Ammonia Chemical Ionization Mass Spectrometry Research Articles

ChemInform Abstract: Optimization of Pyrolysis-Desorption Chemical Ionization Mass Spectrometry and Tandem Mass Spectrometry of Polysaccharides.

The operating conditions for pyrolysis–desorption ammonia chemical ionization mass spectrometry and tandem mass spectrometry have been optimized and the technique evaluated for the production and analysis of structurally-informative pyrolytic fragmentation ions corresponding to intact anhydrohexose oligosaccharides, using amylose as the model polysaccharide. Among the various parameters examined it was found that the nature of the solvent used to adhere the sample to the emitter coil and the configuration of the emitter and the rate at which it is heated all play important roles in determining the efficiency of the pyrolytic process and the production of high mass fragment ions. Adjustment of reagent gas pressure together with source temperature also influence the chemical integrity of high mass oligomeric pyrolysis products. Under optimal operating conditions using ammonia reagent gas, the analyses of cellulose, laminarin, agars, and chitin gave relatively abundant ions corresponding to ammonium (or prot...

Development and validation of a sensitive gas chromatography–ammonia chemical ionization mass spectrometry method for the determination of tabun enantiomers in hemolysed blood and plasma of different species

The aim of this study was to develop and validate a fast, sensitive and easily applicable GC–MS assay for the chiral quantification of the highly toxic organophosphorus compound tabun (O-ethyl-N,N-dimethylphosphoramidocyanidate, GA) in hemolysed swine blood for further use in toxicokinetic and toxicodynamic studies. These requirements were fulfilled best by a GC–MS assay with positive chemical ionization with ammonia (GC–PCI-MS). Separation was carried out on a β-cyclodextrin capillary column (Supelco BetaDex ® 225) after reversed phase (C18) solid-phase extraction. The limit of detection was 1 pg/ml for each enantiomer (approximately 500 fg on column) and the limit of quantification 5 pg/ml. The GC–PCI-MS method was applied for the quantification of tabun enantiomers in spiked swine blood after hemolysis and in spiked plasma of different species including humans.

A retrospective view of mass spectrometry and natural products—sixty years of progress, with a focus on contributions by R. Graham Cooks

Modern mass spectrometry as used by chemists has prospered for the past sixty years. During the first decade of this period, the primary compounds studied were from petroleum, although other organic compounds soon attracted interest. By the mid nineteen fifties, mass spectra were being recorded on thousands of compounds each year. Most of this activity was in industrial laboratories, although by 1960 the academic world had realized the potential of the technique. This retrospective, reviewing the past sixty years, is divided into four quarters. The first two quarters cover the thirty-year period to 1970, by the end of which R. Graham Cooks had begun to plant firm roots into mass spectrometry. The major feature of the third quarter is the development by Cooks and his students of tandem mass spectrometry using isobutane or ammonia chemical ionization mass spectrometry coupled to the mass-analyzed ion kinetic energy spectroscopy (MIKES) technique for the direct, rapid, and efficient analysis of complex biological matrices. A milestone in the work was the direct introduction of plant material into the mass spectrometry (MS) source. The fourth quarter of the review covers an explosive growth in the breadth of mass spectrometry. Work in the Cooks laboratory was focused on the application of a series of ion generation and sample introduction techniques, such as desorption chemical ionization, surface-induced dissociation, secondary ion mass spectrometry, and membrane introduction mass spectrometry, to analyze increasingly complex biological matrices. In contrast to the earlier MIKES technique on a sector spectrometer, tandem MS became more common using a triple quadrupole spectrometer, with the natural products being studied ranging in complexity from ethanol to proteins and DNA.

Molecular characterization of microgram amounts of oceanic colloidal organic matter by direct temperature-resolved ammonia chemical ionization mass spectrometry

Marine colloidal organic matter in coastal waters off the coast of the eastern United States (from Georges Bank and the Mid-Atlantic Bight) is characterized by means of direct temperature-resolved mass spectrometry (DT-MS). Chemical ionization (NH 3) appears to be a very appropriate ionization method for this material. The analytical data confirm the presence of a significant polysaccharide fraction consisting of neutral sugars (normal-, deoxy- and methylated aldoses), N-acetyl aminosugars and, possibly, acidic sugars. The methylated and N-acetyl aminosugars are considered as markers for a bacterial contribution. No evidence is found for polysaccharides with large homopolymeric domains, suggesting an origin distinct from the common structural polysaccharides that comprise major polymers in algae and higher plants. The TIC profiles, which express the number of ions produced as a function of the temperature, often show a bimodal distribution. This indicates that the colloidal matter consists of two fractions with different thermal stabilities and probably also different chemical stabilities. Multivariate “mapping” of the DT-MS spectra reveals that the chemical differences between these two fractions show remarkable conformity amongst samples collected at widespread locations. The relative abundance of the two fractions appears to depend on both depth and location. The more thermally stable fraction is relatively abundant in deep water samples and some surface waters of the Mid-Atlantic Bight.

ChemInform Abstract: Determination of the Sugar Linkage Position in Glycosides Using Ammonia Chemical Ionization Mass Spectrometry at Low Gas Pressure.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Determination of the sugar linkage position in glycosides using ammonia chemical ionization mass spectrometry at low gas pressure

Determination of the sugar linkage position in glycosides using ammonia chemical ionization mass spectrometry at low gas pressure

Pyrolysis chemical ionization mass spectrometry of cellulose ethers

AbstractPyrolysis ammonia chemical ionization (PyCI) mass spectrometry was performed on hy‐droxyethyl‐, hydroxypropyl‐,methyl‐, hydroxypropylmethyl‐, and ethylhydroxyethyl cel‐luloses. The mass peaks in the PyCI mass spectra of these cellulose ethers could be assigned to the ions of pyrolytic dissociation products which form via the [2 + 2 + 2] cycloreversion and the Ei elimination pyrolysis pathway. Structural information about the residual amount of nonderivatized cellulose, the relative chain length distributions of the substituents in hydroxyalkyl celluloses, and the end‐capping of hydroxyalkyl substituents by alkyl groups in the mixed cellulose ethers is obtained. Interference of secondary pyrolysis products in the PyCI mass spectra is found to be of minor importance, especially in the lower mass regions. © 1995 John Wiley & Sons, Inc.

Ammonia chemical ionization mass spectrometry of substituted phenylpropanoids and phenylalkyl phenyl ethers

AbstractThe ammonia chemical ionization (NH3/CI) spectra of phenylpropanoids and substituted phenylalkyl phenyl ethers containing α‐hydroxy or α‐carbonyl functional groups are discussed. Fragmentation reactions which occur in the temperature range 180–450°C are examined to model pyrolysis mass spectrometric experiments of lignin. Hydroxycinnamyl alcohols and α‐hydroxy phenylalkyl phenyl ethers show abundant [M + H − H2O]+ elimination ions and to a lesser extent [M + NH4 − H2O]+ substitution ions while hydroxycinnamic acids and α‐carbonyl phenylalkyl phenyl ethers show predominantly [M + H]+ and [M + NH4]+ ions. The interpretation of functional group information is facilitated by using trideuterioammonia (ND3) and [15N] ammonia (15NH3) as reagent gases. Labile hydrogens undergo essentially complete exchange upon ND3/CI and the number of hydroxyl functional groups is readily determined by comparison of the [M + NH4]+ and [M − nH + nD + ND4]+ adduct ions. Incomplete HD exchange is observed for enolizable and aromatic protons.

Conformation dependence in the chemical ionization mass spectra of 3‐pinanones

AbstractThe conformation of the rigid isomer pair of cis‐ and trans‐3‐pinanones was investigated using methane, isobutane, and ammonia chemical ionization (CI) mass spectrometry as a tool to study the dependence of the mass spectrometric fragmentation patterns. The methane and the isobutane CI mass spectra of the cis and trans isomers were found to be different enough to permit the differentiation of the isomers. Each isomer exhibited distinctive fragmentation paths. The isobutane mass spectra of the cis isomer was dominated by the loss of H2O from the pseudo‐molecular ion, whereas the loss of C2H4O was the predominant fragment for the trans isomer. Molecular modeling and quantum‐chemical computations were used to calculate the conformers of lowest energy for the two isomers. The theoretical calculations were then used to explain the differences observed in the chemical ionization mass spectra.In addition, high resolution mass spectrometry measurements, deuterium labeling experiments and energy calculations of the hypothetical transition states and ionized species were helpful and were used to propose mechanisms for the CI mass spectral fragmentation.

Optimization of pyrolysis–desorption chemical ionization mass spectrometry and tandem mass spectrometry of polysaccharides

The operating conditions for pyrolysis–desorption ammonia chemical ionization mass spectrometry and tandem mass spectrometry have been optimized and the technique evaluated for the production and analysis of structurally-informative pyrolytic fragmentation ions corresponding to intact anhydrohexose oligosaccharides, using amylose as the model polysaccharide. Among the various parameters examined it was found that the nature of the solvent used to adhere the sample to the emitter coil and the configuration of the emitter and the rate at which it is heated all play important roles in determining the efficiency of the pyrolytic process and the production of high mass fragment ions. Adjustment of reagent gas pressure together with source temperature also influence the chemical integrity of high mass oligomeric pyrolysis products. Under optimal operating conditions using ammonia reagent gas, the analyses of cellulose, laminarin, agars, and chitin gave relatively abundant ions corresponding to ammonium (or protonated) adducts of up to anhydrohexose tetrasaccharide. More importantly, the generation of such higher mass fragment ions provided a sustained ionic current of sufficient duration to perform tandem mass spectrometric analyses.

Analysis of cell wall mutants ofSaccharomyces cerevisiaeby pyrolysis mass spectrometry

SUMMARY The main constituents of the cell wall of Saccharomyces cerevisiae, i.e. β-1,3-glucan, β-1,6-glucan and mannan, could be distinguished by pyrolysis ammonia chemical ionization mass spectrometry or Py(CI)MS. Cell walls extracted with alkali, which removes the mannan fraction and part of the glucan from the cell wall, yielded mass spectra that differed clearly from nonextracted cell walls. Multivariate analysis of these spectra showed a shift from ‘mannan-like’ towards ‘glucan-like’ cell walls. Known cell wall mutants, such as mnn9 and kre1, were recognized by this technique. Py(CI)MS in combination with multivariate analysis of the spectra is therefore a useful tool for identifying and characterizing cell wall mutants in yeast.

Triton X‐100 as a reference compound for ammonia high‐resolution chemical ionization mass spectrometry and as a tuning and calibration compound for thermospray

AbstractThe non‐ionic surfactant Triton X‐100, 1‐(1,1,3,3,‐tetramethylbutyl)‐4‐[poly(1,2‐ethanediol)]benzene, has been evaluted as a reference material for positive‐ion high‐resolution ammonia chemical ionization (CI) mass spectrometry and as a tuning and calibration material for positive‐ion thermospray mass spectrometry (TSP). When ammonia is used as the CI reagent gas, Triton‐X‐100 produces evenly spaced ions that 44 u apart. Triton X‐100 cab be volatilized from a solids prove and is routinely used as the reference material for high‐resolution measurements. A reference table has been constructed from the theoretical values for the different masses. Triton X‐100‐Reduced and Triton X‐405‐Reduced were also evaluated as additional reference com‐pounds. As a calibration and tuning compound for TSP, Triton X‐100 affords an envelope of ions centred around m/z 600–700 with ions observed above m/z 1000. Triton X‐100‐Reduced affords a similar envelope although the ions observed are 6 u higher in mass.

Investigation of some 2,3-didehydro amino acids by fast ion bombardment, chemical ionization and mass-selected collision-induced dissociation mass spectrometry

Four 2,3-didehydro amino acids were investigated by fast ion bombardment (FIB) and ammonia chemical ionization (NH3-CI) mass Spectrometry. The protonated molecules formed by the two techniques were mass selected and their respective collision-induced dissociations (CIDs) in the translational energy range 5–200 eV (in the laboratory frame of reference) were investigated. No obvious quantitative differences between the FIB and NH3-CI mass spectra of the (E)- and (Z)-isomers were observed. Different internal excitation of the protonated molecules formed by the two techniques and the role of CID data in clarifying this particular observation are discussed.

Capillary column gas chromatography-ammonia and deuterated ammonia chemical ionization mass spectrometry of sulfur vesicants

Capillary column gas chromatography-ammonia and deuterated ammonia chemical ionization mass spectrometry was found to be a highly specific technique for the detection and identification of three long-chain sulfur vesicants, 2-chloroethyl (2-chloroethoxy)ethyl sulfide, sesquimustard and bis[(2-chloroethylthio)ethyl]ether. All three vesicants exhibited significant (M + NX 4) + (where X = H or 2H) pseudo-molecular ions and structurally significant chemical ionization fragmentation ions during capillary column gas chromatographic-ammonia chemical ionization mass spectrometric analysis. This method was utilized during analysis of contaminated painted panels circulated during the 3rd round robin verification exercise (1991). Chemical ionization data obtained during this exercise complemented the electron impact data obtained for sesquimustard and bis[(2-chloroethylthio)ethyl]ether and the specificity of the technique enabled the confirmation of 2-chloroethyl (2-chloroethyoxy)ethyl sulfide, a compound masked by hydrocarbons in the painted panel extracts.

Control of the regiospecific synthesis of dialkylpyrrolizidinones and their stereochemical behaviour using gas chromatography/mass spectrometry with chemical ionization

Pyrrolizidine alkaloids were synthesized via the cyclization of an epoxide prepared from a lactam. The regiospecific control of this reaction is demonstrated using gas chromatography/mass spectrometry. Ammonia chemical ionization mass spectrometry permits the determination of the cis–trans stereochemistry of the final products.

An analytical pyrolysis mass spectrometric study of Eucryphia cordifolia wood decayed by white-rot and brown-rot fungi

The decay of Eucryphia cordifolia wood by white-rot and brown-rot fungi was studied with pyrolysis electron impact mass spectrometry (Py(EI)MS) and pyrolysis ammonia chemical ionization mass spectrometry (Py(CI)MS). Py(EI)MS spectra of the wood after decay by the white-rot fungus Ganoderma australe no longer show mass peaks indicative for lignin. The relative abundance of syringyl (dimethoxy) compounds decreases faster than the coniferyl (monomethoxy) compounds. In the same spectra the relative abundance of hexosans increases whereas the relative amount of pentosans remains constant. The presence of oligomeric sugars in the Py(CI)MS spectrum points to a preservation of some polysaccharides. Brown-rot fungal degradation of similar wood samples analysed with Py(EI)MS reveals no mass peaks for polysaccharides, resulting in a spectrum with mass peaks specific for lignin. The Py(EI)MS, revealing lignin dimers, and the Py(CI)MS spectra suggest that the lignin was not modified by the brown-rot fungus. However, the pyrolysis gas chromatography mass spectrometry (PyGCMS) data show an increase in oxygenated lignin pyrolysis products suggesting a molecular change in the lignin due to brown-rotting. In the brown-rotted wood one sugar pyrolysis product (levoglucosan) was observed by Py(CI)MS and PyGCMS suggesting that part of the cellulose polymer system is inaccessible to fungal degradation. Comparing data obtained from 13C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) with data obtained from PyMS reveals that the latter method provides much more structural information.

Detection of sarin and soman in a complex airborne matrix by capillary column ammonia chemical ionization gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry

The chemical warefare agents, sarin and soman, were detected and confirmed during full scanning capillary column ammonia chemical ionization mass spectrometry at nanogram levels in spiked extracts of a diesel exhaust environment sampled onto the charcoal of a Canadian C2 respirator canister. The selectivity of ammonia chemical ionization enabled the use of selected ion monitoring and resulted in detection limits of 40 pg and just above 500 pg for sarin and soman respectively in this extract. This diesel exhaust environment, typical of what might be encountered under battlefield conditions, was used to evaluate capillary column ammonia chemical ionization tandem mass spectrometry as a possible verification technology. Chemical interferences were reduced and significantly better detection limits, 15 pg and 80 pg for sarin and soman respectively, were obtained during gas chromatographic-tandem mass spectrometric analysis of these agents in the presence of numerous interfering diesel exhaust and charcoal bed components.

High-pressure ammonia chemical ionization mass spectrometry and mass spectrometry/mass spectrometry for porphyrin structure determination

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHigh-pressure ammonia chemical ionization mass spectrometry and mass spectrometry/mass spectrometry for porphyrin structure determinationGary J. Van Berkel, Gary L. Glish, Scott A. McLuckey, and Albert A. TuinmanCite this: Energy Fuels 1990, 4, 6, 720–729Publication Date (Print):November 1, 1990Publication History Published online1 May 2002Published inissue 1 November 1990https://doi.org/10.1021/ef00024a018RIGHTS & PERMISSIONSArticle Views121Altmetric-Citations8LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Comparative EI, CI and FAB Mass Spectrometry of Dialkyl and Monoalkyl 2-Chloroethylphosphonates

Abstract Comparison is made between electron ionization (EI), methane, isobutane and ammonia chemical ionization (CI) and fast atom bombardment (FAB) mass spectrometry of phosphonates related to 2-chloroethylphosphonic acid

Thermal fragmentation analysis of neutral polysaccharides and the presence of 1,6-anhydrooligosaccharides

Small quantities of pyrolysates were obtained from micro-scale off-line pyrolysis of the neutral polysaccharides: cellulose, amylose, laminaran, nigeran, and a mannan from ivory nut. The pyrolytic fragments were analyzed by desorption chemical ionization – mass spectrometry, trimethylsilyl derivatization – capillary gas chromatography (– ammonia chemical ionization mass spectrometry) and benzoyl derivatization – high pressure liquid chromatography. Intact 1,6-anhydrohexosemonosaccharide, and -disaccharide fragments were identified as major products. By using off-line analytical pyrolysis information on saccharide composition can be obtained from the formation of anhydromonosaccharide products while linkage information is obtainable from distinctive anhydrodisaccharide products. Keywords: pyrolysis, polysaccharides, 1,6-anhydrooligosaccharides, desorption chemical ionization, mass spectrometry, gas chromatography, high pressure liquid chromatography.