Analyzed Ion Kinetic Energy Spectrometry Research Articles

Electron impact mass spectrometry of some 2‐(p‐bromophenyl)‐4,4‐disubstituted‐5(4H)‐oxazolones

AbstractThe mass spectrometric behaviour of four 2‐(p‐bromophenyl)‐4,4‐disubstituted‐5(4H)‐oxazolones has been investigated using linked scans, mass analyzed ion kinetic energy spectrometry, accurate mass measurements and collisional spectroscopy. The study shows the formation of similar ions in all cases, with the presence of skeletal rearrangements, leading to highly stable product ions.

Study on the fragmentation mechanism of isopropyl methacrylate.

Fragmentation mechanism of the molecular ion of isopropyl methacrylate has been investigated by using kinetic energy release measurement, deuterium labelling technique and mass analyzed ion kinetic energy spectrometry. The methyl radical is eliminated from the molecular ion with a hidden hydrogen migration, not a simple cleavage. Further, it is demonstrated that the two hydrogen atoms in double hydrogen migration originate from the individual methyl groups in isopropyl group in the ion source.

Hydroxyl negative chemical ionization mass spectrometry linked with collisionally activated decomposition. A modern analytical tool in inborn errors of metabolism.

Two kinds of inborn errors of metabolism, dicarboxylic aciduria and hyperoxaluria, have been studied by means of hydroxyl negative ion chemical ionization [NICI(OH-)], linked with collisionally activated decomposition experiments on the [M-H]- species of the pathognomonic organic acids. This method has led to non-controversial qualitative determinations of C4-C10 dicarboxylic acids and oxalic, glyceric and glyoxylic acids. NICI(OH-) linked with collisionally activated decomposition mass analysed ion kinetic energy spectrometry (CAD MIKES) is proposed herein for diagnostic purposes, as a valid mass spectrometric alternative to standard gas chromatographic/mass spectrometric analysis. The procedure is characterized by simplified sample treatment and by fast execution.

Correction. Identification of Sulfonamide Drugs in Swine Liver by Collision-Induced Dissociation/Mass Analyzed Ion Kinetic Energy Spectrometry

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCorrection. Identification of Sulfonamide Drugs in Swine Liver by Collision-Induced Dissociation/Mass Analyzed Ion Kinetic Energy SpectrometryWilliam C. Brumley, Zhao. Min, Jean E. Matusik, John A. G. Roach, Charlie J. Barnes, James A. Sphon, and Thomas. FazioCite this: Anal. Chem. 1984, 56, 7, 1200Publication Date (Print):June 1, 1984Publication History Published online6 September 2005Published inissue 1 June 1984https://doi.org/10.1021/ac00271a601RIGHTS & PERMISSIONSArticle Views18Altmetric-Citations-LEARN 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 (77 KB) Get e-Alerts Get e-Alerts

Metastable and collision induced fragmentation of some small cluster ions: Ar2+ Ar3+, ArN2+ and N4+

AbstractThe results of a study on collision induced dissociation and a search for metastable reactions of four gas phase ion‐molecule clusters, Ar2+, Ar3+, ArN2+ and N4+, are presented. The ionic clusters were formed in a high pressure mass spectrometer ion source which was cooled to enhance the association products. Subsequent fragmentations were studied using mass analyzed ion kinetic energy spectrometry. Decomposition pathways consistent with experimental collision induced dissociation peak shapes and ab initio potential diagrams are presented for the fragmentation of Ar2+ and N4+. Mechanisms for the collision induced dissociation of Ar3+ and ArN2+ are suggested. No metastable reactions for any of the cluster ions were observed. This result is in conflict with the results of Märk et al. using electron impact ionization of neutral van der Waals' clusters formed in a supersonic nozzle beam.

In-Beam Electron Ionization Mass Spectra of Penicillins

The characteristics of in-beam electron ionization mass spectra of 6-aminopenicillanic acid and several penicillins, which yield no detectable molecular ion peaks using a conventional direct-insertion probe, have been established. The spectra of all compounds studied, with the exception of amoxicillin, exhibited molecular ion or (M+l) peaks with spectral features similar to the reported methyl ester or amide derivatives of the compounds. The fragmentation of penicillin G on electron impact under in-beam conditions can be described on the basis of data from mass analyzed ion kinetic energy spectrometry. A desorption technique utilizing polyethylene glycol 4000 was used as a means of obtaining satisfactory spectra of ampicillin and amoxicillin.

The fragmentation of metastable NH+3 ions and isotopic analogs: an example of tunneling through a rotational barrier

The fragmentation of metastable NH+3 ions and isotopic analogs via the reaction NH+3 → NH+2 + H has been investigated using mass analysed ion kinetic energy spectrometry (MIKES). Kinetic energy release distributions and the metastable intensity were measured as a function of ion source temperature. Both the average kinetic energy release and the metastable intensity increase with ion source temperature. The data are consistent with the metastable reaction arising from tunneling through a rotational barrier. The experimental data are compared with the predictions of a tunneling model.

ChemInform Abstract: FRAGMENTATION OF METASTABLE METHANE RADICAL IONS(1+) AND ISOTOPIC ANALOGS. KINETIC ENERGY RELEASE DISTRIBUTIONS AND TUNNELING THROUGH A ROTATIONAL BARRIER: EXPERIMENT AND THEORY

The fragmentation of metastable CH/sub 4//sup +/, CD/sub 3/H/sup +/, and CD/sub 4//sup +/ ions has been studied with use of mass analyzed ion kinetic energy spectrometry (MIKES).Kinetic energy release distributions were derived from the MIKES peaks. The average kinetic energy release and metastable intensity were found to increase with ion source temperature. Appearance potential measurements indicated that the metastable reaction arises from CH/sub 4//sup +/ ions with internal energy close to the thermochemical threshold for fragmentation to give ground state CH/sub 3/(/sup 1/A/sub 1/) + H(/sup 2/S). The experimental data suggest that the origin of the metastable process is tunneling through a centrifugal barrier. A statistical model is presented and predictions of the model are compared with the experimental data.

Ortho, Effects in organic molecules on electron impact: X—unusual ortho effects of the methyl group in o‐picolinotoluidide

AbstractThe mass spectrum of o‐picolinotoluidide gives rise to three major fragments at m/z 184, m/z 169 and m/z 168, corresponding to the loss of CO from the molecular ion followed by the loss of ṄH2 and ĊH3 by independent pathways. It has been shown that the ortho methyl group and the nitrogen of the pyridine ring in the 2‐position are involved in the formation of these three major fragments observed in the mass spectrum of o‐picolinotoluidide. The mass spectrum of 2‐(o‐toluidino) pyridine, the molecular ion of which can resemble the [MCO]+ ion in o‐picolinotoluidide, also shows loss of CH3 and NH2 radicals from the molecular ions. Based on these observations coupled with the high resolution data, the mass analysed ion kinetic energy spectrometry and high voltage scans of these fragments in both the compounds, two mechanistic pathways have been proposed for the formation of these ions in o‐picolinotoluidide.

Fragmentation of metastable methane radical ions(1+) and isotopic analogs. Kinetic energy release distributions and tunneling through a rotational barrier: experiment and theory

The fragmentation of metastable CH/sub 4//sup +/, CD/sub 3/H/sup +/, and CD/sub 4//sup +/ ions has been studied with use of mass analyzed ion kinetic energy spectrometry (MIKES).Kinetic energy release distributions were derived from the MIKES peaks. The average kinetic energy release and metastable intensity were found to increase with ion source temperature. Appearance potential measurements indicated that the metastable reaction arises from CH/sub 4//sup +/ ions with internal energy close to the thermochemical threshold for fragmentation to give ground state CH/sub 3/(/sup 1/A/sub 1/) + H(/sup 2/S). The experimental data suggest that the origin of the metastable process is tunneling through a centrifugal barrier. A statistical model is presented and predictions of the model are compared with the experimental data.

Metastable fragment ions from carbinolamine ethers

AbstractThe secondary decomposition of fragment ions produced by electron impact of carbinolamine ethers was studied by mass analysed ion kinetic energy spectrometry. A new case was observed of ions of the same structure leading to the same fragments through different mechanisms competing in the metastable time frame and accompanied by a different partitioning of the excess energy (internal vs translational). The role of a fractional positive charge localized at saturated centres in the reactivity of these gaseous organic ions is discussed.

Characterization of poly(carboxypiperazine) by mass analyzed ion kinetic energy spectrometry

Characterization of poly(carboxypiperazine) by mass analyzed ion kinetic energy spectrometry

The elimination of carbon monoxide from molecular ions of phenol and other [C6H6O]+˙ isomers

AbstractPhenol and five acyclic isomeric compounds have been investigated using electron impact and field ionization techniques, mass analysed ion kinetic energy spectrometry and collision induced dissociation mass analysed ion kinetic energy spectrometry. The kinetic energy release data corresponding to the elimination of carbon monoxide from the molecular ions show that at least two structures of the reactant ion are involved. The electron impact and field ionization collision induced dissociation mass analysed ion kinetic energy spectra indicate that under electron impact conditions, the phenol ion partially isomerizes to another ion structure. An isomerization of about 40% to the structure of cis‐2‐hexen‐4‐yn‐1‐al is in good accordance with the spectral data.

Analysis of nitrated polycyclic aromatic hydrocarbons in diesel particulates

The analysis of nitrated polycyclic aromatic hydrocarbons (nitro-PAH) in diesel particulate extracts using a combination of high-performance liquid chromatography, gas chromatography/mass spectrometry, high-resolution mass spectrometry, and mass spectrometry/mass spectrometry (MS/MS) techniques is described. Triple stage quadrupole (TSQ)-MS/MS operated in the constant neutral loss mode is described for the rapid qualitative screening of nitro-PAH isomer groups in solvent extracts of diesel particulates. Twenty such isomer groups of nitro-PAH derivatives were found, many of these groups containing a large number of possible compounds. Mass analyzed ion kinetic energy spectrometry (MIKES)-MS/MS was found to be much less selective than the TSQ-MS/MS for the analysis of nitro-PAH in unfractionated diesel extracts. HPLC prefractionation was required to remove interferences in the MIKES analysis. Fused silica capillary GC/MS using on-column injection was found to be necessary for identifying specific nitro-PAH isomers and minimizing decomposition. The highly mutagenic 1-nitropyrene (1-NP) was the only compound found in the nitro(pyrenes and fluoranthenes) isomer group. The MIKES and TSQ techniques gave comparable results for the quantitation of 1-NP.

Mechanism of the metastable reaction H 2S + → S + + H 2; product energy distributions and their dependence on temparature

The fragmentation of metastable H 2S + ions to produce S + and H 2 has been investigated by mass analyzed ion kinetic energy spectrometry (MIKES). Kinetic energy release distributions have been derived from the MIKES peaks. Resolved structure is evident in the release distributions. When the metastable reaction is assigned to the specific H 2S +( 2A 1) vibronic, levels (known from fluorescence lifetime measurements to lie in the metastable lifetime range) good correlation is found between the position of the structure in the distributions and predicted transition energies. The data indicate that substantial rotational excitation of the product H 2 is occurring. The average kinetic energy released in the metastable fragmentation was found to increase with ion source temperature. This increase in kinetic energy with temperature is ascribed to the release of the increase in rotational energy of H 2S + as relative kinetic energy of the metastable products. A detailed analysis of the mechanism for the metastable reaction is given.

The mass spectral behaviour of bruceolides

A series of bruceolides isolated from Brucea javanica has been studied by electron impact, chemical ionization and field desorption mass spectrometry, and by metastable ion techniques, including mass analysed ion kinetic energy spectrometry. The spectral data obtained for one of these compounds, bruceine A, are discussed in relation to the molecular structure and are taken as an example for the bruceolide series. The bruceolides occur in plants as mixtures of closely related compounds and some of them have potent anti-cancer activity. It is demonstrated that mass spectrometry provides a valuable tool for the identification and characterization of these compounds.

Site of protonation and bifunctional group interactions in α,ω‐hydroxyalkylamines

AbstractChemical ionization mass spectrometry and mass analyzed ion kinetic energy spectrometry in conjunction with collision induced dissociation are used to study the fragmentation behavior of a series of α,ω‐hydroxyalkylamines. The difference between the ionic population present at equilibrium in the source, and that which is sampled under nonequilibrium conditions, is revealed in the striking differences observed in product distributions in the chemical ionization mass spectra and the mass analyzed ion kinetic energy spectra. The major fragmentations in the mass analyzed ion kinetic energy spectra, loss of NH3 and H2O, show large variations in intensity as a function of the chain length between the hydroxy and amino functionalities. These results are rationalized through analysis of the relevant thermochemical data.

Sequence analysis of underivatized peptides by negative ion chemical ionization and collision induced dissociation

The sequence of amino acids in a series of underivatized di- and tripeptides has been determined via collision induced dissociation of [M—H]− ions produced by chemical ionization using [OH]−. The collision induced dissociation spectra of individual [M—H]− ions are determined via mass analysed ion kinetic energy spectrometry. Isomeric peptides can be readily distinguished by this method and characteristic sidechain reactions permit the distinction between leucine and isoleucine. The capability for selection of ions of specific m/z value enables mixtures of non-isomeric peptides to be handled by the above technique. Dipeptides containing certain aromatic amino acids (e. g. tryptophan and histidine) eliminate water thermally but this does not necessarily preclude the identification of their constituent amino acids.

A study of some cations formed in the ammonia chemical ionization of ketones using mass analysed ion kinetic energy spectrometry

AbstractThe structures of the major adduct ions formed in ammonia chemical ionization of thirteen aliphatic and aromatic ketones have been studied by mass analysed ion kinetic energy spectrometry. The [M+NH3+H]+ ion is shown to have a protonated carbinolamine structure, [M+2NH3+H]+ to be a protonated carbinolamine with hydrogen‐bonded ammonia and [2M+NH3+H]+ to be, at least in part, a protonated carbinolamine with hydrogen‐bonded ketone. These structures may imply a nucleophilic addition of ammonia at the carbonyl of the ketone‐ammonium ion complex. An unusual hydroxy migration is seen in the internal rearrangement of the [2M+NH3+H]+ ion leading to the formation of a protonated imine.

The gas phase structure of some protonated and ethylated aromatic amines

AbstractThe fundamental processes of protonation and ethylation, occurring in a methane chemical ionization source, have been investigated for a variety of aromatic amines. The positions of protonation and ethylation on the substrate amines were determined by generating isomeric ions either by protonation of neutral ethyl substituted amines or by ethylation of the amines themselves. The product ions were investigated for structural differences via collision induced dissociation and subsequent analysis via mass analysed ion kinetic energy spectrometry. Similarities and differences between mass analysed ion kinetic energy/collision induced dissociation spectra of these isomeric ions were used to determine protonation and ethylation sites for imidazole, benzimidazole, indazole, pyrrole, pyridine and aniline.