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Ion-molecule Reactions (ion-molecule + reaction)
Selected AbstractsHydrated metal ions in the gas phaseMASS SPECTROMETRY REVIEWS, Issue 4 2007Martin K. Beyer Abstract Studying metal ion solvation, especially hydration, in the gas phase has developed into a field that is dominated by a tight interaction between experiment and theory. Since the studied species carry charge, mass spectrometry is an indispensable tool in all experiments. Whereas gas-phase coordination chemistry and reactions of bare metal ions are reasonably well understood, systems containing a larger number of solvent molecules are still difficult to understand. This review focuses on the rich chemistry of hydrated metal ions in the gas phase, covering coordination chemistry, charge separation in multiply charged systems, as well as intracluster and ion-molecule reactions. Key ideas of metal ion solvation in the gas phase are illustrated with rare-gas solvated metal ions. © 2007 Wiley Periodicals, Inc., Mass Spectrom. Rev. [source] Mass spectrometric characterization of high-valent metal-oxo, -peroxo and -peroxy intermediates of relevance in oxidation processesMASS SPECTROMETRY REVIEWS, Issue 5 2006Olga Bortolini Abstract The coupling of mass spectrometry with ionization techniques like electrospray ionization (ESI) or matrix-assisted matrix-assisted laser desorption-ionization (MALDI) offers many advantages over other well-established spectroscopic techniques employed for the investigation of intermediates or short-lived species in condensed-phase. In this review we describe some of the applications of mass spectrometry, in particular of ESI-MS to the detection and characterization of high-valent metal-oxo, -peroxo and -peroxy derivatives, crucial intermediates in the oxyfunctionalization of organic substrates. In addition, by utilizing gas-phase ion-molecule reactions and MS/MS experiments, information on the intrinsic reactivity of the short-lived intermediates may be obtained. The combined use of ESI-MS in association with other spectroscopic techniques and theoretical calculations is discussed as well. © 2006 Wiley Periodicals, Inc. [source] Coupling of ion-molecule reactions with liquid chromatography on a quadrupole ion trap mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2008Yuriy Pyatkivskyy We report for the first time a coupling of gas-phase ion-molecule reactions with chromatographic separations on a quadrupole ion trap mass spectrometer. The interface was accomplished by using a pulsed valve for the introduction of a volatile neutral into the ion trap. The pulsed valve controller is synchronized with the mass spectrometer software. The setup requires some minor modifications to the vacuum system of the commercial quadrupole ion trap but most of the modifications are external to the mass spectrometer. Two applications of this interface are described: differentiation between two phosphoglucose positional isomers and detection of a phosphopeptide in a peptide mixture. Both applications are using the reactivity of trimethoxyborate towards a phosphate moiety in the negative ion mode. The detection of phosphopeptides hinges on our findings that non-phosphorylated peptide anions do not react with trimethoxyborate. This LC/MS detection can be easily visualized in terms of selected reaction monitoring. Copyright © 2008 John Wiley & Sons, Ltd. [source] Auxiliary approach to evaluate the isomeric decarboxylated anions from 2-, 3- and 4-sulfobenzoates in the gas phase by using ion-molecule reactions with carbon dioxide in the collision cell,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2006M. Kiran Kumar First page of article [source] Gas-phase ion chemistry of Glu/Met systems,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 1 2002H. Wincel A combined chemical ionisation and tandem mass spectrometry (MS/MS) approach has been used for investigation of the gas-phase ion chemistry of systems containing the amino acids Glu and Met, and the dipeptides ,-Glu-Met and Met-Glu. The metastable fragmentation of the protonated dimer, (Glu)2H+, reveals an intracluster reaction leading to the elimination of the Glu residue. The main features of the ion-molecule reactions observed in the systems containing Glu and Glu,+,Met can be described in terms of sequential adduct formation. The results obtained for the thermal dehydration of Glu were used to rationalise the formation of the proton-bound structures (Glu,,,H2O)···H+··· (Glu,,,H2O) and (Glu,,,H2O)3·H+. The adduct ions, [(Glu,,,H2O),+,H,+,Glu]+ and [(Glu,,,H2O),+ H,+,Met]+, and further association products were also observed. The results lead to a reconsideration of the structural aspects proposed earlier for these species in the sense that they suggest that the systems correspond to a mixture of isomeric covalent and proton-bound structures. The thermal effects on the decomposition of the neutral (,-Glu-Met) and its protonated form, (,-Glu-Met)H+, at m/z 279 were investigated, and dramatic changes in the MI spectra of the m/z 279 ion with temperature were found. A mechanistic explanation for the observed evolution of higher mass ion peaks in the mass spectra is developed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Ion chemistry of chloroethanes in air at atmospheric pressureRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2001Anna Nicoletti Ion chemistry at atmospheric pressure is of major relevance to novel methods for the abatement of volatile organic compounds (VOCs) that employ non-thermal plasmas. For this reason, positive and negative APCI (atmospheric pressure chemical ionization) mass spectra of all six di-, tri- and tetrachloroethanes diluted in air (500,1500,ppm) at atmospheric pressure were investigated at 30,°C and at 300,°C. Spectral changes due to collisional activation of the ions achieved by increasing ,V, the potential difference between sampling and skimmer cones, are informative of structures and ion-molecule reactions. Positive ion chemistry of the chloroethanes (M) can, in general, be ascribed to C-C and C-Cl cleavages of the molecular ion, M+·, never detected but likely formed via exothermic charge exchange from primary ions of the APCI plasma. Exceptions to this characteristic pattern were observed for 1,1-dichloroethane and 1,1,2,2-tetrachloroethane, which give [M,,,H]+ and [M,,,HCl]+· species, respectively. It is suggested that both such species are due to ionization via hydride transfer. Upon increasing ,V, the [M,,,HCl]+· ion formed from 1,1,2,2-tetrachloroethane undergoes the same fragmentation and ion-molecule reactions previously reported for trichloroethene. A nucleophilic reaction of water within the [C2H4Cl+](H2O)n ionic complexes to displace HCl is postulated to account for the [C2H5O+](H2O)m species observed in the positive APCI spectra of the dichloroethanes. Negative ion spectra are, for all investigated chloroethanes, dominated by Cl, and its ion-neutral complexes with one, two and, in some cases, three molecules of the neutral precursor and/or water. Another common feature is the formation of species (X,)(M)n where X, is a background ion of the APCI plasma, namely O2,,O3, and, in some cases, (NO)2,. Peculiar to 1,1,1-trichloroethane are species attributed to Cl, complexes with phosgene, (Cl,)(Cl2C=O)n(n,=,1,2). Such complexes, which were not observed for either the isomeric 1,1,2-trichloroethane or for the tetrachloroethanes, are of interest as oxidation intermediates in the corona-induced decomposition process. No conclusions can be drawn in the case of the dichloroethanes, since, for these compounds, the ions (Cl,)(Cl2C=O)n and (Cl,)(M)n happen to be isobaric. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||