane anchor component of lipopolysaccharide (LPS) and has a pronounced tendency to clog nano-ESI capillaries. We also show that unlike ESI SAWN is capable of ionizing labile phospholipids without fragmentation. Lastly, we compare the ease of use of SAWN to the more conventional infusion-based ESI methods and demonstrate the ability to generate higher order tandem mass spectral data of lipid A for automated structure assignment using our previously reported hierarchical tandem mass spectrometry (HiTMS) algorithm. The ease of generating SAWN-MS(n) data combined with HiTMS interpretation offers the potential for high throughput lipid A structure analysis.

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...

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.

Direct mass spectrometric screening of antibiotics from bacterial surfaces using liquid extraction surface analysis.

Science.gov (United States)

Kai, Marco; González, Ignacio; Genilloud, Olga; Singh, Sheo B; Svatoš, Aleš

2012-10-30

There is a need to find new antibiotic agents to fight resistant pathogenic bacteria. To search successfully for novel antibiotics from bacteria cultivated under diverse conditions, we need a fast and cost-effective screening method. A combination of Liquid Extraction Surface Analysis (LESA), automated chip-based nanoelectrospray ionization, and high-resolution mass or tandem mass spectrometry using an Orbitrap XL was tested as the screening platform. Actinobacteria, known to produce well-recognized thiazolyl peptide antibiotics, were cultivated on a plate of solid medium and the antibiotics were extracted by organic solvent mixtures from the surface of colonies grown on the plate and analyzed using mass spectrometry (MS). LESA combined with high-resolution MS is a powerful tool with which to extract and detect thiazolyl peptide antibiotics from different Actinobacteria. Known antibiotics were correctly detected with high mass accuracy (antibiotics in particular and natural products in general. The method described in this paper is suitable for (1) screening the natural products produced by bacterial colonies on cultivation plates within the first 2 min following extraction and (2) detecting antibiotics at high mass accuracy; the cost is around 2 Euro per sample. Copyright © 2012 John Wiley & Sons, Ltd.

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

Propagation of an ionizing surface electromagnetic wave

Energy Technology Data Exchange (ETDEWEB)

Boev, A.G.; Prokopov, A.V.

1976-11-01

The propagation of an rf surface wave in a plasma which is ionized by the wave itself is analyzed. The exact solution of the nonlinear Maxwell equations is discussed for the case in which the density of plasma electrons is an exponential function of the square of the electric field. The range over which the surface wave exists and the frequency dependence of the phase velocity are found. A detailed analysis is given for the case of a plasma whose initial density exceeds the critical density at the wave frequency. An increase in the wave amplitude is shown to expand the frequency range over which the plasma is transparent; The energy flux in the plasma tends toward a certain finite value which is governed by the effective ionization field.

Laser vaporization/ionization interface for coupling microscale separation techniques with mass spectrometry

Science.gov (United States)

Yeung, E.S.; Chang, Y.C.

1999-06-29

The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent. 8 figs.

Electrospray ionizer for mass spectrometry of aerosol particles

Science.gov (United States)

He, Siqin; Hogan, Chris; Li, Lin; Liu, Benjamin Y. H.; Naqwi, Amir; Romay, Francisco

2017-09-19

A device and method are disclosed to apply ESI-based mass spectroscopy to submicrometer and nanometer scale aerosol particles. Unipolar ionization is utilized to charge the particles in order to collect them electrostatically on the tip of a tungsten rod. Subsequently, the species composing the collected particles are dissolved by making a liquid flow over the tungsten rod. This liquid with dissolved aerosol contents is formed into highly charged droplets, which release unfragmented ions for mass spectroscopy, such as time-of-flight mass spectroscopy. The device is configured to operate in a switching mode, wherein aerosol deposition occurs while solvent delivery is turned off and vice versa.

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

Science.gov (United States)

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

2014-10-01

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

Direct Surface Analysis of Fungal Species by Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Valentine, Nancy B.(BATTELLE (PACIFIC NW LAB)); Wahl, Jon H.(BATTELLE (PACIFIC NW LAB)); Kingsley, Mark T.(BATTELLE (PACIFIC NW LAB)); Wahl, Karen L.(BATTELLE (PACIFIC NW LAB))

2001-12-01

Intact spores and/or hyphae of Aspergillus niger, Rhizopus oryzae, Trichoderma reesei and Phanerochaete chrysosporium are analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). This study investigates various methods of sample preparation and matrices to determine optimum collection and analysis criteria for fungal analysis by MALDI-MS. Fungi are applied to the MALDI sample target as untreated, sonicated, acid/heat treated, or blotted directly from the fungal culture with double-stick tape. Ferulic acid or sinapinic acid matrix solution is layered over the dried samples and analyzed by MALDI-MS. Statistical analysis of the data show that simply using double stick tape to collect and transfer to a MALDI sample plate typically worked as well as the other preparation methods, but requires the least sample handling.

Electric field vector measurements in a surface ionization wave discharge

International Nuclear Information System (INIS)

Goldberg, Benjamin M; Adamovich, Igor V; Lempert, Walter R; Böhm, Patrick S; Czarnetzki, Uwe

2015-01-01

This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ∼100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns −1 . The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (∼100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ∼1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85–95 Td, consistent with dc breakdown field estimated from the Paschen

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.

Forensic Sampling and Analysis from a Single Substrate: Surface-Enhanced Raman Spectroscopy Followed by Paper Spray Mass Spectrometry.

Science.gov (United States)

Fedick, Patrick W; Bills, Brandon J; Manicke, Nicholas E; Cooks, R Graham

2017-10-17

Sample preparation is the most common bottleneck in the analysis and processing of forensic evidence. Time-consuming steps in many forensic tests involve complex separations, such as liquid and gas chromatography or various types of extraction techniques, typically coupled with mass spectrometry (e.g., LC-MS). Ambient ionization ameliorates these slow steps by reducing or even eliminating sample preparation. While some ambient ionization techniques have been adopted by the forensic community, there is significant resistance to discarding chromatography as most forensic analyses require both an identification and a confirmation technique. Here, we describe the use of a paper substrate, the surface of which has been inkjet printed with silver nanoparticles, for surface enhanced Raman spectroscopy (SERS). The same substrate can also act as the paper substrate for paper spray mass spectrometry. The coupling of SERS and paper spray ionization creates a quick, forensically feasible combination.

SURFACE LAYER ACCRETION IN CONVENTIONAL AND TRANSITIONAL DISKS DRIVEN BY FAR-ULTRAVIOLET IONIZATION

International Nuclear Information System (INIS)

Perez-Becker, Daniel; Chiang, Eugene

2011-01-01

Whether protoplanetary disks accrete at observationally significant rates by the magnetorotational instability (MRI) depends on how well ionized they are. Disk surface layers ionized by stellar X-rays are susceptible to charge neutralization by small condensates, ranging from ∼0.01 μm sized grains to angstrom-sized polycyclic aromatic hydrocarbons (PAHs). Ion densities in X-ray-irradiated surfaces are so low that ambipolar diffusion weakens the MRI. Here we show that ionization by stellar far-ultraviolet (FUV) radiation enables full-blown MRI turbulence in disk surface layers. Far-UV ionization of atomic carbon and sulfur produces a plasma so dense that it is immune to ion recombination on grains and PAHs. The FUV-ionized layer, of thickness 0.01-0.1 g cm -2 , behaves in the ideal magnetohydrodynamic limit and can accrete at observationally significant rates at radii ∼> 1-10 AU. Surface layer accretion driven by FUV ionization can reproduce the trend of increasing accretion rate with increasing hole size seen in transitional disks. At radii ∼<1-10 AU, FUV-ionized surface layers cannot sustain the accretion rates generated at larger distance, and unless turbulent mixing of plasma can thicken the MRI-active layer, an additional means of transport is needed. In the case of transitional disks, it could be provided by planets.

Monitoring the on-surface synthesis of graphene nanoribbons by mass spectrometry

KAUST Repository

Zhang, Wen

2017-06-14

We present a mass spectrometric approach to monitor and characterize the intermediates of graphene nanoribbon (GNR) formation by chemical vapor deposition (CVD) on top of Au(111) surfaces. Information regarding the repeating units, lengths, and termini can be obtained directly from the surface sample by a modified matrix assisted laser desorption/ionization (MALDI) method. The mass spectrometric results reveal ample oxidative side reactions under CVD conditions which can, however, be diminished drastically by introduction of protective H2 gas at ambient pressure. Simultaneously, addition of hydrogen extends the lengths of the oligophenylenes and thus the final GNRs. Moreover, the prematurely formed cyclodehydrogenation products during the oligomer growth can be assigned by the mass spectrometric method. The obtained mechanistic insights provide valuable information for optimizing and upscaling the bottom-up fabrication of GNRs. Given the important role of GNRs as semiconductors, the mass spectrometric characterization provides a readily available tool to improve and characterize their structural perfection.

Ionization of xenon Rydberg atoms at Si(1 0 0) surfaces

Energy Technology Data Exchange (ETDEWEB)

Dunham, H.R. [Department of Physics and Astronomy, Rice University MS-61, 6100 Main Street, Houston, TX 77005-1892 (United States); Wethekam, S. [Institut fuer Physik der Humboldt-Universitaet zu Berlin, Newtonstra. 15, D-12489, Berlin (Germany); Lancaster, J.C. [Department of Physics and Astronomy, Rice University MS-61, 6100 Main Street, Houston, TX 77005-1892 (United States); Dunning, F.B. [Department of Physics and Astronomy, Rice University MS-61, 6100 Main Street, Houston, TX 77005-1892 (United States)]. E-mail: fbd@rice.edu

2007-03-15

The ionization of xenon Rydberg atoms excited to the lowest states in the n = 17 and n = 20 Stark manifolds at Si(1 0 0) surfaces is investigated. It is shown that, under appropriate conditions, a sizable fraction of the incident atoms can be detected as ions. Although the onset in the ion signal is perturbed by stray fields present at the surface, the data are consistent with ionization rates similar to those measured earlier at metal surfaces.

Surface analysis by imaging mass spectrometry

Czech Academy of Sciences Publication Activity Database

Vidová, Veronika; Volný, Michael; Lemr, Karel; Havlíček, Vladimír

2009-01-01

Roč. 74, 7-8 (2009), s. 1101-1116 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z50200510 Keywords : secondary ion mass spectrometry * matrix assisted laser desorption ionization * mass spectrometry Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.856, year: 2009

Subcellular analysis by laser ablation electrospray ionization mass spectrometry

Science.gov (United States)

Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh

2014-12-02

In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.

Derivatization of Dextran for Multiply Charged Ion Formation and Electrospray Ionization Time-of-Flight Mass Spectrometric Analysis

Science.gov (United States)

Tapia, Jesus B.; Hibbard, Hailey A. J.; Reynolds, Melissa M.

2017-10-01

We present the use of a simple, one-pot derivatization to allow the polysaccharide dextran to carry multiple positive charges, shifting its molecular weight distribution to a lower m/ z range. We performed this derivatization because molecular weight measurements of polysaccharides by mass spectrometry are challenging because of their lack of readily ionizable groups. The absence of ionizable groups limits proton abstraction and suppresses proton adduction during the ionization process, producing mass spectra with predominantly singly charged metal adduct ions, thereby limiting the detection of large polysaccharides. To address this challenge, we derivatized dextran T1 (approximately 1 kDa) by attaching ethylenediamine, giving dextran readily ionizable, terminal amine functional groups. The attached ethylenediamine groups facilitated proton adduction during the ionization process in positive ion mode. Using the low molecular weight dextran T1, we tracked the number of ethylenediamine attachments by measuring the mass shift from underivatized to derivatized dextran T1. Using electrospray ionization time-of-flight mass spectrometry, we observed derivatized dextran chains ranging from two to nine glucose residues with between one and four attachments/charges. Our success in shifting derivatized dextran T1 toward the low m/ z range suggests potential for this derivatization as a viable route for analysis of high molecular weight polysaccharides using electrospray ionization time-of-flight mass spectrometry. [Figure not available: see fulltext.

Hands-on Electrospray Ionization-Mass Spectrometry for Upper-Level Undergraduate and Graduate Students

Science.gov (United States)

Stock, Naomi L.; March, Raymond E.

2014-01-01

Electrospray ionization-mass spectrometry (ESI-MS) is a powerful technique for the detection, identification, and quantification of organic compounds. As mass spectrometers have become more user-friendly and affordable, many students--often with little experience in mass spectrometry--find themselves needing to incorporate mass spectrometry into…

Analysis of volatile compounds by open-air ionization mass spectrometry.

Science.gov (United States)

Meher, Anil Kumar; Chen, Yu-Chie

2017-05-08

This study demonstrates a simple method for rapid and in situ identification of volatile and endogenous compounds in culinary spice samples through mass spectrometry (MS). This method only requires a holder for solid spice sample (2-3 mm) that is placed close to a mass spectrometer inlet, which is applied with a high voltage. Volatile species responsible for the aroma of the spice samples can be readily detected by the mass spectrometer. Sample pretreatment is not required prior to MS analysis, and no solvent was used during MS analysis. The high voltage applied to the inlet of the mass spectrometer induces the ionization of volatile compounds released from the solid spice samples. Furthermore, moisture in the air also contributes to the ionization of volatile compounds. Dried spices including cinnamon and cloves are used as the model sample to demonstrate this straightforward MS analysis, which can be completed within few seconds. Furthermore, we also demonstrate the suitability of the current method for rapid screening of cinnamon quality through detection of the presence of a hepatotoxic agent, i.e. coumarin. Copyright © 2017 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.)

Trace analysis of plutonium in environmental samples by resonance ionization mass spectroscopy (RIMS)

International Nuclear Information System (INIS)

Erdmann, N.; Herrmann, G.; Huber, G.; Koehler, S.; Kratz, J.V.; Mansel, A.; Nunnemann, M.; Passler, G.; Trautmann, N.; Waldek, A.

1997-01-01

Trace amounts of plutonium in the environment can be detected by resonance ionization mass spectroscopy (RIMS). An atomic beam of plutonium is produced after its chemical separation and deposition on a filament. The atoms are ionized by a three-step excitation using pulsed dye-lasers. The ions are mass-selectively detected in a time-of-flight (TOF) mass spectrometer. With this setup a detection limit of 1·10 6 atoms of plutonium has been achieved. Furthermore, the isotopic composition can be determined. Different samples, including soil from the Chernobyl area, IAEA-certified sediments from the Mururoa Atoll and urine, have been investigated. copyright 1997 American Institute of Physics

Selected cis- and trans-3-fluorostyrene rotamers studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy

Science.gov (United States)

Wu, Pei Ying; Tzeng, Wen Bih

2015-10-01

We applied two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic, photoionization efficiency, and cation spectra of the selected rotamers of 3-fluorostyrene. The adiabatic ionization energies of cis- and trans-3-fluorostyrene were determined to be 69 960 ± 5 and 69 856 ± 5 cm-1, respectively. Cation vibrations 10a, 15, 6b, and 12 of both rotamers have been found to have frequencies of 218, 404, 452, and 971 cm-1, respectively. This finding shows that the relative orientation of the vinyl group with respect to the F atom does not affect these vibrations of the 3-fluorostyrene cation. Our one-dimensional potential energy surface calculations support that the cis-trans isomerization of 3-fluorostyrene does not occur under the present experimental conditions.

Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

Energy Technology Data Exchange (ETDEWEB)

Dunning, F.B. E-mail: fbd@rice.edu; Dunham, H.R.; Oubre, C.; Nordlander, P

2003-04-01

The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

CERN Document Server

Dunning, F B; Oubre, C D; Nordlander, P

2003-01-01

The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

Gas chromatography/chemical ionization triple quadrupole mass spectrometry analysis of anabolic steroids: ionization and collision-induced dissociation behavior.

Science.gov (United States)

Polet, Michael; Van Gansbeke, Wim; Van Eenoo, Peter; Deventer, Koen

2016-02-28

The detection of new anabolic steroid metabolites and new designer steroids is a challenging task in doping analysis. Switching from electron ionization gas chromatography triple quadrupole mass spectrometry (GC/EI-MS/MS) to chemical ionization (CI) has proven to be an efficient way to increase the sensitivity of GC/MS/MS analyses and facilitate the detection of anabolic steroids. CI also extends the possibilities of GC/MS/MS analyses as the molecular ion is retained in its protonated form due to the softer ionization. In EI it can be difficult to find previously unknown but expected metabolites due to the low abundance or absence of the molecular ion and the extensive (and to a large extent unpredictable) fragmentation. The main aim of this work was to study the CI and collision-induced dissociation (CID) behavior of a large number of anabolic androgenic steroids (AAS) as their trimethylsilyl derivatives in order to determine correlations between structures and CID fragmentation. Clarification of these correlations is needed for the elucidation of structures of unknown steroids and new metabolites. The ionization and CID behavior of 65 AAS have been studied using GC/CI-MS/MS with ammonia as the reagent gas. Glucuronidated AAS reference standards were first hydrolyzed to obtain their free forms. Afterwards, all the standards were derivatized to their trimethylsilyl forms. Full scan and product ion scan analyses were used to examine the ionization and CID behavior. Full scan and product ion scan analyses revealed clear correlations between AAS structure and the obtained mass spectra. These correlations were confirmed by analysis of multiple hydroxylated, methylated, chlorinated and deuterated analogs. AAS have been divided into three groups according to their ionization behavior and into seven groups according to their CID behavior. Correlations between fragmentation and structure were revealed and fragmentation pathways were postulated. Copyright © 2016 John Wiley

The application of ionizers in domestic refrigerators for reduction in airborne and surface bacteria.

Science.gov (United States)

Kampmann, Y; Klingshirn, A; Kloft, K; Kreyenschmidt, J

2009-12-01

To investigate the antimicrobial effect of ionization on bacteria in household refrigerators. Ionizer prototypes were tested with respect to their technical requirements and their ability to reduce surface and airborne contamination in household refrigerators. Ion and ozone production of the tested prototypes were measured online by an ion meter and an ozone analyser. The produced negative air ion (NAI) and ozone amounts were between 1.2 and 3.7 x 10(6) NAI cm(-3) and 11 and 19 ppb O(3), respectively. To test the influence of ionization on surface contamination, different materials like plastic, glass and nutrient agar for simulation of food were inoculated with bacterial suspensions. The reduction rate was dependent on surface properties. The effect on airborne bacteria was tested by nebulization of Bacillus subtilis- suspension (containing spores) aerosols in refrigerators with and without an ionizer. A clear reduction in air contamination because of ionization was measured. The antimicrobial effect is dependent on several factors, such as surface construction and airflow patterns within the refrigerator. Ionization seems to be an effective method for reduction in surface and airborne bacteria. This study is an initiation for a new consumer tool to decontaminate domestic refrigerators.

Mass spectrometric evidence for suprathermal ionization in an inductively coupled argon plasma

International Nuclear Information System (INIS)

Houk, R.S.; Svec, H.J.; Fassel, V.A.

1981-01-01

Mass spectra have been obtained of species in the axial channel of an inductively coupled argon plasma by extracting ions from the inductively coupled plasma into a vacuum system housing a quadrupole mass spectrometer. Ionization temperatures (T/sub ion/) are obtained from relative count rates of m/z-resolved ions according to two general types of ionization equilibrium considerations: (a) the radio of doubly/singly charged ions of the same element, and (b) the ratio of singly charged ions from two elements of different ionization energy. The T/sub ion/ values derived from measurement of Ar +2 /Ar + , Ba +2 /Ba + , Sr +2 /Sr + , and Cd + /I + are all greater than those expected from excitation temperatures measured by other workers. The latter three values for T/sub ion/ are in reasonable agreement with values obtained by optical spectrometry for a variety of argon inductively coupled plasmas

Study of surface ionization and LASER ionization processes using the SOMEIL ion source: application to the Spiral 2 laser ion source development

Energy Technology Data Exchange (ETDEWEB)

Bajeat, O., E-mail: bajeat@ganil.fr; Lecesne, N.; Leroy, R.; Maunoury, L.; Osmond, B.; Sjodin, M. [GANIL (France); Maitre, A.; Pradeilles, N. [Laboratoire Science des Procedes Ceramiques et de Traitements de Surface (SPCTS) 12 (France)

2013-04-15

SPIRAL2 is the new project under construction at GANIL to provide radioactive ion beams to the Nuclear Physics Community and in particular neutron rich ion beams. For the production of condensable radioactive elements, a resonant ionization laser ion source is under development at GANIL. In order to generate the ions of interest with a good selectivity and purity, our group is studying the way to minimize surface ionization process by using refractory materials with low work function as ionizer tube. To do those investigations a dedicated ion source, called SOMEIL (Source Optimisee pour les Mesures d'Efficacite d'Ionisation Laser) is used. Numerous types of ionizer tubes made in various materials and geometry are tested. Surface ionization and laser ionization efficiencies can be measured for each of them.

Determination of Aspartame and Caffeine in Carbonated Beverages Utilizing Electrospray Ionization-Mass Spectrometry

Science.gov (United States)

Bergen, H. Robert, III; Benson, Linda M.; Naylor, Stephen

2000-10-01

Mass spectrometry has undergone considerable changes in the past decade. The advent of "soft ionization" techniques such as electrospray ionization (ESI) affords the direct analysis of very polar molecules without need for the complex inefficient derivatization procedures often required in GC-MS. These ionization techniques make possible the direct mass spectral analysis of polar nonvolatile molecules such as DNA and proteins, which previously were difficult or impossible to analyze by MS. Compounds that readily take on a charge (acids and bases) lend themselves to ESI-MS analysis, whereas compounds that do not readily accept a charge (e.g. sugars) are often not seen or are seen only as inefficient adducts (e.g., M+Na+). To gain exposure to this state-of-the-art analytical procedure, high school students utilize ESI-MS in an analysis of aspartame and caffeine. They dilute a beverage sample and inject the diluted sample into the ESI-MS. The lab is procedurally simple and the results clearly demonstrate the potential and limitations of ESI-coupled mass spectrometry. Depending upon the instructional goals, the outlined procedures can be used to quantify the content of caffeine and aspartame in beverages or to understand the capabilities of electrospray ionization.

Hyphenation of two simultaneously employed soft photo ionization mass spectrometers with thermal analysis of biomass and biochar

International Nuclear Information System (INIS)

Fendt, Alois; Geissler, Robert; Streibel, Thorsten

2013-01-01

Highlights: ► First simultaneous hyphenation of two time-of-flight mass spectrometers with different soft photo ionization techniques (SPI and REMPI) to Thermal Analysis using a newly developed prototype for EGA is presented. ► Resonance enhanced multi-photon ionization (REMPI) enables sensitive and selective analysis of aromatic species. ► Single photon ionization (SPI) using VUV light supplied by an innovative electron-beam pumped excimer light source (EBEL) comprehensively ionizes (nearly) all organic molecules. ► The resulting mass spectra show distinct patterns for the evolved gases of the miscellaneous biomasses and chars thereof. ► The potential for detailed kinetic studies is apparent on account of the complex pyrolysis gas compositions. - Abstract: Evolved gas analysis (EGA) is a powerful and complementary tool for Thermal Analysis. In this context, two time-of-flight mass spectrometers with different soft photo-ionization techniques are simultaneously hyphenated to a thermo balance and applied in form of a newly developed prototype for EGA of pyrolysis gases from biomass and biochar. Resonance enhanced multi-photon ionization (REMPI) is applied for selective analysis of aromatic species. Furthermore, single photon ionization (SPI) using VUV light supplied by an electron-beam pumped excimer light source (EBEL) was used to comprehensively ionize (nearly) all organic molecules. The soft ionization capability of photo-ionization techniques allows direct and on-line analysis of the evolved pyrolysis gases. Characteristic mass spectra with specific patterns could be obtained for the miscellaneous biomass feeds used. Temperature profiles of the biochars reveal a desorption step, followed by pyrolysis as observed for the biomasses. Furthermore, the potential for kinetic studies is apparent for this instrumental setup.

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.

Atmospheric pressure photo ionization hydrogen/deuterium exchange mass spectrometry--a method to differentiate isomers by mass spectrometry.

Science.gov (United States)

Ahmed, Arif; Kim, Sunghwan

2013-12-01

In this report, a method for in-source hydrogen/deuterium (H/D) exchange at atmospheric pressure is reported. The method was named atmospheric pressure photo ionization hydrogen/deuterium exchange mass spectrometry (APPI HDX MS). H/D exchange was performed by mixing samples dissolved in toluene with CH3OD solvent and analyzing the mixture using atmospheric pressure photo ionization mass spectrometry (APPI-MS). The APPI HDX spectra obtained with contact times between the analyte solution and methanol-OD (CH3OD) of atmospheric pressure. H/D exchange can be performed in any laboratory with a mass spectrometer and a commercial APPI source. Using this method, multiple H/D exchanges of aromatic hydrogen and/or H/D exchange of active hydrogen were observed. These results demonstrated that H/D exchange can be used to distinguish between isomers containing primary, secondary, and tertiary amines, as well as pyridine and pyrrole functional groups.

Analytical applications of resonance ionization mass spectrometry (RIMS)

International Nuclear Information System (INIS)

Fassett, J.D.; Travis, J.C.

1988-01-01

A perspective on the role of resonance ionization mass spectrometry (RIMS) in the field of analytical chemistry is presented. RIMS provides new, powerful, and complementary capabilities relative to traditional methods of inorganic mass spectrometry. Much of the initial work in RIMS has been to illustrate these capabilities and define the potential of RIMS in the generalized field of chemical analysis. Three areas of application are reviewed here: (1) noble gas measurements; (2) materials analysis using isotope dilution (IDMS); and, (3) solids analysis using direct sampling. The role of RIMS is discussed relative to the more traditional mass spectrometric methods of analysis in these areas. The applications are meant to illustrate the present state-of-the-art as well as point to the future state-of-the-art of RIMS in chemical analysis. (author)

Electrospray Ionization Mass Spectrometric Analysis of Highly Reactive Glycosyl Halides

Directory of Open Access Journals (Sweden)

Lajos Kovács

2012-07-01

Full Text Available Highly reactive glycosyl chlorides and bromides have been analysed by a routine mass spectrometric method using electrospray ionization and lithium salt adduct-forming agents in anhydrous acetonitrile solution, providing salient lithiated molecular ions [M+Li]⁺, [2M+Li]⁺ etc. The role of other adduct-forming salts has also been evaluated. The lithium salt method is useful for accurate mass determination of these highly sensitive compounds.

Detection of trace organics in Mars analog samples containing perchlorate by laser desorption/ionization mass spectrometry.

Science.gov (United States)

Li, Xiang; Danell, Ryan M; Brinckerhoff, William B; Pinnick, Veronica T; van Amerom, Friso; Arevalo, Ricardo D; Getty, Stephanie A; Mahaffy, Paul R; Steininger, Harald; Goesmann, Fred

2015-02-01

Evidence from recent Mars missions indicates the presence of perchlorate salts up to 1 wt % level in the near-surface materials. Mixed perchlorates and other oxychlorine species may complicate the detection of organic molecules in bulk martian samples when using pyrolysis techniques. To address this analytical challenge, we report here results of laboratory measurements with laser desorption mass spectrometry, including analyses performed on both commercial and Mars Organic Molecule Analyzer (MOMA) breadboard instruments. We demonstrate that the detection of nonvolatile organics in selected spiked mineral-matrix materials by laser desorption/ionization (LDI) mass spectrometry is not inhibited by the presence of up to 1 wt % perchlorate salt. The organics in the sample are not significantly degraded or combusted in the LDI process, and the parent molecular ion is retained in the mass spectrum. The LDI technique provides distinct potential benefits for the detection of organics in situ on the martian surface and has the potential to aid in the search for signs of life on Mars.

Aerosol Vacuum-Assisted Plasma Ionization (Aero-VaPI) Coupled to Ion Mobility-Mass Spectrometry

Science.gov (United States)

Blair, Sandra L.; Ng, Nga L.; Zambrzycki, Stephen C.; Li, Anyin; Fernández, Facundo M.

2018-02-01

In this communication, we report on the real-time analysis of organic aerosol particles by Vacuum-assisted Plasma Ionization-Mass Spectrometry (Aero-VaPI-MS) using a home-built VaPI ion source coupled to a Synapt G2-S HDMS ion mobility-mass spectrometry (IM-MS) system. Standards of organic molecules of interest in prebiotic chemistry were used to generate aerosols. Monocaprin and decanoic acid aerosol particles were successfully detected in both the positive and negative ion modes, respectively. A complex aerosol mixture of different sizes of polymers of L-malic acid was also examined through ion mobility (IM) separations, resulting in the detection of polymers of up to eight monomeric units. This noncommercial plasma ion source is proposed as a low cost alternative to other plasma ionization platforms used for aerosol analysis, and a higher-performance alternative to more traditional aerosol mass spectrometers. VaPI provides robust online ionization of organics in aerosols without extensive ion activation, with the coupling to IM-MS providing higher peak capacity and excellent mass accuracy. [Figure not available: see fulltext.

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.

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.

Biomarker research for moyamoya disease in cerebrospinal fluid using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

Science.gov (United States)

Maruwaka, Mikio; Yoshikawa, Kazuhiro; Okamoto, Sho; Araki, Yoshio; Sumitomo, Masaki; Kawamura, Akino; Yokoyama, Kinya; Wakabayashi, Toshihiko

2015-01-01

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by steno-occlusive change in bilateral internal carotid arteries with unknown etiology. To discover biomarker candidates in cerebrospinal fluid from MMD patients, proteome analysis was performed by the surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Three peptides, 4473Da, 4475Da, and 6253Da, were significantly elevated in MMD group. A positive correlation between 4473Da peptide and postoperative angiogenesis was determined. Twenty MMD patients were enrolled in this pilot study, including 11 pediatric cases less than 18 years of age (mean age, 8.67 years) and 9 adult MMD patients (mean age, 38.1 years). This study also includes 17 control cases with the mean age of 27.9 years old. In conclusion, 4473Da peptide is supposed to be a reliable biomarker of MMD. 4473Da peptide showed higher intensity peaks especially in younger MMD patients, and it was proved to be highly related to postoperative angiogenesis. Further study is needed to show how 4473Da peptide is involved with the etiology and the onset of MMD. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Note: a novel vacuum ultraviolet light source assembly with aluminum-coated electrodes for enhancing the ionization efficiency of photoionization mass spectrometry.

Science.gov (United States)

Zhu, Zhixiang; Wang, Jian; Qiu, Keqing; Liu, Chengyuan; Qi, Fei; Pan, Yang

2014-04-01

A novel vacuum ultraviolet (VUV) light source assembly (VUVLSA) for enhancing the ionization efficiency of photoionization mass spectrometer has been described. The VUVLSA composes of a Krypton lamp and a pair of disk electrodes with circular center cavities. The two interior surfaces that face the photoionization region were aluminum-coated. VUV light can be reflected back and forth in the photoionization region between the electrodes, thus the photoionization efficiency can be greatly enhanced. The performances of two different shaped electrodes, the coated double flat electrodes (DFE), and double conical electrodes, were studied. We showed that the signal amplification of coated DFE is around 4 times higher than that of uncoated electrodes without VUV light reflection. The relationship between the pressure of ionization chamber and mass signal enhancement has also been studied.

Hyphenation of two simultaneously employed soft photo ionization mass spectrometers with thermal analysis of biomass and biochar

Energy Technology Data Exchange (ETDEWEB)

Fendt, Alois [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Joint Mass Spectrometry Centre, Cooperation Group for Analysis of Complex Molecular Systems, Institute of Ecological Chemistry, Helmholtz Zentrum Muenchen - German Research Center for Environmental Health (GmbH), IngolstaedterLandstr. 1, 85764 Neuherberg (Germany); Analytical Chemistry, Institute of Physics, University of Augsburg, 86159 Augsburg (Germany); Geissler, Robert [Joint Mass Spectrometry Centre, Cooperation Group for Analysis of Complex Molecular Systems, Institute of Ecological Chemistry, Helmholtz Zentrum Muenchen - German Research Center for Environmental Health (GmbH), IngolstaedterLandstr. 1, 85764 Neuherberg (Germany); Analytical Chemistry, Institute of Physics, University of Augsburg, 86159 Augsburg (Germany); Streibel, Thorsten, E-mail: thorsten.streibel@uni-rostock.de [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Joint Mass Spectrometry Centre, Cooperation Group for Analysis of Complex Molecular Systems, Institute of Ecological Chemistry, Helmholtz Zentrum Muenchen - German Research Center for Environmental Health (GmbH), IngolstaedterLandstr. 1, 85764 Neuherberg (Germany); and others

2013-01-10

Highlights: Black-Right-Pointing-Pointer First simultaneous hyphenation of two time-of-flight mass spectrometers with different soft photo ionization techniques (SPI and REMPI) to Thermal Analysis using a newly developed prototype for EGA is presented. Black-Right-Pointing-Pointer Resonance enhanced multi-photon ionization (REMPI) enables sensitive and selective analysis of aromatic species. Black-Right-Pointing-Pointer Single photon ionization (SPI) using VUV light supplied by an innovative electron-beam pumped excimer light source (EBEL) comprehensively ionizes (nearly) all organic molecules. Black-Right-Pointing-Pointer The resulting mass spectra show distinct patterns for the evolved gases of the miscellaneous biomasses and chars thereof. Black-Right-Pointing-Pointer The potential for detailed kinetic studies is apparent on account of the complex pyrolysis gas compositions. - Abstract: Evolved gas analysis (EGA) is a powerful and complementary tool for Thermal Analysis. In this context, two time-of-flight mass spectrometers with different soft photo-ionization techniques are simultaneously hyphenated to a thermo balance and applied in form of a newly developed prototype for EGA of pyrolysis gases from biomass and biochar. Resonance enhanced multi-photon ionization (REMPI) is applied for selective analysis of aromatic species. Furthermore, single photon ionization (SPI) using VUV light supplied by an electron-beam pumped excimer light source (EBEL) was used to comprehensively ionize (nearly) all organic molecules. The soft ionization capability of photo-ionization techniques allows direct and on-line analysis of the evolved pyrolysis gases. Characteristic mass spectra with specific patterns could be obtained for the miscellaneous biomass feeds used. Temperature profiles of the biochars reveal a desorption step, followed by pyrolysis as observed for the biomasses. Furthermore, the potential for kinetic studies is apparent for this instrumental setup.

Degradation of Adenine on the Martian Surface in the Presence of Perchlorates and Ionizing Radiation: A Reflectron Time-of-flight Mass Spectrometric Study

Energy Technology Data Exchange (ETDEWEB)

Góbi, Sándor; Bergantini, Alexandre; Kaiser, Ralf I., E-mail: ralfk@hawaii.edu [Department of Chemistry, University of Hawaii at Mānoa, Honolulu, HI 96822 (United States)

2017-04-01

The aim of the present work is to unravel the radiolytic decomposition of adenine (C{sub 5}H{sub 5}N{sub 5}) under conditions relevant to the Martian surface. Being the fundamental building block of (deoxy)ribonucleic acids, the possibility of survival of this biomolecule on the Martian surface is of primary importance to the astrobiology community. Here, neat adenine and adenine–magnesium perchlorate mixtures were prepared and irradiated with energetic electrons that simulate the secondary electrons originating from the interaction of the galactic cosmic rays with the Martian surface. Perchlorates were added to the samples since they are abundant—and therefore relevant oxidizers on the surface of Mars—and they have been previously shown to facilitate the radiolysis of organics such as glycine. The degradation of the samples were monitored in situ via Fourier transformation infrared spectroscopy and the electron ionization quadruple mass spectrometric method; temperature-programmed desorption profiles were then collected by means of the state-of-the-art single photon photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), allowing for the detection of the species subliming from the sample. The results showed that perchlorates do increase the destruction rate of adenine by opening alternative reaction channels, including the concurrent radiolysis/oxidation of the sample. This new pathway provides a plethora of different radiolysis products that were identified for the first time. These are carbon dioxide (CO{sub 2}), isocyanic acid (HNCO), isocyanate (OCN{sup −}), carbon monoxide (CO), and nitrogen monoxide (NO); an oxidation product containing carbonyl groups (R{sub 1}R{sub 2}–C=O) with a constrained five-membered cyclic structure could also be observed. Cyanamide (H{sub 2}N–C≡N) was detected in both irradiated samples as well.

Degradation of Adenine on the Martian Surface in the Presence of Perchlorates and Ionizing Radiation: A Reflectron Time-of-flight Mass Spectrometric Study

International Nuclear Information System (INIS)

Góbi, Sándor; Bergantini, Alexandre; Kaiser, Ralf I.

2017-01-01

The aim of the present work is to unravel the radiolytic decomposition of adenine (C 5 H 5 N 5 ) under conditions relevant to the Martian surface. Being the fundamental building block of (deoxy)ribonucleic acids, the possibility of survival of this biomolecule on the Martian surface is of primary importance to the astrobiology community. Here, neat adenine and adenine–magnesium perchlorate mixtures were prepared and irradiated with energetic electrons that simulate the secondary electrons originating from the interaction of the galactic cosmic rays with the Martian surface. Perchlorates were added to the samples since they are abundant—and therefore relevant oxidizers on the surface of Mars—and they have been previously shown to facilitate the radiolysis of organics such as glycine. The degradation of the samples were monitored in situ via Fourier transformation infrared spectroscopy and the electron ionization quadruple mass spectrometric method; temperature-programmed desorption profiles were then collected by means of the state-of-the-art single photon photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), allowing for the detection of the species subliming from the sample. The results showed that perchlorates do increase the destruction rate of adenine by opening alternative reaction channels, including the concurrent radiolysis/oxidation of the sample. This new pathway provides a plethora of different radiolysis products that were identified for the first time. These are carbon dioxide (CO 2 ), isocyanic acid (HNCO), isocyanate (OCN − ), carbon monoxide (CO), and nitrogen monoxide (NO); an oxidation product containing carbonyl groups (R 1 R 2 –C=O) with a constrained five-membered cyclic structure could also be observed. Cyanamide (H 2 N–C≡N) was detected in both irradiated samples as well.

A Photo-Ionization Method for Black Hole Mass Estimation in Quasars

Directory of Open Access Journals (Sweden)

Marziani Paola

2011-09-01

Full Text Available Determining the masses of the central compact object believed to power all active galactic nuclei is relevant to our understanding of their evolution and of their inner workings. Keys to present-day mass estimates are: (1 the assumption of line broadening due to virial motion of the emitting gas, (2 an estimate of the distance of broad-line emitting gas from the central compact object, and (3 a measure of the AGN luminosity. We discuss the merits and the limitations of an alternative method based on estimates of physical conditions in the broad line emitting region derived from an appropriate multi-component analysis of emission line profiles. This ‘photo-ionization method’, applied to UV intermediate-ionization lines appears to be promising for at least a sizable population of high-z quasars.

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

Laser desorption/ionization mass spectrometry for direct profiling and imaging of small molecules from raw biological materials

Energy Technology Data Exchange (ETDEWEB)

Cha, Sangwon [Iowa State Univ., Ames, IA (United States)

2008-01-01

Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS protocols with various alternative assisting materials were developed and applied to many biological systems of interest. Colloidal graphite was used as a matrix for IMS of small molecules for the first time and methodologies for analyses of small metabolites in rat brain tissues, fruits, and plant tissues were developed. With rat brain tissues, the signal enhancement for cerebroside species by colloidal graphite was observed and images of cerebrosides were successfully generated by IMS. In addition, separation of isobaric lipid ions was performed by imaging tandem MS. Directly from Arabidopsis flowers, flavonoids were successfully profiled and heterogeneous distribution of flavonoids in petals was observed for the first time by graphite-assisted LDI(GALDI) IMS.

Fast quantitative detection of cocaine in beverages using nanoextractive electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Hu, Bin; Peng, Xuejiao; Yang, Shuiping; Gu, Haiwei; Chen, Huanwen; Huan, Yanfu; Zhang, Tingting; Qiao, Xiaolin

2010-02-01

Without any sample pretreatment, effervescent beverage fluids were manually sprayed into the primary ion plume created by using a nanoelectrospray ionization source for direct ionization, and the analyte ions of interest were guided into an ion trap mass spectrometer for tandem mass analysis. Functional ingredients (e.g., vitamins, taurine, and caffeine, etc.) and spiked impurity (e.g., cocaine) in various beverages, such as Red Bull energy drink, Coco-cola, and Pepsi samples were rapidly identified within 1.5 s. The limit of detection was found to be 7-15 fg (S/N = 3) for cocaine in different samples using the characteristic fragment (m/z 150) observed in the MS(3) experiments. Typical relative standard deviation and recovery of this method were 6.9%-8.6% and 104%-108% for direct analysis of three actual samples, showing that nanoextractive electrospray ionization tandem mass spectrometry is a useful technique for fast screening cocaine presence in beverages. 2010. Published by Elsevier Inc.

Highly informative multiclass profiling of lipids by ultra-high performance liquid chromatography - Low resolution (quadrupole) mass spectrometry by using electrospray ionization and atmospheric pressure chemical ionization interfaces.

Science.gov (United States)

Beccaria, Marco; Inferrera, Veronica; Rigano, Francesca; Gorynski, Krzysztof; Purcaro, Giorgia; Pawliszyn, Janusz; Dugo, Paola; Mondello, Luigi

2017-08-04

A simple, fast, and versatile method, using an ultra-high performance liquid chromatography system coupled with a low resolution (single quadrupole) mass spectrometer was optimized to perform multiclass lipid profiling of human plasma. Particular attention was made to develop a method suitable for both electrospray ionization and atmospheric pressure chemical ionization interfaces (sequentially in positive- and negative-ion mode), without any modification of the chromatographic conditions (mobile phase, flow-rate, gradient, etc.). Emphasis was given to the extrapolation of the structural information based on the fragmentation pattern obtained using atmospheric pressure chemical ionization interface, under each different ionization condition, highlighting the complementary information obtained using the electrospray ionization interface, of support for related molecule ions identification. Furthermore, mass spectra of phosphatidylserine and phosphatidylinositol obtained using the atmospheric pressure chemical ionization interface are reported and discussed for the first time. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-time breath analysis with active capillary plasma ionization-ambient mass spectrometry.

Science.gov (United States)

Bregy, Lukas; Sinues, Pablo Martinez-Lozano; Nudnova, Maryia M; Zenobi, Renato

2014-06-01

On-line analysis of exhaled human breath is a growing area in analytical science, for applications such as fast and non-invasive medical diagnosis and monitoring. In this work, we present a novel approach based on ambient ionization of compounds in breath and subsequent real-time mass spectrometric analysis. We introduce a plasma ionization source for this purpose, which has no need for additional gases, is very small, and is easily interfaced with virtually any commercial atmospheric pressure ionization mass spectrometer (API-MS) without major modifications. If an API-MS instrument exists in a laboratory, the cost to implement this technology is only around [Formula: see text]500, far less than the investment for a specialized mass spectrometric system designed for volatile organic compounds (VOCs) analysis. In this proof-of-principle study we were able to measure mass spectra of exhaled human breath and found these to be comparable to spectra obtained with other electrospray-based methods. We detected over 100 VOCs, including relevant metabolites like fatty acids, with molecular weights extending up to 340 Da. In addition, we were able to monitor the time-dependent evolution of the peaks and show the enhancement of the metabolism after a meal. We conclude that this approach may complement current methods to analyze breath or other types of vapors, offering an affordable option to upgrade any pre-existing API-MS to a real-time breath analyzer.

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

Quantum dots assisted laser desorption/ionization mass spectrometric detection of carbohydrates: qualitative and quantitative analysis.

Science.gov (United States)

Bibi, Aisha; Ju, Huangxian

2016-04-01

A quantum dots (QDs) assisted laser desorption/ionization mass spectrometric (QDA-LDI-MS) strategy was proposed for qualitative and quantitative analysis of a series of carbohydrates. The adsorption of carbohydrates on the modified surface of different QDs as the matrices depended mainly on the formation of hydrogen bonding, which led to higher MS intensity than those with conventional organic matrix. The effects of QDs concentration and sample preparation method were explored for improving the selective ionization process and the detection sensitivity. The proposed approach offered a new dimension to the application of QDs as matrices for MALDI-MS research of carbohydrates. It could be used for quantitative measurement of glucose concentration in human serum with good performance. The QDs served as a matrix showed the advantages of low background, higher sensitivity, convenient sample preparation and excellent stability under vacuum. The QDs assisted LDI-MS approach has promising application to the analysis of carbohydrates in complex biological samples. Copyright © 2016 John Wiley & Sons, Ltd.

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.

Multi photon ionization mass spectrometry of carbamate pesticides, herbicides and fungicides

International Nuclear Information System (INIS)

Grun, Carsten; Koenig, Marcelle; Grotemeyer, Juergen

2001-01-01

Pesticides and herbicides are useful for a wide range of applications today. The determination of these substances either in the pure form or in complex matrices is of high analytical interest. Especially since these substances can by found in every day products. The combination of multi photon ionization (MUPI) and time of flight laser mass spectrometry may be a powerful tool for achieving fast well interpretable mass spectra for analytical purposes. In this paper we will discuss the mass spectra of several pesticides and herbicides accessed by MUPI-time-of-flight mass spectrometry. The influence of the laser pulse duration on the mass spectra are discussed

Microplasma discharge vacuum ultraviolet photoionization source for atmospheric pressure ionization mass spectrometry.

Science.gov (United States)

Symonds, Joshua M; Gann, Reuben N; Fernández, Facundo M; Orlando, Thomas M

2014-09-01

In this paper, we demonstrate the first use of an atmospheric pressure microplasma-based vacuum ultraviolet (VUV) photoionization source in atmospheric pressure mass spectrometry applications. The device is a robust, easy-to-operate microhollow cathode discharge (MHCD) that enables generation of VUV photons from Ne and Ne/H(2) gas mixtures. Photons were detected by excitation of a microchannel plate detector and by analysis of diagnostic sample ions using a mass spectrometer. Reactive ions, charged particles, and metastables produced in the discharge were blocked from entering the ionization region by means of a lithium fluoride window, and photoionization was performed in a nitrogen-purged environment. By reducing the output pressure of the MHCD, we observed heightened production of higher-energy photons, making the photoionization source more effective. The initial performance of the MHCD VUV source has been evaluated by ionizing model analytes such as acetone, azulene, benzene, dimethylaniline, and glycine, which were introduced in solid or liquid phase. These molecules represent species with both high and low proton affinities, and ionization energies ranging from 7.12 to 9.7 eV.

All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry.

Science.gov (United States)

Yuan, Chengqian; Liu, Xianhu; Zeng, Chenghui; Zhang, Hanyu; Jia, Meiye; Wu, Yishi; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

2016-02-01

We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ∼15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture.

Ionization by ion impact at grazing incidence on insulator surface

CERN Document Server

Martiarena, M L

2003-01-01

We have calculated the energy distribution of electrons produced by ionization of the ionic crystal electrons in grazing fast ion-insulator surface collision. The ionized electrons originate in the 2p F sup - orbital. We observe that the binary peak appears as a double change in the slope of the spectra, in the high energy region. The form of the peak is determined by the initial electron distribution and its position will be affected by the binding energy of the 2p F sup - electron in the crystal. This BEP in insulator surfaces will appear slightly shifted to the low energy side with respect the ion-atom one.

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 pharmaceutical compounds in surface- and ground-water samples by solid-phase extraction and high-performance liquid chromatography-electrospray ionization mass spectrometry

Science.gov (United States)

Cahill, J.D.; Furlong, E.T.; Burkhardt, M.R.; Kolpin, D.; Anderson, L.G.

2004-01-01

Commonly used prescription and over-the-counter pharmaceuticals are possibly present in surface- and ground-water samples at ambient concentrations less than 1 μg/L. In this report, the performance characteristics of a combined solid-phase extraction isolation and high-performance liquid chromatography–electrospray ionization mass spectrometry (HPLC–ESI-MS) analytical procedure for routine determination of the presence and concentration of human-health pharmaceuticals are described. This method was developed and used in a recent national reconnaissance of pharmaceuticals in USA surface waters. The selection of pharmaceuticals evaluated for this method was based on usage estimates, resulting in a method that contains compounds from diverse chemical classes, which presents challenges and compromises when applied as a single routine analysis. The method performed well for the majority of the 22 pharmaceuticals evaluated, with recoveries greater than 60% for 12 pharmaceuticals. The recoveries of angiotensin-converting enzyme inhibitors, a histamine (H2) receptor antagonist, and antihypoglycemic compound classes were less than 50%, but were retained in the method to provide information describing the potential presence of these compounds in environmental samples and to indicate evidence of possible matrix enhancing effects. Long-term recoveries, evaluated from reagent-water fortifications processed over 2 years, were similar to initial method performance. Method detection limits averaged 0.022 μg/L, sufficient for expected ambient concentrations. Compound-dependent matrix effects on HPLC/ESI-MS analysis, including enhancement and suppression of ionization, were observed as a 20–30% increase in measured concentrations for three compounds and greater than 50% increase for two compounds. Changing internal standard and more frequent ESI source maintenance minimized matrix effects. Application of the method in the national survey demonstrates that several

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability

Energy Technology Data Exchange (ETDEWEB)

Isselhardt, Brett H. [Univ. of California, Berkeley, CA (United States)

2011-09-01

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of ²³⁵U/²³⁸U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.

Field ionization mass spectrometry (FIMS) applied to tracer studies and isotope dilution analysis

International Nuclear Information System (INIS)

Anbar, M.; Heck, H.d'A.; McReynolds, J.H.; St John, G.A.

1975-01-01

The nonfragmenting nature of field ionization mass spectrometry makes it a preferred technique for the isotopic analysis of multilabeled organic compounds. The possibility of field ionization of nonvolatile thermolabile materials significantly extends the potential uses of this technique beyond those of conventional ionization methods. Multilabeled tracers may be studied in biological systems with a sensitivity comparable to that of radioactive tracers. Isotope dilution analysis may be performed reliably by this technique down to picogram levels. These techniques will be illustrated by a number of current studies using multilabeled metabolites and drugs. The scope and limitations of the methodology are discussed

Group velocity measurement from the propagation of the ionization front in a surface-wave-produced plasma

International Nuclear Information System (INIS)

Cotrino, J.; Gamero, A.; Sola, A.; Lao, C.

1989-01-01

During the first instant, previous to steady-state in a surface-wave-produced plasma, an ionization front advance front the launcher to the plasma column end. The velocity of the ionization front is much slower than the group velocity of the surface wave, this give a reflection of the incident signal on the moving ionization front. In this paper, the authors use this effect to calculate the surface wave group velocity

Toward single-cell analysis by plume collimation in laser ablation electrospray ionization mass spectrometry.

Science.gov (United States)

Stolee, Jessica A; Vertes, Akos

2013-04-02

Ambient ionization methods for mass spectrometry have enabled the in situ and in vivo analysis of biological tissues and cells. When an etched optical fiber is used to deliver laser energy to a sample in laser ablation electrospray ionization (LAESI) mass spectrometry, the analysis of large single cells becomes possible. However, because in this arrangement the ablation plume expands in three dimensions, only a small portion of it is ionized by the electrospray. Here we show that sample ablation within a capillary helps to confine the radial expansion of the plume. Plume collimation, due to the altered expansion dynamics, leads to greater interaction with the electrospray plume resulting in increased ionization efficiency, reduced limit of detection (by a factor of ~13, reaching 600 amol for verapamil), and extended dynamic range (6 orders of magnitude) compared to conventional LAESI. This enhanced sensitivity enables the analysis of a range of metabolites from small cell populations and single cells in the ambient environment. This technique has the potential to be integrated with flow cytometry for high-throughput metabolite analysis of sorted cells.

Solitary ionizing surface waves on low-temperature plasmas

International Nuclear Information System (INIS)

Vladimirov, S.V.; Yu, M.Y.

1993-01-01

It is demonstrated that at the boundary of semi-infinite low-temperature plasma new types of localized ionizing surface wave structures can propagate. The solitary waves are described by an evolution equation similar to the KdV equation, but the solutions differ considerably from that of the latter

Mass spectrometric characterization of a pyrolytic radical source using femtosecond ionization

Energy Technology Data Exchange (ETDEWEB)

Frey, H M; Beaud, P; Mischler, B; Radi, P P; Tzannis, A P; Gerber, T [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

Radicals play, as reactive species, an important role in the chemistry of combustion. In contrast to atmospheric flames where spectra are congested due to high vibrational and rotational excitation, experiments in the cold environment of a molecular beam (MB) yield clean spectra that can be easily attributed to one species by Resonantly Enhanced Multi Photon Ionization (REMP). A pyrolytic radical source has been set up. To characterize the efficiency of the source `soft` ionization with femto second pulses is applied which results in less fragmentation, simplifying the interpretation of the mass spectrum. (author) figs., tabs., refs.

Simplified sample preparation method for protein identification by matrix-assisted laser desorption/ionization mass spectrometry: in-gel digestion on the probe surface

DEFF Research Database (Denmark)

Stensballe, A; Jensen, Ole Nørregaard

2001-01-01

/ionization-time of flight mass spectrometry (MALDI-TOF-MS) is used as the first protein screening method in many laboratories because of its inherent simplicity, mass accuracy, sensitivity and relatively high sample throughput. We present a simplified sample preparation method for MALDI-MS that enables in-gel digestion...... for protein identification similar to that obtained by the traditional protocols for in-gel digestion and MALDI peptide mass mapping of human proteins, i.e. approximately 60%. The overall performance of the novel on-probe digestion method is comparable with that of the standard in-gel sample preparation...... protocol while being less labour intensive and more cost-effective due to minimal consumption of reagents, enzymes and consumables. Preliminary data obtained on a MALDI quadrupole-TOF tandem mass spectrometer demonstrated the utility of the on-probe digestion protocol for peptide mass mapping and peptide...

Silver nanoparticles as matrix for laser desorption/ionization mass spectrometry of peptides

International Nuclear Information System (INIS)

Hua Lin; Chen Jianrong; Ge Liya; Tan, Swee Ngin

2007-01-01

Silver nanoparticle synthesized from chemical reduction has been successfully utilized as a matrix in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of peptides. Acting as a substrate to adsorb analytes, as well as a transmission medium for UV laser, silver nanoparticle was found to assist in the desorption/ionization of peptides with little or no induced fragmentation. The size of the nanoparticle was typically in the range of 160 ± 20 nm. One of the key advantages of silver nanoparticle for peptides analysis is its simple step for on-probe sample preparation. In addition, it also minimizes the interferences of sodium dodecyl sulfate (SDS) surfactant background signal, resulting in cleaner mass spectra and more sensitive signal, when compared to α-cyano-4-hydroxycinnamic acid (CCA) matrix

Calibration of matrix-assisted laser desorption/ionization time-of-flight peptide mass fingerprinting spectra

DEFF Research Database (Denmark)

Hjernø, Karin; Højrup, Peter

2007-01-01

This chapter describes a number of aspects important for calibration of matrix-assisted laser desorption/ionization time-of-flight spectra prior to peptide mass fingerprinting searches. Both multipoint internal calibration and mass defect-based calibration is illustrated. The chapter describes ho...

Detection of Staphylococcus aureus by functional gold nanoparticle-based affinity surface-assisted laser desorption/ionization mass spectrometry.

Science.gov (United States)

Lai, Hong-Zheng; Wang, Sin-Ge; Wu, Ching-Yi; Chen, Yu-Chie

2015-02-17

Staphylococcus aureus is one of the common pathogenic bacteria responsible for bacterial infectious diseases and food poisoning. This study presents an analytical method based on the affinity nanoprobe-based mass spectrometry that enables detection of S. aureus in aqueous samples. A peptide aptamer DVFLGDVFLGDEC (DD) that can recognize S. aureus and methicillin-resistant S. aureus (MRSA) was used as the reducing agent and protective group to generate DD-immobilized gold nanoparticles (AuNPs@DD) from one-pot reactions. The thiol group from cysteine in the peptide aptamer, i.e., DD, can interact with gold ions to generate DD-immobilized AuNPs in an alkaline solution. The generated AuNPs@DD has an absorption maximum at ∼518 nm. The average particle size is 7.6 ± 1.2 nm. Furthermore, the generated AuNPs@DD can selectively bind with S. aureus and MRSA. The conjugates of the target bacteria with AuNPs were directly analyzed by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The gold ions generated from the AuNPs@DD anchored on the target bacteria were monitored. Gold ions (m/z 197 and 394) were only generated from the conjugates of the target bacterium-AuNP@DD in the SALDI process. Thus, the gold ions could be used as the indicators for the presence of the target bacteria. The detection limit of S. aureus using this method is in the order of a few tens of cells. The low detection limit is due to the ease of generation of gold cluster ion derived from AuNPs under irradiation with a 355 nm laser beam. Apple juice mixed with S. aureus was used as the sample to demonstrate the suitability of the method for real-world application. Because of its low detection limit, this approach can potentially be used to screen the presence of S. aureus in complex samples.

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

Tandem mass spectrometry characteristics of polyester anions and cations formed by electrospray ionization.

Science.gov (United States)

Arnould, Mark A; Buehner, Rita W; Wesdemiotis, Chrys; Vargas, Rafael

2005-01-01

Electrospray ionization of polyesters composed of isophthalic acid and neopentyl glycol produces carboxylate anions in negative mode and mainly sodium ion adducts in positive mode. A tandem mass spectrometry (MS/MS) study of these ions in a quadrupole ion trap shows that the collisionally activated dissociation pathways of the anions are simpler than those of the corresponding cations. Charge-remote fragmentations predominate in both cases, but the spectra obtained in negative mode are devoid of the complicating cation exchange observed in positive mode. MS/MS of the Na(+) adducts gives rise to a greater number of fragments but not necessarily more structural information. In either positive or negative mode, polyester oligomers with different end groups fragment by similar mechanisms. The observed fragments are consistent with rearrangements initiated by the end groups. Single-stage ESI mass spectra also are more complex in positive mode because of extensive H/Na substitutions; this is also true for matrix-assisted laser desorption ionization (MALDI) mass spectra. Hence, formation and analysis of anions might be the method of choice for determining block length, end group structure and copolymer sequence, provided the polyester contains at least one carboxylic acid end group that is ionizable to anions.

Characterization of a Distributed Plasma Ionization Source (DPIS) for Ion Mobility Spectrometry and Mass Spectrometry

International Nuclear Information System (INIS)

Waltman, Melanie J.; Dwivedi, Prabha; Hill, Herbert; Blanchard, William C.; Ewing, Robert G.

2008-01-01

A recently developed atmospheric pressure ionization source, a distributed plasma ionization source (DPIS), was characterized and compared to commonly used atmospheric pressure ionization sources with both mass spectrometry and ion mobility spectrometry. The source consisted of two electrodes of different sizes separated by a thin dielectric. Application of a high RF voltage across the electrodes generated plasma in air yielding both positive and negative ions depending on the polarity of the applied potential. These reactant ions subsequently ionized the analyte vapors. The reactant ions generated were similar to those created in a conventional point-to-plane corona discharge ion source. The positive reactant ions generated by the source were mass identified as being solvated protons of general formula (H2O)nH+ with (H2O)2H+ as the most abundant reactant ion. The negative reactant ions produced were mass identified primarily as CO3-, NO3-, NO2-, O3- and O2- of various relative intensities. The predominant ion and relative ion ratios varied depending upon source construction and supporting gas flow rates. A few compounds including drugs, explosives and environmental pollutants were selected to evaluate the new ionization source. The source was operated continuously for several months and although deterioration was observed visually, the source continued to produce ions at a rate similar that of the initial conditions. The results indicated that the DPIS may have a longer operating life than a conventional corona discharge.

Dustbuster: a New Generation Impact-ionization Time-of-flight Mass Spectrometer for in situ Analysis of Cosmic Dust

Science.gov (United States)

Austin, D. E.; Ahrens, T. J.; Beauchamp, J. L.

2000-10-01

We have developed and tested a small impact-ionization time-of-flight mass spectrometer for analysis of cosmic dust, suitable for use on deep space missions. This mass spectrometer, named Dustbuster, incorporates a large target area and a reflectron, simultaneously optimizing mass resolution, sensitivity, and collection efficiency. Dust particles hitting the 65-cm2 target plate are partially ionized. The resulting ions are accelerated through a modified reflectron that focuses the ions in space and time to produce high-resolution spectra. The instrument, shown below, measures 10 x 10 x 20 cm, has a mass of 500 g, and consumes little power. Laser desorption ionization of metal and mineral samples (embedded in the impact plate) simulates particle impacts for instrument performance tests. Mass resolution in these experiments is near 200, permitting resolution of isotopes. The mass spectrometer can be combined with other instrument components to determine dust particle trajectories and sizes. This project was funded by NASA's Planetary Instrument Definition and Development Program.

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

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

Quasar Black Hole Mass Estimates from High-Ionization Lines: Breaking a Taboo?

Directory of Open Access Journals (Sweden)

Paola Marziani

2017-09-01

Full Text Available Can high ionization lines such as CIV λ 1549 provide useful virial broadening estimators for computing the mass of the supermassive black holes that power the quasar phenomenon? The question has been dismissed by several workers as a rhetorical one because blue-shifted, non-virial emission associated with gas outflows is often prominent in CIV λ 1549 line profiles. In this contribution, we first summarize the evidence suggesting that the FWHM of low-ionization lines like H β and MgII λ 2800 provide reliable virial broadening estimators over a broad range of luminosity. We confirm that the line widths of CIV λ 1549 is not immediately offering a virial broadening estimator equivalent to the width of low-ionization lines. However, capitalizing on the results of Coatman et al. (2016 and Sulentic et al. (2017, we suggest a correction to FWHM CIV λ 1549 for Eddington ratio and luminosity effects that, however, remains cumbersome to apply in practice. Intermediate ionization lines (IP ∼ 20–30 eV; AlIII λ 1860 and SiIII] λ 1892 may provide a better virial broadening estimator for high redshift quasars, but larger samples are needed to assess their reliability. Ultimately, they may be associated with the broad-line region radius estimated from the photoionization method introduced by Negrete et al. (2013 to obtain black hole mass estimates independent from scaling laws.

Cs+ ion source for secondary ion mass spectrometry

International Nuclear Information System (INIS)

Bentz, B.L.; Weiss, H.; Liebl, H.

1981-12-01

Various types of cesium ionization sources currently used in secondary ion mass spectrometry are briefly reviewed, followed by a description of the design and performance of a novel, thermal surface ionization Cs + source developed in this laboratory. The source was evaluated for secondary ion mass spectrometry applications using the COALA ion microprobe mass analyzer. (orig.)

Instantaneous characterization of vegetable oils via TAG and FFA profiles by easy ambient sonic-spray ionization mass spectrometry.

Science.gov (United States)

Simas, Rosineide C; Catharino, Rodrigo R; Cunha, Ildenize B S; Cabral, Elaine C; Barrera-Arellano, Daniel; Eberlin, Marcos N; Alberici, Rosana M

2010-04-01

A fast and reliable method is presented for the analysis of vegetable oils. Easy ambient sonic-spray ionization mass spectrometry (EASI-MS) is shown to efficiently desorb and ionize the main oil constituents from an inert surface under ambient conditions and to provide comprehensive triacylglyceride (TAG) and free fatty acid (FFA) profiles detected mainly as either [TAG + Na](+) or [FFA-H](-) ions. EASI(+/-)-MS analysis is simple, easily implemented, requires just a tiny droplet of the oil and is performed without any pre-separation or chemical manipulation. It also causes no fragmentation of TAG ions hence diacylglyceride (DAG) and monoacylglyceride (MAG) profiles and contents can also be measured. The EASI(+/-)-MS profiles of TAG and FFA permit authentication and quality control and can be used, for instance, to access levels of adulteration, acidity, oxidation or hydrolysis of vegetable oils in general.

Analysis of femtogram-sized plutonium samples by thermal ionization mass spectrometry

International Nuclear Information System (INIS)

Smith, D.H.; Duckworth, D.C.; Bostick, D.T.; Coleman, R.M.; McPherson, R.L.; McKown, H.S.

1994-01-01

The goal of this investigation was to extend the ability to perform isotopic analysis of plutonium to samples as small as possible. Plutonium ionizes thermally with quite good efficiency (first ionization potential 5.7 eV). Sub-nanogram sized samples can be analyzed on a near-routine basis given the necessary instrumentation. Efforts in this laboratory have been directed at rhenium-carbon systems; solutions of carbon in rhenium provide surfaces with work functions higher than pure rhenium (5.8 vs. ∼ 5.4 eV). Using a single resin bead as a sample loading medium both concentrates the sample nearly to a point and, due to its interaction with rhenium, produces the desired composite surface. Earlier work in this area showed that a layer of rhenium powder slurried in solution containing carbon substantially enhanced precision of isotopic measurements for uranium. Isotopic fractionation was virtually eliminated, and ionization efficiencies 2-5 times better than previously measured were attained for both Pu and U (1.7 and 0.5%, respectively). The other side of this coin should be the ability to analyze smaller samples, which is the subject of this report

Comparison of Electrospray Ionization and Atmospheric Chemical Ionization Coupled with the Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Cholesteryl Esters

Directory of Open Access Journals (Sweden)

Hae-Rim Lee

2015-01-01

Full Text Available The approach of two different ionization techniques including electrospray ionization (ESI and atmospheric pressure chemical ionization (APCI coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS was tested for the analysis of cholesteryl esters (CEs. The retention time (RT, signal intensity, protonated ion, and product ion of CEs were compared between ESI and APCI. RT of CEs from both ionizations decreased with increasing double bonds, while it increased with longer carbon chain length. The ESI process generated strong signal intensity of precursor ions corresponding to [M+Na]+ and [M+NH4]+ regardless of the number of carbon chains and double bonds in CEs. On the other hand, the APCI process produced a protonated ion of CEs [M+H]+ with a weak signal intensity, and it is selectively sensitive to detect precursor ions of CEs with unsaturated fatty acids. The ESI technique proved to be effective in ionizing more kinds of CEs than the APCI technique.

Characterization of Rhodamine Self-Assembled Films Using Desorption Electrospray Ionization Mass Spectrometry

Science.gov (United States)

Shi, Ruixia; Na, Na; Jiang, Fubin; Ouyang, Jin

2013-06-01

Growth process information and molecular structure identification are very important for characterization of self-assembled films. Here, we explore the possible application of desorption electrospray ionization mass spectrometry (DESI-MS) that provides the assembled information of rhodamine B (Rh B) and rhodamine 123 (Rh 123) films. With the help of lab-made DESI source, two characteristic ions [Rh B]+ and [Rh 123]+ are observed directly in the open environment. To evaluate the reliability of this technique, a comparative study of ultraviolet-visible (UV-vis) spectroscopy and our method is carried out, and the result shows good correlation. According to the signal intensity of characteristic ions, the layer-by-layer adsorption process of dyes can be monitored, and the thicknesses of multilayer films can also be comparatively determined. Combining the high sensitivity, selectivity, and speed of mass spectrometry, the selective adsorption of similar structure molecules under different pH is recognized easily from extracted ion chronograms. The variation trend of dyes signalling intensity with concentration of polyelectrolyte is studied as well, which reflects the effect of surface charge on dyes deposition. Additionally, the desorption area, surface morphology, and thicknesses of multilayer films are investigated using fluorescence microscope, scanning electron microscope (SEM), and atomic force microscopy (AFM), respectively. Because the desorption area was approximately as small as 2 mm2, the distribution situation of organic dyes in an arbitrary position could be gained rapidly, which means DESI-MS has advantages on in situ analysis.

Surface acoustic wave nebulization of peptides as a microfluidic interface for mass spectrometry.

Science.gov (United States)

Heron, Scott R; Wilson, Rab; Shaffer, Scott A; Goodlett, David R; Cooper, Jonathan M

2010-05-15

We describe the fabrication of a surface acoustic wave (SAW) device on a LiNbO(3) piezoelectric transducer for the transfer of nonvolatile analytes to the gas phase at atmospheric pressure (a process referred to as nebulization or atomization). We subsequently show how such a device can be used in the field of mass spectrometry (MS) detection, demonstrating that SAW nebulization (SAWN) can be performed either in a discontinuous or pulsed mode, similar to that for matrix assisted laser desorption ionization (MALDI) or in a continuous mode like electrospray ionization (ESI). We present data showing the transfer of peptides to the gas phase, where ions are detected by MS. These peptide ions were subsequently fragmented by collision-induced dissociation, from which the sequence was assigned. Unlike MALDI mass spectra, which are typically contaminated with matrix ions at low m/z, the SAWN generated spectra had no such interference. In continuous mode, the SAWN plume was sampled on a microsecond time scale by a linear ion trap mass spectrometer and produced multiply charged peptide precursor ions with a charge state distribution shifted to higher m/z compared to an identical sample analyzed by ESI. The SAWN technology also provides the opportunity to re-examine a sample from a flat surface, repeatedly. The process can be performed without the need for capillaries, which can clog, reservoirs, which dilute the sample, and electrodes, which when in direct contact with sample, cause unwanted electrochemical oxidation. In both continuous and pulsed sampling modes, the quality of precursor ion scans and tandem mass spectra of peptides was consistent across the plume's lifetime.

Chemical analysis of surfaces by resonance ionization mass spectroscopy associated to ionic pulverization; Analyse chimique de surfaces par spectrometrie d`ionisation resonante associee a la pulverisation ionique

Energy Technology Data Exchange (ETDEWEB)

Kern, P

1995-12-19

This work shows that if resonance ionization mass spectroscopy was first applied in isotopic separation, it`s also an analyzing method adapted to the study of semi-conductor materials and thin foils. We have improved this technic: a neodymium laser coupled with a dye laser, a new argon ions gun, a gallium ions gun and a new collection optic for the secondary ions quadrupole spectrometer to allow quantitative and selective measurements. (S.G.). 84 refs.

Resin bead-thermal ionization mass spectrometry for determination of plutonium concentration in irradiated fuel dissolver solution

International Nuclear Information System (INIS)

Paul, Sumana; Shah, R.V.; Aggarwal, S.K.; Pandey, A.K.

2015-01-01

Determination of isotopic composition (IC) and concentration of plutonium (Pu) is necessary at various stages of nuclear fuel cycle which involves analysis of complex matrices like dissolver solution of irradiated fuel, nuclear waste stream etc. Mass spectrometry, e.g. thermal ionization mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICP-MS) are commonly used for determination of IC and concentration of plutonium. However, to circumvent matrix interferences, efficient separation as well as preconcentration of Pu is required prior to mass spectrometric analysis. Purification steps employing ion-exchange resins are widely used for the separation of Pu from dissolver solution or from mixture of other actinides e.g. U, Am. However, an alternative way is to selectively preconcentrate Pu on a resin bead, followed by direct loading of the bead on the filament of thermal ionization mass spectrometer

Chemical separation of plutonium from air filters and preparation of filaments for resonance ionization mass spectroscopy

International Nuclear Information System (INIS)

Eberhardt, K.; Erdmann, N.; Funk, H.; Herrmann, G.; Naehler, A.; Passler, G.; Trautmann, N.; Urban, F.

1995-01-01

Resonance ionization mass spectroscopy (RIMS) is used for the determination of plutonium in environmental samples. A chemical procedure based on an ion-exchange technique for the separation of plutonium from a polycarbonate filter is described. The overall yield is about 60% as determined by α-particle spectroscopy. A technique for the subsequent preparation of samples for RIMS measurements is developed. Plutonium is electrode-posited as hydroxide and covered with a thin metallic layer. While heating such a sandwich filament the plutonium hydroxide is reduced to the metal and an atomic beam is evaporated from the surface, as required for RIMS. copyright American Institute of Physics 1995

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.

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.

Carbon nanotubes as adsorbent of solid-phase extraction and matrix for laser desorption/ionization mass spectrometry.

Science.gov (United States)

Pan, Chensong; Xu, Songyun; Zou, Hanfa; Guo, Zhong; Zhang, Yu; Guo, Baochuan

2005-02-01

A method with carbon nanotubes functioning both as the adsorbent of solid-phase extraction (SPE) and the matrix for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) to analyze small molecules in solution has been developed. In this method, 10 microL suspensions of carbon nanotubes in 50% (vol/vol) methanol were added to the sample solution to extract analytes onto surface of carbon nanotubes because of their dramatic hydrophobicity. Carbon nanotubes in solution are deposited onto the bottom of tube with centrifugation. After removing the supernatant fluid, carbon nanotubes are suspended again with dispersant and pipetted directly onto the sample target of the MALDI-MS to perform a mass spectrometric analysis. It was demonstrated by analysis of a variety of small molecules that the resolution of peaks and the efficiency of desorption/ionization on the carbon nanotubes are better than those on the activated carbon. It is found that with the addition of glycerol and sucrose to the dispersant, the intensity, the ratio of signal to noise (S/N), and the resolution of peaks for analytes by mass spectrometry increased greatly. Compared with the previously reported method by depositing sample solution onto thin layer of carbon nanotubes, it is observed that the detection limit for analytes can be enhanced about 10 to 100 times due to solid-phase extraction of analytes in solution by carbon nanotubes. An acceptable result of simultaneously quantitative analysis of three analytes in solution has been achieved. The application in determining drugs spiked into urine has also been realized.

Ghost peaks observed after atmospheric pressure matrix-assisted laser desorption/ionization experiments may disclose new ionization mechanism of matrix-assisted hypersonic velocity impact ionization.

Science.gov (United States)

Moskovets, Eugene

2015-08-30

Understanding the mechanisms of matrix-assisted laser desorption/ionization (MALDI) promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample had been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laser-less matrix-assisted ionization. An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser had been turned off and the MALDI sample removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly and doubly charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. The observations were partially consistent

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.

Mass Spectrometry Imaging under Ambient Conditions

Science.gov (United States)

Wu, Chunping; Dill, Allison L.; Eberlin, Livia S.; Cooks, R. Graham; Ifa, Demian R.

2012-01-01

Mass spectrometry imaging (MSI) has emerged as an important tool in the last decade and it is beginning to show potential to provide new information in many fields owing to its unique ability to acquire molecularly specific images and to provide multiplexed information, without the need for labeling or staining. In MSI, the chemical identity of molecules present on a surface is investigated as a function of spatial distribution. In addition to now standard methods involving MSI in vacuum, recently developed ambient ionization techniques allow MSI to be performed under atmospheric pressure on untreated samples outside the mass spectrometer. Here we review recent developments and applications of MSI emphasizing the ambient ionization techniques of desorption electrospray ionization (DESI), laser ablation electrospray ionization (LAESI), probe electrospray ionization (PESI), desorption atmospheric pressure photoionization (DAPPI), femtosecond laser desorption ionization (fs-LDI), laser electrospray mass spectrometry (LEMS), infrared laser ablation metastable-induced chemical ionization (IR-LAMICI), liquid microjunction surface sampling probe mass spectrometry (LMJ-SSP MS), nanospray desorption electrospray ionization (nano-DESI), and plasma sources such as the low temperature plasma (LTP) probe and laser ablation coupled to flowing atmospheric-pressure afterglow (LA-FAPA). Included are discussions of some of the features of ambient MSI including the ability to implement chemical reactions with the goal of providing high abundance ions characteristic of specific compounds of interest and the use of tandem mass spectrometry to either map the distribution of targeted molecules with high specificity or to provide additional MS information in the structural identification of compounds. We also describe the role of bioinformatics in acquiring and interpreting the chemical and spatial information obtained through MSI, especially in biological applications for tissue

Electrospray Ionization Mass Spectrometry: A Technique to Access the Information beyond the Molecular Weight of the Analyte

Science.gov (United States)

Banerjee, Shibdas; Mazumdar, Shyamalava

2012-01-01

The Electrospray Ionization (ESI) is a soft ionization technique extensively used for production of gas phase ions (without fragmentation) of thermally labile large supramolecules. In the present review we have described the development of Electrospray Ionization mass spectrometry (ESI-MS) during the last 25 years in the study of various properties of different types of biological molecules. There have been extensive studies on the mechanism of formation of charged gaseous species by the ESI. Several groups have investigated the origin and implications of the multiple charge states of proteins observed in the ESI-mass spectra of the proteins. The charged analytes produced by ESI can be fragmented by activating them in the gas-phase, and thus tandem mass spectrometry has been developed, which provides very important insights on the structural properties of the molecule. The review will highlight recent developments and emerging directions in this fascinating area of research. PMID:22611397

Electrospray ionization mass spectrometry: a technique to access the information beyond the molecular weight of the analyte.

Science.gov (United States)

Banerjee, Shibdas; Mazumdar, Shyamalava

2012-01-01

The Electrospray Ionization (ESI) is a soft ionization technique extensively used for production of gas phase ions (without fragmentation) of thermally labile large supramolecules. In the present review we have described the development of Electrospray Ionization mass spectrometry (ESI-MS) during the last 25 years in the study of various properties of different types of biological molecules. There have been extensive studies on the mechanism of formation of charged gaseous species by the ESI. Several groups have investigated the origin and implications of the multiple charge states of proteins observed in the ESI-mass spectra of the proteins. The charged analytes produced by ESI can be fragmented by activating them in the gas-phase, and thus tandem mass spectrometry has been developed, which provides very important insights on the structural properties of the molecule. The review will highlight recent developments and emerging directions in this fascinating area of research.

Approaches for the analysis of low molecular weight compounds with laser desorption/ionization techniques and mass spectrometry.

Science.gov (United States)

Bergman, Nina; Shevchenko, Denys; Bergquist, Jonas

2014-01-01

This review summarizes various approaches for the analysis of low molecular weight (LMW) compounds by different laser desorption/ionization mass spectrometry techniques (LDI-MS). It is common to use an agent to assist the ionization, and small molecules are normally difficult to analyze by, e.g., matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) using the common matrices available today, because the latter are generally small organic compounds themselves. This often results in severe suppression of analyte peaks, or interference of the matrix and analyte signals in the low mass region. However, intrinsic properties of several LDI techniques such as high sensitivity, low sample consumption, high tolerance towards salts and solid particles, and rapid analysis have stimulated scientists to develop methods to circumvent matrix-related issues in the analysis of LMW molecules. Recent developments within this field as well as historical considerations and future prospects are presented in this review.

Generation of CsI cluster ions for mass calibration in matrix-assisted laser desorption/ionization mass spectrometry

NARCIS (Netherlands)

Lou, X.; Dongen, van J.L.J.; Meijer, E.W.

2010-01-01

A simple method was developed for the generation of cesium iodide (CsI) cluster ions up to m/z over 20,000 in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Calibration ions in both positive and negative ion modes can readily be generated from a single MALDI spot of CsI(3)

One-photon mass-analyzed threshold ionization (MATI) spectroscopy of pyridine: Determination of accurate ionization energy and cationic structure

Energy Technology Data Exchange (ETDEWEB)

Lee, Yu Ran; Kang, Do Won; Kim, Hong Lae, E-mail: chkwon@kangwon.ac.kr, E-mail: hlkim@kangwon.ac.kr; Kwon, Chan Ho, E-mail: chkwon@kangwon.ac.kr, E-mail: hlkim@kangwon.ac.kr [Department of Chemistry and Institute for Molecular Science and Fusion Technology, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 (Korea, Republic of)

2014-11-07

Ionization energies and cationic structures of pyridine were intensively investigated utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The present one-photon high-resolution MATI spectrum of pyridine demonstrated a much finer and richer vibrational structure than that of the previously reported two-photon MATI spectrum. From the MATI spectrum and photoionization efficiency curve, the accurate ionization energy of the ionic ground state of pyridine was confidently determined to be 73 570 ± 6 cm{sup −1} (9.1215 ± 0.0007 eV). The observed spectrum was almost completely assigned by utilizing Franck-Condon factors and vibrational frequencies calculated through adjustments of the geometrical parameters of cationic pyridine at the B3LYP/cc-pVTZ level. A unique feature unveiled through rigorous analysis was the prominent progression of the 10 vibrational mode, which corresponds to in-plane ring bending, and the combination of other totally symmetric fundamentals with the ring bending overtones, which contribute to the geometrical change upon ionization. Notably, the remaining peaks originate from the upper electronic state ({sup 2}A{sub 2}), as predicted by high-resolution photoelectron spectroscopy studies and symmetry-adapted cluster configuration interaction calculations. Based on the quantitatively good agreement between the experimental and calculated results, it was concluded that upon ionization the pyridine cation in the ground electronic state should have a planar structure of C{sub 2v} symmetry through the C-N axis.

Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

Science.gov (United States)

Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

2009-06-01

The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy

Synthesis and Electrospray Ionization Mass Spectra of N-(1,3,2-Dioxaphosphorinan-2-ylmethyl)thiophosphoramidates

Institute of Scientific and Technical Information of China (English)

MIAO,Zhi-Wei; FU,Cui-Rong; WANG,Bin; CUI,Zhan-Wei; ZHANG,Jian-Feng; CHEN,Ru-Yu

2007-01-01

N-(1,3,2-Dioxaphosphorinan-2-ylmethyl) thiophosphoramidates were synthesized and determined by NMR spectra and positive ion electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). The fragmentation pathways were investigated. The results show that these characteristic ions in ESI mass spectra are useful in the structural determination of N-(1,3,2-dioxaphosphorinan-2-ylmethyl)thiophosphoramidates.

Mass spectrometry imaging of illicit drugs in latent fingerprints by matrix-free and matrix-assisted desorption/ionization techniques.

Science.gov (United States)

Skriba, Anton; Havlicek, Vladimir

2018-02-01

Compared with classical matrix-assisted laser-desorption ionization mass spectrometry (MALDI), the matrix free-based strategies generate a cleaner background, without significant noise or interference coming from an applied matrix, which is beneficial for the analysis of small molecules, such as drugs of abuse. In this work, we probed the detection efficiency of methamphetamine, heroin and cocaine in nanostructure-assisted laser desorption-ionization (NALDI) and desorption electrospray ionization and compared the sensitivity of these two matrix-free tools with a standard MALDI mass spectrometry experiment. In a typical mass spectrometry imaging (MSI) setup, papillary line latent fingerprints were recorded as a mixture a common skin fatty acid or interfering cosmetics with a drug. In a separate experiment, all drugs (1 µL of 1 μM standard solution) were detected by all three ionization techniques on a target. In the case of cocaine and heroin, NALDI mass spectrometry was the most sensitive and revealed signals even from 0.1 μM solution. The drug/drug contaminant (fatty acid or cosmetics) MSI approach could be used by law enforcement personnel to confirm drug abusers of having come into contact with the suspected drug by use of fingerprint scans at time of apprehension which can aid in reducing the work of lab officials.

Use of electron ionization and atmospheric pressure chemical ionization in gas chromatography coupled to time-of-flight mass spetrometry for screening and identification of organic pollutants in waters

NARCIS (Netherlands)

Portoles, T.; Mol, J.G.J.; Sancho, J.V.; Hernandez, F.

2014-01-01

A new approach has been developed for multiclass screening of organic contaminants in water based on the use of gas chromatography coupled to hybrid quadrupole high-resolution time-of-flight mass spectrometry with atmospheric pressure chemical ionization (GC–(APCI)QTOF MS). The soft ionization

Document authentication at molecular levels using desorption atmospheric pressure chemical ionization mass spectrometry imaging.

Science.gov (United States)

Li, Ming; Jia, Bin; Ding, Liying; Hong, Feng; Ouyang, Yongzhong; Chen, Rui; Zhou, Shumin; Chen, Huanwen; Fang, Xiang

2013-09-01

Molecular images of documents were obtained by sequentially scanning the surface of the document using desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS), which was operated in either a gasless, solvent-free or methanol vapor-assisted mode. The decay process of the ink used for handwriting was monitored by following the signal intensities recorded by DAPCI-MS. Handwritings made using four types of inks on four kinds of paper surfaces were tested. By studying the dynamic decay of the inks, DAPCI-MS imaging differentiated a 10-min old from two 4 h old samples. Non-destructive forensic analysis of forged signatures either handwritten or computer-assisted was achieved according to the difference of the contour in DAPCI images, which was attributed to the strength personalized by different writers. Distinction of the order of writing/stamping on documents and detection of illegal printings were accomplished with a spatial resolution of about 140 µm. A Matlab® written program was developed to facilitate the visualization of the similarity between signature images obtained by DAPCI-MS. The experimental results show that DAPCI-MS imaging provides rich information at the molecular level and thus can be used for the reliable document analysis in forensic applications. © 2013 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons, Ltd.

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.

Uniform elemental analysis of materials by sputtering and photoionization mass spectrometry

International Nuclear Information System (INIS)

Chun, He; Basler, J.N.; Becker, C.H.

1997-01-01

Analysis of the elemental composition of surfaces commonly involves techniques in which atoms or ions are ablated from the material's surface and detected by mass spectrometry. Secondary-ion mass spectrometry is widely used for detection with high sensitivity (down to a few parts per billion) but technical problems prevent it from being truly quantitative. Some of these problems are circumvented by nonresonant laser post-ionization of sputtered atoms followed by time-of-flight mass spectrometry (surface analysis by laser ionization: SALI). But when there are large differences in ionization probabilities amongst different elements in the material, the detection sensitivity can be non-uniform and accurate quantification remains out of reach. Here we report that highly uniform, quantitative and sensitive analysis of materials can be achieved using a high-energy (5-keV) ion beam for sputtering coupled with a very-high-intensity laser to induce multiphoton ionization of the sputtered atoms. We show uniform elemental sensitivity for several samples containing elements with very different ionization potentials, suggesting that this approach can now be regarded as quantitative for essentially any material. (author)

Application of pyrolysis–mass spectrometry and pyrolysis–gas chromatography–mass spectrometry with electron-ionization or resonance-enhanced-multi-photon ionization for characterization of crude oils

Energy Technology Data Exchange (ETDEWEB)

Otto, Stefan [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Streibel, Thorsten, E-mail: thorsten.streibel@uni-rostock.de [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Joint Mass Spectrometry Centre, Cooperation Group Comprehensive Molecular Analytics, Institute of Ecological Chemistry, Helmholtz Zentrum München-German Research Center of Environmental Health (GmbH), Ingolstädter Landstrasse 1, 85764 Neuherberg (Germany); Erdmann, Sabrina [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Sklorz, Martin [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Joint Mass Spectrometry Centre, Cooperation Group Comprehensive Molecular Analytics, Institute of Ecological Chemistry, Helmholtz Zentrum München-German Research Center of Environmental Health (GmbH), Ingolstädter Landstrasse 1, 85764 Neuherberg (Germany); Schulz-Bull, Detlef [Marine Chemistry, Leibniz Institute for Baltic Sea Research, Warnemünde, Seestrasse 15, 18119 Rostock (Germany); Zimmermann, Ralf [Joint Mass Spectrometry Centre, Chair of Analytical Chemistry, Institute of Chemistry, University of Rostock, 18059 Rostock (Germany); Joint Mass Spectrometry Centre, Cooperation Group Comprehensive Molecular Analytics, Institute of Ecological Chemistry, Helmholtz Zentrum München-German Research Center of Environmental Health (GmbH), Ingolstädter Landstrasse 1, 85764 Neuherberg (Germany)

2015-01-15

Highlights: • Gas chromatography setup with two MS detectors applying different ionization methods. • In parallel structural information and sensitive detection of aromatic species. • Characterization of setup and application for crude oil samples. • Detection of polycyclic aromatic hydrocarbons next to sulfur containing aromatics. - Abstract: A novel analytical system for gas-chromatographic investigation of complex samples has been developed, that combines the advantages of several analytical principles to enhance the analytical information. Decomposition of high molecular weight structures is achieved by pyrolysis and a high separation capacity due to the chromatographic step provides both an universal as well as a selective and sensitive substance detection. The latter is achieved by simultaneously applying electron ionization quadrupole mass spectrometry (EI-QMS) for structural elucidation and [1 + 1]-resonance-enhanced-multi-photon ionization (REMPI) combined with time-of-flight mass spectrometry (ToFMS). The system has been evaluated and tested with polycyclic aromatic hydrocarbon (PAH) standards. It was applied to crude oil samples for the first time. In such highly complex samples several thousands of compounds are present and the identification especially of low concentrated chemical species such as PAH or their polycyclic aromatic sulfur containing heterocyclic (PASH) derivatives is often difficult. Detection of unalkylated and alkylated PAH together with PASH is considerably enhanced by REMPI–ToFMS, at times revealing aromatic structures which are not observable by EI-QMS due to their low abundance. On the other hand, the databased structure proposals of the EI-QMS analysis are needed to confirm structural information and isomers distinction. The technique allows a complex structure analysis as well as selective assessment of aromatic substances in one measurement. Information about the content of sulfur containing compounds plays a

Application of pyrolysis–mass spectrometry and pyrolysis–gas chromatography–mass spectrometry with electron-ionization or resonance-enhanced-multi-photon ionization for characterization of crude oils

International Nuclear Information System (INIS)

Otto, Stefan; Streibel, Thorsten; Erdmann, Sabrina; Sklorz, Martin; Schulz-Bull, Detlef; Zimmermann, Ralf

2015-01-01

Highlights: • Gas chromatography setup with two MS detectors applying different ionization methods. • In parallel structural information and sensitive detection of aromatic species. • Characterization of setup and application for crude oil samples. • Detection of polycyclic aromatic hydrocarbons next to sulfur containing aromatics. - Abstract: A novel analytical system for gas-chromatographic investigation of complex samples has been developed, that combines the advantages of several analytical principles to enhance the analytical information. Decomposition of high molecular weight structures is achieved by pyrolysis and a high separation capacity due to the chromatographic step provides both an universal as well as a selective and sensitive substance detection. The latter is achieved by simultaneously applying electron ionization quadrupole mass spectrometry (EI-QMS) for structural elucidation and [1 + 1]-resonance-enhanced-multi-photon ionization (REMPI) combined with time-of-flight mass spectrometry (ToFMS). The system has been evaluated and tested with polycyclic aromatic hydrocarbon (PAH) standards. It was applied to crude oil samples for the first time. In such highly complex samples several thousands of compounds are present and the identification especially of low concentrated chemical species such as PAH or their polycyclic aromatic sulfur containing heterocyclic (PASH) derivatives is often difficult. Detection of unalkylated and alkylated PAH together with PASH is considerably enhanced by REMPI–ToFMS, at times revealing aromatic structures which are not observable by EI-QMS due to their low abundance. On the other hand, the databased structure proposals of the EI-QMS analysis are needed to confirm structural information and isomers distinction. The technique allows a complex structure analysis as well as selective assessment of aromatic substances in one measurement. Information about the content of sulfur containing compounds plays a

Optimization of information content in a mass spectrometry based flow-chemistry system by investigating different ionization approaches.

Science.gov (United States)

Martha, Cornelius T; Hoogendoorn, Jan-Carel; Irth, Hubertus; Niessen, Wilfried M A

2011-05-15

Current development in catalyst discovery includes combinatorial synthesis methods for the rapid generation of compound libraries combined with high-throughput performance-screening methods to determine the associated activities. Of these novel methodologies, mass spectrometry (MS) based flow chemistry methods are especially attractive due to the ability to combine sensitive detection of the formed reaction product with identification of introduced catalyst complexes. Recently, such a mass spectrometry based continuous-flow reaction detection system was utilized to screen silver-adducted ferrocenyl bidentate catalyst complexes for activity in a multicomponent synthesis of a substituted 2-imidazoline. Here, we determine the merits of different ionization approaches by studying the combination of sensitive detection of product formation in the continuous-flow system with the ability to simultaneous characterize the introduced [ferrocenyl bidentate+Ag](+) catalyst complexes. To this end, we study the ionization characteristics of electrospray ionization (ESI), atmospheric-pressure chemical ionization (APCI), no-discharge APCI, dual ESI/APCI, and dual APCI/no-discharge APCI. Finally, we investigated the application potential of the different ionization approaches by the investigation of ferrocenyl bidentate catalyst complex responses in different solvents. Copyright © 2011 Elsevier B.V. All rights reserved.

A high efficiency thermal ionization source adapted to mass spectrometers

International Nuclear Information System (INIS)

Chamberlin, E.P.; Olivares, J.A.

1996-01-01

A tungsten crucible thermal ionization source mounted on a quadrupole mass spectrometer is described. The crucible is a disposable rod with a fine hole bored in one end; it is heated by electron bombardment. The schematic design of the assembly, including water cooling, is described and depicted. Historically, the design is derived from that of ion sources used on ion separators at Los Alamos and Dubna, but the crucible is made smaller and simplified. 10 refs., 4 figs

Desorption electrospray ionization mass spectrometry for trace analysis of agrochemicals in food.

Science.gov (United States)

García-Reyes, Juan F; Jackson, Ayanna U; Molina-Díaz, Antonio; Cooks, R Graham

2009-01-15

Desorption electrospray ionization (DESI) is applied to the rapid, in situ, direct qualitative and quantitative (ultra)trace analysis of agrochemicals in foodstuffs. To evaluate the potential of DESI mass spectrometry (MS) in toxic residue testing in food, 16 representative multiclass agricultural chemicals (pesticides, insecticides, herbicides, and fungicides) were selected (namely, ametryn, amitraz, azoxystrobin, bitertanol, buprofezin, imazalil, imazalil metabolite, isofenphos-methyl, malathion, nitenpyram, prochloraz, spinosad, terbuthylazine, thiabendazole, and thiacloprid). The DESI-MS experiments were performed using 3 microL of solution spotted onto conventional smooth poly(tetrafluoroethylene) (PTFE) surfaces, with examination by MS and tandem mass spectrometry (MS/MS) using an ion trap mass spectrometer. Optimization of the spray solvent led to the use of acetonitrile/water (80:20) (v/v), with 1% formic acid. Most of the compounds tested showed remarkable sensitivity in the positive ion mode, approaching that attainable with conventional direct infusion electrospray mass spectrometry. To evaluate the potential of the proposed approach in real samples, different experiments were performed including the direct DESI-MS/MS analysis of fruit peels and also of fruit/vegetable extracts. The results proved that DESI allows the detection and confirmation of traces of agrochemicals in actual market-purchased samples. In addition, MS/MS confirmation of selected pesticides in spiked vegetable extracts was obtained at absolute levels as low as 1 pg for ametryn. Quantitation of imazalil residues was also undertaken using an isotopically labeled standard. The data obtained were in agreement with those from the liquid chromatography mass spectrometry (LC-MS) reference method, with relative standard deviation (RSD) values consistently below 15%. The results obtained demonstrate the sensitivity of DESI as they meet the stringent European Union pesticide regulation

Improved analytical sensitivity for uranium and plutonium in environmental samples: Cavity ion source thermal ionization mass spectrometry

International Nuclear Information System (INIS)

Ingeneri, Kristofer; Riciputi, L.

2001-01-01

Following successful field trials, environmental sampling has played a central role as a routine part of safeguards inspections since early 1996 to verify declared and to detect undeclared activity. The environmental sampling program has brought a new series of analytical challenges, and driven a need for advances in verification technology. Environmental swipe samples are often extremely low in concentration of analyte (ng level or lower), yet the need to analyze these samples accurately and precisely is vital, particularly for the detection of undeclared nuclear activities. Thermal ionization mass spectrometry (TIMS) is the standard method of determining isotope ratios of uranium and plutonium in the environmental sampling program. TIMS analysis typically employs 1-3 filaments to vaporize and ionize the sample, and the ions are mass separated and analyzed using magnetic sector instruments due to their high mass resolution and high ion transmission. However, the ionization efficiency (the ratio of material present to material actually detected) of uranium using a standard TIMS instrument is low (0.2%), even under the best conditions. Increasing ionization efficiency by even a small amount would have a dramatic impact for safeguards applications, allowing both improvements in analytical precision and a significant decrease in the amount of uranium and plutonium required for analysis, increasing the sensitivity of environmental sampling

Matrix-assisted laser-desorption-ionization mass spectrometry of proteins using a free-electron laser

International Nuclear Information System (INIS)

Cramer, R.; Hillenkamp, F.; Haglund, R.

1995-01-01

Matrix-assisted laser desorption-ionization (MALDI) mass spectrometry (MS) is one of the most promising techniques for spectral fingerprinting large molecules, such as proteins, oligonucleotides and carbohydrates. In the usual implementation of this technique, the analyte molecule is dissolved in an aromatic liquid matrix material which resonantly absorbs ultraviolet laser light. Resonant absorption by π-π* transitions volatilizes the matrix and initiates subsequent charge transfer to the analyte molecules, which are detected by time-of-flight mass spectrometry. Recent MALDI-MS studies with Er:YAG (2.94 μm) and CO 2 4 (9.4-10.6 μm) lasers suggest that them is significant unexplored potential for mass spectrometry of macromolecules, including oligonucleotide, in the mid-infrared. Preliminary experiments show that it is possible to capitalize on the rich rovibronic absorption spectrum of virtually all organics to initiate resonant desorption in matrix material over the entire range of pH values. However, the mechanism of charge transfer is particularly problematic for infrared MALDI because of the low photon energy. In this paper, we report the results of MALI-MS studies on small proteins using the Vanderbilt FEL and several matrix materials. Proteins with masses up to roughly 6,000 amu were detected with high resolution in a linear time-of-flight mass spectrometer. By varying the pulse duration using a broadband Pockels cell, we have been able to compare the results of relatively long (5 μs) and short (0.1 μs) irradiation on the desorption and ionization processes. Compared to uv-MALDI spectra of identical analytes obtained with a nitrogen laser (337 nm) in the same time-of-flight spectrometer, the infrared results appear to show that the desorption and ionization process goes on over a somewhat longer time scale

Identifying the related compounds using electrospray ionization tandem mass spectrometry: bromotyrosine alkaloids from marine sponge Psammaplysilla purpurea

Digital Repository Service at National Institute of Oceanography (India)

Tilvi, S.; DeSouza, L.

electrospray ionization tandem mass spectrometry (ESI-MS/MS). This sponge has tremendous chemical diversity of bromotyrosine alkaloids. Here we have used the proteomics approach in identifying related bromotyrosine alkaloids based on the predicated mass...

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.

Detection of Biosignatures by Geomatrix-Assisted Laser Desorption/Ionization (GALDI) Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Jill R. Scott; Beizhan Yan; Daphne L. Stoner; J. Michelle Kotler; Nancy W. Hinman

2007-04-01

Identification of mineral-associated biosignatures is of significance for retrieving biochemical information from geological records here on Earth and detecting signs of life on other planets, such as Mars. The importance of the geomatrix for identifying amino acids (e.g., histidine, threonine, and cysteine) and small proteins (e.g., gramicidin S) was investigated by laser desorption Fourier transform mass spectrometry. The investigated geomatrices include analogues of Fe-bearing minerals such as hematite and Na-bearing evaporites (e.g., halite). Samples were prepared by two methods: 1) application of analyte to the geomatrix surface and 2) production of homogenous analyte:geomatrix mixtures. Comparison of the two sample preparation methods revealed that the mixing method produces a better signal/noise ratio than surface application for the analyses of amino acids. The composition of the geomatrix has a profound influence on the detection of biomolecules. Peaks corresponding to the cation-attached biomolecular ions were observed for the Na-bearing evaporite analogue. No detectable peaks for the biomolecular ion species were observed when the biomolecules were associated with Fe-bearing minerals. Instead, only minor peaks were observed that may correspond to ions from fragments of the biomolecules. Depending on the underlying mineral composition, geomatrix-assisted laser desorption/ionization shows promise for directly identifying biosignatures associated with minerals.

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

Complexation of malic acid with cadmium(II) probed by electrospray ionization mass spectrometry

Czech Academy of Sciences Publication Activity Database

Jaklová Dytrtová, Jana; Jakl, M.; Schröder, Detlef

2012-01-01

Roč. 90, 15 Feb (2012), s. 63-68 ISSN 0039-9140 Institutional research plan: CEZ:AV0Z40550506 Keywords : electrospray ionization * hazardous metal s * mass spectrometry * root exudates * soil solution Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.498, year: 2012

Feasibility of nonvolatile buffers in capillary electrophoresis-electrospray ionization-mass spectrometry of proteins

NARCIS (Netherlands)

Eriksson, Jonas H.C.; Mol, Roelof; Somsen, Govert W.; Hinrichs, Wouter L.J.; Frijlink, Henderik W.; de Jong, Gerhardus J.

2004-01-01

The combination of capillary electrophoresis (CE) and electrospray ionization-mass spectrometry (ESI-MS) via a triaxial interface was studied as a potential means for the characterization of intact proteins. To evaluate the possibility to use a nonvolatile electrolyte for CE, the effect of sodium

Determination of iodine in oyster tissue by isotope dilution laser resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Fassett, J.D.; Murphy, T.J.

1990-01-01

The technique of laser resonance ionization mass spectrometry has been combined with isotope dilution analysis to determine iodine in oyster tissue. The long-lived radioisotope, 129I, was used to spike the samples. Samples were equilibrated with the 129I, wet ashed under controlled conditions, and iodine separated by coprecipitation with silver chloride. The analyte was dried as silver ammonium iodide upon a tantalum filament from which iodine was thermally desorbed in the resonance ionization mass spectrometry instrument. A single-color, two-photon resonant plus one-photon ionization scheme was used to form positive iodine ions. Long-lived iodine signals were achieved from 100 ng of iodine. The precision of 127I/129I measurement has been evaluated by replicate determinations of the spike, the spike calibration samples, and the oyster tissue samples and was 1.0%. Measurement precision among samples was 1.9% for the spike calibration and 1.4% for the oyster tissue. The concentration of iodine determined in SRM 1566a, Oyster Tissue, was 4.44 micrograms/g with an estimate of the overall uncertainty for the analysis of +/- 0.12 microgram/g

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.

Solar irradiance changes and photobiological effects at earth's surface following astrophysical ionizing radiation events.

Science.gov (United States)

Thomas, Brian C; Neale, Patrick J; Snyder, Brock R

2015-03-01

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the Tropospheric Ultraviolet and Visible (TUV) radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance but that relative estimates for increase in exposure to DNA-damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in very limited geographical areas; instead we found a net increase for most of the modeled time-space region. This result has implications for proposed climate changes associated with ionizing radiation events.

Mars Surface Ionizing Radiation Environment: Need for Validation

Science.gov (United States)

Wilson, J. W.; Kim, M. Y.; Clowdsley, M. S.; Heinbockel, J. H.; Tripathi, R. K.; Singleterry, R. C.; Shinn, J. L.; Suggs, R.

1999-01-01

Protection against the hazards from exposure to ionizing radiation remains an unresolved issue in the Human Exploration and Development of Space (HEDS) enterprise [1]. The major uncertainty is the lack of data on biological response to galactic cosmic ray (GCR) exposures but even a full understanding of the physical interaction of GCR with shielding and body tissues is not yet available and has a potentially large impact on mission costs. "The general opinion is that the initial flights should be short-stay missions performed as fast as possible (so-called 'Sprint' missions) to minimize crew exposure to the zero-g and space radiation environment, to ease requirements on system reliability, and to enhance the probability of mission success." The short-stay missions tend to have long transit times and may not be the best option due to the relatively long exposure to zero-g and ionizing radiation. On the other hand the short-transit missions tend to have long stays on the surface requiring an adequate knowledge of the surface radiation environment to estimate risks and to design shield configurations. Our knowledge of the surface environment is theoretically based and suffers from an incomplete understanding of the physical interactions of GCR with the Martian atmosphere, Martian surface, and intervening shield materials. An important component of Mars surface robotic exploration is the opportunity to test our understanding of the Mars surface environment. The Mars surface environment is generated by the interaction of Galactic Cosmic Rays (GCR) and Solar Particle Events (SPEs) with the Mars atmosphere and Mars surface materials. In these interactions, multiple charged ions are reduced in size and secondary particles are generated, including neutrons. Upon impact with the Martian surface, the character of the interactions changes as a result of the differing nuclear constituents of the surface materials. Among the surface environment are many neutrons diffusing from

On-chip electromembrane extraction for monitoring drug metabolism in real time by electrospray ionization mass spectrometry

DEFF Research Database (Denmark)

Petersen, Nickolaj J.; Pedersen, Jacob Sønderby; Poulsen, Nicklas Nørgård

2012-01-01

A temperature controlled (37 °C) metabolic reaction chamber with a volume of 1 mL was coupled directly to electrospray ionization mass spectrometry (ESI-MS) by the use of a 50 µm deep counter flow micro-chip electromembrane extraction (EME) system. The EME/ESI-MS system was used to study the in v......A temperature controlled (37 °C) metabolic reaction chamber with a volume of 1 mL was coupled directly to electrospray ionization mass spectrometry (ESI-MS) by the use of a 50 µm deep counter flow micro-chip electromembrane extraction (EME) system. The EME/ESI-MS system was used to study...

Simulation study of the ionizing front in the critical ionization velocity phenomenon

International Nuclear Information System (INIS)

Machida, S.; Goertz, C.K.; Lu, G.

1988-01-01

Simulations of the Critical Ionization Velocity (CIV) for a neutral gas cloud moving across the static magnetic field are made. We treat a low-β plasma and use a 2-1/2 D electrostatic code linked with our Plasma and Neutral Interaction Code (PANIC). Our study is focused on the understanding of the interface between the neutral gas cloud and the surrounding plasma where the strong interaction takes place. We assume the existence of some hot electrons in the ambient plasma to provide a seed ionization for CIV. When the ionization starts a sheath-like structure is formed at the surface of the neutral gas (Ionizing Front). In that region the crossfield component of the electric field causes the electron to E x B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. Thus the kinetic energy of the drifting electrons can be large enough for electron impact ionization. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the ionization front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating and additional ionization. The overall structure is studied by developing a simple analytic model as well as making simulation runs. (author)

Analysis of polycyclic aromatic hydrocarbons using desorption atmospheric pressure chemical ionization coupled to a portable mass spectrometer.

Science.gov (United States)

Jjunju, Fred P M; Maher, Simon; Li, Anyin; Badu-Tawiah, Abraham K; Taylor, Stephen; Cooks, R Graham

2015-02-01

Desorption atmospheric pressure chemical ionization (DAPCI) is implemented on a portable mass spectrometer and applied to the direct detection of polycyclic aromatic hydrocarbons (PAHs) and alkyl substituted benzenes. The presence of these compounds in the environment poses a significant threat to the health of both humans and wildlife because of their carcinogenic, toxic, and mutagenic properties. As such, instant detection outside of the laboratory is of particular importance to allow in-situ measurement at the source. Using a rapid, high throughput, miniature, handheld mass spectrometer, several alkyl substituted benzenes and PAHs (i.e., 1,2,3,5-tetramethylbenzene, pentamethylbenzene, hexamethylbenzene, fluoranthene, anthracene, benzo[k]fluoranthene, dibenz[a,h]anthracene, acenaphthene, indeno[1,2,3-c,d]pyrene, 9-ethylfluorene, and 1-benzyl-3-methyl-naphthalene) were identified and characterized using tandem mass spectrometry (MS/MS) from ambient surfaces, in the open air. This method can provide almost instantaneous information while minimizing sample preparation, which is advantageous in terms of both cost and simplicity of analysis. This MS-based technique is applicable to a wide range of environmental organic molecules.

Electrospray ionization tandem mass spectrometry of ammonium cationized polyethers.

Science.gov (United States)

Nasioudis, Andreas; Heeren, Ron M A; van Doormalen, Irene; de Wijs-Rot, Nicolette; van den Brink, Oscar F

2011-05-01

Quaternary ammonium salts (Quats) and amines are known to facilitate the MS analysis of high molar mass polyethers by forming low charge state adduct ions. The formation, stability, and behavior upon collision-induced dissociation (CID) of adduct ions of polyethers with a variety of Quats and amines were studied by electrospray ionization quadrupole time-of-flight, quadrupole ion trap, and linear ion trap tandem mass spectrometry (MS/MS). The linear ion trap instrument was part of an Orbitrap hybrid mass spectrometer that allowed accurate mass MS/MS measurements. The Quats and amines studied were of different degree of substitution, structure, and size. The stability of the adduct ions was related to the structure of the cation, especially the amine's degree of substitution. CID of singly/doubly charged primary and tertiary ammonium cationized polymers resulted in the neutral loss of the amine followed by fragmentation of the protonated product ions. The latter reveals information about the monomer unit, polymer sequence, and endgroup structure. In addition, the detection of product ions retaining the ammonium ion was observed. The predominant process in the CID of singly charged quaternary ammonium cationized polymers was cation detachment, whereas their doubly charged adduct ions provided the same information as the primary and tertiary ammonium cationized adduct ions. This study shows the potential of specific amines as tools for the structural elucidation of high molar mass polyethers. © American Society for Mass Spectrometry, 2011

Direct analyte-probed nanoextraction coupled to nanospray ionization-mass spectrometry of drug residues from latent fingerprints.

Science.gov (United States)

Clemons, Kristina; Wiley, Rachel; Waverka, Kristin; Fox, James; Dziekonski, Eric; Verbeck, Guido F

2013-07-01

Here, we present a method of extracting drug residues from fingerprints via Direct Analyte-Probed Nanoextraction coupled to nanospray ionization-mass spectrometry (DAPNe-NSI-MS). This instrumental technique provides higher selectivity and lower detection limits over current methods, greatly reducing sample preparation, and does not compromise the integrity of latent fingerprints. This coupled to Raman microscopy is an advantageous supplement for location and identification of trace particles. DAPNe uses a nanomanipulator for extraction and differing microscopies for localization of chemicals of interest. A capillary tip with solvent of choice is placed in a nanopositioner. The surface to be analyzed is placed under a microscope, and a particle of interest is located. Using a pressure injector, the solvent is injected onto the surface where it dissolves the analyte, and then extracted back into the capillary tip. The solution is then directly analyzed via NSI-MS. Analyses of caffeine, cocaine, crystal methamphetamine, and ecstasy have been performed successfully. © 2013 American Academy of Forensic Sciences.

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.

Non-polar lipids characterization of Quinoa (Chenopodium quinoa) seed by comprehensive two-dimensional gas chromatography with flame ionization/mass spectrometry detection and non-aqueous reversed-phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection.

Science.gov (United States)

Fanali, Chiara; Beccaria, Marco; Salivo, Simona; Tranchida, Peter; Tripodo, Giusy; Farnetti, Sara; Dugo, Laura; Dugo, Paola; Mondello, Luigi

2015-07-08

A chemical characterization of major lipid components, namely, triacylglycerols, fatty acids and the unsaponifiable fraction, in a Quinoa seed lipids sample is reported. To tackle such a task, non-aqueous reversed-phase high-performance liquid chromatography with mass spectrometry detection was employed. The latter was interfaced with atmospheric pressure chemical ionization for the analysis of triacylglycerols. The main triacylglycerols (>10%) were represented by OLP, OOL and OLL (P = palmitoyl, O = oleoyl, L = linoleoyl); the latter was present in the oil sample at the highest percentage (18.1%). Furthermore, fatty acid methyl esters were evaluated by gas chromatography with flame ionization detection. 89% of the total fatty acids was represented by unsaturated fatty acid methyl esters with the greatest percentage represented by linoleic and oleic acids accounting for approximately 48 and 28%, respectively. An extensive characterization of the unsaponifiable fraction of Quinoa seed lipids was performed for the first time, by using comprehensive two-dimensional gas chromatography with dual mass spectrometry/flame ionization detection. Overall, 66 compounds of the unsaponifiable fraction were tentatively identified, many constituents of which (particularly sterols) were confirmed by using gas chromatography with high-resolution time-of-flight mass spectrometry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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,

UV Ionizer for Neutral Wind Mass Spectrometers

Data.gov (United States)

National Aeronautics and Space Administration — Current neutral particle instrumentation relies on hot cathode filaments or an electron gun for ionizing the target medium.  These ionization sources represent a...

Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

International Nuclear Information System (INIS)

Young, J.P.; Shaw, R.W.

1995-01-01

A diode-laser step has been incorporated into a resonance-ionization mass spectrometry optical excitation process to enhance the isotopic selectivity of the technique. Lanthanum isotope ratio enhancements as high as 10 3 were achieved by use of a single-frequency cw diode laser tuned to excite the first step of a three-step excitation--ionization optical process; the subsequent steps were excited by use of a pulsed dye laser. Applying the same optical technique, we measured atomic hyperfine constants for the high-lying even-parity 4 D 5/2 state of lanthanum at 30 354 cm --1 . The general utility of this spectral approach is discussed

Quantitation of peptides and proteins by matrix-assisted laser desorption/ionization mass spectrometry using (18)O-labeled internal standards

DEFF Research Database (Denmark)

Mirgorodskaya, O A; Kozmin, Y P; Titov, M I

2000-01-01

A method for quantitating proteins and peptides in the low picomole and sub-picomole range has been developed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with internal (18)O-labeled standards. A simple procedure is proposed to produce such internal standards for...... inhibitor, were quantified by MALDI-time-of-flight (TOF) mass spectrometry.......A method for quantitating proteins and peptides in the low picomole and sub-picomole range has been developed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with internal (18)O-labeled standards. A simple procedure is proposed to produce such internal standards...

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

Dark Matter Detection Using Helium Evaporation and Field Ionization.

Science.gov (United States)

Maris, Humphrey J; Seidel, George M; Stein, Derek

2017-11-03

We describe a method for dark matter detection based on the evaporation of helium atoms from a cold surface and their subsequent detection using field ionization. When a dark matter particle scatters off a nucleus of the target material, elementary excitations (phonons or rotons) are produced. Excitations which have an energy greater than the binding energy of helium to the surface can result in the evaporation of helium atoms. We propose to detect these atoms by ionizing them in a strong electric field. Because the binding energy of helium to surfaces can be below 1 meV, this detection scheme opens up new possibilities for the detection of dark matter particles in a mass range down to 1  MeV/c^{2}.

Dark Matter Detection Using Helium Evaporation and Field Ionization

Science.gov (United States)

Maris, Humphrey J.; Seidel, George M.; Stein, Derek

2017-11-01

We describe a method for dark matter detection based on the evaporation of helium atoms from a cold surface and their subsequent detection using field ionization. When a dark matter particle scatters off a nucleus of the target material, elementary excitations (phonons or rotons) are produced. Excitations which have an energy greater than the binding energy of helium to the surface can result in the evaporation of helium atoms. We propose to detect these atoms by ionizing them in a strong electric field. Because the binding energy of helium to surfaces can be below 1 meV, this detection scheme opens up new possibilities for the detection of dark matter particles in a mass range down to 1 MeV /c2 .

Comprehensive biothreat cluster identification by PCR/electrospray-ionization mass spectrometry.

Directory of Open Access Journals (Sweden)

Rangarajan Sampath

Full Text Available Technology for comprehensive identification of biothreats in environmental and clinical specimens is needed to protect citizens in the case of a biological attack. This is a challenge because there are dozens of bacterial and viral species that might be used in a biological attack and many have closely related near-neighbor organisms that are harmless. The biothreat agent, along with its near neighbors, can be thought of as a biothreat cluster or a biocluster for short. The ability to comprehensively detect the important biothreat clusters with resolution sufficient to distinguish the near neighbors with an extremely low false positive rate is required. A technological solution to this problem can be achieved by coupling biothreat group-specific PCR with electrospray ionization mass spectrometry (PCR/ESI-MS. The biothreat assay described here detects ten bacterial and four viral biothreat clusters on the NIAID priority pathogen and HHS/USDA select agent lists. Detection of each of the biothreat clusters was validated by analysis of a broad collection of biothreat organisms and near neighbors prepared by spiking biothreat nucleic acids into nucleic acids extracted from filtered environmental air. Analytical experiments were carried out to determine breadth of coverage, limits of detection, linearity, sensitivity, and specificity. Further, the assay breadth was demonstrated by testing a diverse collection of organisms from each biothreat cluster. The biothreat assay as configured was able to detect all the target organism clusters and did not misidentify any of the near-neighbor organisms as threats. Coupling biothreat cluster-specific PCR to electrospray ionization mass spectrometry simultaneously provides the breadth of coverage, discrimination of near neighbors, and an extremely low false positive rate due to the requirement that an amplicon with a precise base composition of a biothreat agent be detected by mass spectrometry.

Rapid screening of basic colorants in processed vegetables through mass spectrometry using an interchangeable thermal desorption electrospray ionization source.

Science.gov (United States)

Chao, Yu-Ying; Chen, Yen-Ling; Lin, Hong-Yi; Huang, Yeou-Lih

2018-06-20

Thermal desorption electrospray ionization/mass spectrometry (TD-ESI-MS) employing a quickly interchangeable ionization source is a relatively new ambient ionization mass spectrometric technique that has had, to date, only a limited number of applications related to food safety control. With reallocation of resources, this direct-analysis technique has had wider use in food analysis when operated in dual-working mode (pretreatment-free qualitative screening and conventional quantitative confirmation) after switching to an ambient ionization source from a traditional atmospheric pressure ionization source. Herein, we describe the benefits and challenges associated with the use of a TD-ESI source to detect adulterants in processed vegetables (PVs), as a proof-of-concept for the detection of basic colorants. While TD-ESI can offer direct qualitative screening analyses for PVs with detection capabilities lower than those provided with liquid chromatography/UV detection within 30 s, the use of TD-ESI for semi-quantification is applicable only for homogeneous food matrices. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterization of typical chemical background interferences in atmospheric pressure ionization liquid chromatography-mass spectrometry

NARCIS (Netherlands)

Guo, Xinghua; Bruins, Andries P.; Covey, Thomas R.

2006-01-01

The structures and origins of typical chemical background noise ions in positive atmospheric pressure ionization liquid chromatography/mass spectrometry (API LC/MS) are investigated and summarized in this study. This was done by classifying chemical background ions using precursor and product ion

Desorption electrospray ionization mass spectrometry in the analysis of chemical food contaminants in food

NARCIS (Netherlands)

Nielen, M.W.F.; Hooijerink, H.; Zomer, P.; Mol, J.G.J.

2011-01-01

Since its introduction, desorption electrospray ionization (DESI) mass spectrometry (MS) has been mainly applied in pharmaceutical and forensic analysis. We expect that DESI will find its way in many different fields, including food analysis. In this review, we summarize DESI developments aimed at

Development of a surface ionization source for the production of radioactive alkali ion beams in SPIRAL

International Nuclear Information System (INIS)

Eleon, C.; Jardin, P.; Gaubert, G.; Saint-Laurent, M.-G.; Alcantara-Nunez, J.; Alves Conde, R.; Barue, C.; Boilley, D.; Cornell, J.; Delahaye, P.; Dubois, M.; Jacquot, B.; Leherissier, P.; Leroy, R.; Lhersonneau, G.; Marie-Jeanne, M.; Maunoury, L.; Pacquet, J.Y.; Pellemoine, F.; Pierret, C.

2008-01-01

In the framework of the production of radioactive alkali ion beams by the isotope separation on-line (ISOL) method in SPIRAL I, a surface ionization source has been developed at GANIL to produce singly-charged ions of Li, Na and K. This new source has been designed to work in the hostile environment whilst having a long lifetime. This new system of production has two ohmic heating components: the first for the target oven and the second for the ionizer. The latter, being in carbon, offers high reliability and competitive ionization efficiency. This surface ionization source has been tested on-line using a 48 Ca primary beam at 60.3 A MeV with an intensity of 0.14 pA. The ionization efficiencies obtained for Li, Na and K are significantly better than the theoretical values of the ionization probability per contact. The enhanced efficiency, due to the polarization of the ionizer, is shown to be very important also for short-lived isotopes. In the future, this source will be associated with the multicharged electron-cyclotron-resonance (ECR) ion source NANOGAN III for production of multicharged alkali ions in SPIRAL. The preliminary tests of the set up are also presented in this contribution.

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.

Ion optics of a new time-of-flight mass spectrometer for quantitative surface analysis

International Nuclear Information System (INIS)

Veryovkin, Igor V.; Calaway, Wallis F.; Pellin, Michael J.

2004-01-01

A new time-of-flight instrument for quantitative surface analysis was developed and constructed at Argonne National Laboratory. It implements ion sputtering and laser desorption for probing analyzed samples and can operate in regimes of secondary neutral mass spectrometry with laser post-ionization and secondary ion mass spectrometry. The instrument incorporates two new ion optics developments: (1) 'push-pull' front end ion optics and (2) focusing and deflecting lens. Implementing these novel elements significantly enhance analytical capabilities of the instrument. Extensive three-dimensional computer simulations of the instrument were conducted in SIMION 3D (c) to perfect its ion optics. The operating principles of the new ion optical systems are described, and a scheme of the new instrument is outlined together with its operating modes

High precision analysis of trace lithium isotope by thermal ionization mass spectrometry

International Nuclear Information System (INIS)

Tang Lei; Liu Xuemei; Long Kaiming; Liu Zhao; Yang Tianli

2010-01-01

High precision analysis method of ng lithium by thermal ionization mass spectrometry is developed. By double-filament measurement,phosphine acid ion enhancer and sample pre-baking technique,the precision of trace lithium analysis is improved. For 100 ng lithium isotope standard sample, relative standard deviation is better than 0.086%; for 10 ng lithium isotope standard sample, relative standard deviation is better than 0.90%. (authors)

The Cryogenic Dark Matter Search: First 5-Tower Data and Improved Understanding of Ionization Collection

Energy Technology Data Exchange (ETDEWEB)

Bailey, Catherine N. [Case Western Reserve Univ., Cleveland, OH (United States)

2010-01-01

The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic particle detectors. These detectors have the ability to discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS-II experiment has completed analysis of the first data runs with 30 semiconductor detectors at the Soudan Underground Laboratory, resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c². As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events. Incomplete ionization collection results in the largest background in the CDMS detectors as this causes electron recoil background interactions to appear as false candidate events. Two primary causes of incomplete ionization collection are surface and bulk trapping. Recent work has been focused on reducing surface trapping through the modification of fabrication methods for future detectors. Analyzing data taken with test devices has shown that hydrogen passivation of the amorphous silicon blocking layer worsens surface trapping. Additional data has shown that the iron-ion implantation used to lower the critical temperature of the tungsten transition-edge sensors causes a degradation of the ionization collection. Using selective implantation on future detectors may improve ionization collection for events near the phonon side detector surface. Bulk trapping is minimized by neutralizing ionized lattice impurities. Detector investigations at testing facilities and in situ at the experimental site have provided methods to optimize the neutralization process and monitor running conditions to maintain full ionization collection. This work details my contribution to the 5-tower data taking, monitoring, and analysis effort as

In Situ Analysis of Bacterial Lipopeptide Antibiotics by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Science.gov (United States)

Debois, Delphine; Ongena, Marc; Cawoy, Hélène; De Pauw, Edwin

2016-01-01

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) is a technique developed in the late 1990s enabling the two-dimensional mapping of a broad variety of biomolecules present at the surface of a sample. In many applications including pharmaceutical studies or biomarker discovery, the distribution of proteins, lipids or drugs, and metabolites may be visualized within tissue sections. More recently, MALDI MSI has become increasingly applied in microbiology where the versatility of the technique is perfectly suited to monitor the metabolic dynamics of bacterial colonies. The work described here is focused on the application of MALDI MSI to map secondary metabolites produced by Bacilli, especially lipopeptides, produced by bacterial cells during their interaction with their environment (bacteria, fungi, plant roots, etc.). This chapter addresses the advantages and challenges that the implementation of MALDI MSI to microbiological samples entails, including detailed protocols on sample preparation (from both microbiologist and mass spectrometrist points of view), matrix deposition, and data acquisition and interpretation. Lipopeptide images recorded from confrontation plates are also presented.

Perfume fingerprinting by easy ambient sonic-spray ionization mass spectrometry: nearly instantaneous typification and counterfeit detection.

Science.gov (United States)

Haddad, Renato; Catharino, Rodrigo Ramos; Marques, Lygia Azevedo; Eberlin, Marcos Nogueira

2008-11-01

Perfume counterfeiting is an illegal worldwide practice that involves huge economic losses and potential consumer risk. EASI is a simple, easily performed and rapidly implemented desorption/ionization technique for ambient mass spectrometry (MS). Herein we demonstrate that EASI-MS allows nearly instantaneous perfume typification and counterfeit detection. Samples are simply sprayed onto a glass rod or paper surface and, after a few seconds of ambient drying, a profile of the most polar components of the perfume is acquired. These components provide unique and reproducible chemical signatures for authentic perfume samples. Counterfeiting is readily recognized since the exact set and relative proportions of the more polar chemicals, sometimes at low concentrations, are unknown or hard to reproduce by the counterfeiters and hence very distinct and variable EASI-MS profiles are observed for the counterfeit samples.

Development of resonance ionization spectroscopy system for fusion material surface analysis

Energy Technology Data Exchange (ETDEWEB)

Iguchi, Tetsuo [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.; Satoh, Yasushi; Nakazawa, Masaharu

1996-10-01

A Resonance Ionization Spectroscopy (RIS) system is now under development aiming at in-situ observation and analysis neutral particles emitted from fusion material surfaces under irradiation of charged particles and neutrons. The basic performance of the RIS system was checked through a preliminary experiment on Xe atom detection. (author)

Determination of the fine structure in the ionization plots obtained from a mass spectrometer with a large energy dispersion

International Nuclear Information System (INIS)

Deruaz, Daniel.

1974-01-01

The precise determination of ionization potentials, fragment ion appearance potentials and different excited state levels of the positive ions formed, together with phenomena due to an electron impact, were studied from ionization efficiency curves obtained by mass spectrometry. A standard ion source and an analytical method of electron energy dispersion reduction were used to study fine structures of ionization efficiency curves. Since the mass spectrometer was not adapted for the acquisition of ionization efficiency curve data an electronic system was designed to record these curves automatically. A precise stepwise potential variation of 45+-0.04mV was obtained, and for each step an intensity proportional to the number of ions created by the fragment considered, the additional gain being 4.4 and the linearity greater than 1% over a 13-volt region. Before each set of measurements the scattering was determined by calculation of the second derivative of a logistic function deduced from the cubic regression of the experimental helium function ionization efficiency curve values. The precision, given by the variance analysis SNEDECOR F test, is higher than 1/1000. For each series of recordings the numerical values were processed by a computer to raise by twenty the signal to noise ratio and calculate the ionization efficiency curve values by the energy difference method and the iterative unfolding method. In this way a high sensitivity was obtained for the determination of the curves near the ionization threshold, and a precision below 50MeV (at least equivalent to that given by ionization cells with quasi-monoenergetic electron beams) for the values of the ionization potentials, the appearance potentials and the excited state energy levels. In order to judge the reliability of the technique the ionization potentials of a set of eleven complex molecules were determined and compared with the results obtained by photoionization and photoelectron spectrometry [fr

Application of silicon nanowires and indium tin oxide surfaces in desorption electrospray ionization

Czech Academy of Sciences Publication Activity Database

Pól, Jaroslav; Novák, Petr; Volný, Michael; Kruppa, G. H.; Kostiainen, R.; Lemr, Karel; Havlíček, Vladimír

2008-01-01

Roč. 14, č. 6 (2008), s. 391-399 ISSN 1469-0667 R&D Projects: GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50200510 Keywords : mass spectrometry * desorption electrospray ionization * nanowires Subject RIV: CE - Biochemistry Impact factor: 1.167, year: 2008

A Versatile Integrated Ambient Ionization Source Platform

Science.gov (United States)

Ai, Wanpeng; Nie, Honggang; Song, Shiyao; Liu, Xiaoyun; Bai, Yu; Liu, Huwei

2018-04-01

The pursuit of high-throughput sample analysis from complex matrix demands development of multiple ionization techniques with complementary specialties. A versatile integrated ambient ionization source (iAmIS) platform is proposed in this work, based on the idea of integrating multiple functions, enhancing the efficiency of current ionization techniques, extending the applications, and decreasing the cost of the instrument. The design of the iAmIS platform combines flowing atmospheric pressure afterglow (FAPA) source/direct analysis in real time (DART), dielectric barrier discharge ionization (DBDI)/low-temperature plasma (LTP), desorption electrospray ionization (DESI), and laser desorption (LD) technique. All individual and combined ionization modes can be easily attained by modulating parameters. In particular, the FAPA/DART&DESI mode can realize the detection of polar and nonpolar compounds at the same time with two different ionization mechanisms: proton transfer and charge transfer. The introduction of LD contributes to the mass spectrometry imaging and the surface-assisted laser desorption (SALDI) under ambient condition. Compared with other individual or multi-mode ion source, the iAmIS platform provides the flexibility of choosing different ionization modes, broadens the scope of the analyte detection, and facilitates the analysis of complex samples. [Figure not available: see fulltext.

Single-Photon Ionization Soft-X-Ray Laser Mass Spectrometry of Potential Hydrogen Storage Materials

Science.gov (United States)

Dong, F.; Bernstein, E. R.; Rocca, J. J.

A desk-top size capillary discharge 46.9 nm lasear is applied in the gas phase study of nanoclusters. The high photon energy allows for single-photon ionization mass spectrometry with reduced cluster fragmentation. In the present studies, neutral Al m C n and Al m C n H x cluster are investigation for the first time. Single photon ionization through 46.9 nm, 118 nm, 193 nm lasers is used to detect neutral cluster distributions through time of flight mass spectrometry. Al m C n clusters are generated through laser ablation of a mixture of Al and C powders pressed into a disk. An oscillation of the vertical ionization energies (VIEs) of Al m C n clusters is observed in the experiments. The VIEs of Al m C n clusters changes as a function of the numbers of Al and C atoms in the clusters. Al m C n H x clusters are generated through an Al ablation plasma-hydrocarbon reaction, an Al-C ablation plasma reacting with H2 gas, or through cold Al m C n clusters reacting with H2 gas in a fast flow reactor. DFT and ab inito calculations are carried out to explore the structures, IEs, and electronic structures of Al m C n H x clusters. C=C bonds are favored for the lowest energy structures for Al m C n clusters. Be m C n H x are generated through a beryllium ablation plasma-hydrocarbon reaction and detected by single photon ionization of 193 nm laser. Both Al m C n H x and Be m C n H x are considered as potential hydrogen storage materials.

The updated bottom up solution applied to atmospheric pressure photoionization and electrospray ionization mass spectrometry

Science.gov (United States)

The Updated Bottom Up Solution (UBUS) was recently applied to atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of triacylglycerols (TAGs). This report demonstrates that the UBUS applies equally well to atmospheric pressure photoionization (APPI) MS and to electrospray ionizatio...

Comparison of the properties polyamide 6.6 surfaces treated by plasma and by ionizing radiation

International Nuclear Information System (INIS)

Irineu, Rosa Maria da Silva

2010-01-01

This study aims to compare the surface properties of polyamide 6.6 plasma treatment and ionizing radiation, as well as determine the best technique and condition of the surface activation, adhesion of the same order and polyacrylic rubber used in manufacturing of automotive retainers. Treatment of polyamide 6.6 plasma was performed using an equipment 'Electronic Diener - Plasma - Surface-Technology LFG40' with nitrogen gas at a pressure of 1.40 kg/cm 2 . Samples of polyamide 6.6 were also treated with ionizing radiation, atmospheric pressure and in vacuum, using an industrial electron accelerator, Dynamitron JOB 188 with radiation dose of 5, 10, 20, 40, 50, 100, 200, 300, 400 and 500kGy with a dose rate of 11.22 kGy/s for all doses and rate of 11.22 kGy/s and 22.38 kGy/s for a dose of 20kGy. After the processes of surface modification of polyamide 6.6, part of the untreated samples, treated by plasma and by ionizing radiation were incorporated into the polyacrylic rubber, and another part was designed to characterize the surface using the techniques of SEM / EDS, FT- IR, PIXE / RBS, AFM and contact angle. Untreated samples and the irradiated samples did not join the polyacrylic rubber. The samples treated by plasma joined the polyacrylic rubber efficiently and showed differences in roughness in SEM and AFM, and an increase in contact angle when compared with untreated samples. The irradiated samples showed no significant differences in the analysis of properties used in this study when compared with untreated samples. Ionizing radiation was not effective in surface modification of polyamide 6.6 for adherence with polyacrylic rubber. (author)

Laser desorption ionization mass spectrometry: Recent progress in matrix-free and label-assisted techniques.

Science.gov (United States)

Mandal, Arundhoti; Singha, Monisha; Addy, Partha Sarathi; Basak, Amit

2017-10-13

The MALDI-based mass spectrometry, over the last three decades, has become an important analytical tool. It is a gentle ionization technique, usually applicable to detect and characterize analytes with high molecular weights like proteins and other macromolecules. The earlier difficulty of detection of analytes with low molecular weights like small organic molecules and metal ion complexes with this technique arose due to the cluster of peaks in the low molecular weight region generated from the matrix. To detect such molecules and metal ion complexes, a four-prong strategy has been developed. These include use of alternate matrix materials, employment of new surface materials that require no matrix, use of metabolites that directly absorb the laser light, and the laser-absorbing label-assisted LDI-MS (popularly known as LALDI-MS). This review will highlight the developments with all these strategies with a special emphasis on LALDI-MS. © 2017 Wiley Periodicals, Inc.

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.

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

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).

High-resolution, three-step resonance ionization mass spectrometry of gadolinium

International Nuclear Information System (INIS)

Blaum, K.; Wendt, K.; Bushaw, B.A.; Noertershaeuser, W.

2001-01-01

High-resolution resonance ionization mass spectrometry has been used to measure triple-resonance autoionization (AI) spectra of gadolinium. Al resonances as narrow as 10 MHz have been observed and isotope shifts and hyperfine structure have been measured in selected AI states. The strongest AI state observed at 49663.576 cm-1 with a photoionization cross section of >3.6x10 -15 cm 2 was found to have an overall detection efficiency of >3x10 -5 , allowing application to a number of ultratrace determination problems. Analytical measurements with a diode-laser-based system have been successfully performed on bio-medical tissue samples

Small sample analysis using sputter atomization/resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Christie, W.H.; Goeringer, D.E.

1986-01-01

We have used secondary ion mass spectrometry (SIMS) to investigate the emission of ions via argon sputtering from U metal, UO 2 , and U 3 O 8 samples. We have also used laser resonance ionization techniques to study argon-sputtered neutral atoms and molecules emitted from these same samples. For the case of U metal, a significant enhancement in detection sensitivity for U is obtained via SA/RIMS. For U in the fully oxidized form (U 3 O 8 ), SA/RIMS offers no improvement in U detection sensitivity over conventional SIMS when sputtering with argon. 9 refs., 1 fig., 2 tabs

Enzyme-coupled nanoparticles-assisted laser desorption ionization mass spectrometry for searching for low-mass inhibitors of enzymes in complex mixtures.

Science.gov (United States)

Salwiński, Aleksander; Da Silva, David; Delépée, Raphaël; Maunit, Benoît

2014-04-01

In this report, enzyme-coupled magnetic nanoparticles (EMPs) were shown to be an effective affinity-based tool for finding specific interactions between enzymatic targets and the low-mass molecules in complex mixtures using classic MALDI-TOF apparatus. EMPs used in this work act as nonorganic matrix enabling ionization of small molecules without any interference in the low-mass range (enzyme-coupled nanoparticles-assisted laser desorption ionization MS, ENALDI MS) and simultaneously carry the superficial specific binding sites to capture inhibitors present in a studied mixture. We evaluated ENALDI approach in two complementary variations: 'ion fading' (IF-ENALDI), based on superficial adsorption of inhibitors and 'ion hunting' (IH-ENALDI), based on selective pre-concentration of inhibitors. IF-ENALDI was applied for two sets of enzyme-inhibitor pairs: tyrosinase-glabridin and trypsin-leupeptin and for the real plant sample: Sparrmannia discolor leaf and stem methanol extract. The efficacy of IH-ENALDI was shown for the pair of trypsin-leupeptin. Both ENALDI approaches pose an alternative for bioassay-guided fractionation, the common method for finding inhibitors in the complex mixtures.

Surface-ionization ion source designed for in-beam operation with the BEMS-2 isotope separator

International Nuclear Information System (INIS)

Bogdanov, D.D.; Voboril, J.; Demyanov, A.V.; Karnaukhov, V.A.; Petrov, L.A.

1976-01-01

A surface-ionization ion source designed to operate in combination with the BEMS-2 isotope separator in a heavy ion beam is described. The ion source is adjusted for the separation of rare-earth elements. The separation efficiency for 150 Dy is determined to be equal to about 20% at the ionizer temperature of 2600 deg K. The hold-up times for praseodymium, promethium and dysprosium in the ion source range from 5 to 10 sec at the ionizer temperature of 2500-2700 deg K

Mass measurements of neutron-rich strontium and rubidium isotopes in the region $A \\approx 100$ and development of an electrospray ionization ion source

CERN Document Server

de Roubin, Antoine

An extension of the atomic mass surface in the region $A \\approx 100$ is performed via mass measurements of the $^{100−102}$Sr and $^{100−102}$Rb isotopes with the ion-trap mass spectrometer ISOLTRAP at CERN-ISOLDE. The first direct mass measurements of $^{102}$Sr and $^{101,102}$Rb are reported here. These measurements confirm the continuation of the region of nuclear deformation with the increase of neutron number, at least as far as $N = 65$. In order to interpret the deformation in the strontium isotopic chain and to determine whether an onset of deformation is present in heavier krypton isotopes, a comparison is made between experimental values and theoretical calculations available in the literature. To complete this comparison, Hartree-Fock-Bogoliubov calculations for even and odd isotopes are also presented, illustrating the competition of nuclear shapes in the region. The development of an electrospray ionization ion source is presented. This source can deliver a large range of isobaric masses ...

Quantitative Profiling of Major Neutral Lipid Classes in Human Meibum by Direct Infusion Electrospray Ionization Mass Spectrometry

Science.gov (United States)

Chen, Jianzhong; Green, Kari B.; Nichols, Kelly K.

2013-01-01

Purpose. The purpose of this investigation was to better understand lipid composition in human meibum. Methods. Intact lipids in meibum samples were detected by direct infusion electrospray ionization mass spectrometry (ESI-MS) analysis in positive detection mode using sodium iodide (NaI) as an additive. The peak intensities of all major types of lipid species, that is, wax esters (WEs), cholesteryl esters (CEs), and diesters (DEs) were corrected for peak overlapping and isotopic distribution; an additional ionization efficiency correction was performed for WEs and CEs, which was simplified by the observation that the corresponding ionization efficiency was primarily dependent on the specific lipid class and saturation degree of the lipids while independent of the carbon chain length. A set of WE and CE standards was spiked in meibum samples for ionization efficiency determination and absolute quantitation. Results. The absolute amount (μmol/mg) for each of 51 WEs and 31 CEs in meibum samples was determined. The summed masses for 51 WEs and 31 CEs accounted for 48 ± 4% and 40 ± 2%, respectively, of the total meibum lipids. The mass percentages of saturated and unsaturated species were determined to be 75 ± 2% and 25 ± 1% for CEs and 14 ± 1% and 86 ± 1% for WEs. The profiles for two types of DEs were also obtained, which include 42 α,ω Type II DEs, and 21 ω Type I-St DEs. Conclusions. Major neutral lipid classes in meibum samples were quantitatively profiled by ESI-MS analysis with NaI additive. PMID:23847307

Gas-phase copper and silver complexes with phosphorothioate and phosphorodithioate pesticides investigated using electrospray ionization mass spectrometry.

Science.gov (United States)

Mustapha, Adetayo M; Pasilis, Sofie P

2015-01-01

Efforts to improve agricultural productivity have led to a growing dependency on organophosphorus pesticides. Phosphorothioate and phosphorodithioate pesticides are organophosphorus pesticide subclasses with widespread application for the control of insects feeding on vegetables and fruits. However, even low doses of these pesticides can cause neurological problems in humans; thus, their determination and monitoring in agricultural foodstuffs is important for human health. Phosphorothioate and phosphorodithioate pesticides may be poorly ionized during electrospray, adversely affecting limits of detection. These pesticides can form complexes with Cu(2+) and Ag(+) , however, potentially improving ionization. In the present work, we used electrospray ionization/mass spectrometry (ESI/MS) to study fenitrothion, parathion, diazinon, and malathion coordination complexes with silver and copper ions. Stable 1 : 1 and 1 : 2 metal/pesticide complexes were detected. Mass spectra acquired from pesticide solutions containing Ag(+) or Cu(2+) showed a significant increase in signal-to-background ratio over those acquired from solutions containing only the pesticides, with Ag(+) improving detection more effectively than Cu(2+). Addition of Ag(+) to a pesticide solution improved the limit of detection by ten times. The relative affinity of each pesticide for Ag(+) was related to complex stability, following the order diazinon > malathion > fenitrothion > parathion. The formation of Ag(+)-pesticide complexes can significantly improve the detection of phosphorothioate and phosphorodithioate pesticides using ESI/MS. The technique could potentially be used in reactive desorption electrospray ionization/mass spectrometry to detect phosphorothioate and phosphorodithioate pesticides on fruit and vegetable skins. Copyright © 2015 John Wiley & Sons, Ltd.

Alkali suppression within laser ion-source cavities and time structure of the laser ionized ion-bunches

CERN Document Server

Lettry, Jacques; Köster, U; Georg, U; Jonsson, O; Marzari, S; Fedosseev, V

2003-01-01

The chemical selectivity of the target and ion-source production system is an asset for Radioactive Ion-Beam (RIB) facilities equipped with mass separators. Ionization via laser induced multiple resonant steps Ionization has such selectivity. However, the selectivity of the ISOLDE Resonant Ionization Laser Ion-Source (RILIS), where ionization takes place within high temperature refractory metal cavities, suffers from unwanted surface ionization of low ionization potential alkalis. In order to reduce this type of isobaric contaminant, surface ionization within the target vessel was used. On-line measurements of the efficiency of this method is reported, suppression factors of alkalis up to an order of magnitude were measured as a function of their ionization potential. The time distribution of the ion bunches produced with the RILIS was measured for a variety of elements and high temperature cavity materials. While all ions are produced within a few nanoseconds, the ion bunch sometimes spreads over more than 1...

Ab initio dynamics and photoionization mass spectrometry reveal ion-molecule pathways from ionized acetylene clusters to benzene cation.

Science.gov (United States)

Stein, Tamar; Bandyopadhyay, Biswajit; Troy, Tyler P; Fang, Yigang; Kostko, Oleg; Ahmed, Musahid; Head-Gordon, Martin

2017-05-23

The growth mechanism of hydrocarbons in ionizing environments, such as the interstellar medium (ISM), and some combustion conditions remains incompletely understood. Ab initio molecular dynamics (AIMD) simulations and molecular beam vacuum-UV (VUV) photoionization mass spectrometry experiments were performed to understand the ion-molecule growth mechanism of small acetylene clusters (up to hexamers). A dramatic dependence of product distribution on the ionization conditions is demonstrated experimentally and understood from simulations. The products change from reactive fragmentation products in a higher temperature, higher density gas regime toward a very cold collision-free cluster regime that is dominated by products whose empirical formula is (C 2 H 2 ) n + , just like ionized acetylene clusters. The fragmentation products result from reactive ion-molecule collisions in a comparatively higher pressure and temperature regime followed by unimolecular decomposition. The isolated ionized clusters display rich dynamics that contain bonded C 4 H 4 + and C 6 H 6 + structures solvated with one or more neutral acetylene molecules. Such species contain large amounts (>2 eV) of excess internal energy. The role of the solvent acetylene molecules is to affect the barrier crossing dynamics in the potential energy surface (PES) between (C 2 H 2 ) n + isomers and provide evaporative cooling to dissipate the excess internal energy and stabilize products including the aromatic ring of the benzene cation. Formation of the benzene cation is demonstrated in AIMD simulations of acetylene clusters with n > 3, as well as other metastable C 6 H 6 + isomers. These results suggest a path for aromatic ring formation in cold acetylene-rich environments such as parts of the ISM.

Ab initio dynamics and photoionization mass spectrometry reveal ion–molecule pathways from ionized acetylene clusters to benzene cation

Science.gov (United States)

Stein, Tamar; Bandyopadhyay, Biswajit; Troy, Tyler P.; Fang, Yigang; Kostko, Oleg

2017-01-01

The growth mechanism of hydrocarbons in ionizing environments, such as the interstellar medium (ISM), and some combustion conditions remains incompletely understood. Ab initio molecular dynamics (AIMD) simulations and molecular beam vacuum-UV (VUV) photoionization mass spectrometry experiments were performed to understand the ion–molecule growth mechanism of small acetylene clusters (up to hexamers). A dramatic dependence of product distribution on the ionization conditions is demonstrated experimentally and understood from simulations. The products change from reactive fragmentation products in a higher temperature, higher density gas regime toward a very cold collision-free cluster regime that is dominated by products whose empirical formula is (C2H2)n+, just like ionized acetylene clusters. The fragmentation products result from reactive ion–molecule collisions in a comparatively higher pressure and temperature regime followed by unimolecular decomposition. The isolated ionized clusters display rich dynamics that contain bonded C4H4+ and C6H6+ structures solvated with one or more neutral acetylene molecules. Such species contain large amounts (>2 eV) of excess internal energy. The role of the solvent acetylene molecules is to affect the barrier crossing dynamics in the potential energy surface (PES) between (C2H2)n+ isomers and provide evaporative cooling to dissipate the excess internal energy and stabilize products including the aromatic ring of the benzene cation. Formation of the benzene cation is demonstrated in AIMD simulations of acetylene clusters with n > 3, as well as other metastable C6H6+ isomers. These results suggest a path for aromatic ring formation in cold acetylene-rich environments such as parts of the ISM. PMID:28484019

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.

Computerized study of several electrostatic, surface-ionization ion-source configurations

Energy Technology Data Exchange (ETDEWEB)

Balestrini, S.J.; Schuster, B.G.

1984-08-01

A computer-based method is presented whereby the optics of electrostatic, surface-ionization ion-source designs can be analyzed theoretically. The analysis solves for the luminosity and disperstion of a beam of charged particles at the final collimating slit and at locations preceding the slit. The performance of an ion source tested in 1960 and also some newer optical configurations are compared with theory.

Fully Automated Laser Ablation Liquid Capture Sample Analysis using NanoElectrospray Ionization Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Lorenz, Matthias [ORNL; Ovchinnikova, Olga S [ORNL; Van Berkel, Gary J [ORNL

2014-01-01

RATIONALE: Laser ablation provides for the possibility of sampling a large variety of surfaces with high spatial resolution. This type of sampling when employed in conjunction with liquid capture followed by nanoelectrospray ionization provides the opportunity for sensitive and prolonged interrogation of samples by mass spectrometry as well as the ability to analyze surfaces not amenable to direct liquid extraction. METHODS: A fully automated, reflection geometry, laser ablation liquid capture spot sampling system was achieved by incorporating appropriate laser fiber optics and a focusing lens into a commercially available, liquid extraction surface analysis (LESA ) ready Advion TriVersa NanoMate system. RESULTS: Under optimized conditions about 10% of laser ablated material could be captured in a droplet positioned vertically over the ablation region using the NanoMate robot controlled pipette. The sampling spot size area with this laser ablation liquid capture surface analysis (LA/LCSA) mode of operation (typically about 120 m x 160 m) was approximately 50 times smaller than that achievable by direct liquid extraction using LESA (ca. 1 mm diameter liquid extraction spot). The set-up was successfully applied for the analysis of ink on glass and paper as well as the endogenous components in Alstroemeria Yellow King flower petals. In a second mode of operation with a comparable sampling spot size, termed laser ablation/LESA , the laser system was used to drill through, penetrate, or otherwise expose material beneath a solvent resistant surface. Once drilled, LESA was effective in sampling soluble material exposed at that location on the surface. CONCLUSIONS: Incorporating the capability for different laser ablation liquid capture spot sampling modes of operation into a LESA ready Advion TriVersa NanoMate enhanced the spot sampling spatial resolution of this device and broadened the surface types amenable to analysis to include absorbent and solvent resistant

Chemical vapor deposition of aminopropyl silanes in microfluidic channels for highly efficient microchip capillary electrophoresis-electrospray ionization-mass spectrometry.

Science.gov (United States)

Batz, Nicholas G; Mellors, J Scott; Alarie, Jean Pierre; Ramsey, J Michael

2014-04-01

We describe a chemical vapor deposition (CVD) method for the surface modification of glass microfluidic devices designed to perform electrophoretic separations of cationic species. The microfluidic channel surfaces were modified using aminopropyl silane reagents. Coating homogeneity was inferred by precise measurement of the separation efficiency and electroosmotic mobility for multiple microfluidic devices. Devices coated with (3-aminopropyl)di-isopropylethoxysilane (APDIPES) yielded near diffusion-limited separations and exhibited little change in electroosmotic mobility between pH 2.8 and pH 7.5. We further evaluated the temporal stability of both APDIPES and (3-aminopropyl)triethoxysilane (APTES) coatings when stored for a total of 1 week under vacuum at 4 °C or filled with pH 2.8 background electrolyte at room temperature. Measurements of electroosmotic flow (EOF) and separation efficiency during this time confirmed that both coatings were stable under both conditions. Microfluidic devices with a 23 cm long, serpentine electrophoretic separation channel and integrated nanoelectrospray ionization emitter were CVD coated with APDIPES and used for capillary electrophoresis (CE)-electrospray ionization (ESI)-mass spectrometry (MS) of peptides and proteins. Peptide separations were fast and highly efficient, yielding theoretical plate counts over 600,000 and a peak capacity of 64 in less than 90 s. Intact protein separations using these devices yielded Gaussian peak profiles with separation efficiencies between 100,000 and 400,000 theoretical plates.

Real-time analysis of self-assembled nucleobases by Venturi easy ambient sonic-spray ionization mass spectrometry.

Science.gov (United States)

Na, Na; Shi, Ruixia; Long, Zi; Lu, Xin; Jiang, Fubin; Ouyang, Jin

2014-10-01

In this study, the real-time analysis of self-assembled nucleobases was employed by Venturi easy ambient sonic-spray ionization mass spectrometry (V-EASI-MS). With the analysis of three nucleobases including 6-methyluracil (6MU), uracil (U) and thymine (T) as examples, different orders of clusters centered with different metal ions were recorded in both positive and negative modes. Compared with the results obtained by traditional electrospray ionization mass spectrometry (ESI-MS) under the same condition, more clusters with high orders, such as [6MU7+Na](+), [6MU15+2NH4](2+), [6MU10+Na](+), [T7+Na](+), and [T15+2NH4](2+) were detected by V-EASI-MS, which demonstrated the soft ionization ability of V-EASI for studying the non-covalent interaction in a self-assembly process. Furthermore, with the injection of K(+) to the system by a syringe pumping, the real-time monitoring of the formation of nucleobases clusters was achieved by the direct extraction of samples from the system under the Venturi effect. Therefore, the effect of cations on the formation of clusters during self-assembly of nucleobases was demonstrated, which was in accordance with the reports. Free of high voltage, heating or radiation during the ionization, this technique is much soft and suitable for obtaining the real-time information of the self-assembly system, which also makes it quite convenient for extraction samples from the reaction system. This "easy and soft" ionization technique has provided a potential pathway for monitoring and controlling the self-assembly processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Trace analysis of actinides in the environment using resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Raeder, Sebastian

2011-01-01

In this work the resonant ionization of neutral atoms using laser radiation was applied and optimized for ultra-trace analysis of the actinides thorium, uranium, neptunium and plutonium. The sensitive detection of these actinides is a challange for the monitoring and quantification of radioactive releases from nuclear facilities. Using resonance ionization spectroscopy combined with a newly developed quadrupole-mass-spectrometer, numerous energy levels in the atomic structure of these actinides could be identified. With this knowledge efficient excitation schemes for the mentioned actinides could be identified and characterised. The applied in-source-ionization ensures for a high detection efficiency due to the good overlap of laser radiation with the atomic beam and allows therefore for a low sample consumption which is required for the analysis of radio nuclides. The selective excitation processes in the resonant ionization method supresses unwanted contaminations and was optimized for analytical detection of ultra-trace amounts in environmental samples as well as for determination of isotopic compositions. The efficient in-source-ionization combined with high power pulsed laser radiation allows for detections efficiency up to 1%. For plutonium detection limits in the range of 10 4 -10 5 atoms could be demonstrated for synthetic samples as well as for first environmental samples. The usage of narrow bandwidth continuous wave lasers in combination with a transversal overlap of the laser radiation and the free propagating atomic beam enable for resolving individual isotopic shifts of the resonant transitions. This results in a high selectivity against dominant neighboring isotopes but with a significant loss in detection efficiency. For the ultra-trace isotope 236 U a detection limit down to 10 -9 for the isotope ratio N ( 236 U)/N ( 238 U) could be determined.

Combination of electrospray ionization, atmospheric pressure photoionization and laser desorption ionization Fourier transform ion cyclotronic resonance mass spectrometry for the investigation of complex mixtures – Application to the petroleomic analysis of bio-oils

Energy Technology Data Exchange (ETDEWEB)

Hertzog, Jasmine [LCP-A2MC, FR 2843 Institut Jean Barriol de Chimie et Physique Moléculaires et Biomoléculaires, FR 3624 Réseau National de Spectrométrie de Masse FT-ICR à très haut champ, Université de Lorraine, ICPM, 1 boulevard Arago, 57078 Metz Cedex 03 (France); Carré, Vincent, E-mail: vincent.carre@univ-lorraine.fr [LCP-A2MC, FR 2843 Institut Jean Barriol de Chimie et Physique Moléculaires et Biomoléculaires, FR 3624 Réseau National de Spectrométrie de Masse FT-ICR à très haut champ, Université de Lorraine, ICPM, 1 boulevard Arago, 57078 Metz Cedex 03 (France); Le Brech, Yann [LRGP, CNRS, Université de Lorraine, ENSIC, 1, Rue Grandville, 54000 Nancy (France); Mackay, Colin Logan [SIRCAMS, School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, Scotland (United Kingdom); Dufour, Anthony [LRGP, CNRS, Université de Lorraine, ENSIC, 1, Rue Grandville, 54000 Nancy (France); Mašek, Ondřej [UK Biochar Research Center, School of Geosciences, University of Edinburgh, Kings Buildings, Edinburgh, EH9 3JN (United Kingdom); and others

2017-05-29

The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to C{sub x}H{sub y}O{sub z} with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture. - Highlights: • Non-targeted mass spectrometry by combining electrospray ionization, atmospheric pressure photoionization and laser/desorption ionization. • Exhaustive description of pyrolytic bio-oil components. • Distinction of sugaric derivatives, lignin derivatives and lipids contained in a woody-based pyrolytic bio-oil.

Direct analysis of samples by mass spectrometry: From elements to bio-molecules using laser ablation inductively couple plasma mass spectrometry and laser desorption/ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Perdian, David C. [Iowa State Univ., Ames, IA (United States)

2009-01-01

Mass spectrometric methods that are able to analyze solid samples or biological materials with little or no sample preparation are invaluable to science as well as society. Fundamental research that has discovered experimental and instrumental parameters that inhibit fractionation effects that occur during the quantification of elemental species in solid samples by laser ablation inductively coupled plasma mass spectrometry is described. Research that determines the effectiveness of novel laser desorption/ionization mass spectrometric methods for the molecular analysis of biological tissues at atmospheric pressure and at high spatial resolution is also described. A spatial resolution is achieved that is able to analyze samples at the single cell level.

Solvent Composition-Dependent Signal-Reduction of Molecular Ions Generated from Aromatic Compounds in (+) Atmospheric Pressure Photo Ionization Mass Spectrometry.

Science.gov (United States)

Lee, Seulgidaun; Ahmed, Arif; Kim, Sunghwan

2018-03-30

The ionization process is essential for successful mass spectrometry (MS) analysis because of its influence on selectivity and sensitivity. In particular, certain solvents reduce the ionization of the analyte, thereby reducing the overall sensitivity in APPI. Since the sensitivity varies greatly depending on the solvents, a fundamental understanding of the mechanism is required. Standard solutions were analyzed by (+) Atmospheric pressure photo ionization (APPI) QExactive ion trap mass spectrometer (Thermo Scientific). Each solution was infused directly to the APPI source at a flow rate 100 μl/min and the APPI source temperature was 300 °C. Other operating mass spectrometric parameters were maintained under the same conditions. Quantum mechanical calculations were carried out using the Gaussian 09 suite program. Density functional theory was used to calculate the reaction enthalpies (∆H) of reaction between toluene and other solvents. The experimental and theoretical results showed good agreement. The abundances of analyte ions were well correlated with the calculated ∆H values. Therefore, the results strongly support the suggested signal reduction mechanism. In addition, linear correlations between the abundance of toluene and analyte molecular ions were observed, which also supports the suggested mechanism. A solvent composition-dependent signal reduction mechanism was suggested and evaluated for the (+) atmospheric pressure photo ionization (APPI) mass spectrometry analysis of poly-aromatic hydrocarbons (PAHs) generating mainly molecular ions. Overall, the evidence provided in this work suggests that reactions between solvent cluster(s) and toluene molecular ions are responsible for the observed signal reductions. This article is protected by copyright. All rights reserved.

Alkaloid profiling of the Chinese herbal medicine Fuzi by combination of matrix-assisted laser desorption ionization mass spectrometry with liquid chromatography-mass spectrometry

NARCIS (Netherlands)

Wang, J.; Heijden, R. van der; Spijksma, G.; Reijmers, T.; Wang, M.; Xu, G.; Hankemeier, T.; Greef, J. van der

2009-01-01

A matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) method was developed for the high throughput and robust qualitative profiling of alkaloids in Fuzi-the processed lateral roots of the Chinese herbal medicine Aconitum carmichaeli Debx (A. carmichaeli). After optimization,

Laser ionization time of flight mass spectrometer for isotope mass detection and elemental analysis of materials

Science.gov (United States)

Ahmed, Nasar; Ahmed, Rizwan; Umar, Z. A.; Aslam Baig, M.

2017-08-01

In this paper we present the construction and modification of a linear time-of-flight mass spectrometer to improve its mass resolution. This system consists of a laser ablation/ionization section based on a Q-switched Nd:YAG laser (532 nm, 500 mJ, 5 ns pulse duration) integrated with a one meter linear time-of-flight mass spectrometer coupled with an electric sector and a magnetic lens and outfitted with a channeltron electron multiplier for ion detection. The resolution of the system has been improved by optimizing the accelerating potential and inserting a magnetic lens after the extraction region. The isotopes of lithium, lead and cadmium samples have been resolved and detected in accordance with their natural abundance. The capability of the system has been further exploited to determine the elemental composition of a brass alloy, having a certified composition of zinc and copper. Our results are in excellent agreement with its certified composition. This setup is found to be extremely efficient and convenient for fast analyses of any solid sample.

Solar Irradiance Changes And Photobiological Effects At Earth's Surface Following Astrophysical Ionizing Radiation Events

Science.gov (United States)

Thomas, Brian; Neale, Patrick

2016-01-01

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth for decades. Although there is some direct biological damage on the surface from redistributed radiation several studies have indicated that the greatest long term threat is from ozone depletion and subsequent heightened solar ultraviolet (UV) radiation. It is known that organisms exposed to this irradiation experience harmful effects such as sunburn and even direct damage to DNA, proteins, or other cellular structures. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In the present work, we employed a radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light). Using biological weighting functions we have considered a wide range of effects, including: erythema and skin cancer in humans; inhibition of photosynthesis in the diatom Phaeodactylum sp. and dinoflagellate Prorocentrum micans inhibition of carbon fixation in Antarctic phytoplankton; inhibition of growth of oat (Avena sativa L. cv. Otana) seedlings; and cataracts. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in

Stable isotope dilution analysis by thermal ionization mass spectrometry. Pt. 2

International Nuclear Information System (INIS)

Broekman, A.; Raaphorst, J.G. van

1984-01-01

The combination of stable isotope dilution analysis (SIDA) and thermal ionization mass spectrometry (TIMS) is in use for lead and uranium determination at milligram per kilogram levels for over 20 years. However, several other elements can also be determined accurately by SIDA/TIMS. In this study the determinations of cadmium and copper are described. Details of the digestion, electrochemical and ion-exchange separations and the loading of the elements on a filament are given. The advantages of the SIDA/TIMS technique are shown and illustrated with results for several certified reference materials. (orig.) [de

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

KAUST Repository

Hourani, Nadim; Andersson, Jan T.; Mö ller, Isabelle; Amad, Maan H.; Witt, Matthí as; Sarathy, Mani

2013-01-01

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

Resonance ionization mass spectrometry of ion beam sputtered neutrals for element- and isotope-selective analysis of plutonium in micro-particles

Energy Technology Data Exchange (ETDEWEB)

Erdmann, N. [Institute for Transuranium Elements, European Commission Joint Research Centre, Karlsruhe (Germany); Kratz, J.V.; Trautmann, N. [Johannes Gutenberg-University Mainz, Institute of Nuclear Chemistry, Mainz (Germany); Passler, G. [Johannes Gutenberg-University Mainz, Institute of Physics, Mainz (Germany)

2009-11-15

Micro-particles containing actinides are of interest for risk assessments of contaminated areas, nuclear forensic analyses, and IAEA as well as Euratom safeguards programs. For their analysis, secondary ion mass spectrometry (SIMS) has been established as the state-of-the-art standard technique. In the case of actinide mixtures within the particles, however, SIMS suffers from isobaric interferences (e.g., {sup 238}U/{sup 238}Pu, {sup 241}Am/{sup 241}Pu). This can be eliminated by applying resonance ionization mass spectrometry which is based on stepwise resonant excitation and ionization of atoms with laser light, followed by mass spectrometric detection of the produced ions, combining high elemental selectivity with the analysis of isotopic compositions. This paper describes the instrumental modifications for coupling a commercial time-of-flight (TOF)-SIMS apparatus with three-step resonant post-ionization of the sputtered neutrals using a high-repetition-rate (kHz) Nd:YAG laser pumped tunable titanium:sapphire laser system. Spatially resolved ion images obtained from actinide-containing particles in TOF-SIMS mode demonstrate the capability for isotopic and spatial resolution. Results from three-step resonant post-ionization of bulk Gd and Pu samples successfully demonstrate the high elemental selectivity of this process. (orig.)

Determination of molybdenum in plant reference material by thermal-ionization isotope-dilution mass spectrometry

International Nuclear Information System (INIS)

Saumer, M.; Gantner, E.; Reinhardt, J.; Ache, H.J.

1992-01-01

An analytical method is described for the determination of the concentration and the isotopic composition of molybdenum in plant samples using thermal ionization mass spectrometry. After microwave acid digestion and liquid-liquid extractive separation with Amberlite LA-2, the molybdenum isotopes are measured as MoO 3 - -ions in a quadrupole mass spectrometer. In all cases, the relative standard deviation of the measurements of both natural and spike molybdenum was better than 3% for all ratios measured. The concentration of molybdenum found in three different plant reference materials agreed well with the certified values. (orig.)

Monitoring of wine aging process by electrospray ionization mass spectrometry

Directory of Open Access Journals (Sweden)

Alexandra Christine Helena Frankland Sawaya

2011-09-01

Full Text Available The characterization of wine samples by direct insertion electrospray ionization mass spectrometry (ESI-MS, without pre-treatment or chromatographic separation, in a process denominated fingerprinting, has been applied to several samples of wine produced with grapes of the Pinot noir, Merlot and Cabernet Sauvignon varieties from the state o Rio Grande do Sul, in Brazil. The ESI-MS fingerprints of the samples detected changes which occurred during the aging process in the three grape varieties. Principal Component Analysis (PCA of the negative ion mode fingerprints was used to group the samples, pinpoint the main changes in their composition, and indicate marker ions for each group of samples.

Direct Visualization of Neurotransmitters in Rat Brain Slices by Desorption Electrospray Ionization Mass Spectrometry Imaging (DESI - MS)

Science.gov (United States)

Fernandes, Anna Maria A. P.; Vendramini, Pedro H.; Galaverna, Renan; Schwab, Nicolas V.; Alberici, Luciane C.; Augusti, Rodinei; Castilho, Roger F.; Eberlin, Marcos N.

2016-12-01

Mass spectrometry imaging (MSI) of neurotransmitters has so far been mainly performed by matrix-assisted laser desorption/ionization (MALDI) where derivatization reagents, deuterated matrix and/or high resolution, or tandem MS have been applied to circumvent problems with interfering ion peaks from matrix and from isobaric species. We herein describe the application of desorption electrospray ionization mass spectrometry imaging (DESI)-MSI in rat brain coronal and sagittal slices for direct spatial monitoring of neurotransmitters and choline with no need of derivatization reagents and/or deuterated materials. The amino acids γ-aminobutyric (GABA), glutamate, aspartate, serine, as well as acetylcholine, dopamine, and choline were successfully imaged using a commercial DESI source coupled to a hybrid quadrupole-Orbitrap mass spectrometer. The spatial distribution of the analyzed compounds in different brain regions was determined. We conclude that the ambient matrix-free DESI-MSI is suitable for neurotransmitter imaging and could be applied in studies that involve evaluation of imbalances in neurotransmitters levels.

Ghost peaks observed after AP-MALDI experiment may disclose new ionization mechanism of matrix assisted hypersonic velocity impact ionization

Science.gov (United States)

Moskovets, Eugene

2015-01-01

RATIONALE Understanding the mechanisms of MALDI promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample has been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laserless matrix-assisted ionization. METHODS An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser was turned off and MALDI sample was removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly- and doubly-charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. RESULTS The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. CONCLUSIONS The observations were partially consistent with a model of

The Characterization of Laser Ablation Patterns and a New Definition of Resolution in Matrix Assisted Laser Desorption Ionization Imaging Mass Spectrometry (MALDI-IMS).

Science.gov (United States)

O'Rourke, Matthew B; Raymond, Benjamin B A; Padula, Matthew P

2017-05-01

Matrix assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) is a technique that has seen a sharp rise in both use and development. Despite this rapid adoption, there have been few thorough investigations into the actual physical mechanisms that underlie the acquisition of IMS images. We therefore set out to characterize the effect of IMS laser ablation patterns on the surface of a sample. We also concluded that the governing factors that control spatial resolution have not been correctly defined and therefore propose a new definition of resolution. Graphical Abstract ᅟ.

Detection and quantification of neurotensin in human brain tissue by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

DEFF Research Database (Denmark)

Gobom, J; Kraeuter, K O; Persson, R

2000-01-01

A method was developed for mass spectrometric detection of neurotensin (NT)-like immunoreactivity and quantification of NT in human brain tissue. The method is based on immunoprecipitation followed by analysis using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF......-MS). The identity of the major component of the immunoprecipitates as neurotensin was confirmed by fragment ion analysis on an electrospray ionization quadrupole time-of-flight instrument. MALDI-TOF-MS quantification of NT was achieved using stable-isotope-labeled NT as the internal standard, yielding an error...

Origin of cell surface proteins released from Micrococcus radiodurans by ionizing radiation

International Nuclear Information System (INIS)

Mitchel, R.E.J.

1975-01-01

The exposure of Micrococcus radiodurans to sublethal doses of ionizing radiation causes the release of certain proteins into the surrounding medium. As estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, these proteins range from approximately 20,000 to 125,000 daltons. At least some of the proteins, including an exonuclease, have a surface location and appear to originate from the lipid-rich midwall layer. The exonuclease has two functionally distinct locations, one with its active site available to external substrate and a second with the active site masked from the exterior. Ionizing radiation releases both the masked and unmasked activity into the surrounding medium

Ionization chamber

International Nuclear Information System (INIS)

Jilbert, P.H.

1975-01-01

The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

Ambient ionization mass spectrometry imaging for characterizing plant-microbe interactions using liquid extraction surface analysis (LESA)

Science.gov (United States)

Chu, R. K.; Anderton, C.; Weston, D. J.; Carrell, A. A.; Paša-Tolić, L.; Veličković, D.; Tfaily, M.

2017-12-01

The rhizosphere consists of a diverse community of plants, bacteria and fungi that are interacting with each other and with complex soil matrix they occupy. By studying the chemical signaling and processes that occur within this dynamic microenvironment, we will further our understanding of the symbiotic and competitive interaction within microbial communities. Field studies and bulk analyses shed light on the mechanisms by which environmental perturbations alter carbon and nitrogen cycling, but what is less clear are the intra- and interspecies molecular transformations and transactions between the different constituents within the rhizosphere. Chemical imaging by liquid extraction surface analysis mass spectrometry (LESA-MS) is a highly sensitive technique capable of providing both spatial and molecular information. Here, we examined the chemical interactions among a tripartite system of peat moss (Sphagnum fallax), cyanobacteria (Nostoc muscorium), and fungus (Trizdiaspa). We coupled LESA source to both a 15 Tesla Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS), for ultrahigh mass resolution and mass accuracy results, and a Thermo Velos-LTQ mass spectrometer, for tandem MS of selected molecules to increase confidence in molecular identifications. With LESA-MS approach we spatially probed the tripartite interactions and isolated cultures using a coordinate system that can be mapped back and overlaid onto the original image. Using this method, we mapped an array of metabolic distributions within the model sphagnum microbiome. For instance, we identified carbendazim, an anti-fungal agent, distributed within the interaction zone between the bacteria and fungi, while glyceropcholine and sucrose were localized within the sphagnum and fungus interaction zone. Further analysis will look into larger metabolites, lipids, and small proteins.

Surface oxidation on thin films affects ionization cross section induced by proton beam

International Nuclear Information System (INIS)

Bertol, Ana Paula Lamberti; Vasconcellos, M.A.Z.; Hinrichs, Ruth; Limandri, Silvina; Trincavelli, Jorge

2012-01-01

Full text: In microanalysis techniques such as Particle Induced X-ray Emission (PIXE), the transformation from intensity to concentration is made by standard less software that needs exact values of fundamental parameters such as the ionization cross section, transition probabilities of the different electronic levels, and fluorescent yield. The three parameters together measure the photon generating probability of an electronic transition and can be determined experimentally under the name of production cross section. These measurements are performed on thin films, with thickness around 10 nm, but most studies do not take into account any spontaneous surface oxidation. In this work, in the attempt to obtain cross section values of Al, Si and Ti, in metallic and oxide films, the influence of surface oxidation on the metallic films was established. Simulations considering the oxidation with the software SIMNRA on the Rutherford backscattering (RBS) spectra obtained from the films provided mass thickness values used to calculate the cross section data that were compared with theoretical values (PWBA and ECPSSR), and with experimental values and empirical adjustments from other studies. The inclusion of the natural oxidation affects the values of cross section, and may be one of the causes of discrepancies between the experimental values published in literature. (author)

Organization of medical aid and treatment of victims of mass ionizing radiation injuries

International Nuclear Information System (INIS)

Gus'kova, A.K.; Burenin, P.I.; Barabanova, A.V.

1987-01-01

General organization points on medical aid and treatment of mass ionizing radiation injuries in population are presented. Characteristic of losses and structure of injuries induced by a nuclear explosion are given. Destructions in a town caused by a nuclear explosion and medical aid conditions for patients are analysed. Main information about structure of medical surveillance of civil defence and criteria of medical classification and evacuation of the injured are presented

Matrix-assisted laser desorption/ionization mass spectrometry for the structural characterization of modified oligonucleotides

International Nuclear Information System (INIS)

Hurst, G.B.; Hettich, R.L.; Buchanan, M.V.; Stemmler, E.A.

1993-01-01

Matrix-assisted laser desorption ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry (FTMS) and MALDI time-of-flight mass spectrometry (TOFMS) are being used to characterize conditions for the efficient desorption and ionization of normal and modified nucleic acid components. Basic and acidic matrix materials have been evaluated on the components. Basic and acidic matrix materials have been evaluated on the FTMS and TOFMS. Using MALDI-FTMS at 355 nm, less fragmentation has been observed using 2,5-dihydroxybenzoic acid, while more extensive fragmentation is observed for basic matrices, such as 1,5-diaminonaphthalene and 9-aminophenanthrene. Elevation of the cell pressure by the addition of Ar or CO 2 provides collisional cooling of desorbed ions, resulting in an enhancement of [M--H] - and structurally significant high-mass fragment ions. Using MALDI-TOFMS at 337 nm, fragmentation is significantly reduced relative to that observed on the FTMS, perhaps as a consequence of the longer times required for FTMS detection. On the FTMS and TOFMS, cluster ions have been observed in the negative ion mode when metal ions are present in the 2,5-dihydroxybenzoic acid matrix. Metal ion additions and clusters with matrix salts have also been observed for dinucleotides. Applications of MALDI-FTMS and MALDI-TOF to the detection of hydroxylated PAH nucleoside adducts are presented

Measurement of laser activated electron tunneling from semiconductor zinc oxide to adsorbed organic molecules by a matrix assisted laser desorption ionization mass spectrometer

International Nuclear Information System (INIS)

Zhong Hongying; Fu Jieying; Wang Xiaoli; Zheng Shi

2012-01-01

Highlights: ► Irradiation of photons with energies more than the band gap generates electron–hole pairs. ► Electron tunneling probability is dependent on the electron mobility. ► Tunneling electrons are captured by charge deficient atoms. ► Unpaired electrons induce cleavages of chemical bonds. - Abstract: Measurement of light induced heterogeneous electron transfer is important for understanding of fundamental processes involved in chemistry, physics and biology, which is still challenging by current techniques. Laser activated electron tunneling (LAET) from semiconductor metal oxides was observed and characterized by a MALDI (matrix assisted laser desorption ionization) mass spectrometer in this work. Nanoparticles of ZnO were placed on a MALDI sample plate. Free fatty acids and derivatives were used as models of organic compounds and directly deposited on the surface of ZnO nanoparticles. Irradiation of UV laser (λ = 355 nm) with energy more than the band gap of ZnO produces ions that can be detected in negative mode. When TiO 2 nanoparticles with similar band gap but much lower electron mobility were used, these ions were not observed unless the voltage on the sample plate was increased. The experimental results indicate that laser induced electron tunneling is dependent on the electron mobility and the strength of the electric field. Capture of low energy electrons by charge-deficient atoms of adsorbed organic molecules causes unpaired electron-directed cleavages of chemical bonds in a nonergodic pathway. In positive detection mode, electron tunneling cannot be observed due to the reverse moving direction of electrons. It should be able to expect that laser desorption ionization mass spectrometry is a new technique capable of probing the dynamics of electron tunneling. LAET offers advantages as a new ionization dissociation method for mass spectrometry.

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.

Feasibility study of the single particle analysis of uranium by laser ionization time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Ha, Yeong Keong; Han, Sun Ho; Pyo, Hyung Yeol; Park, Yong Joon; Song, Kyu Seok

2004-01-01

The control of activities in nuclear facilities worldwide is one of the most important tasks of nuclear safeguard. To meet the needs for nuclear safeguard, International Atomic Energy Agency (IAEA) strengthened the control of nuclear activities to detect these activities earlier. Thus, it is very important to develop analytical techniques to determine the isotopic composition of hot particles from swipe samples. The precise measurement of the 234 U/ 238 U, 235 U/ 238 U and 236 U/ 238 U ratios is important because it provides information about the initial enrichment of reactor uranium, core history, and post accident story. Because conventional α-spectrometry is not sufficiently sensitive for the determination of long-lived radionuclides in environmental samples, several analytical techniques, such as SNMS (Sputtered Neutral Mass Spectrometry), RIMS (Resonance Ionization Mass Spectrometry), AMS (Accelerator Mass Spectrometry) etc., have been proposed for uranium isotope measurements. In case of microparticles, analytical techniques such as SIMS (Secondary Ion Mass Spectrometry) have been applied for the isotopic characterization. The aim of this work was the development of a sensitive analytical technique for determination of isotopic ratio of uranium in swipe samples. In this work, feasibility of LIMS (Laser Ionization Mass Spectrometry) for the determination of such particles has been evaluated using a reference material of natural uranium

Ionization Suppression and Recovery in Direct Biofluid Analysis Using Paper Spray Mass Spectrometry

Science.gov (United States)

Vega, Carolina; Spence, Corina; Zhang, Chengsen; Bills, Brandon J.; Manicke, Nicholas E.

2016-04-01

Paper spray mass spectrometry is a method for the direct analysis of biofluid samples in which extraction of analytes from dried biofluid spots and electrospray ionization occur from the paper on which the dried sample is stored. We examined matrix effects in the analysis of small molecule drugs from urine, plasma, and whole blood. The general method was to spike stable isotope labeled analogs of each analyte into the spray solvent, while the analyte itself was in the dried biofluid. Intensity of the labeled analog is proportional to ionization efficiency, whereas the ratio of the analyte intensity to the labeled analog in the spray solvent is proportional to recovery. Ion suppression and recovery were found to be compound- and matrix-dependent. Highest levels of ion suppression were obtained for poor ionizers (e.g., analytes lacking basic aliphatic amine groups) in urine and approached -90%. Ion suppression was much lower or even absent for good ionizers (analytes with aliphatic amines) in dried blood spots. Recovery was generally highest in urine and lowest in blood. We also examined the effect of two experimental parameters on ion suppression and recovery: the spray solvent and the sample position (how far away from the paper tip the dried sample was spotted). Finally, the change in ion suppression and analyte elution as a function of time was examined by carrying out a paper spray analysis of dried plasma spots for 5 min by continually replenishing the spray solvent.

State of the Art of Hard and Soft Ionization Mass Spectrometry

International Nuclear Information System (INIS)

Helal, A.I.

2008-01-01

The principles of hard and soft ionization sources, providing some details on the practical aspects of their uses as well as ionization mechanisms are discussed. The conditions and uses of hard ionization methods such as electron impact, thermal ionization and inductively coupled plasma techniques are discussed. Moreover, new generation of soft ionization methods such as matrix-assisted laser desorption/ionization, electro spray ionization and direct analysis in real time are illustrated

Electrospray ionization mass spectrometric method for the determination of cannabinoid precursors

DEFF Research Database (Denmark)

Hansen, H.H.; Hansen, S.H.; Bøjrnsdottir, I.

1999-01-01

electrospray ionization mass spectrometry (ESI-MS). The procedure provides complete positioning of all acyl and alkenyl groups contained in each NAPE species. The calibration curve for standard NAPE was linear over the range 100 fmol-50 pmol (0.1-50 ng) per injection. The lower limit of detection (signal......-to-noise ratio of 3) was 100 fmol, implying that this method is superior to previous methods for the determination of NAPE. These results suggest that this ESI-MS method can be used to identify and quantify NAPE species in mammalian tissues and provide information on the corresponding NAEs to be released from...

Constant-Distance Mode Nanospray Desorption Electrospray Ionization Mass Spectrometry Imaging of Biological Samples with Complex Topography

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Son N.; Liyu, Andrey V.; Chu, Rosalie K.; Anderton, Christopher R.; Laskin, Julia

2017-01-17

A new approach for constant distance mode mass spectrometry imaging of biological samples using nanospray desorption electrospray ionization (nano-DESI MSI) was developed by integrating a shear-force probe with nano-DESI probe. The technical concept and basic instrumental setup as well as general operation of the system are described. Mechanical dampening of resonant oscillations due to the presence of shear forces between the probe and the sample surface enables constant-distance imaging mode via a computer controlled closed feedback loop. The capability of simultaneous chemical and topographic imaging of complex biological samples is demonstrated using living Bacillus Subtilis ATCC 49760 colonies on agar plates. The constant-distance mode nano-DESI MSI enabled imaging of many metabolites including non-ribosomal peptides (surfactin, plipastatin and iturin) and iron-bound heme on the surface of living bacterial colonies ranging in diameter from 10 mm to 13 mm with height variations of up to 0.8 mm above the agar plate. Co-registration of ion images to topographic images provided higher-contrast images. Constant-mode nano-DESI MSI is ideally suited for imaging biological samples of complex topography in their native state.

Recent developments in and applications of resonance ionization mass spectrometry

International Nuclear Information System (INIS)

Wendt, K.; Blaum, K.; Horn, R.; Huber, G.; Kunz, P.; Mueller, P.; Noertershaeuser, W.; Nunnemann, M.; Passler, G.; Schmitt, A.; Gruening, C.; Kratz, J.V.; Trautmann, N.; Waldek, A.

1999-01-01

Resonance Ionization Mass Spectrometry (RIMS) has nowadays reached the status of a routine method for sensitive and selective ultratrace determination of long-lived radioactive isotopes in environmental, biomedical and technical samples. It provides high isobaric suppression, high to ultra-high isotopic selectivity and good overall efficiency. Experimental detection limits are as low as 10 6 atoms per sample and permit the fast and sensitive determination of ultratrace amounts of radiotoxic contaminations. Experimental arrangements for the detection of different radiotoxic isotopes, e.g. 236-244 Pu, 89,90 Sr and 99 Tc in environmental samples are described, and the application of RIMS to the ultrarare long-lived radioisotope 41 Ca for cosmochemical, radiodating and medical purposes are presented. (orig.)

Quantitative analysis of abused drugs in physiological fluids by gas chromatography/chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Foltz, R.L.

1978-01-01

Methods have been developed for quantitative analysis of commonly abused drugs in physiological fluids using gas chromatography/chemical ionization mass spectrometry. The methods are being evaluated in volunteer analytical and toxicological laboratories, and analytical manuals describing the methods are being prepared. The specific drug and metabolites included in this program are: Δ 9 -tetrahydrocannabinol, methadone, phencyclidine, methaqualone, morphine, amphetamine, methamphetamine, mescaline, 2,5-dimethoxy-4-methyl amphetamine, cocaine, benzoylecgonine, diazepam, and N-desmethyldiazepam. The current analytical methods utilize relatively conventional instrumentation and procedures, and are capable of measuring drug concentrations as low as 1 ng/ml. Various newer techniques such as sample clean-up by high performance liquid chromatography, separation by glass capillary chromatography, and ionization by negative ion chemical ionization are being investigated with respect to their potential for achieving higher sensitivity and specificity, as well as their ability to facilitate simultaneous analysis of more than one drug and metabolite. (Auth.)

Rapid in situ detection of alkaloids in plant tissue under ambient conditions using desorption electrospray ionization.

Science.gov (United States)

Talaty, Nari; Takáts, Zoltán; Cooks, R Graham

2005-12-01

Desorption electrospray ionization (DESI) mass spectrometry is applied to the in situ detection of alkaloids in the tissue of poison hemlock (Conium maculatum), jimsonweed (Datura stramonium) and deadly nightshade (Atropa belladonna). The experiment is carried out by electrospraying micro-droplets of solvent onto native or freshly-cut plant tissue surfaces. No sample preparation is required and the mass spectra are recorded under ambient conditions, in times of a few seconds. The impact of the sprayed droplets on the surface produces gaseous ions from organic compounds originally present in the plant tissue. The effects of operating parameters, including the electrospray high voltage, heated capillary temperature, the solvent infusion rate and the carrier gas pressure on analytical performance are evaluated and optimized. Different types of plant material are analyzed including seeds, stems, leaves, roots and flowers. All the previously reported alkaloids have been detected in C. maculatum, while fifteen out of nineteen known alkaloids for D. stramonium and the principal alkaloids of A. belladonna were also identified. All identifications were confirmed by tandem mass spectrometry. Results obtained show similar mass spectra, number of alkaloids, and signal intensities to those obtained when extraction and separation processes are performed prior to mass spectrometric analysis. Evidence is provided that DESI ionization occurs by both a gas-phase ionization process and by a droplet pick-up mechanism. Quantitative precision of DESI is compared with conventional electrospray ionization mass spectrometry (after sample workup) and the RSD values for the same set of 25 dicotyledonous C. maculatum seeds (one half of each seed analyzed by ESI and the other by DESI) are 9.8% and 5.2%, respectively.

Simultaneous mass detection for direct inlet mass spectrometry

International Nuclear Information System (INIS)

Gordon, R.L.

1979-05-01

The evolution of analytical techniques for application in trace analysis has led to interest in practical methods for real-time monitoring. Direct inlet mass spectrometry (DIMS) has been the subject of considerable activity in recent years. A DIMS instrument is described which consists of an inlet system designed to permit particles entrained in the inlet air stream to strike a hot, oxidized rhenium filament which serves as a surface ionization source. A mass analyzer and detection system then permits identification of the elemental composition of particulates which strike the filament

Tissue imaging with a stigmatic mass microscope using laser desorption/ionization

Science.gov (United States)

Awazu, Kunio; Hazama, Hisanao; Hamanaka, Tomonori; Aoki, Jun; Toyoda, Michisato; Naito, Yasuhide

2012-03-01

A novel stigmatic mass microscope using laser desorption/ionization and a multi-turn time-of-flight mass spectrometer, MULTUM-IMG, has been developed. Stigmatic ion images of crystal violet masked by a fine square mesh grid with a 12.7 μm pitch were clearly observed, and the estimated spatial resolution was about 3 μm in the linear mode with a 20-fold ion optical magnification. Tissue sections of a brain and eyes of a mouse stained with crystal violet and methylene blue were observed in the linear mode, and the stigmatic total ion images of crystal violet and methylene blue agreed well with the optical photomicrograph of the same sections. Especially, the fine structure in the cornea tissue was clearly observed with a spatial resolution in the range of micrometers. Although the total measurement time of the stigmatic ion image for the whole-eye section was about 59 minutes using a laser with a 10 Hz repetition rate, the measurement time could be reduced to about 35 s using a laser with a 1 kHz repetition rate and automation of measurements. The stigmatic mass microscope developed in this research should be suitable for high-spatial resolution and high-throughput imaging mass spectrometry for pathology, pharmacokinetics, and so on.

Focused Electrospray Deposition for Matrix-assisted Laser Desorption/Ionization Mass Spectrometry

International Nuclear Information System (INIS)

Jeong, Kyung Hwan; Seo, Jong Cheol; Yoon, Hye Joo; Shin, Seung Koo

2010-01-01

Focused electrospray (FES) deposition method is presented for matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. FES ion optics consists of two cylindrical focusing electrodes capped with a truncated conical electrode through which an electrospray emitter passes along the cylindrical axis. A spray of charged droplets is focused onto a sample well on a MALDI target plate under atmospheric pressure. The shape and size distributions of matrix crystals are visualized by scanning electron microscope and the mass spectra are obtained by time-of-flight mass spectrometry. Angiotensin II, bradykinin, and substance P are used as test samples, while α-cyano-4-hydroxycinnamic acid and dihydroxybenzoic acid are employed as matrices. FES of a sample/matrix mixture produces fine crystal grains on a 1.3 mm spot and reproducibly yields the mass spectra with little shot-to-shot and spot-to-spot variations. Although FES greatly stabilizes the signals, the space charge due to matrix ions limits the detection sensitivity of peptides. To avoid the space charge problem, we adopted a dual FES/FES mode, which separately deposits matrix and sample by FES in sequence. The dual FES/FES mode reaches the detection sensitivity of 0.88 amol, enabling ultrasensitive detection of peptides by homogeneously depositing matrix and sample under atmospheric pressure

[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.

Matrix-Assisted Laser Desorption Ionization Mass Spectrometry Imaging for Peptide and Protein Analyses: A Critical Review of On-Tissue Digestion

NARCIS (Netherlands)

Cillero-Pastor, B.; Heeren, R.M.A.

2013-01-01

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has established itself among the plethora of mass spectrometry applications. In the biomedical field, MALDI-MSI is being more frequently recognized as a new method for the discovery of biomarkers and targets of

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...

Differentiation of isomeric 2-aryldimethyltetrahydro-5-quinolinones by electron ionization and electrospray ionization mass spectrometry.

Science.gov (United States)

Kumar, Ch Dinesh; Chary, V Naresh; Dinesh, A; Reddy, P S; Srinivas, K; Gayatri, G; Sastry, G N; Prabhakar, S

2011-10-15

A series of isomeric 2-aryl-6,6-dimethyltetrahydro-5-quinolinones (set I) and 2-aryl-7,7-dimethyltetrahydro-5-quinolinones (set II) were studied under positive ion electron ionization (EI) and electrospray ionization (ESI) techniques. Under EI conditions, the molecular ions were found to be less stable in set I isomers, and they resulted in abundant fragment ions, i.e., [M-CH(3)](+), [M-CO](+.), [M-HCO](+), [M-(CH(3),CO)](+), and [M-(CH(3),CH(2)O)](+), when compared with set II isomers. In addition, the set I isomers showed specific fragment ions corresponding to [M-OH](+) and [M-OCH(3)](+). The retro-Diels-Alder (RDA) product ion was always higher in set II isomers. The ESI mass spectra produced [M + H](+) ions, and their decomposition showed favorable loss of CH(3) radical, CH(4) and C(2)H(6) molecules in set I isomers. The set II isomers, however, showed predominant RDA product ions, and specific loss of H(2)O. The selectivity in EI and ESI was attributed to the instability of set I isomers by the presence of a gem-dimethyl group at the α-position, and it was supported by the data from model compounds without a gem-dimethyl group. Density functional theory (DFT) calculations successfully corroborated the fragmentation pathways for diagnostic ions. This study revealed the effect of a gem-dimethyl group located at the α-position to the carbonyl having aromatic/unsaturated carbon on the other side of the carbonyl group. Copyright © 2011 John Wiley & Sons, Ltd.

A qualitative study of amlodipine and its related compounds by electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Gibbons, John; Pugh, Jonathan; Dimopoulos-Italiano, Gina; Pike, Richard

2006-01-01

A comprehensive structural analysis of amlodipine and certain related compounds was performed by electrospray ionization tandem mass spectrometry. Triple quadrupole and quadrupole time-of-flight instruments were used to provide collision-induced dissociation and accurate mass measurement for selected product and second-generation product ions. A unique ion rearrangement was observed, which was found to be characteristic of certain dihydropyridines. This study provides a fundamental understanding of the fragmentation of these compounds. The structural elucidation of an unknown impurity is presented as an example. Copyright (c) 2006 John Wiley & Sons, Ltd.

Laser ablation/ionization studies in a glow discharge

International Nuclear Information System (INIS)

Hess, K.R.; Harrison, W.W.

1985-01-01

The pin cathode glow discharge is used in the laboratory as an atomization/ionization source for a variety of applications, including solids mass spectrometry. Coupled with a tunable dye laser, the glow discharge may also serve as an atom reservoir for resonance ionization mass spectrometry in which the laser ionizes the discharge sputtered atoms. By tightly focusing the laser onto solid samples, various ablation effects may also be investigated. The laser may be used to generate an ionized plasma which may be directly analyzed by mass spectrometry. Alternatively, the ablated neutral atoms may be used in post-ablation excitation/ionization processes, in this case the glow discharge. The results of these investigations are the basis of this paper

Continuous-flow liquid microjunction surface sampling probe connected on-line with high-performance liquid chromatography/mass spectrometry for spatially resolved analysis of small molecules and proteins.

Science.gov (United States)

Van Berkel, Gary J; Kertesz, Vilmos

2013-06-30

A continuous-flow liquid microjunction surface sampling probe extracts soluble material from surfaces for direct ionization and detection by mass spectrometry. Demonstrated here is the on-line coupling of such a probe with high-performance liquid chromatography/mass spectrometry (HPLC/MS) enabling extraction, separation and detection of small molecules and proteins from surfaces in a spatially resolved (~0.5 mm diameter spots) manner. A continuous-flow liquid microjunction surface sampling probe was connected to a six-port, two-position valve for extract collection and injection to an HPLC column. A QTRAP® 5500 hybrid triple quadrupole linear ion trap equipped with a Turbo V™ ion source operated in positive electrospray ionization (ESI) mode was used for all experiments. The system operation was tested with the extraction, separation and detection of propranolol and associated metabolites from drug dosed tissues, caffeine from a coffee bean, cocaine from paper currency, and proteins from dried sheep blood spots on paper. Confirmed in the tissue were the parent drug and two different hydroxypropranolol glucuronides. The mass spectrometric response for these compounds from different locations in the liver showed an increase with increasing extraction time (5, 20 and 40 s). For on-line separation and detection/identification of extracted proteins from dried sheep blood spots, two major protein peaks dominated the chromatogram and could be correlated with the expected masses for the hemoglobin α and β chains. Spatially resolved sampling, separation, and detection of small molecules and proteins from surfaces can be accomplished using a continuous-flow liquid microjunction surface sampling probe coupled on-line with HPLC/MS detection. Published in 2013. This article is a U.S. Government work and is in the public domain in the USA.

Matrix-assisted laser desorption-ionization mass spectrometry peptide mass fingerprinting for proteome analysis: identification efficiency after on-blot or in-gel digestion with and without desalting procedures.

Science.gov (United States)

Lamer, S; Jungblut, P R

2001-03-10

In theory, peptide mass fingerprinting by matrix assisted laser desorption-ionization mass spectrometry (MALDI-MS) has the potential to identify all of the proteins detected by silver staining on gels. In practice, if the genome of the organism investigated is completely sequenced, using current techniques, all proteins stained by Coomassie Brilliant Blue can be identified. This loss of identification sensitivity of ten to hundred-fold is caused by loss of peptides by surface contacts. Therefore, we performed digestion and transfer of peptides in the lower microl range and reduced the number of steps. The peptide mix obtained from in-gel or on-blot digestion was analyzed directly after digestion or after concentration on POROS R2 beads. Eight protein spots of a 2-DE gel from Mycobacterium bovis BCG were identified using these four preparation procedures for MALDI-MS. Overall, on-blot digestion was as effective as in-gel digestion. Whereas higher signal intensities resulted after concentration, hydrophilic peptides are better detected by direct measurement of the peptide mix without POROS R2 concentration.

Phenotypic identification of Porphyromonas gingivalis validated with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

NARCIS (Netherlands)

Rams, Thomas E; Sautter, Jacqueline D; Getreu, Adam; van Winkelhoff, Arie J

OBJECTIVE: Porphyromonas gingivalis is a major bacterial pathogen in human periodontitis. This study used matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry to assess the accuracy of a rapid phenotypic identification scheme for detection of cultivable P.

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.

Stable Chlorine Isotopes and Elemental Chlorine by Thermal Ionization Mass Spectrometry and Ion Chromatography; Martian Meteorites, Carbonaceous Chondrites and Standard Rocks

Science.gov (United States)

Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C.-Y.; Fujitani, T.; Okano, O.

2011-01-01

Recently significantly large mass fractionation of stable chlorine isotopes has been reported for terrestrial and lunar samples [1,2]. In addition, in view of possible early solar system processes [3] and also potential perchlorate-related fluid/microbial activities on the Martian surface [4,5], a large chlorine isotopic fractionation might be expected for some types of planetary materials. Due to analytical difficulties of isotopic and elemental analyses, however, current chlorine analyses for planetary materials are controversial among different laboratories, particularly between IRMS (gas source mass spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1,6,7] for isotopic analyses, as well as between those doing pyrohydrolysis and other groups [i.e. 6,8]. Additional careful investigations of Cl isotope and elemental abundances are required to confirm real chlorine isotope and elemental variations for planetary materials. We have developed a TIMS technique combined with HF-leaching/ion chromatography at NASA JSC that is applicable to analysis of small amounts of meteoritic and planetary materials. We present here results for several standard rocks and meteorites, including Martian meteorites.

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.

Formation of positive cluster ions Li(n) Br (n = 2-7) and ionization energies studied by thermal ionization mass spectrometry.

Science.gov (United States)

Veličković, S R; Đustebek, J B; Veljković, F M; Veljković, M V

2012-05-01

Clusters of the type Li(n)X (X = halides) can be considered as potential building blocks of cluster-assembly materials. In this work, Li(n)Br (n = 2-7) clusters were obtained by a thermal ionization source of modified design and selected by a magnetic sector mass spectrometer. Positive ions of the Li(n)Br (n = 4-7) cluster were detected for the first time. The order of ion intensities was Li(2)Br(+) > Li(4)Br(+) > Li(5)Br(+) > Li(6)Br(+) > Li(3)Br(+). The ionization energies (IEs) were measured and found to be 3.95 ± 0.20 eV for Li(2)Br, 3.92 ± 0.20 eV for Li(3)Br, 3.93 ± 0.20 eV for Li(4)Br, 4.08 ± 0.20 eV for Li(5)Br, 4.14 ± 0.20 eV for Li(6)Br and 4.19 ± 0.20 eV for Li(7)Br. All of these clusters have a much lower ionization potential than that of the lithium atom, so they belong to the superalkali class. The IEs of Li(n)Br (n = 2-4) are slightly lower than those in the corresponding small Li(n) or Li(n)H clusters, whereas the IEs of Li(n)Br are very similar to those of Li(n) or Li(n)H for n = 5 and 6. The thermal ionization source of modified design is an important means for simultaneously obtaining and measuring the IEs of Li(n)Br (n = 2-7) clusters (because their ions are hermodynamically stable with respect to the loss of lithium atoms in the gas phase) and increasingly contributes toward the development of clusters for practical applications. Copyright © 2012 John Wiley & Sons, Ltd.

Development of soft ionization using direct current pulse glow discharge plasma source in mass spectrometry for volatile organic compounds analysis

Science.gov (United States)

Nunome, Yoko; Kodama, Kenji; Ueki, Yasuaki; Yoshiie, Ryo; Naruse, Ichiro; Wagatsuma, Kazuaki

2018-01-01

This study describes an ionization source for mass analysis, consisting of glow discharge plasma driven by a pulsed direct-current voltage for soft plasma ionization, to detect toxic volatile organic compounds (VOCs) rapidly and easily. The novelty of this work is that a molecular adduct ion, in which the parent molecule attaches with an NO+ radical, [M + NO]+, can be dominantly detected as a base peak with little or no fragmentation of them in an ambient air plasma at a pressure of several kPa. Use of ambient air as the discharge plasma gas is suitable for practical applications. The higher pressure in an ambient air discharge provided a stable glow discharge plasma, contributing to the soft ionization of organic molecules. Typical mass spectra of VOCs toluene, benzene, o-xylene, chlorobenzene and n-hexane were observed as [M + NO]+ adduct ion whose peaks were detected at m/z 122, 108, 136, 142 and 116, respectively. The NO generation was also confirmed by emission bands of NO γ-system. The ionization reactions were suggested, such that NO+ radical formed in an ambient air discharge could attach with the analyte molecule.

EVIDENCE FOR DCO+ AS A PROBE OF IONIZATION IN THE WARM DISK SURFACE

International Nuclear Information System (INIS)

Favre, Cécile; Bergin, Edwin A.; Cleeves, L. Ilsedore; Hersant, Franck; Qi, Chunhua; Aikawa, Yuri

2015-01-01

In this Letter, we model the chemistry of DCO + in protoplanetary disks. We find that the overall distribution of the DCO + abundance is qualitatively similar to that of CO but is dominated by a thin layer located at the inner disk surface. To understand its distribution, we investigate the different key gas-phase deuteration pathways that can lead to the formation of DCO + . Our analysis shows that the recent update in the exothermicity of the reaction involving CH 2 D + as a parent molecule of DCO + favors deuterium fractionation in warmer conditions. As a result, the formation of DCO + is enhanced in the inner warm surface layers of the disk where X-ray ionization occurs. Our analysis points out that DCO + is not a reliable tracer of the CO snow line as previously suggested. We thus predict that DCO + is a tracer of active deuterium and, in particular, X-ray ionization of the inner disk

Display of charged ionizing particles

International Nuclear Information System (INIS)

Cano S, D.; Ortiz A, M. D.; Amarillas S, L. E.; Vega C, H. R.

2017-10-01

The human being is exposed to sources of ionizing and non-ionizing radiation, both of natural or anthropogenic origin. None of these, except non-ionizing such as visible light and infrared radiation, can be detected by the sense of sight and touch respectively. The sun emits charged particles with speeds close to the light that interact with the atoms of the gases present in the atmosphere, producing nuclear reactions that in turn produce other particles that reach the surface of the Earth and reach the living beings. On Earth there are natural radioisotopes that, when they disintegrate, emit ionizing radiation that contributes to the dose we receive. A very old system that allows the visualization of the trajectories of the charged ionizing particles is the Fog Chamber that uses a saturated steam that when crossed by particles with mass and charge, as alpha and beta particles produce condensation centers along its path leaves a trace that can be seen. The objective of this work was to build a fog chamber using easily accessible materials. To measure the functioning of the fog chamber, cosmic rays were measured, as well as a source of natural metal uranium. The fog chamber allowed seeing the presence of traces in alcohol vapor that are produced in a random way. Introducing the uranium foil inside the fog chamber, traces of alpha particles whose energy varies from 4 to 5 MeV were observed. (Author)

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.

Dehydrodimerization of pterostilbene during electrospray ionization mass spectrometry

KAUST Repository

Raji, Misjudeen

2013-04-30

RATIONALE Pterostilbene is a member of the hydroxystilbene family of compounds commonly found in plants such as blueberry and grapes. During the analysis of this compound by electrospray ionization mass spectrometry (ESI-MS), an ion was observed that corresponds to the dehydrodimer of pterostilbene in mass-to-charge ratio. Since such unexpected dimerization may lead to decreased monomer signal during quantitative analysis, it was of interest to identify the origin and structure of the observed pterostilbene dimer and examine the experimental conditions that influence its formation. METHODS Liquid Chromatography/Mass Spectrometry (LC/MS), Nuclear Magnetic Resonance (NMR), and High-Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) were used to examine the origin of the dimerization products. The structure of the formed pterostilbene dimer was examined by performing MSn analysis on the dimer ion. Effects of solvent composition, analyte concentration, radical scavenger, and other experimental conditions on the dimerization were also studied. RESULTS LC/MS and NMR analyses clearly showed that the starting solution did not contain the pterostilbene dimer. Solvent type and radical scavenger concentration were found to have pronounced effects on the dimer formation. Particularly, presence of acetonitrile or ammonium acetate had favorable effects on the extent of dimerization during ESI-MS analysis whereas hydroquinone and butylated hydroquinone had negative effects. Dimer formation decreased at high flow rates and when fused-silica capillary was used as the spray needle. CONCLUSIONS The data indicate that this dimerization occurs as a result of solution-phase electrochemical reactions taking place during the electrospray process. A possible structure for this dimer was proposed based on the MSn analysis and was similar to that of the enzymatically derived pterostilbene dehydrodimer already reported in the literature. Copyright © 2013 John Wiley & Sons, Ltd

An energy-filtering device coupled to a quadrupole mass spectrometer for soft-landing molecular ions on surfaces with controlled energy

Energy Technology Data Exchange (ETDEWEB)

Bodin, A.; Laloo, R.; Abeilhou, P.; Guiraud, L.; Gauthier, S.; Martrou, D. [Nanosciences Group, CEMES, CNRS UPR 8011 and University Toulouse III - Paul Sabatier, 29 rue Jeanne Marvig, BP94347, F-31055 Toulouse Cedex 4 (France)

2013-09-15

We have developed an energy-filtering device coupled to a quadrupole mass spectrometer to deposit ionized molecules on surfaces with controlled energy in ultra high vacuum environment. Extensive numerical simulations as well as direct measurements show that the ion beam flying out of a quadrupole exhibits a high-energy tail decreasing slowly up to several hundred eV. This energy distribution renders impossible any direct soft-landing deposition of molecular ions. To remove this high-energy tail by energy filtering, a 127° electrostatic sector and a specific triplet lenses were designed and added after the last quadrupole of a triple quadrupole mass spectrometer. The results obtained with this energy-filtering device show clearly the elimination of the high-energy tail. The ion beam that impinges on the sample surface satisfies now the soft-landing criterion for molecular ions, opening new research opportunities in the numerous scientific domains involving charges adsorbed on insulating surfaces.

Gemini NIFS survey of feeding and feedback processes in nearby active galaxies - II. The sample and surface mass density profiles

Science.gov (United States)

Riffel, R. A.; Storchi-Bergmann, T.; Riffel, R.; Davies, R.; Bianchin, M.; Diniz, M. R.; Schönell, A. J.; Burtscher, L.; Crenshaw, M.; Fischer, T. C.; Dahmer-Hahn, L. G.; Dametto, N. Z.; Rosario, D.

2018-02-01

We present and characterize a sample of 20 nearby Seyfert galaxies selected for having BAT 14-195 keV luminosities LX ≥ 1041.5 erg s-1, redshift z ≤ 0.015, being accessible for observations with the Gemini Near-Infrared Field Spectrograph (NIFS) and showing extended [O III]λ5007 emission. Our goal is to study Active Galactic Nucleus (AGN) feeding and feedback processes from near-infrared integral-field spectra, which include both ionized (H II) and hot molecular (H2) emission. This sample is complemented by other nine Seyfert galaxies previously observed with NIFS. We show that the host galaxy properties (absolute magnitudes MB, MH, central stellar velocity dispersion and axial ratio) show a similar distribution to those of the 69 BAT AGN. For the 20 galaxies already observed, we present surface mass density (Σ) profiles for H II and H2 in their inner ˜500 pc, showing that H II emission presents a steeper radial gradient than H2. This can be attributed to the different excitation mechanisms: ionization by AGN radiation for H II and heating by X-rays for H2. The mean surface mass densities are in the range (0.2 ≤ ΣH II ≤ 35.9) M⊙ pc-2, and (0.2 ≤ ΣH2 ≤ 13.9)× 10-3 M⊙ pc-2, while the ratios between the H II and H2 masses range between ˜200 and 8000. The sample presented here will be used in future papers to map AGN gas excitation and kinematics, providing a census of the mass inflow and outflow rates and power as well as their relation with the AGN luminosity.

A Low-Cost, Simplified Platform of Interchangeable, Ambient Ionization Sources for Rapid, Forensic Evidence Screening on Portable Mass Spectrometric Instrumentation

Directory of Open Access Journals (Sweden)

Patrick W. Fedick

2018-03-01

Full Text Available Portable mass spectrometers (MS are becoming more prevalent due to improved instrumentation, commercialization, and the robustness of new ionization methodologies. To increase utility towards diverse field-based applications, there is an inherent need for rugged ionization source platforms that are simple, yet robust towards analytical scenarios that may arise. Ambient ionization methodologies have evolved to target specific real-world problems and fulfill requirements of the analysis at hand. Ambient ionization techniques continue to advance towards higher performance, with specific sources showing variable proficiency depending on application area. To realize the full potential and applicability of ambient ionization methods, a selection of sources may be more prudent, showing a need for a low-cost, flexible ionization source platform. This manuscript describes a centralized system that was developed for portable MS systems that incorporates modular, rapidly-interchangeable ionization sources comprised of low-cost, commercially-available parts. Herein, design considerations are reported for a suite of ambient ionization sources that can be crafted with minimal machining or customization. Representative spectral data is included to demonstrate applicability towards field processing of forensic evidence. While this platform is demonstrated on portable instrumentation, retrofitting to lab-scale MS systems is anticipated.

Ionization techniques in capillary electrophoresis-mass spectrometry: principles, design, and application.

Science.gov (United States)

Hommerson, Paul; Khan, Amjad M; de Jong, Gerhardus J; Somsen, Govert W

2011-01-01

A major step forward in the development and application of capillary electrophoresis (CE) was its coupling to ESI-MS, first reported in 1987. More than two decades later, ESI has remained the principal ionization technique in CE-MS, but a number of other ionization techniques have also been implemented. In this review the state-of-the-art in the employment of soft ionization techniques for CE-MS is presented. First the fundamentals and general challenges of hyphenating conventional CE and microchip electrophoresis with MS are outlined. After elaborating on the characteristics and role of ESI, emphasis is put on alternative ionization techniques including sonic spray ionization (SSI), thermospray ionization (TSI), atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), matrix-assisted laser desorption ionization (MALDI) and continuous-flow fast atom bombardment (CF-FAB). The principle of each ionization technique is outlined and the experimental set-ups of the CE-MS couplings are described. The strengths and limitations of each ionization technique with respect to CE-MS are discussed and the applicability of the various systems is illustrated by a number of typical examples. Copyright © 2011 Wiley Periodicals, Inc.

[Special application of matrix-assisted laser desorption ionization time-of-flight mass spectrometry in clinical microbiological diagnostics].

Science.gov (United States)

Nagy, Erzsébet; Abrók, Marianna; Bartha, Noémi; Bereczki, László; Juhász, Emese; Kardos, Gábor; Kristóf, Katalin; Miszti, Cecilia; Urbán, Edit

2014-09-21

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry as a new possibility for rapid identification of bacteria and fungi revolutionized the clinical microbiological diagnostics. It has an extreme importance in the routine microbiological laboratories, as identification of the pathogenic species rapidly will influence antibiotic selection before the final determination of antibiotic resistance of the isolate. The classical methods for identification of bacteria or fungi, based on biochemical tests, are influenced by many environmental factors. The matrix-assisted laser desorption ionization time-of-flight mass spectrometry is a rapid method which is able to identify a great variety of the isolated bacteria and fungi based on the composition of conserved ribosomal proteins. Recently several other applications of the method have also been investigated such as direct identification of pathogens from the positive blood cultures. There are possibilities to identify bacteria from the urine samples in urinary tract infection or from other sterile body fluids. Using selective enrichment broth Salmonella sp from the stool samples can be identified more rapidly, too. The extended spectrum beta-lactamase or carbapenemase production of the isolated bacteria can be also detected by this method helping the antibiotic selection in some cases. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry based methods are suitable to investigate changes in deoxyribonucleic acid or ribonucleic acid, to carry out rapid antibiotic resistance determination or other proteomic analysis. The aim of this paper is to give an overview about present possibilities of using this technique in the clinical microbiological routine procedures.

Identification of Guest-Host Inclusion Complexes in the Gas Phase by Electrospray Ionization-Mass Spectrometry

Science.gov (United States)

Mendes, De´bora C.; Ramamurthy, Vaidhyanathan; Da Silva, Jose´ P.

2015-01-01

In this laboratory experiment, students follow a step-by-step procedure to prepare and study guest-host complexes in the gas phase using electrospray ionization-mass spectrometry (ESI-MS). Model systems are the complexes of hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) with the guest 4-styrylpyridine (SP). Aqueous solutions of CB7 or CB8…

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

Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

OpenAIRE

Megumi Sakurai; Taro Sato; Jiawei Xu; Soichi Sato; Tatsuya Fujino

2018-01-01

Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe....

Detection of polychlorinated biphenyls in transformer oils in Vietnam by multiphoton ionization mass spectrometry using a far-ultraviolet femtosecond laser as an ionization source.

Science.gov (United States)

Duong, Vu Thi Thuy; Duong, Vu; Lien, Nghiem Thi Ha; Imasaka, Tomoko; Tang, Yuanyuan; Shibuta, Shinpei; Hamachi, Akifumi; Hoa, Do Quang; Imasaka, Totaro

2016-03-01

Polychlorinated biphenyls (PCBs) in transformer and food oils were measured using gas chromatography combined with multiphoton ionization mass spectroscopy. An ultrashort laser pulse emitting in the far-ultraviolet region was utilized for efficient ionization of the analytes. Numerous signal peaks were clearly observed for a standard sample mixture of PCBs when the third and fourth harmonic emissions (267 and 200nm) of a femtosecond Ti:sapphire laser (800nm) were employed. The signal intensities were found to be greater when measured at 200nm compared with those measured at 267nm, providing lower detection limits especially for highly chlorinated PCBs at shorter wavelengths. After simple pretreatment using disposable columns, PCB congeners were measured and found to be present in the transformer oils used in Vietnam. Copyright © 2015 Elsevier B.V. All rights reserved.

Contact ionization ion source

International Nuclear Information System (INIS)

Hashmi, N.; Van Der Houven Van Oordt, A.J.

1975-01-01

An ion source in which an apertured or foraminous electrode having a multiplicity of openings is spaced from one or more active surfaces of an ionisation electrode, the active surfaces comprising a material capable of ionising by contact ionization a substance to be ionized supplied during operation to the active surface or surfaces comprises means for producing during operation a magnetic field which enables a stable plasma to be formed in the space between the active surface or surfaces and the apertured electrode, the field strength of the magnetic field being preferably in the range between 2 and 8 kilogauss. (U.S.)

The yeast metabolome addressed by electrospray ionization mass spectrometry: Initiation of a mass spectral library and its applications for metabolic footprinting by direct infusion mass spectrometry

DEFF Research Database (Denmark)

Højer-Pedersen, Jesper Juul; Smedsgaard, Jørn; Nielsen, Jens

2008-01-01

Mass spectrometry (MS) has been a major driver for metabolomics, and gas chromatography (GC)-MS has been one of the primary techniques used for microbial metabolomics. The use of liquid chromatography (LC)-MS has however been limited, but electrospray ionization (ESI) is very well suited...... for ionization of microbial metabolites without any previous derivatization needed. To address the capabilities of ESI-MS in detecting the metabolome of Saccharomyces cerevisiae, the in silico metabolome of this organism was used as a template to present a theoretical metabolome. This showed that in combination......, which could be assigned using the in silico metabolome. By this approach metabolic footprinting can advance from a classification method that is used to derive biological information based on guilt-by-association, to a tool for extraction of metabolic differences, which can guide new targeted biological...

Time-of-flight secondary ion mass spectrometry with energetic cluster ion impact ionization for highly sensitive chemical structure characterization

Energy Technology Data Exchange (ETDEWEB)

Hirata, K., E-mail: k.hirata@aist.go.jp [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Saitoh, Y.; Chiba, A.; Yamada, K.; Narumi, K. [Takasaki Advanced Radiation Research Institute (TARRI), Japan Atomic Energy Agency (JAEA), Takasaki, Gumma 370-1292 (Japan)

2013-11-01

Energetic cluster ions with energies of the order of sub MeV or greater were applied to time-of-flight (TOF) secondary ion (SI) mass spectrometry. This gave various advantages including enhancement of SIs required for chemical structure characterization and prevention of charging effects in SI mass spectra for organic targets. We report some characteristic features of TOF SI mass spectrometry using energetic cluster ion impact ionization and discuss two future applications of it.

Comparison of Gas Chromatography-Mass Spectrometry and Gas Chromatography-Tandem Mass Spectrometry with Electron Ionization and Negative-Ion Chemical Ionization for Analyses of Pesticides at Trace Levels in Atmospheric Samples

Directory of Open Access Journals (Sweden)

Renata Raina

2008-01-01

Full Text Available A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS in selected ion monitoring (SIM with gas chromatography-tandem mass spectrometry (GC-MS/MS in selected reaction monitoring (SRM mode with both electron ionization (EI and negative-ion chemical ionization (NCI are presented for over 50 pesticides ranging from organochlorines (OCs, organophosphorus pesticides (OPs and pre-emergent herbicides used in the Canadian prairies (triallate, trifluralin, ethalfluralin. The developed GC-EI/SIM, GC-NCI/SIM, and GC-NCI/SRM are suitable for the determination of pesticides in air sample extracts at concentrations <100 pg µL -1 (< 100 pg m -3 in air. No one method could be used to analyze the range of pre-emergent herbicides, OPs, and OCs investigated. In general GC-NCI/SIM provided the lowest method detection limits (MDLs commonly 2.5-10 pg µL -1 along with best confirmation (<25% RSD of ion ratio, while GC-NCI/SRM is recommended for use where added selectivity or confirmation is required (such as parathion-ethyl, tokuthion, carbofenothion. GC-EI/SRM at concentration < 100 pg µL -1 was not suitable for most pesticides. GC-EI/SIM was more prone to interference issues than NCI methods, but gave good sensitivity (MDLs 1-10 pg µL -1 for pesticides with poor NCI response (OPs: sulfotep, phorate, aspon, ethion, and OCs: alachlor, aldrin, perthane, and DDE, DDD, DDT.

Properties of multiple field ion emitters of tungsten and a simple method for improving their ionization efficiency

International Nuclear Information System (INIS)

Okuyama, F.; Beckey, H.D.

1978-01-01

The ion emission properties of the multiple tungsten emitters developed recently for field ionization mass spectrometry were investigated with the aid of a sector type mass spectrometer at emitter-cathode voltages of 10-15 kV using acetone, n-heptane and benzene as test substances. The emitters, which comprised a 10-μm tungsten filament bearing thickly arrayed microneedles of tungsten, produced very weak and unstable signals at voltages of about 10 kV, but increasing the voltage to 14 kV led to intensifying ion currents high enough to yield mass spectra of satisfactory quality. During the course of the experiments, it was observed that nucleating tungsten carbide particles on the emitter surface by means of a high-field chemical reaction with benzene vapours can significanlty promote the field ionization of gas molecules, presumably as a result of the field enhancement resulting from roughening of the surface. (Auth.)

Calcium isotope effects in ion exchange electromigration and calcium isotope analysis by thermo-ionization mass spectrometry

International Nuclear Information System (INIS)

Fujii, Y.; Hoshi, J.; Iwamoto, H.; Okamoto, M.; Kakihana, H.

1985-01-01

Calcium ions were made to electromigrate along a cation exchange membrane. The abundance ratios of the calcium isotopes (Ca-40, 42, 43, 44, 48) in the migrated bands were measured by thermo-ionization mass spectrometry. The lighter isotopes were enriched in the front part of the migrated band. The increments in the isotope abundance ratios were found to be proportional to the mass difference of the isotopes. The observed epsilon-values per unit mass difference (epsilon/ΔM) were 1.26 x 10 -4 (at 20 0 C), 1.85 x 10 -4 (at 25 0 C) and 2.4 x 10 -4 (at 40 0 C). The mass spectrometry was improved by using a low temperature for the evaporation of CaI 2 . (orig.)

1,8-Bis(dimethylamino)naphthalene/9-aminoacridine: A new binary matrix for lipid fingerprinting of intact bacteria by matrix assisted laser desorption ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Calvano, C.D., E-mail: cosimadamiana.calvano@uniba.it [Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy); Monopoli, A.; Ditaranto, N. [Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy); Palmisano, F. [Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy); Centro Interdipartimentale di Ricerca S.M.A.R.T., Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70126 Bari (Italy)

2013-10-10

Graphical abstract: -- Highlights: •New binary matrix for less ionizable lipid analysis with no interfering peaks. •Combined MALDI and X-ray photoelectron spectroscopy (XPS) analyses. •Fast lipid fingerprint on Gram positive and Gram negative bacteria by MALDI MS. •Mapping of phospholipids by XPS imaging. •Very fast membrane lipid extraction procedure. -- Abstract: The effectiveness of a novel binary matrix composed of 1,8-bis(dimethylamino)naphthalene (DMAN; proton sponge) and 9-aminoacridine (9AA) for the direct lipid analysis of whole bacterial cells by matrix assisted laser desorption ionization mass spectrometry (MALDI MS) is demonstrated. Deprotonated analyte signals nearly free of matrix-related ions were observed in negative ion mode. The effect of the most important factors (laser energy, pulse voltage, DMAN/9AA ratio, analyte/matrix ratio) was investigated using a Box–Behnken response surface design followed by multi-response optimization in order to simultaneously maximize signal-to-noise (S/N) ratio and resolution. The chemical surface composition of single or mixed matrices was explored by X-ray photoelectron spectroscopy (XPS). Moreover, XPS imaging was used to map the spatial distribution of a model phospholipid in single or binary matrices. The DMAN/9AA binary matrix was then successfully applied to the analysis of intact Gram positive (Lactobacillus sanfranciscensis) or Gram negative (Escherichia coli) microorganisms. About fifty major membrane components (free fatty acids, mono-, di- and tri-glycerides, phospholipids, glycolipids and cardiolipins) were quickly and easily detected over a mass range spanning from ca. 200 to ca. 1600 m/z. Moreover, mass spectra with improved S/N ratio (compared to single matrices), reduced chemical noise and no formation of matrix-clusters were invariably obtained demonstrating the potential of this binary matrix to improve sensitivity.

1,8-Bis(dimethylamino)naphthalene/9-aminoacridine: A new binary matrix for lipid fingerprinting of intact bacteria by matrix assisted laser desorption ionization mass spectrometry

International Nuclear Information System (INIS)

Calvano, C.D.; Monopoli, A.; Ditaranto, N.; Palmisano, F.

2013-01-01

Graphical abstract: -- Highlights: •New binary matrix for less ionizable lipid analysis with no interfering peaks. •Combined MALDI and X-ray photoelectron spectroscopy (XPS) analyses. •Fast lipid fingerprint on Gram positive and Gram negative bacteria by MALDI MS. •Mapping of phospholipids by XPS imaging. •Very fast membrane lipid extraction procedure. -- Abstract: The effectiveness of a novel binary matrix composed of 1,8-bis(dimethylamino)naphthalene (DMAN; proton sponge) and 9-aminoacridine (9AA) for the direct lipid analysis of whole bacterial cells by matrix assisted laser desorption ionization mass spectrometry (MALDI MS) is demonstrated. Deprotonated analyte signals nearly free of matrix-related ions were observed in negative ion mode. The effect of the most important factors (laser energy, pulse voltage, DMAN/9AA ratio, analyte/matrix ratio) was investigated using a Box–Behnken response surface design followed by multi-response optimization in order to simultaneously maximize signal-to-noise (S/N) ratio and resolution. The chemical surface composition of single or mixed matrices was explored by X-ray photoelectron spectroscopy (XPS). Moreover, XPS imaging was used to map the spatial distribution of a model phospholipid in single or binary matrices. The DMAN/9AA binary matrix was then successfully applied to the analysis of intact Gram positive (Lactobacillus sanfranciscensis) or Gram negative (Escherichia coli) microorganisms. About fifty major membrane components (free fatty acids, mono-, di- and tri-glycerides, phospholipids, glycolipids and cardiolipins) were quickly and easily detected over a mass range spanning from ca. 200 to ca. 1600 m/z. Moreover, mass spectra with improved S/N ratio (compared to single matrices), reduced chemical noise and no formation of matrix-clusters were invariably obtained demonstrating the potential of this binary matrix to improve sensitivity

In situ analysis of corrosion inhibitors using a portable mass spectrometer with paper spray ionization.

Science.gov (United States)

Jjunju, Fred P M; Li, Anyin; Badu-Tawiah, Abraham; Wei, Pu; Li, Linfan; Ouyang, Zheng; Roqan, Iman S; Cooks, R Graham

2013-07-07

Paper spray (PS) ambient ionization is implemented using a portable mass spectrometer and applied to the detection of alkyl quaternary ammonium salts in a complex oil matrix. These salts are commonly used as active components in the formulation of corrosion inhibitors. They were identified in oil and confirmed by their fragmentation patterns recorded using tandem mass spectrometry (MS/MS). The cations of alkyl and benzyl-substituted quaternary ammonium salts showed characteristic neutral losses of CnH2n (n carbon number of the longest chain) and C7H8, respectively. Individual quaternary ammonium compounds were detected at low concentrations (oil samples without prior sample preparation or pre-concentration was also demonstrated using a home-built miniature mass spectrometer at levels below 1 ng μL(-1).

Atmospheric Pressure-Thermal Desorption (AP-TD)/Electrospray Ionization-Mass Spectrometry for the Rapid Analysis of Bacillus Spores

Science.gov (United States)

A technique is described where an atmospheric pressure-thermal desorption (AP-TD) device and electrospray ionization (ESI)-mass spectrometry are coupled and used for the rapid analysis of Bacillus spores in complex matrices. The resulting AP-TD/ESI-MS technique combines the generation of volatile co...

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...

Dissociation mechanism of HNIW ions investigated by chemical ionization and electron impact mass spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yang, Rongjie; Xiao, Hemiao [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2006-04-15

Chemical Ionization (CI) with Collision-Induced Dissociation (CID) spectroscopy and Electron Impacting (EI) with metastable Mass analyzed Ion Kinetic Energy (MIKE) spectroscopy have been applied to study ionic dissociations of Hexanitrohexaazaisowurtzitane (HNIW). Similarities and differences between EI/MIKE and CI/CID mass spectra of HNIW were analyzed. In EI mass spectra, the ions [HNIW-n NO{sub 2}]{sup +} (n=2-5), such as the ion at m/z 347, were less frequent (1-2% relative abundance), but in CI mass spectra, these ions were very abundant. For some ions of large molar mass from HNIW, their dissociations pathways from parent ions to daughter ions were built according to CID and MIKE spectra. Molecular ions of HNIW with a protonated nitro group at five-member ring seem more stable than at six-member ring. The HNIW ions losing five of six nitro groups are very stable based on CID spectra, which agrees with some research results for thermal decomposition of HNIW in literature. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

The mass dependence of the signal peak height of a Bragg-curve ionization chamber

International Nuclear Information System (INIS)

Shenhav, N.J.; Stelzer, H.

1985-01-01

The Bragg-curve detector of the parallel plate ionization chamber type generates a signal that is a distorted replica of the original Bragg-curve. In result of this distortion, the signal peak height is not only a function of the atomic number of the heavy ion, as it is often stated, but also of the particle mass. This mass effect was studied with the aid of computer simulation, and it was found to be dependent on the Frisch grid to anode gap width and on the detector gas. The charge resolution of the detector is affected very significantly by this mass dependence of the signal peak height. Therefore, a careful selection of the detector gas and the grid to anode gap width is necessary, if good charge resolution over a wide range of heavy ions is required. (orig.)

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

Science.gov (United States)

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

Three-Dimensional Imaging of Lipids and Metabolites in Tissues by Nanospray Desorption Electrospray Ionization Mass Spectrometry

Energy Technology Data Exchange (ETDEWEB)

Lanekoff, Ingela T.; Burnum-Johnson, Kristin E.; Thomas, Mathew; Cha, Jeeyeon; Dey, Sudhansu K.; yang, Pengxiang; Prieto, Mari; Laskin, Julia

2015-03-01

Abstract Three-dimensional (3D) imaging of tissue sections is a new frontier in mass spectrometry imaging (MSI). Here we report on fast 3D imaging of lipids and metabolites associated with mouse uterine decidual cells and embryo at the implantation site on day 6 of pregnancy. 2D imaging of 16-20 serial tissue sections deposited on the same glass slide was performed using nanospray desorption electrospray ionization (nano-DESI) – an ambient ionization technique that enables sensitive localized analysis of analytes on surfaces without special sample pre-treatment. In this proof-of-principle study, nano-DESI was coupled to a high-resolution Q-Exactive instrument operated at high repetition rate of >5 Hz with moderate mass resolution of 35,000 (m/Δm at m/z 200), which enabled acquisition of the entire 3D image with a spatial resolution of ~150 μm in less than 4.5 hours. The results demonstrate localization of acetylcholine in the primary decidual zone (PDZ) of the implantation site throughout the depth of the tissue examined, indicating an important role of this signaling molecule in decidualization. Choline and phosphocholine – metabolites associated with cell growth – are enhanced in the PDZ and abundant in other cellular regions of the implantation site. Very different 3D distributions were obtained for fatty acids (FA), oleic acid and linoleic acid (FA 18:1 and FA 18:2), differing only by one double bond. Localization of FA 18:2 in the PDZ indicates its important role in decidualization while FA 18:1 is distributed more evenly throughout the tissue. In contrast, several lysophosphatidylcholines (LPC) observed in this study show donut-like distributions with localization around the PDZ. Complementary distributions with minimal overlap were observed for LPC 18:0 and FA 18:2 while the 3D image of the potential precursor phosphatidylcholine (PC 36:2) showed a significant overlap with both LPC 18:0 and FA 18:2.

Detection of Metastatic Breast and Thyroid Cancer in Lymph Nodes by Desorption Electrospray Ionization Mass Spectrometry Imaging

Science.gov (United States)

Zhang, Jialing; Feider, Clara L.; Nagi, Chandandeep; Yu, Wendong; Carter, Stacey A.; Suliburk, James; Cao, Hop S. Tran; Eberlin, Livia S.

2017-06-01

Ambient ionization mass spectrometry has been widely applied to image lipids and metabolites in primary cancer tissues with the purpose of detecting and understanding metabolic changes associated with cancer development and progression. Here, we report the use of desorption electrospray ionization mass spectrometry (DESI-MS) to image metastatic breast and thyroid cancer in human lymph node tissues. Our results show clear alterations in lipid and metabolite distributions detected in the mass spectra profiles from 42 samples of metastatic thyroid tumors, metastatic breast tumors, and normal lymph node tissues. 2D DESI-MS ion images of selected molecular species allowed discrimination and visualization of specific histologic features within tissue sections, including regions of metastatic cancer, adjacent normal lymph node, and fibrosis or adipose tissues, which strongly correlated with pathologic findings. In thyroid cancer metastasis, increased relative abundances of ceramides and glycerophosphoinisitols were observed. In breast cancer metastasis, increased relative abundances of various fatty acids and specific glycerophospholipids were seen. Trends in the alterations in fatty acyl chain composition of lipid species were also observed through detailed mass spectra evaluation and chemical identification of molecular species. The results obtained demonstrate DESI-MSI as a potential clinical tool for the detection of breast and thyroid cancer metastasis in lymph nodes, although further validation is needed. [Figure not available: see fulltext.

Electrospray Ionization Mass Spectrometry: From Cluster Ions to Toxic metal Ions in Biology

Energy Technology Data Exchange (ETDEWEB)

Lentz, Nicholas B. [Iowa State Univ., Ames, IA (United States)

2007-01-01

This dissertation focused on using electrospray ionization mass spectrometry to study cluster ions and toxic metal ions in biology. In Chapter 2, it was shown that primary, secondary and quarternary amines exhibit different clustering characteristics under identical instrument conditions. Carbon chain length also played a role in cluster ion formation. In Chapters 3 and 4, the effects of solvent types/ratios and various instrumental parameters on cluster ion formation were examined. It was found that instrument interface design also plays a critical role in the cluster ion distribution seen in the mass spectrum. In Chapter 5, ESI-MS was used to investigate toxic metal binding to the [Gln¹¹]-amyloid β-protein fragment (1-16). Pb and Cd bound stronger than Zn, even in the presence of excess Zn. Hg bound weaker than Zn. There are endless options for future work on cluster ions. Any molecule that is poorly ionized in positive ion mode can potentially show an increase in ionization efficiency if an appropriate anion is used to produce a net negative charge. It is possible that drug protein or drug/DNA complexes can also be stabilized by adding counter-ions. This would preserve the solution characteristics of the complex in the gas phase. Once in the gas phase, CID could determine the drug binding location on the biomolecule. There are many research projects regarding toxic metals in biology that have yet to be investigated or even discovered. This is an area of research with an almost endless future because of the changing dynamics of biological systems. What is deemed safe today may show toxic effects in the future. Evolutionary changes in protein structures may render them more susceptible to toxic metal binding. As the understanding of toxicity evolves, so does the demand for new toxic metal research. New instrumentation designs and software make it possible to perform research that could not be done in the past. What was undetectable yesterday will

Electrostatic-spray ionization mass spectrometry sniffing for perfume fingerprinting.

Science.gov (United States)

Tobolkina, Elena; Qiao, Liang; Xu, Guobin; Girault, Hubert H

2013-11-15

The perfume market is growing significantly, and it is easy to find imitative fragrances of probably all types of perfume. Such imitative fragrances are usually of lower quality than the authentic ones, creating a possible threat for perfume companies. Therefore, it is important to develop efficient chemical analysis techniques to screen rapidly perfume samples. Electrostatic-spray ionization (ESTASI) was used to analyze directly samples sprayed or deposited on different types of paper. A linear ion trap mass spectrometer was used to detect the ions produced by ESTASI with a modified extended transfer capillary for 'sniffing' ions from the paper. Several commercial perfumes and a model perfume were analyzed by ESTASI-sniffing. The results obtained by paper ESTASI-MS of commercial fragrances were compared with those obtained from ESI-MS. In addition, a commercial fragrance was first nebulized on the hand and then soaked up by blotting paper, which was afterwards placed on an insulating plate for ESTASI-MS analysis. Analysis of peptides and proteins was also performed to show that the paper ESTASI-MS could be used for samples with very different molecular masses. Paper ESTASI-MS yields a rapid fingerprinting characterization of perfume fragrances, avoiding time-consuming sample-preparation steps, and thereby performing a rapid screening in a few seconds. Copyright © 2013 John Wiley & Sons, Ltd.

Study of Low Work Function Materials for Hot Cavity Resonance Ionization Laser Ion Sources

CERN Document Server

Catherall, R; Fedosseev, V; Marsh, B; Mattolat, C; Menna, Mariano; Österdahl, F; Raeder, S; Schwellnus, F; Stora, T; Wendt, K; CERN. Geneva. AB Department

2008-01-01

The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization on the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high-temperature, low-work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE / CERN, Geneva and RISIKO / University of Mainz.

Study of low work function materials for hot cavity resonance ionization laser ion sources

CERN Document Server

Schwellnus, F; Crepieux, B; Fedosseev, V N; Marsh, B A; Mattolat, Ch; Menna, M; Österdahl, F K; Raeder, S; Stora, T; Wendta, K

2009-01-01

The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization of the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high temperature, low work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place at the off-line mass separators at ISOLDE/CERN, Geneva and RISIKO/University of Mainz.

Matrix-assisted laser desorption/ionization time-of-flight and nano-electrospray ionization ion trap mass spectrometric characterization of 1-cyano-2-substituted-benz[f]isoindole derivatives of peptides for fluorescence detection

DEFF Research Database (Denmark)

Linnemayr, K; Brückner, A; Körner, R

1999-01-01

A series of hexa- to decapeptides (molecular mass range 800-1200) were labeled with naphthalene-2,3-dicarboxaldehyde, which preferentially reacts with the primary amino groups of a peptide. A highly stable peptide conjugate is formed, which allows selective analysis by fluorescence at excitation...... and emission wavelengths of 420 and 490 nm, respectively. After removal of unreacted compounds, the peptide conjugates were characterized by matrix-assisted laser desorption/ionization (MALDI) time-of-flight and nano-electrospray ionization (ESI) ion trap mass spectrometry. They readily form both [M + H]+ ions...... by MALDI and both [M + H]+ and [M + 2H]2+ ions by ESI. Furthermore, the fragmentation behavior of the N-terminally tagged peptides, exhibiting an uncharged N-terminus, was investigated applying post-source decay fragmentation with a curved field reflector and collision-induced dissociation...

Isotopic analysis of boron by thermal ionization mass spectrometry

International Nuclear Information System (INIS)

Kakazu, M.H.; Sarkis, J.E.S.; Souza, I.M.S.

1991-07-01

This paper presents a methodology for isotopic analysis of boron by thermal ionization mass spectrometry technique through the ion intensity measurement of Na 2 BO + 2 in H 3 BO 3 , B o and B 4 C. The samples were loaded on single tantalum filaments by different methods. In the case of H 3 BO 3 , the method of neutralization with NaOH was used. For B 4 C the alcaline fusion with Na 2 CO 3 and for B o dissolution with 1:1 nitric sulfuric acid mixture followed by neutralization with NaOH was used. The isotopic ratio measurements were obtained by the use of s Faraday cup detector with external precision of ±0,4% and accuracy of ±0,1%, relative to H 3 BO 3 isotopic standard NBS 951. The effects of isotopic fractionation was studied in function of the time during the analyses and the different chemical forms of deposition. (author)

Detection of Bacteriocins by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

OpenAIRE

Rose, Natisha L.; Sporns, Peter; McMullen, Lynn M.

1999-01-01

The use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the detection of bacteriocins was investigated. A 30-s water wash of the sample on the MALDI-TOF MS probe was effective in removing contaminants of the analyte. This method was used for rapid detection of nisin, pediocin, brochocin A and B, and enterocin A and B from culture supernatants and for detection of enterocin B throughout its purification.

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...

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 of High Resolution Resonance Ionization Mass Spectrometry for Neutron Dosimetry Technique with93Nb(n,n'93mNb Reaction

Directory of Open Access Journals (Sweden)

Tomita Hideki

2016-01-01

Full Text Available We have proposed an advanced technique to measure the 93mNb yield precisely by Resonance Ionization Mass Spectrometry, instead of conventional characteristic X-ray spectroscopy. 93mNb-selective resonance ionization is achievable by distinguishing the hyperfine splitting of the atomic energy levels between 93Nb and 93mNb at high resolution. In advance of 93mNb detection, we could successfully demonstrate high resolution resonant ionization spectroscopy of stable 93Nb using an all solid-state, narrow-band and tunable Ti:Sapphire laser system operated at 1 kHz repetition rate.

29 CFR 1910.1096 - Ionizing radiation.

Science.gov (United States)

2010-07-01

... 29 Labor 6 2010-07-01 2010-07-01 false Ionizing radiation. 1910.1096 Section 1910.1096 Labor... Ionizing radiation. (a) Definitions applicable to this section. (1) Radiation includes alpha rays, beta... the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the...

MoS_2/Ag nanohybrid: A novel matrix with synergistic effect for small molecule drugs analysis by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Zhao, Yaju; Deng, Guoqing; Liu, Xiaohui; Sun, Liang; Li, Hui; Cheng, Quan; Xi, Kai; Xu, Danke

2016-01-01

This paper reports a facile synthesis of molybdenum disulfide nanosheets/silver nanoparticles (MoS_2/Ag) hybrid and its use as an effective matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The nanohybrid exerts a strong synergistic effect, leading to high performance detection of small molecule analytes including amino acids, peptides, fatty acids and drugs. The enhancement of laser desorption/ionization (LDI) efficiency is largely attributed to the high surface roughness and large surface area for analyte adsorption, better dispersibility, increased thermal conductivity and enhanced UV energy absorption as compared to pure MoS_2. Moreover, both Ag nanoparticles and the edge of the MoS_2 layers function as deprotonation sites for proton capture, facilitating the charging process in negative ion mode and promoting formation of negative ions. As a result, the MoS_2/Ag nanohybrid proves to be a highly attractive matrix in MALDI-TOF MS, with desired features such as high desorption/ionization efficiency, low fragmentation interference, high salt tolerance, and no sweet-spots for mass signal. These characteristic properties allowed for simultaneous analysis of eight different drugs and quantification of acetylsalicylic acid in the spiked human serum. This work demonstrates for the first time the fabrication and application of a novel MoS_2/Ag hybrid, and provides a new platform for use in the rapid and high throughput analysis of small molecules by mass spectrometry. - Highlights: • MoS_2/Ag nanohybrid was applied as a novel matrix in negative-ion MALDI-TOF MS. • The MoS_2/Ag nanohybrid exerted synergistic effect on the detection of small molecules. • The MoS_2/Ag nanohybrid showed good signal reproducibility and low background interferences comparing to organic matrices. • MoS_2/Ag allows simultaneous analysis of multiple drugs and quantification of acetylsalicylic acid in spiked serum samples.

Mass spectrometry of acoustically levitated droplets.

Science.gov (United States)

Westphall, Michael S; Jorabchi, Kaveh; Smith, Lloyd M

2008-08-01

Containerless sample handling techniques such as acoustic levitation offer potential advantages for mass spectrometry, by eliminating surfaces where undesired adsorption/desorption processes can occur. In addition, they provide a unique opportunity to study fundamental aspects of the ionization process as well as phenomena occurring at the air-droplet interface. Realizing these advantages is contingent, however, upon being able to effectively interface levitated droplets with a mass spectrometer, a challenging task that is addressed in this report. We have employed a newly developed charge and matrix-assisted laser desorption/ionization (CALDI) technique to obtain mass spectra from a 5-microL acoustically levitated droplet containing peptides and an ionic matrix. A four-ring electrostatic lens is used in conjunction with a corona needle to produce bursts of corona ions and to direct those ions toward the droplet, resulting in droplet charging. Analyte ions are produced from the droplet by a 337-nm laser pulse and detected by an atmospheric sampling mass spectrometer. The ion generation and extraction cycle is repeated at 20 Hz, the maximum operating frequency of the laser employed. It is shown in delayed ion extraction experiments that both positive and negative ions are produced, behavior similar to that observed for atmospheric pressure matrix-assisted laser absorption/ionization. No ion signal is observed in the absence of droplet charging. It is likely, although not yet proven, that the role of the droplet charging is to increase the strength of the electric field at the surface of the droplet, reducing charge recombination after ion desorption.

Benefits of 2.94 μm infrared matrix-assisted laser desorption/ionization for analysis of labile molecules by Fourier transform mass spectrometry

DEFF Research Database (Denmark)

Budnik, Bogdan A.; Jensen, Kenneth Bendix; Jørgensen, Thomas J. D.

2000-01-01

A 2.94 microm Er:YAG laser was used together with a commercial Fourier transform mass spectrometer to study labile biomolecules. The combination has shown superior performance over conventional 337 nm ultraviolet matrix-assisted laser desorption/ionization (UV-MALDI) Fourier transform mass...

Extending and refining the mass surface around $^{208}$Pb by high-precision Penning-trap mass spectrometry with ISOLTRAP

CERN Multimedia

Herfurth, F; Stora, T; Blaum, K; Beck, D; Kowalska, M; Schwarz, S; Stanja, J; Herlert, A J; Yamaguchi, T

We propose high-precision mass spectrometry of nuclides around the doubly magic $^{208}$Pb. On the neutron-rich side, we aim to extend the knowledge of Fr, At, Hg, and Au masses to study the robustness of the N = 126 shell closure and to provide mass data necessary for modeling the rapid-neutron-capture process. On the proton-rich side, we aim at high-resolution mass spectrometry of selected Au, At, and Fr isotopes to verify the predicted existence of very low-lying isomeric states. The proposal will make use of newly-available laser-ionization schemes for Au and At. Finally, the recently implemented multi-reflection time-of-flight mass separator for auxiliary isobaric purification now allows measurements which were not feasible before.

Electron impact ionization of the gas-phase sorbitol

Science.gov (United States)

Chernyshova, Irina; Markush, Pavlo; Zavilopulo, Anatoly; Shpenik, Otto

2015-03-01

Ionization and dissociative ionization of the sorbitol molecule by electron impact have been studied using two different experimental methods. In the mass range of m/ z = 10-190, the mass spectra of sorbitol were recorded at the ionizing electron energies of 70 and 30 eV. The ion yield curves for the fragment ions have been analyzed and the appearance energies of these ions have been determined. The relative total ionization cross section of the sorbitol molecule was measured using monoenergetic electron beam. Possible fragmentation pathways for the sorbitol molecule were proposed.

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.

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.

Planar Functionalized Surfaces for Direct Immunoaffinity Desorption/Ionization Mass Spectrometry

Czech Academy of Sciences Publication Activity Database

Pompach, Petr; Kavan, Daniel; Benada, Oldřich; Růžička, V.; Volný, M.; Novák, Petr

2016-01-01

Roč. 62, č. 1 (2016), s. 270-278 ISSN 0009-9147 R&D Projects: GA MŠk LO1509; GA MŠk(CZ) EE2.3.30.0003; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388971 Keywords : TREATED METAL-SURFACE * IN-SITU ENRICHMENT * ELECTROSPRAY DEPOSITION Subject RIV: CE - Biochemistry Impact factor: 8.008, year: 2016

Identification of volatile and semivolatile compounds in chemical ionization GC-MS using a mass-to-structure (MTS) Search Engine with integral isotope pattern ranking.

Science.gov (United States)

Liao, Wenta; Draper, William M

2013-02-21

The mass-to-structure or MTS Search Engine is an Access 2010 database containing theoretical molecular mass information for 19,438 compounds assembled from common sources such as the Merck Index, pesticide and pharmaceutical compilations, and chemical catalogues. This database, which contains no experimental mass spectral data, was developed as an aid to identification of compounds in atmospheric pressure ionization (API)-LC-MS. This paper describes a powerful upgrade to this database, a fully integrated utility for filtering or ranking candidates based on isotope ratios and patterns. The new MTS Search Engine is applied here to the identification of volatile and semivolatile compounds including pesticides, nitrosoamines and other pollutants. Methane and isobutane chemical ionization (CI) GC-MS spectra were obtained from unit mass resolution mass spectrometers to determine MH(+) masses and isotope ratios. Isotopes were measured accurately with errors of Search Engine and details performance testing with over 50 model compounds.

Analysis of selected antibiotics in surface freshwater and seawater using direct injection in liquid chromatography electrospray ionization tandem mass spectrometry.

Science.gov (United States)

Bayen, Stéphane; Yi, Xinzhu; Segovia, Elvagris; Zhou, Zhi; Kelly, Barry C

2014-04-18

Emerging contaminants such as antibiotics have received recent attention as they have been detected in natural waters and health concerns over potential antibiotic resistance. With the purpose to investigate fast and high-throughput analysis, and eventually the continuous on-line analysis of emerging contaminants, this study presents results on the analysis of seven selected antibiotics (sulfadiazine, sulfamethazine, sulfamerazine, sulfamethoxazole, chloramphenicol, lincomycin, tylosin) in surface freshwater and seawater using direct injection of a small sample volume (20μL) in liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Notably, direct injection of seawater in the LC-ESI-MS/MS was made possible on account of the post-column switch on the system, which allows diversion of salt-containing solutions flushed out of the column to the waste. Mean recoveries based on the isotope dilution method average 95±14% and 96±28% amongst the compounds for spiked freshwater and seawater, respectively. Linearity across six spiking levels was assessed and the response was linear (r(2)>0.99) for all compounds. Direct injection concentrations were compared for real samples to those obtained with the conventional SPE-based analysis and both techniques concurs on the presence/absence and levels of the compounds in real samples. These results suggest direct injection is a reliable method to detect antibiotics in both freshwater and seawater. Method detection limits for the direct injection technique (37pg/L to 226ng/L in freshwater, and from 16pg/to 26ng/L in seawater) are sufficient for a number of environmental applications, for example the fast screening of water samples for ecological risk assessments. In the present study of real samples, this new method allowed for example the positive detection of some compounds (e.g. lincomycin) down to the sub ng/L range. The direct injection method appears to be relatively cheaper and faster

Protein profiling of single epidermal cell types from Arabidopsis thaliana using surface-enhanced laser desorption and ionization technology.

Science.gov (United States)

Ebert, Berit; Melle, Christian; Lieckfeldt, Elke; Zöller, Daniela; von Eggeling, Ferdinand; Fisahn, Joachim

2008-08-25

Here, we describe a novel approach for investigating differential protein expression within three epidermal cell types. In particular, 3000 single pavement, basal, and trichome cells from leaves of Arabidopsis thaliana were harvested by glass micro-capillaries. Subsequently, these single cell samples were joined to form pools of 100 individual cells and analyzed using the ProteinChip technology; SELDI: surface-enhanced laser desorption and ionization. As a result, numerous protein signals that were differentially expressed in the three epidermal cell types could be detected. One of these proteins was characterized by tryptical digestion and subsequent identification via tandem quadrupole-time of flight (Q-TOF) mass spectrometry. Down regulation of this sequenced small subunit precursor of ribulose-1,5 bisphosphate carboxylase(C) oxygenase(O) (RuBisCo) in trichome and basal cells indicates the sink status of these cell types that are located on the surface of A. thaliana source leaves. Based on the obtained protein profiles, we suggest a close functional relationship between basal and trichome cells at the protein level.

Development of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) for plant metabolite analysis

Energy Technology Data Exchange (ETDEWEB)

Korte, Andrew R [Iowa State Univ., Ames, IA (United States)

2014-12-01

This thesis presents efforts to improve the methodology of matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) as a method for analysis of metabolites from plant tissue samples. The first chapter consists of a general introduction to the technique of MALDI-MSI, and the sixth and final chapter provides a brief summary and an outlook on future work.

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 Comparison of Alternating Current and Direct Current Electrospray Ionization for Mass Spectrometry

Science.gov (United States)

Sarver, Scott A.; Chetwani, Nishant; Dovichi, Norman J.; Go, David B.; Gartner, Carlos A.

2014-04-01

A series of studies comparing the performance of alternating current electrospray ionization (AC ESI) mass spectrometry (MS) and direct current electrospray ionization (DC ESI) MS have been conducted, exploring the absolute signal intensity and signal-to-background ratios produced by both methods using caffeine and a model peptide as targets. Because the high-voltage AC signal was more susceptible to generating gas discharges, the operating voltage range of AC ESI was significantly smaller than that for DC ESI, such that the absolute signal intensities produced by DC ESI at peak voltages were one to two orders of magnitude greater than those for AC ESI. Using an electronegative nebulizing gas, sulfur hexafluoride (SF6), instead of nitrogen (N2) increased the operating range of AC ESI by ~50 %, but did not appreciably improve signal intensities. While DC ESI generated far greater signal intensities, both ionization methods produced comparable signal-to-background noise, with AC ESI spectra appearing qualitatively cleaner. A quantitative calibration analysis was performed for two analytes, caffeine and the peptide MRFA. AC ESI utilizing SF6 outperforms all other techniques for the detection of MRFA, producing chromatographic limits of detection nearly one order of magnitude lower than that of DC ESI utilizing N2, and one-half that of DC ESI utilizing SF6. However, DC ESI outperforms AC ESI for the analysis of caffeine, indicating that improvements in spectral quality may benefit certain compounds or classes of compounds, on an individual basis.

Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

Energy Technology Data Exchange (ETDEWEB)

Garcia de Abajo, F J [Dept. de Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, Univ. del Pais Vasco, San Sebastian (Spain); Pitarke, J M [Materia Kondentsatuaren Fisika Saila, Zientzi Fakultatea, Euskal Herriko Univ., Bilbo (Spain)

1994-05-01

The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

Resonant coherent ionization in grazing ion/atom-surface collisions at high velocities

International Nuclear Information System (INIS)

Garcia de Abajo, F.J.; Pitarke, J.M.

1994-01-01

The resonant coherent interaction of a fast ion/atom with an oriented crystal surface under grazing incidence conditions is shown to contribute significantly to ionize the probe for high enough velocities and motion along a random direction. The dependence of this process on both the distance to the surface and the velocity of the projectile is studied in detail. We focus on the case of hydrogen moving with a velocity above 2 a.u. Comparison with other mechanisms of charge transfer, such as capture from inner shells of the target atoms, permits us to draw some conclusions about the charge state of the outgoing projectiles. (orig.)

Electron ionization and dissociation of aliphatic amino acids

Science.gov (United States)

Papp, P.; Shchukin, P.; Kočíšek, J.; Matejčík, Š.

2012-09-01

We present experimental and theoretical study of electron ionization and dissociative ionization to the gas phase amino acids valine, leucine, and isoleucine. A crossed electron/molecular beams technique equipped with quadrupole mass analyzer has been applied to measure mass spectra and ion efficiency curves for formation of particular ions. From experimental data the ionization energies of the molecules and the appearance energies of the fragment ions were determined. Ab initio calculations (Density Functional Theory and G3MP2 methods) were performed in order to calculate the fragmentation paths and interpret the experimental data. The experimental ionization energies of parent molecules [P]+ 8.91 ± 0.05, 8.85 ± 0.05, and 8.79 ± 0.05 eV and G3MP2 ionization energies (adiabatic) of 8.89, 8.88, and 8.81 eV were determined for valine, leucine, and isoleucine, respectively, as well as the experimental and theoretical threshold energies for dissociative ionization channels. The comparison of experimental data with calculations resulted in identification of the ions as well as the neutral fragments formed in the dissociative reactions. Around 15 mass/charge ratio fragments were identified from the mass spectra by comparison of experimental appearance energies with calculated reaction enthalpies for particular dissociative reactions.

Tissue spray ionization mass spectrometry for rapid recognition of human lung squamous cell carcinoma

Science.gov (United States)

Wei, Yiping; Chen, Liru; Zhou, Wei; Chingin, Konstantin; Ouyang, Yongzhong; Zhu, Tenggao; Wen, Hua; Ding, Jianhua; Xu, Jianjun; Chen, Huanwen

2015-05-01

Tissue spray ionization mass spectrometry (TSI-MS) directly on small tissue samples has been shown to provide highly specific molecular information. In this study, we apply this method to the analysis of 38 pairs of human lung squamous cell carcinoma tissue (cancer) and adjacent normal lung tissue (normal). The main components of pulmonary surfactants, dipalmitoyl phosphatidylcholine (DPPC, m/z 757.47), phosphatidylcholine (POPC, m/z 782.52), oleoyl phosphatidylcholine (DOPC, m/z 808.49), and arachidonic acid stearoyl phosphatidylcholine (SAPC, m/z 832.43), were identified using high-resolution tandem mass spectrometry. Monte Carlo sampling partial least squares linear discriminant analysis (PLS-LDA) was used to distinguish full-mass-range mass spectra of cancer samples from the mass spectra of normal tissues. With 5 principal components and 30 - 40 Monte Carlo samplings, the accuracy of cancer identification in matched tissue samples reached 94.42%. Classification of a tissue sample required less than 1 min, which is much faster than the analysis of frozen sections. The rapid, in situ diagnosis with minimal sample consumption provided by TSI-MS is advantageous for surgeons. TSI-MS allows them to make more informed decisions during surgery.

Spatially resolved protein hydrogen exchange measured by subzero-cooled chip-based nanoelectrospray ionization tandem mass spectrometry

DEFF Research Database (Denmark)

Amon, Sabine; Trelle, Morten B; Jensen, Ole N

2012-01-01

. After a given period of deuteration, the exchange reaction is quenched by acidification (pH 2.5) and cooling (0 °C) and the deuterated protein (or a digest thereof) is analyzed by mass spectrometry. The unavoidable loss of deuterium (back-exchange) that occurs under quench conditions is undesired...... as it leads to loss of information. Here we describe the successful application of a chip-based nanoelectrospray ionization mass spectrometry top-down fragmentation approach based on cooling to subzero temperature (-15 °C) which reduces the back-exchange at quench conditions to very low levels. For example...

Real Time Monitoring of Containerless Microreactions in Acoustically Levitated Droplets via Ambient Ionization Mass Spectrometry.

Science.gov (United States)

Crawford, Elizabeth A; Esen, Cemal; Volmer, Dietrich A

2016-09-06

Direct in-droplet (in stillo) microreaction monitoring using acoustically levitated micro droplets has been achieved by combining acoustic (ultrasonic) levitation for the first time with real time ambient tandem mass spectrometry (MS/MS). The acoustic levitation and inherent mixing of microliter volumes of reactants (3 μL droplets), yielding total reaction volumes of 6 μL, supported monitoring the acid-catalyzed degradation reaction of erythromycin A. This reaction was chosen to demonstrate the proof-of-principle of directly monitoring in stillo microreactions via hyphenated acoustic levitation and ambient ionization mass spectrometry. The microreactions took place completely in stillo over 30, 60, and 120 s within the containerless stable central pressure node of an acoustic levitator, thus readily promoting reaction miniaturization. For the evaluation of the miniaturized in stillo reactions, the degradation reactions were also carried out in vials (in vitro) with a total reaction volume of 400 μL. The reacted in vitro mixtures (6 μL total) were similarly introduced into the acoustic levitator prior to ambient ionization MS/MS analysis. The in stillo miniaturized reactions provided immediate real-time snap-shots of the degradation process for more accurate reaction monitoring and used a fraction of the reactants, while the larger scale in vitro reactions only yielded general reaction information.

High Surface Area of Porous Silicon Drives Desorption of Intact Molecules

Science.gov (United States)

Northen, Trent R.; Woo, Hin-Koon; Northen, Michael T.; Nordström, Anders; Uritboonthail, Winnie; Turner, Kimberly L.; Siuzdak, Gary

2007-01-01

The surface structure of porous silicon used in desorption/ionization on porous silicon (DIOS) mass analysis is known to play a primary role in the desorption/ionization (D/I) process. In this study, mass spectrometry and scanning electron microscopy (SEM) are used to examine the correlation between intact ion generation with surface ablation, and surface morphology. The DIOS process is found to be highly laser energy dependent and correlates directly with the appearance of surface ions (Sin+ and OSiH+). A threshold laser energy for DIOS is observed (10 mJ/cm2), which supports that DIOS is driven by surface restructuring and is not a strictly thermal process. In addition, three DIOS regimes are observed which correspond to surface restructuring and melting. These results suggest that higher surface area silicon substrates may enhance DIOS performance. A recent example which fits into this mechanism is silicon nanowires surface which have a high surface energy and concomitantly requires lower laser energy for analyte desorpton. PMID:17881245

Subtle differences in molecular recognition between modified glycopeptide antibiotics and bacterial receptor peptides identified by electrospray ionization mass spectrometry

DEFF Research Database (Denmark)

Jørgensen, Thomas J. D.; Staroske, T; Roepstorff, P

1999-01-01

showing that electrospray ionization mass spectrometry (ESI-MS) can be used in the rapid quantitative analysis of mixtures of vancomycin-group antibiotics and their bacterial cell-wall receptors allowing the identification of even subtle differences in binding constants. Differences in affinities...

Identification of molecules in graphite furnace by laser ionization time-of-flight mass spectrometry: sulfur and chlorine containing compounds

CSIR Research Space (South Africa)

Raseleka, RM

2004-01-01

Full Text Available An electro thermal vaporizer (ETV) coupled to a time-of-flight mass spectrometer (TOF-MS) with laser ionization (LI) was applied to the identification of molecules from sulphur and chlorine matrices in the furnace. An interface was developed...

Ionization Processes in the Atmosphere of Titan (Research Note). III. Ionization by High-Z Nuclei Cosmic Rays

Science.gov (United States)

Gronoff, G.; Mertens, C.; Lilensten, J.; Desorgher, L.; Fluckiger, E.; Velinov, P.

2011-01-01

Context. The Cassini-Huygens mission has revealed the importance of particle precipitation in the atmosphere of Titan thanks to in-situ measurements. These ionizing particles (electrons, protons, and cosmic rays) have a strong impact on the chemistry, hence must be modeled. Aims. We revisit our computation of ionization in the atmosphere of Titan by cosmic rays. The high-energy high-mass ions are taken into account to improve the precision of the calculation of the ion production profile. Methods. The Badhwahr and O Neill model for cosmic ray spectrum was adapted for the Titan model. We used the TransTitan model coupled with the Planetocosmics model to compute the ion production by cosmic rays. We compared the results with the NAIRAS/HZETRN ionization model used for the first time for a body that differs from the Earth. Results. The cosmic ray ionization is computed for five groups of cosmic rays, depending on their charge and mass: protons, alpha, Z = 8 (oxygen), Z = 14 (silicon), and Z = 26 (iron) nucleus. Protons and alpha particles ionize mainly at 65 km altitude, while the higher mass nucleons ionize at higher altitudes. Nevertheless, the ionization at higher altitude is insufficient to obscure the impact of Saturn s magnetosphere protons at a 500 km altitude. The ionization rate at the peak (altitude: 65 km, for all the different conditions) lies between 30 and 40/cu cm/s. Conclusions. These new computations show for the first time the importance of high Z cosmic rays on the ionization of the Titan atmosphere. The updated full ionization profile shape does not differ significantly from that found in our previous calculations (Paper I: Gronoff et al. 2009, 506, 955) but undergoes a strong increase in intensity below an altitude of 400 km, especially between 200 and 400 km altitude where alpha and heavier particles (in the cosmic ray spectrum) are responsible for 40% of the ionization. The comparison of several models of ionization and cosmic ray spectra (in

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)

Ion surface collisions on surfaces relevant for fusion devices

International Nuclear Information System (INIS)

Rasul, B.; Endstrasser, N.; Zappa, F.; Grill, V.; Scheier, P.; Mark, T.

2006-01-01

Full text: One of the great challenges of fusion research is the compatibility of reactor grade plasmas with plasma facing materials coating the inner walls of a fusion reactor. The question of which surface coating should be used is of particular interest for the design of ITER. The impact of energetic plasma particles leads to sputtering of wall material into the plasma. A possible solution for the coating of plasma facing walls would be the use of special carbon surfaces. Investigations of these various surfaces have been started at BESTOF ion-surface collision apparatus. Experiment beam of singly charged molecular ions of hydrocarbon molecules, i.e. C 2 H + 4 , is generated in a Nier-type electron impact ionization source at an electron energy of about 70 eV. In the first double focusing mass spectrometer the ions are mass and energy analyzed and afterwards refocused onto a surface. The secondary reaction products are monitored using a Time Of Flight mass spectrometer. The secondary ion mass spectra are recorded as a function of the collision energy for different projectile ions and different surfaces. A comparison of these spectra show for example distinct changes in the survival probability of the same projectile ion C 2 H + 4 for different surfaces. (author)

MoS{sub 2}/Ag nanohybrid: A novel matrix with synergistic effect for small molecule drugs analysis by negative-ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yaju, E-mail: daisy19900911@hotmail.com [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Deng, Guoqing, E-mail: denggqq@sina.com [Department of Polymer Science and Engineering, Nanjing University, Nanjing, 210023 (China); Liu, Xiaohui, E-mail: lcswyh@126.com [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Sun, Liang, E-mail: sunliang@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Li, Hui, E-mail: lihui@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China); Cheng, Quan, E-mail: quan.cheng@ucr.edu [Department of Chemistry, University of California, Riverside, CA, 92521 (United States); Xi, Kai, E-mail: xikai@nju.edu.cn [Department of Polymer Science and Engineering, Nanjing University, Nanjing, 210023 (China); Xu, Danke, E-mail: xudanke@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023 (China)

2016-09-21

This paper reports a facile synthesis of molybdenum disulfide nanosheets/silver nanoparticles (MoS{sub 2}/Ag) hybrid and its use as an effective matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The nanohybrid exerts a strong synergistic effect, leading to high performance detection of small molecule analytes including amino acids, peptides, fatty acids and drugs. The enhancement of laser desorption/ionization (LDI) efficiency is largely attributed to the high surface roughness and large surface area for analyte adsorption, better dispersibility, increased thermal conductivity and enhanced UV energy absorption as compared to pure MoS{sub 2}. Moreover, both Ag nanoparticles and the edge of the MoS{sub 2} layers function as deprotonation sites for proton capture, facilitating the charging process in negative ion mode and promoting formation of negative ions. As a result, the MoS{sub 2}/Ag nanohybrid proves to be a highly attractive matrix in MALDI-TOF MS, with desired features such as high desorption/ionization efficiency, low fragmentation interference, high salt tolerance, and no sweet-spots for mass signal. These characteristic properties allowed for simultaneous analysis of eight different drugs and quantification of acetylsalicylic acid in the spiked human serum. This work demonstrates for the first time the fabrication and application of a novel MoS{sub 2}/Ag hybrid, and provides a new platform for use in the rapid and high throughput analysis of small molecules by mass spectrometry. - Highlights: • MoS{sub 2}/Ag nanohybrid was applied as a novel matrix in negative-ion MALDI-TOF MS. • The MoS{sub 2}/Ag nanohybrid exerted synergistic effect on the detection of small molecules. • The MoS{sub 2}/Ag nanohybrid showed good signal reproducibility and low background interferences comparing to organic matrices. • MoS{sub 2}/Ag allows simultaneous analysis of multiple drugs and quantification of

Different target surfaces for the analysis of peptides, peptide mixtures and peptide mass fingerprints by AP-MALDI ion trap-mass spectrometry.

Science.gov (United States)

Pittenauer, Ernst; Kassler, Alexander; Haubner, Roland; Allmaier, Günter

2011-06-10

The desorption/ionization behavior of individual peptides, an equimolare peptide mixture and a tryptic digest was investigated by AP-MALDI-IT-MS using four different target materials (gold-covered stainless steel (SS), titanium nitride-covered SS, hand-polished SS, and microdiamond-covered hardmetal) under identical conditions. Gold-covered as well as polished SS targets yielded comparable mass spectra for peptides and peptide mixture in the low pMol-range. The first target exhibited superior data down to the 10fMol-range. In contrast, titanium nitride-covered SS and microdiamond-covered hardmetal AP-MALDI-targets yielded poor sensitivity. These observations could be correlated with the surface roughness of the targets determined by 3D-confocal-white-light-microscopy. The roughest surfaces were found for titanium nitride-covered SS and microdiamond-covered hardmetal material showing both poor MS sensitivity. A less rough surface could be determined for the hand-polished SS target and the smoothest surface was found for the gold-covered target yielding the best sensitivity of all surfaces. These differences in the roughness having a strong impact on the ultimate sensitivity obtainable for peptide samples could be corroborated by electron microscopy. A peptide mixture covering a wide range of molecular weights and a tryptic protein digest (from 2-DE) exhibit the same behavior. This clearly indicates that the smooth gold-covered SS target is the surface of choice in AP-MALDI MS proteomics. Copyright © 2010. Published by Elsevier B.V.

Imprint Desorption Electrospray Ionization Mass Spectrometry Imaging for Monitoring Secondary Metabolites Production during Antagonistic Interaction of Fungi.

Science.gov (United States)

Tata, Alessandra; Perez, Consuelo; Campos, Michel L; Bayfield, Mark A; Eberlin, Marcos N; Ifa, Demian R

2015-12-15

Direct analysis of microbial cocultures grown on agar media by desorption electrospray ionization mass spectrometry (DESI-MS) is quite challenging. Due to the high gas pressure upon impact with the surface, the desorption mechanism does not allow direct imaging of soft or irregular surfaces. The divots in the agar, created by the high-pressure gas and spray, dramatically change the geometry of the system decreasing the intensity of the signal. In order to overcome this limitation, an imprinting step, in which the chemicals are initially transferred to flat hard surfaces, was coupled to DESI-MS and applied for the first time to fungal cocultures. Note that fungal cocultures are often disadvantageous in direct imaging mass spectrometry. Agar plates of fungi present a complex topography due to the simultaneous presence of dynamic mycelia and spores. One of the most devastating diseases of cocoa trees is caused by fungal phytopathogen Moniliophthora roreri. Strategies for pest management include the application of endophytic fungi, such as Trichoderma harzianum, that act as biocontrol agents by antagonizing M. roreri. However, the complex chemical communication underlying the basis for this phytopathogen-dependent biocontrol is still unknown. In this study, we investigated the metabolic exchange that takes place during the antagonistic interaction between M. roreri and T. harzianum. Using imprint-DESI-MS imaging we annotated the secondary metabolites released when T. harzianum and M. roreri were cultured in isolation and compared these to those produced after 3 weeks of coculture. We identified and localized four phytopathogen-dependent secondary metabolites, including T39 butenolide, harzianolide, and sorbicillinol. In order to verify the reliability of the imprint-DESI-MS imaging data and evaluate the capability of tape imprints to extract fungal metabolites while maintaining their localization, six representative plugs along the entire M. roreri/T. harzianum

Scanning electron microscopic imaging of surface effects in desorption and nano-desorption electrospray ionization

Czech Academy of Sciences Publication Activity Database

Kaftan, Filip; Kofroňová, Olga; Benada, Oldřich; Lemr, Karel; Havlíček, Vladimír; Cvačka, Josef; Volný, Michael

2011-01-01

Roč. 46, č. 3 (2011), s. 256-261 ISSN 1076-5174 R&D Projects: GA ČR GPP206/10/P018; GA MŠk LC545; GA MŠk(CZ) ME10013 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50200510 Keywords : ionization * DESI * nano-DESI * electron microscopy * mass spectrometry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.268, year: 2011

Neutron accelerator tube having improved ionization section

International Nuclear Information System (INIS)

Givens, W.W.

1982-01-01

A neutron accelerator tube is described having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least one cathode member located in the tube adjacent to th replenisher section may have a protuberant portion extending axially into the ionization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

A new instrument of VUV laser desorption/ionization mass spectrometry imaging with micrometer spatial resolution and low level of molecular fragmentation.

Science.gov (United States)

Wang, Jia; Liu, Feng; Mo, Yuxiang; Wang, Zhaoying; Zhang, Sichun; Zhang, Xinrong

2017-11-01

Mass spectrometry imaging (MSI) has important applications in material research, biology, and medicine. The MSI method based on UV laser desorption/ionization (UVLDI) can obtain images of intact samples, but has a high level of molecular fragmentation. In this work, we report a new MSI instrument that uses a VUV laser (125.3 nm) as a desorption/ionization source to exploit its advantages of high single photon energy and small focus size. The new instrument was tested by the mass spectra of Nile red and FGB (Fibrinogen beta chain) samples and mass spectrometric images of a fly brain section. For the tested samples, the VUVDI method offers lower levels of molecular fragmentations and higher sensitivities than those of the UVLDI method and second ion mass spectrometry imaging method using a Bi 3 + beam. The ablation crater produced by the focused VUV laser on a quartz plate has an area of 10 μm 2 . The VUV laser is prepared based on the four-wave mixing method using three collimated laser beams and a heated Hg cell.

A new instrument of VUV laser desorption/ionization mass spectrometry imaging with micrometer spatial resolution and low level of molecular fragmentation

Science.gov (United States)

Wang, Jia; Liu, Feng; Mo, Yuxiang; Wang, Zhaoying; Zhang, Sichun; Zhang, Xinrong

2017-11-01

Mass spectrometry imaging (MSI) has important applications in material research, biology, and medicine. The MSI method based on UV laser desorption/ionization (UVLDI) can obtain images of intact samples, but has a high level of molecular fragmentation. In this work, we report a new MSI instrument that uses a VUV laser (125.3 nm) as a desorption/ionization source to exploit its advantages of high single photon energy and small focus size. The new instrument was tested by the mass spectra of Nile red and FGB (Fibrinogen beta chain) samples and mass spectrometric images of a fly brain section. For the tested samples, the VUVDI method offers lower levels of molecular fragmentations and higher sensitivities than those of the UVLDI method and second ion mass spectrometry imaging method using a Bi3+ beam. The ablation crater produced by the focused VUV laser on a quartz plate has an area of 10 μm2. The VUV laser is prepared based on the four-wave mixing method using three collimated laser beams and a heated Hg cell.

Thallium determination in reference materials by isotope dilution mass spectrometry (IDMS) using thermal ionization

International Nuclear Information System (INIS)

Waidmann, E.; Hilpert, K.; Stoeppler, M.

1990-01-01

Using Isotope Dilution Mass Spectrometry (IDMS) with thermal ionization, thallium concentrations were determined in reference materials from NIST and BCR, from other sources, and reference materials from the German Environmental Specimen Bank 203 Tl spike solution is applied for the isotope dilution technique. Thallium concentrations in the investigated materials range from 2.67 μg Tl.kg -1 to 963 μg Tl.kg -1 with a relative standard deviation from 0.14 to 10%. The detection limit was 0.1 ng thallium for this work. (orig.)

Species identification of Aspergillus, Fusarium and Mucorales with direct surface analysis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

Science.gov (United States)

De Carolis, E; Posteraro, B; Lass-Flörl, C; Vella, A; Florio, A R; Torelli, R; Girmenia, C; Colozza, C; Tortorano, A M; Sanguinetti, M; Fadda, G

2012-05-01

Accurate species discrimination of filamentous fungi is essential, because some species have specific antifungal susceptibility patterns, and misidentification may result in inappropriate therapy. We evaluated matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification through direct surface analysis of the fungal culture. By use of culture collection strains representing 55 species of Aspergillus, Fusarium and Mucorales, a reference database was established for MALDI-TOF MS-based species identification according to the manufacturer's recommendations for microflex measurements and MALDI BioTyper 2.0 software. The profiles of young and mature colonies were analysed for each of the reference strains, and species-specific spectral fingerprints were obtained. To evaluate the database, 103 blind-coded fungal isolates collected in the routine clinical microbiology laboratory were tested. As a reference method for species designation, multilocus sequencing was used. Eighty-five isolates were unequivocally identified to the species level (≥99% sequence similarity); 18 isolates producing ambiguous results at this threshold were initially rated as identified to the genus level only. Further molecular analysis definitively assigned these isolates to the species Aspergillus oryzae (17 isolates) and Aspergillus flavus (one isolate), concordant with the MALDI-TOF MS results. Excluding nine isolates that belong to the fungal species not included in our reference database, 91 (96.8%) of 94 isolates were identified by MALDI-TOF MS to the species level, in agreement with the results of the reference method; three isolates were identified to the genus level. In conclusion, MALDI-TOF MS is suitable for the routine identification of filamentous fungi in a medical microbiology laboratory. © 2011 The Authors. Clinical Microbiology and Infection © 2011 European Society of Clinical Microbiology and Infectious Diseases.

Use of a discharge in an hollow cathode as neutral atom source for resonant ionization mass spectrometry

International Nuclear Information System (INIS)

Berthoud, T.; Briand, A.; Khelifa, N.; Mauchien, P.

1987-01-01

The resonance ionization mass spectrometry in our laboratory is aimed at simplification of isotope measurements of elements present in mixtures and at measurement of very small isotopes. An atomization source which produces an atomic beam collimated from a discharge in a hollow cathode has been developed. First results of this spectrometry with an uranium atomic jet are presented [fr

Rapid Analysis of Bisphenol A and Its Analogues in Food Packaging Products by Paper Spray Ionization Mass Spectrometry.

Science.gov (United States)

Chen, Shuo; Chang, Quanying; Yin, Kai; He, Qunying; Deng, Yongxiu; Chen, Bo; Liu, Chengbin; Wang, Ying; Wang, Liping

2017-06-14

In this study, a paper spray ionization mass spectrometric (PS-MS) method was developed for the rapid in situ screening and simultaneous quantitative analysis of bisphenol A and its analogues, i.e., bisphenol S, bisphenol F, and bisphenol AF, in food packaging products. At the optimal PS-MS conditions, the calibration curves of bisphenols in the range of 1-100 μg/mL were linear. The correlation coefficients were higher than 0.998, and the LODs of the target compounds were 0.1-0.3 μg/mL. After a simple treatment by dichloromethane on the surface, the samples were analyzed by PS-MS in situ for rapid screening without a traditional sample pretreatment procedure, such as powdering, extraction, and enrichment steps. The analytical time of the PS-MS method was less than 1 min. In comparison with conventional HPLC-MS/MS, it was demonstrated that PS-MS was a more effective high-throughput screening and quantitative analysis method.

Combination of electrospray ionization, atmospheric pressure photoionization and laser desorption ionization Fourier transform ion cyclotronic resonance mass spectrometry for the investigation of complex mixtures - Application to the petroleomic analysis of bio-oils.

Science.gov (United States)

Hertzog, Jasmine; Carré, Vincent; Le Brech, Yann; Mackay, Colin Logan; Dufour, Anthony; Mašek, Ondřej; Aubriet, Frédéric

2017-05-29

The comprehensive description of complex mixtures such as bio-oils is required to understand and improve the different processes involved during biological, environmental or industrial operation. In this context, we have to consider how different ionization sources can improve a non-targeted approach. Thus, the Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been coupled to electrospray ionization (ESI), laser desorption ionization (LDI) and atmospheric pressure photoionization (APPI) to characterize an oak pyrolysis bio-oil. Close to 90% of the all 4500 compound formulae has been attributed to C x H y O z with similar oxygen class compound distribution. Nevertheless, their relative abundance in respect with their double bound equivalent (DBE) value has evidenced significant differences depending on the ion source used. ESI has allowed compounds with low DBE but more oxygen atoms to be ionized. APPI has demonstrated the efficient ionization of less polar compounds (high DBE values and less oxygen atoms). The LDI behavior of bio-oils has been considered intermediate in terms of DBE and oxygen amounts but it has also been demonstrated that a significant part of the features are specifically detected by this ionization method. Thus, the complementarity of three different ionization sources has been successfully demonstrated for the exhaustive characterization by petroleomic approach of a complex mixture. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

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...

Negative ion electrospray ionization mass spectrometry of nucleoside phosphoramidate monoesters: elucidation of novel rearrangement mechanisms by multistage mass spectrometry incorporating in-source deuterium labelling.

Science.gov (United States)

Xu, Peng-Xiang; Hu, An-Fu; Hu, Dan; Gao, Xiang; Zhao, Yu-Fen

2008-10-01

Several O-2',3'-isopropylideneuridine-O-5'-phosphoramidate monoesters were synthesized and analyzed by negative ion electrospray ionization tandem mass spectrometry (ESI-MS(n)). Two kinds of novel rearrangement reactions were observed due to the difference in the amino acid in the nucleoside phosphoramidate monoesters, and possible mechanisms were proposed. One involves a five-membered cyclic transition state. The other is formation of a stable five-membered ring intermediate by Michael addition. Results were confirmed by tandem mass spectrometry and isotopically labeled hydrogen atoms. Furthermore, the internal hydrogen exchange between active hydrogen and methyl acrylate in the heated capillary of the mass spectrometer was found. The characteristic fragmentation behavior in ESI-MS may be used to monitor this kind of compounds in the biological metabolism.

Methods of direct (non-chromatographic) quantification of body metabolites utilizing chemical ionization mass spectrometry

International Nuclear Information System (INIS)

Mee, J.M.L.

1978-01-01

For quantitative determination of known metabolites from the biological sample by direct chemical ionization mass spectrometry (CI-MS), the method of internal standard using stable isotopically labelled analogs appears to be the method of choice. In the case where stable isotope ratio determinations could not be applied, and alternative quantification can be achieved using non-labelled external or internal standards and a calibration curve (sum of peak height per a given number of scans versus concentration). The technique of computer monitoring permits display and plotting of ion current profiles (TIC and SIC) or spectra per a given number of scans or a given range of mass per charge. Examples are given in areas of clinical application and the quantitative data show very good agreement with the conventional chromatographic measurements. (Auth.)

Determining picogram quantities of U in human urine by thermal ionization mass spectrometry

International Nuclear Information System (INIS)

Kelly, W.R.; Fassett, J.D.; Hotes, S.A.

1987-01-01

The U concentration in Standard Reference Material 2670 (Toxic Metals in Freeze-Dried Urine) and the urine of two preschool-age children were determined by measuring the chemically separated U by isotope dilution thermal ionization mass spectrometry using ion counting detection. This procedure can detect about 1% of the U atoms loaded into the mass spectrometer and has a total chemical blank of about 5 pg U. The U concentration in SRM 2670 was found to be 113 +/- 2 pg 238 U/ml (1 s). At this concentration, a 1-ml sample is sufficient for a determination with a total uncertainty of less than 5%. The U concentrations in the two children were 3.1 +/- 0.9 and 3.6 +/- 0.9 pg 238 U/g. These values suggest that the U concentration in urine of unexposed persons may be at this low level or lower

Solvent jet desorption capillary photoionization-mass spectrometry.

Science.gov (United States)

Haapala, Markus; Teppo, Jaakko; Ollikainen, Elisa; Kiiski, Iiro; Vaikkinen, Anu; Kauppila, Tiina J; Kostiainen, Risto

2015-03-17

A new ambient mass spectrometry method, solvent jet desorption capillary photoionization (DCPI), is described. The method uses a solvent jet generated by a coaxial nebulizer operated at ambient conditions with nitrogen as nebulizer gas. The solvent jet is directed onto a sample surface, from which analytes are extracted into the solvent and ejected from the surface in secondary droplets formed in collisions between the jet and the sample surface. The secondary droplets are directed into the heated capillary photoionization (CPI) device, where the droplets are vaporized and the gaseous analytes are ionized by 10 eV photons generated by a vacuum ultraviolet (VUV) krypton discharge lamp. As the CPI device is directly connected to the extended capillary inlet of the MS, high ion transfer efficiency to the vacuum of MS is achieved. The solvent jet DCPI provides several advantages: high sensitivity for nonpolar and polar compounds with limit of detection down to low fmol levels, capability of analyzing small and large molecules, and good spatial resolution (250 μm). Two ionization mechanisms are involved in DCPI: atmospheric pressure photoionization, capable of ionizing polar and nonpolar compounds, and solvent assisted inlet ionization capable of ionizing larger molecules like peptides. The feasibility of DCPI was successfully tested in the analysis of polar and nonpolar compounds in sage leaves and chili pepper.

Mass spectrometry in nuclear technology - a review of application of thermal ionization mass spectrometry in fuel reprocessing plants. PD-7-1

International Nuclear Information System (INIS)

Dakshinamoorthy, A.

2007-01-01

Mass spectrometry finds the widespread application in nuclear science and technology due to the fact that it can be employed for isotope composition measurements of different elements of interest and also concentration measurements of these elements using isotope dilution techniques. Thermal ionization mass spectrometer (TIMS), Inductively coupled plasma mass spectrometer (ICP-MS) and gas chromatography mass spectrometer (GC-MS) are the different types of mass spectrometers used in nuclear industry for the analyses of isotope composition of special nuclear material, trace impurities in nuclear fuels and components and characterization of various solvents respectively. Among them, TIMS plays a vital role in the nuclear fuel cycle in determining precisely the isotope composition of uranium, plutonium, D/H ratio in heavy water etc. TIMS is an indispensable analytical tool for nuclear material accounting at the input stage of a reprocessing plant by carrying out precise and accurate concentration measurement of plutonium and uranium by isotope dilution mass spectrometry (IDMS). It is the only accepted measurement technique for the purpose because of its high precision, better sensitivity and no quantitative separation is needed. The isotope abundance measurements of uranium and plutonium at this point are also useful for burn-up studies and isotope correlations. Mass spectrometric analysis of uranium and plutonium is also required for nuclear data measurements and calibrating other chemical methods

Pesticide residue determination in surface waters by stir bar sorptive extraction and liquid chromatography/tandem mass spectrometry.

Science.gov (United States)

Giordano, A; Fernández-Franzón, M; Ruiz, M J; Font, G; Picó, Y

2009-03-01

In this stir bar sorptive extraction (SBSE) method, 16 pesticides were extracted from surface water samples by sorption onto 1 mm polydimethylsiloxane layer coated on a 10-mm-length stir bar magnet. After liquid desorption of the analytes with 1 ml of methanol, the detection was performed on a liquid chromatography-tandem mass spectrometry with a triple quadrupole (QqQ) analyzer using selected reaction monitoring mode via electrospray ionization. Parameters affecting SBSE operation, including sample volume, salt addition, extraction time, stirring rate, and desorption conditions, have been evaluated. The optimized SBSE method required two 50 ml aliquots of surface water samples, one aliquot was added of 30% NaCl and stirred at 900 rpm during 1 h for testing five pesticides with log K(o/w) 3. The method was validated in spiked surface water samples at limits of quantifications (LOQs) and ten times the LOQs showing recoveries Albufera Lake and surrounding channels, showing that SBSE is a powerful tool for routine control analysis of pesticide residues in surface water.

Study of cyclization of chelating compounds using electrospray ionization mass spectrometry

International Nuclear Information System (INIS)

Shi Ying; Campbell, J.A.

2000-01-01

Electrospray ionization mass spectrometry (ESI-MS) was used for the study of cyclization of organic chelating compounds (chelators). Four chelating compounds were studied: Symmetrical ethylenediaminediacetic acid (s-EDDA), Unsymmetrical ethylenediaminediacetic acid (u-EDDA), N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), and N-(2-hydroxyethyl)iminodiacetic acid (HEIDA). The chelators were cyclized with treatments of acids and heating. The open and cyclized form of the chelators were semi-quantified by both positive and negative ion modes ESI-MS. The kinetics of chelator cyclization was studied as a function of reaction temperature and the pH of the matrix. The cyclization of s-EDDA was found to be a pseudo-first order reaction in s-EDDA and overall second order. The cyclizations of HEIDA and HEDTA are reversible reactions. Higher temperature and lower pH favors cyclization. (author)

Development of sodium leak detection technology using laser resonance ionization mass spectrometry. Design and functional test using prototype sodium detection system

International Nuclear Information System (INIS)

Aoyama, Takafumi; Ito, Chikara; Harano, Hideki; Okazaki, Koki; Watanabe, Kenichi; Iguchi, Tetsuo

2009-01-01

In a sodium-cooled fast reactor, highly sensitive technology is required to detect small amounts of sodium leaking from the cooling system piping or components. The conventional sodium leak detectors have a fundamental difficulty in improving the detection sensitivity for a sodium leak because of the presence of salinity ( 23 NaCl) in the atmosphere around the components and piping of cooling systems. In order to overcome this problem, an innovative technology has been developed to selectively detect the radioactive sodium ( 22 Na) produced by a neutron reaction in the primary cooling system using Laser Resonance Ionization Mass Spectrometry (RIMS). In this method, sodium ions produced with the two processes of (1) atomization of sodium aerosols and (2) resonance ionization of sodium atom, are detected selectively using a time-of-flight mass spectrometer. The 22 Na can be distinguished from the stable isotope ( 23 Na) by mass spectrometry, which is the advantage of RIMS comparing to the other methods. The design and the construction of the prototype system based on fundamental experiments are shown in the paper. The aerodynamic lens was newly introduced, which can transfer aerosols at atmospheric pressure into a vacuum chamber while increasing the aerosol density at the same time. Furthermore, the ionization process was applied by using the external electric field after resonance exciting from the ground level to the Rydberg level in order to increase the ionization efficiency. The preliminary test results using the stable isotope ( 23 Na) showed that prototype system could easily detect sodium aerosol of 100 ppb, equivalent to the sensitivity of the conventional detectors. (author)

Angle resolved electron spectroscopy of spontaneous ionization processes occurring in doubly charged ion-surface collisions at grazing incidence

International Nuclear Information System (INIS)

Wouters, P.A.A.F.; Emmichoven, P.A.Z. van; Niehaus, A.

1989-01-01

The experimental setup used to measure electron spectra at well defined detection angles for grazing incidence doubly charged ion-surface collisions at keV-energies is described. Electron spectra are reported for the rare gas ions colliding with a Cu(110)-surface. The spectra are analyzed in terms of various spontaneous ionization processes using a newly developed model. It is found that double capture followed by atomic auto-ionization on the incoming trajectory and Auger-capture processes in which the first and second hole in the doubly charged projectiles are successively filled are the main processes contributing to the electron spectra. From a comparison of model calculations with measured spectra it is concluded that the metal electrons cannot adapt adiabatically to the sudden changes of the charge state of the projectile in front of the surface. A parameter characterizing the partly diabatic behavior is determined. The variation of spectra upon adsorption of a monolayer of oxygen on the surface is reported and discussed. (author)

Investigation on a TEA-CO II laser with surface corona pre-ionization

Science.gov (United States)

Behjat, A.; Aram, M.; Soltanmoradi, F.; Shabanzadeh, M.

2006-05-01

The construction of a surface corona UV pre-ionized TEA CO II laser is described and dependence of its average output energy of the laser to gas mixture, discharge voltage and repetition rate is investigated. The electric circuit diagram and geometry of the pre-ionization system are presented. Configuration of circuit has been designed to produce only impulsive voltage difference between the laser electrodes. Also, the triggering configuration of trigatron is prepared for fast operation to minimize the arc occurrence as much as possible. Some data of current, voltage, laser pulses and average output energy versus gas mixture and applied voltages are given. IR spectrometer is used for measurements of central output wavelength of the laser. Operation of the laser on two adjacent vibrational-rotational transitions of CO II molecule has been observed that shows the ability of this laser for working on multi-line in a same time for special applications.

Standard addition strip for quantitative electrostatic spray ionization mass spectrometry analysis: determination of caffeine in drinks.

Science.gov (United States)

Tobolkina, Elena; Qiao, Liang; Roussel, Christophe; Girault, Hubert H

2014-12-01

Standard addition strips were prepared for the quantitative determination of caffeine in different beverages by electrostatic spray ionization mass spectrometry (ESTASI-MS). The gist of this approach is to dry spots of caffeine solutions with different concentrations on a polymer strip, then to deposit a drop of sample mixed with an internal standard, here theobromine on each spot and to measure the mass spectrometry signals of caffeine and theobromine by ESTASI-MS. This strip approach is very convenient and provides quantitative analyses as accurate as the classical standard addition method by MS or liquid chromatography. Copyright © 2014 Elsevier B.V. All rights reserved.

Glycomics expression analysis of sulfated glycosaminoglycans of human colorectal cancer tissues and non-neoplastic mucosa by electrospray ionization mass spectrometry.

Science.gov (United States)

Marolla, Ana Paula Cleto; Waisberg, Jaques; Saba, Gabriela Tognini; Waisberg, Daniel Reis; Margeotto, Fernando Beani; Pinhal, Maria Aparecida da Silva

2015-01-01

To determine the presence of glycosaminoglycans in the extracellular matrix of connective tissue from neoplastic and non-neoplastic colorectal tissues, since it has a central role in tumor development and progression. Tissue samples from neoplastic and non-neoplastic colorectal tissues were obtained from 64 operated patients who had colorectal carcinoma with no distant metastases. Expressions of heparan sulphate, chondroitin sulphate, dermatan sulphate and their fragments were analyzed by electrospray ionization mass spectrometry, with the technique for extraction and quantification of glycosaminoglycans after proteolysis and electrophoresis. The statistical analysis included mean, standard deviation, and Student'st test. The glycosaminoglycans extracted from colorectal tissue showed three electrophoretic bands in agarose gel. Electrospray ionization mass spectrometry showed characteristic disaccharide fragments from glycosaminoglycans, indicating their structural characterization in the tissues analyzed. Some peaks in the electrospray ionization mass spectrometry were not characterized as fragments of sugars, indicating the presence of fragments of the protein structure of proteoglycans generated during the glycosaminoglycan purification. The average amount of chondroitin and dermatan increased in the neoplastic tissue compared to normal tissue (p=0.01). On the other hand, the average amount of heparan decreased in the neoplastic tissue compared to normal tissue (p= 0.03). The method allowed the determination of the glycosaminoglycans structural profile in colorectal tissue from neoplastic and non-neoplastic colorectal tissue. Neoplastic tissues showed greater amounts of chondroitin sulphate and dermatan sulphate compared to non-neoplastic tissues, while heparan sulphate was decreased in neoplastic tissues.

Glycomics expression analysis of sulfated glycosaminoglycans of human colorectal cancer tissues and non-neoplastic mucosa by electrospray ionization mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Marolla, Ana Paula Cleto [Universidade Federal de São Paulo, São Paulo, SP (Brazil); Waisberg, Jaques [Hospital do Servidor Público Estadual, São Paulo, SP (Brazil); Faculdade de Medicina do ABC, Santo André, SP (Brazil); Saba, Gabriela Tognini [Faculdade de Medicina do ABC, Santo André, SP (Brazil); Waisberg, Daniel Reis [Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP (Brazil); Margeotto, Fernando Beani; Pinhal, Maria Aparecida da Silva [Faculdade de Medicina do ABC, Santo André, SP (Brazil)

2015-07-01

To determine the presence of glycosaminoglycans in the extracellular matrix of connective tissue from neoplastic and non-neoplastic colorectal tissues, since it has a central role in tumor development and progression. Tissue samples from neoplastic and non-neoplastic colorectal tissues were obtained from 64 operated patients who had colorectal carcinoma with no distant metastases. Expressions of heparan sulphate, chondroitin sulphate, dermatan sulphate and their fragments were analyzed by electrospray ionization mass spectrometry, with the technique for extraction and quantification of glycosaminoglycans after proteolysis and electrophoresis. The statistical analysis included mean, standard deviation, and Student’s t test. The glycosaminoglycans extracted from colorectal tissue showed three electrophoretic bands in agarose gel. Electrospray ionization mass spectrometry showed characteristic disaccharide fragments from glycosaminoglycans, indicating their structural characterization in the tissues analyzed. Some peaks in the electrospray ionization mass spectrometry were not characterized as fragments of sugars, indicating the presence of fragments of the protein structure of proteoglycans generated during the glycosaminoglycan purification. The average amount of chondroitin and dermatan increased in the neoplastic tissue compared to normal tissue (p=0.01). On the other hand, the average amount of heparan decreased in the neoplastic tissue compared to normal tissue (p= 0.03). The method allowed the determination of the glycosaminoglycans structural profile in colorectal tissue from neoplastic and non-neoplastic colorectal tissue. Neoplastic tissues showed greater amounts of chondroitin sulphate and dermatan sulphate compared to non-neoplastic tissues, while heparan sulphate was decreased in neoplastic tissues.

Glycomics expression analysis of sulfated glycosaminoglycans of human colorectal cancer tissues and non-neoplastic mucosa by electrospray ionization mass spectrometry

International Nuclear Information System (INIS)

Marolla, Ana Paula Cleto; Waisberg, Jaques; Saba, Gabriela Tognini; Waisberg, Daniel Reis; Margeotto, Fernando Beani; Pinhal, Maria Aparecida da Silva

2015-01-01

To determine the presence of glycosaminoglycans in the extracellular matrix of connective tissue from neoplastic and non-neoplastic colorectal tissues, since it has a central role in tumor development and progression. Tissue samples from neoplastic and non-neoplastic colorectal tissues were obtained from 64 operated patients who had colorectal carcinoma with no distant metastases. Expressions of heparan sulphate, chondroitin sulphate, dermatan sulphate and their fragments were analyzed by electrospray ionization mass spectrometry, with the technique for extraction and quantification of glycosaminoglycans after proteolysis and electrophoresis. The statistical analysis included mean, standard deviation, and Student’s t test. The glycosaminoglycans extracted from colorectal tissue showed three electrophoretic bands in agarose gel. Electrospray ionization mass spectrometry showed characteristic disaccharide fragments from glycosaminoglycans, indicating their structural characterization in the tissues analyzed. Some peaks in the electrospray ionization mass spectrometry were not characterized as fragments of sugars, indicating the presence of fragments of the protein structure of proteoglycans generated during the glycosaminoglycan purification. The average amount of chondroitin and dermatan increased in the neoplastic tissue compared to normal tissue (p=0.01). On the other hand, the average amount of heparan decreased in the neoplastic tissue compared to normal tissue (p= 0.03). The method allowed the determination of the glycosaminoglycans structural profile in colorectal tissue from neoplastic and non-neoplastic colorectal tissue. Neoplastic tissues showed greater amounts of chondroitin sulphate and dermatan sulphate compared to non-neoplastic tissues, while heparan sulphate was decreased in neoplastic tissues

Matrix effect in the analysis of drugs of abuse from urine with desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS) and desorption electrospray ionization-mass spectrometry (DESI-MS)

International Nuclear Information System (INIS)

Suni, Niina M.; Lindfors, Pia; Laine, Olli; Ostman, Pekka; Ojanperae, Ilkka; Kotiaho, Tapio; Kauppila, Tiina J.; Kostiainen, Risto

2011-01-01

Highlights: → DAPPI-MS and DESI-MSI in the analysis of drugs of abuse from urine. → DAPPI-MS has better urine matrix tolerance over DESI-MS. → Urine matrix can affect the ionization mechanism in DAPPI. → DAPPI-MS/MS can be used for screening of drugs from urine after sample pretreatment. - Abstract: We have studied the matrix effect within direct analysis of benzodiazepines and opioids from urine with desorption electrospray ionization-mass spectrometry (DESI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). The urine matrix was found to affect the ionization mechanism of the opioids in DAPPI-MS favoring proton transfer over charge exchange reaction. The sensitivity for the drugs in solvent matrix was at the same level with DESI-MS and DAPPI-MS (LODs 0.05-6 μg mL -1 ) but the decrease in sensitivity due to the urine matrix was higher with DESI (typically 20-160-fold) than with DAPPI (typically 2-15-fold) indicating better matrix tolerance of DAPPI over DESI. Also in MS/MS mode, DAPPI provided better sensitivity than DESI for the drugs in urine. The feasibility of DAPPI-MS/MS was then studied in screening the same drugs from five authentic, forensic post mortem urine samples. A reference measurement with gas chromatography-mass spectrometry (GC-MS) (including pretreatment) revealed 16 findings from the samples, whereas with DAPPI-MS/MS after sample pretreatment, 15 findings were made. Sample pretreatment was found necessary, since only eight findings were made from the same samples untreated.

Matrix effect in the analysis of drugs of abuse from urine with desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS) and desorption electrospray ionization-mass spectrometry (DESI-MS)

Energy Technology Data Exchange (ETDEWEB)

Suni, Niina M.; Lindfors, Pia; Laine, Olli [Division of Pharmaceutical Chemistry, University of Helsinki, P.O. Box 56, Helsinki FI-00014 (Finland); Ostman, Pekka; Ojanperae, Ilkka [Hjelt Institute, Department of Forensic Medicine, University of Helsinki, P.O. Box 40, Helsinki FI-00014 (Finland); Kotiaho, Tapio [Division of Pharmaceutical Chemistry, University of Helsinki, P.O. Box 56, Helsinki FI-00014 (Finland); Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FI-00014 (Finland); Kauppila, Tiina J. [Division of Pharmaceutical Chemistry, University of Helsinki, P.O. Box 56, Helsinki FI-00014 (Finland); Kostiainen, Risto, E-mail: risto.kostiainen@helsinki.fi [Division of Pharmaceutical Chemistry, University of Helsinki, P.O. Box 56, Helsinki FI-00014 (Finland)

2011-08-05

Highlights: {yields} DAPPI-MS and DESI-MSI in the analysis of drugs of abuse from urine. {yields} DAPPI-MS has better urine matrix tolerance over DESI-MS. {yields} Urine matrix can affect the ionization mechanism in DAPPI. {yields} DAPPI-MS/MS can be used for screening of drugs from urine after sample pretreatment. - Abstract: We have studied the matrix effect within direct analysis of benzodiazepines and opioids from urine with desorption electrospray ionization-mass spectrometry (DESI-MS) and desorption atmospheric pressure photoionization-mass spectrometry (DAPPI-MS). The urine matrix was found to affect the ionization mechanism of the opioids in DAPPI-MS favoring proton transfer over charge exchange reaction. The sensitivity for the drugs in solvent matrix was at the same level with DESI-MS and DAPPI-MS (LODs 0.05-6 {mu}g mL{sup -1}) but the decrease in sensitivity due to the urine matrix was higher with DESI (typically 20-160-fold) than with DAPPI (typically 2-15-fold) indicating better matrix tolerance of DAPPI over DESI. Also in MS/MS mode, DAPPI provided better sensitivity than DESI for the drugs in urine. The feasibility of DAPPI-MS/MS was then studied in screening the same drugs from five authentic, forensic post mortem urine samples. A reference measurement with gas chromatography-mass spectrometry (GC-MS) (including pretreatment) revealed 16 findings from the samples, whereas with DAPPI-MS/MS after sample pretreatment, 15 findings were made. Sample pretreatment was found necessary, since only eight findings were made from the same samples untreated.

Investigation of the spectroscopy and relaxation dynamics of benzaldehyde using molecular orbital calculations and laser ionization time-of-flight mass spectroscopy

Science.gov (United States)

da Silva, Maria Cristina Rodrigues

1998-11-01

Molecular orbital methods and laser ionization mass spectrometry measurements are used to investigate the spectroscopy and relaxation dynamics of benzaldehyde following excitation to its S2(/pi/pi/sp/*) state. Energies, equilibrium geometries and vibrational frequencies of ground and low-lying excited states of benzaldehyde neutral and cation determined by ab initio calculations provide a theoretical description of the electronic spectroscopy of benzaldehyde and of the changes occurring on excitation and ionization. The S2(/pi/pi/sp/*)[/gets]S0 excitation spectrum of jet-cooled benzaldehyde acquired using two-color laser ionization mass spectrometry techniques is interpreted with the aid of these calculations. The spectrum is dominated by the origin band and by transitions involving some of the ring modes consistent with the results of the molecular orbital calculations that indicate that the major geometric changes on excitation to S2 are located in the aromatic ring. Ten fundamental vibrations of the S2(/pi/pi/sp/*) state are assigned. The dissociation dynamics of benzaldehyde into benzene and carbon monoxide following excitation to its S2(/pi/pi/sp/*) state are investigated under jet- cooled conditions by two-color laser ionization mass spectrometry using a pump-probe technique. This experimental arrangement allows monitoring the benzaldehyde reactant and the benzene product ion signals as a function of the time delay between the excitation and ionization steps. A kinetic model is proposed to explain the observed biexponential decay of the benzaldehyde signal and the single exponential growth of the benzene product signal in terms of a sequential decay of two excited states of benzaldehyde, one of which leads to formation of benzene molecules in its lowest triplet state. Reactant disappearance and product appearance rates are determined for a number of vibronic transitions of the S2 state. They are found to increase with excitation energy without any indication

Proceedings of the second Alfred O. Nier symposium on inorganic mass spectrometry

International Nuclear Information System (INIS)

Green, L.W.

1996-01-01

The proceedings are organized under the following headings: thermal ionization mass spectrometry, applications and instrumentation; inductively coupled plasma and glow discharge mass spectrometry; gases; laser resonance ionization; general. Topics of nuclear significance include: determination of trace iron in zirconium; characterization of uranium in surface waters; subpicogram quantities of technetium; measurement of isotope ratios; determination of hydrogen and deuterium in zirconium and its alloys; Kr and Xe isotopic measurements; Kr-85 detection; SIMS study of zirconium corrosion; isotopes at CEA (Commissariat a l'Energie Atomique). All the papers have been abstracted separately for INIS