Isobutane Chemical Ionization Mass Spectrometry Research Articles

Regio-and Stereochemical Effects in the Chemical Ionization Mass Spectra of Isomeric Bicyclo|3, 2, O| Heptan-2-One Trimethylsiloxy Derivatives1

Isomers of bicyclo |3, 2, O| heptan-2-one trimethylsiloxy derivatives, produced by (π2+π2) photocycloaddition reactions between cyclopent-2-enones and trimethylsiloxy alkenes, have been investigated by methane and isobutane chemical ionization mass spectrometry. Head-to-head and head-to-tail regioisomers and the syn-and anti-epimers in each regioisomeric set can be identified by means of these ionization methods. Prominent fragmentation patterns are discussed.

Chemical composition and origin of fossil resins from Utah Wasatch Plateau coal

In order to arrive at a more detailed chemical description of fossil coal associated resins we need to distinguish between micropetrographic, organic geochemical and process technological definitions, each of which may encompass varying quantities of constituents unrelated to fossil tree resins. New information on composition and origin of Utah Wasatch Plateau coal resins obtained by Curie-point pyrolysis/evaporation in combination with iso-butane chemical ionization mass spectrometry, as presented in this paper, points to the presence of four more or less distinct resin components: (1) a sesquiterpenoid polymer; (2) sesqui- and triterpenoid monomers and dimers; (3) a suite of triterpenoid alcohols, ketones and acids; and (4) a series of increasingly aromatized hydrocarbons with naphthalene and picene type skeletons. Moreover, a strong similarity is found between the composition of recent dammar resin and fossil Wasatch Plateau coal resins indicating a possible Angiosperm (fam. Dipterocarpaceae) origin of these Upper Cretaceous coal resins. Some of the technological implications of these findings and the consequent need for a more precise chemical definition and nomenclature are discussed.

Identification and determination of propafenone and its principal metabolites in human urine using capillary gas chromatography/mass spectrometry

The capillary gas chromatography/mass spectrometry of trimethylsilyl-trifluoroacetyl, trifluoroacetyl and pentafluoropropionyl (PFP) derivatives of the antiarrhythmic agent propafenone (Rytmonorm), as well as its main metabolites N-despropyl-propafenone and 5-hydroxy-propafenone, have been investigated. Both electron impact and positive isobutane chemical ionization mass spectrometry using the Ion Trap Detector have been evaluated. The presence of propafenone and its co-extracted metabolites in human urine at time intervals after the oral administration of 150 mg Rytmonorm to healthy volunteers was established, and the urinary excretion of propafenone and 5-hydroxy-propafenone was calculated using selective chemical ionization mass spectrometric detection. Only a few per cent of the dose was excreted unchanged in the urine. Large intersubject variabilities had been observed also. The large dynamic range of the Ion Trap Detector and the high correlation coefficients (0.92-0.99) of the calibration curves were striking.

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

Straight‐chain alkanes as reference compounds for accurate mass determination in isobutane chemical ionization mass spectrometry

Straight‐chain alkanes as reference compounds for accurate mass determination in isobutane chemical ionization mass spectrometry

Capillary column isobutane chemical ionization mass spectrometry of mustard and related compounds

Capillary column isobutane chemical ionization was found to be an excellent method for the mass spectral characterization of mustard, other sulfur vesicants and related compounds. Interpretation of [M + H]+ and fragmentation ion information afforded by this technique enabled the identification of many previously unreported mustard impurities. The developed methodology was applied to the analysis of an Iran/Iraq soil sample suspected to have been contaminated with mustard. Mustard and 17 other mustard related impurities were identified and characterized in this sample under electron impact and isobutane chemical ionization conditions.

Poly(dimethylsiloxane) as mass reference for accurate mass determination in isobutane chemical ionization mass spectrometry

Poly(dimethylsiloxane) as mass reference for accurate mass determination in isobutane chemical ionization mass spectrometry

質量スペクトル法による有機すず化合物のキャラクタリゼーション

In-beam electron impact ionization, isobutane chemical ionization and field desorption mass spectrometry were applied for the characterization of organic tin compounds.In these compounds, primary cleavages of the Sn-C, Sn-X, S n-O and Sn-S bonds took place prior to other reactions so that the analysis of their mass spectra was relatively simple. The ten isotopes of the tin atom gave the information whether a fragment ion con tained tin or not.Moreo ver, the kind and the distribution of alkyl or carboxyl group attached directly to the tin atom were easily determined from their mass spectral cracking pattern.

THE ANALYSIS OF METALLOPORPHYRINS IN PETROLEUM USING TANDEM MASS SPECTROMETRY

ABSTRACT Vanadyl deoxophy lloerythroetioporphyrins (DPEP) and vanadyl etioporphyrins (ETIO) have been identified in Gato Ridge and Boscan petroleum samples using a combination of isobutane chemical ionization and tandem mass spectrometry. In addition, particular porphyrins such as the C30 vanadyl DPEP and ETIO species were identified in a crude oil containing approximately 500 ppm total porphyrins, with only minimal sample clean-up.

Analysis of deuterium labeled blood lipids by chemical ionization mass spectrometry.

A quantitative analytical method has been developed to analyze methyl esters of blood fatty acids derived from human subjects fed deuterium-labeled fats. The GCMS computer method provides for the analysis of the fed deuterium-labeled fatty acids, the naturally occurring blood fatty acids and new fatty acids formed by chain elongation or shortening of the fed labeled fats. Approximately 20 fatty acids including 16, 17, 18 and 20 carbon chain acids were analyzed with a relative standard deviation of 0.02 at the microgram level and a sensitivity of less than one nanogram. The method uses capillary GC to separate the fatty acid esters and isobutane chemical ionization mass spectrometry with multiple ion detection to determine the isotopic constituents of the GC peaks. The technique provides for the determination of overlapping GC peaks labeled with 2, 4 and 6 deuterium atoms and makes extensive use of computers both for data acquisition and processing.

5α(H)-cholestan-3α-ol in sediments: Characterization and geochemical significance

The top five centimeters of sediment collected at the deepest point of Lake Léman (Switzerland), 309 meters below water level, contain concentrations of 5α(H)-cholestan-3α-ol (epicholestanol) up to 10% of the total sterol content. Isobutane chemical ionization mass spectrometry and coinjection with an authentic standard on a SP-1000 glass capillary column were used in order to successfully characterize this epimer of cholestanol. The distribution of this stanol throughout the sediment core studied suggests in situ bacterial production. The change in concentration of epicholestanol with depth is different from those found for other C 27 stanols, such as cholestanol or coprostanol. It is probably the result of a change in the bacterial fauna in the most recently deposited sediment, related to the increasing eutrophication of the lake rather than the consequence of its lower stability due to the axial conformation of the OH substituent.

Hydrogenation of unsaturated fatty esters during isobutane chemical ionization mass spectrometry

AbstractHydrogenation of double bonds was observed to occur during the isobutane chemical ionization mass spectrometry (MS) of unsaturated fatty esters. Chemical ionization (CI) spectra of a series of methyl esters in the C16–C20 carbon range containing 0–4 double bonds showed a variety of ionization characteristics in the molecular ion cluster, including hydride abstraction, charge exchange, protonation and, for the unsaturated fatty acids (FA), hydrogenation of the double bond followed by protonation.

Ammonia chemical ionization mass spectrometry of alcohols: Structural, stereochemical, molecular‐size and temperature effects

AbstractAmmonia chemical ionization (CI) mass spectra of various open‐chain, cyclic and unsaturated C5‐ to C10‐alcohols were obtained at source temperatures ranging from 60° to 250°C. The reactivity of the ammonia adduct ion MNH and its fragmentation channels are characteristic for substrate structure. Although strongly temperature‐dependent, the spectra give nevertheless information on the OH‐group environment as well as on the C‐skeleton at any source temperature. Primary, secondary and tertiary alcohols as well as allylic and simple olefinic alcohols can be distinguished by their spectra, which show ammonium adduct ions [MNH4]+, adduct dehydrogenation ions [MNH4‐H2], ammonium substitution ions [MNH4‐H2O]+ and [M‐OH]+‐ions as the main characteristic peaks. Moreover, konfigurational assignments of stereoisomeric alcohols are possible for larger substrate‐size and source‐temperature ranges than with isobutane CI mass spectrometry. Homologous M NH‐ions show molecular‐size control of fragmentation and linear MNH‐ions are less stable than branched isomers due to incomplete energy randomization.

Adduct ion formation in isobutane chemical ionization of aliphatic olefins.

The formation of the adduct ion, (M + C4H9)+, from aliphatic olefins was investigated in isobutane chemical ionization (CI) mass spectrometry by using a conventional mass spectrometer. In the spectra of 1-olefins, the adduct ion was most abundant above 0.05 Torr at the ionization chamber. Methyl substitutions on the unsaturated carbon atom made this ion less abundant for 1-olefins and cyclohexenes. Other adduct ions such as (M+C3H7)+ or (M+C3H3)+ were not found in significant amount under usual conditions. Temperature and repeller effects on the adduct ion formation were also studied.

ChemInform Abstract: LOSS OF H2O FROM M + TERT‐BUTYL COMPLEX IONS OF BENZYL ALCOHOL IN ISOBUTANE CHEMICAL IONIZATION MASS SPECTROMETRY

Chemischer InformationsdienstVolume 12, Issue 30 Physical Organic Chemistry ChemInform Abstract: LOSS OF H2O FROM M + TERT-BUTYL COMPLEX IONS OF BENZYL ALCOHOL IN ISOBUTANE CHEMICAL IONIZATION MASS SPECTROMETRY J. G. LIEHR, J. G. LIEHRSearch for more papers by this authorG. A. BRENTON, G. A. BRENTONSearch for more papers by this authorJ. H. BEYNON, J. H. BEYNONSearch for more papers by this authorJ. A. MCCLOSKEY, J. A. MCCLOSKEYSearch for more papers by this authorW. BLUM, W. BLUMSearch for more papers by this authorW. J. RICHTER, W. J. RICHTERSearch for more papers by this author J. G. LIEHR, J. G. LIEHRSearch for more papers by this authorG. A. BRENTON, G. A. BRENTONSearch for more papers by this authorJ. H. BEYNON, J. H. BEYNONSearch for more papers by this authorJ. A. MCCLOSKEY, J. A. MCCLOSKEYSearch for more papers by this authorW. BLUM, W. BLUMSearch for more papers by this authorW. J. RICHTER, W. J. RICHTERSearch for more papers by this author First published: July 28, 1981 https://doi.org/10.1002/chin.198130069AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue30July 28, 1981 RelatedInformation

Loss of H2O from M + t‐Butyl Complex Ions of Benzyl Alcohol in Isobutane Chemical Ionization Mass Spectrometry

AbstractIn isobutane chemical ionization mass spectrometry benzyl alcohol exhibits ions at m/z 147 (‘M + 39’) that arise by a loss of H2O from [M + C4H9]+, i.e. ‘M + 57’ complex ions. Electrophilic aromatic substitution of a proton at an ortho‐position of neutral C6H5CH2OH with [t‐C4H9]+ and, alternatively, nucleophilic substitution of H2O at the benzylic carbon in \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm C_6 H_5 CH_2}\mathop {\rm O}\limits^+ {\rm H}_2 $\end{document} with CH2C (CH3)2 are discussed as possible pathways. Evidence in favor of the latter is derived from the analysis of C6D5CH2OH and C6H5CD2OH for the origin of the H‐atoms lost in H2O. The inferred ion structure of m/z 147 is verified by mass‐analyzed ion kinetic energy (MIKE.) measurements of its collision‐activated (CA.) decomposition. MIKE./CA. spectra of mass‐selected m/z 147 ions, once generated by (CI(i‐C4H10) from benzyl alcohol and, once, from 2‐methyl‐4‐phenyl‐2‐butanol match closely and, thus, reflect identical ion structures. With reference to the simple genesis of this ion from the latter precursor, the structure in question can be concluded to be \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm C_6 H_5 CH_2 CH_2}\mathop {\rm C}\limits^+ ({\rm CH}_3)_2 $\end{document} .

Isobutane chemical ionization mass spectrometry of β‐amino alcohols. Evaluation of populations of conformers at equilibrium in the gas phase

AbstractThe conformer populations of conformationally mobile β‐amino alcohols in the gas phase, can be evaluated from the relative intensity of the dehydration peak [MHH2O]+ in isobutane chemical ionization mass spectrometry.

Evidence for the occurrence of an oxygen to oxygen acyl shift in 7‐acetoxybicyclo|3,2,0|heptan‐2‐ones upon chemical ionization mass spectrometry

AbstractAn oxygen to oxygen acyl migration has been observed in 7‐acetoxybicyclo|3,2,0|heptan‐2‐ones upon isobutane chemical ionization mass spectrometry. The mechanism of this rearrangement is discussed and is investigated by means of deuterium labelling techniques.

Role of .sigma.-.pi. conjugation in the gas phase: electrophilic cleavage reactions of benzyltin compounds by isobutane chemical ionization mass spectrometry

Role of .sigma.-.pi. conjugation in the gas phase: electrophilic cleavage reactions of benzyltin compounds by isobutane chemical ionization mass spectrometry

Chemical ionization mass spectrometry of some crown ethers

AbstractMethane and isobutane chemical ionization mass spectrometry is superior to the classical electron impact technique for the analysis of aliphatic macrocyclic polyethers of the 4n‐crown‐n type. The latter reagent gas is particularly suited for molecular weight determinations.