AbstractA new scan is described which responds to ions that are intermediates in the dissociation of a mass‐selected parent ion (mp) to give a mass‐selected daughter ion (md). The scan gives a simple mass v. abundance output for ions which satisfy this condition. It is implemented here on a BEQQ hybrid mass spectrometer using, in sequence, collision‐induced dissociation occurring at high energy in the first reaction region, and low‐energy collisional activation in the collision quadrupole. The experiment provides information on reaction sequences not available from single scans of other types. In the several cases examined, it is demonstrated that, among many conceivable fragmentation routes connecting a parent ion with a particular fragment ion, only a few are significant. Examination of reaction intermediate spectra also appears to be a fruitful new approach to mechanistic questions, as illustrated by consideration of the behavior of several isomeric octanones. These new spectra also have analytical value: they show good signal‐to‐noise ratios and allow ready distinction between isobaric and isomeric ions. A comparison of the reaction intermediate spectrum with a daughter spectrum obtained by the B/E linked‐scanning technique reveals the contributions of artifact peaks which result from poor parent ion mass resolution in the latter. Reaction intermediate spectra combine information from the daughter spectra of mp and the parent spectra of md and, as a specified portion of this data domain, have unique characteristics.

Hybrid mass spectrometers combine the advantages of different types of mass analyzers to produce highly versatile scientific tools. Improvement on the traditional MS-MS scans is achieved enabling the extraction of additional information. In addition, new MS-MS scan modes have been discovered which display great promise. A new method of obtaining structural information by MS, surface-induced dissociation, is also implemented using the hybrid mass spectrometer.

When sampled by laser irradiation from a suitable matrix, cationized sugars can be desorbed in far higher yields for longer periods than in experiments which do not employ a matrix. Daughter spectra reveal that Li+ reacts differently from the other alkali ions in that it can catalyse ring opening; collision-induced dissociation then causes successive CC cleavage reactions. Selectivity is also exhibited by the substrate; some isomers yield much more intense ion currents with the alkali metals than do others. These findings should contribute to a wider use of laser desorption, including selective examination of mixtures for particular types of compounds, as well as detailed structural studies on individual substances.

A new hybrid mass spectrometer is described for the characterization of structures of products generated in a flowing afterglow apparatus by triple quadrupole tandem mass spectrometry. Examples are given of isomeric ion differentiation using daughter spectra generated by collision-induced dissociation of mass selected ions. Parent spectra allow systematic characterization of the complex mixture of product ions produced by electron impact ionization and subsequent ion/molecule condensation reactions of Fe(CO)5. Cluster ions, including trimers consisting of three amines solvating a proton, can be generated and their unimolecular kinetics provides information about gas phase basicities. Small differences in dimer and trimer fragmentation behavior are interpreted in terms of steric effects operating in the trimer.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew scan modes accessed with a hybrid mass spectrometerJohn N. Louris, Larry G. Wright, R. Graham. Cooks, and Alan E. SchoenCite this: Anal. Chem. 1985, 57, 14, 2918–2924Publication Date (Print):December 1, 1985Publication History Published online1 May 2002Published inissue 1 December 1985https://pubs.acs.org/doi/10.1021/ac00291a039https://doi.org/10.1021/ac00291a039research-articleACS PublicationsRequest reuse permissionsArticle Views448Altmetric-Citations79LEARN 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 InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Chemical ionization of mixtures of aliphatic acids yields proton-bound dicarboxylate anions, R1CO2−⋯H+⋯−O2CR2, which are mass-selected and subjected to collision-induced dissociation (CID) at 5–30 eV. The branching ratio for formation of the principal fragments, R1CO2− and R2CO2−, is used to follow internal energy deposition in the proton-bound anion as a function of collision energy and target pressure. Increased energy deposition is observed with increases in pressure and in translational energy, although the branching ratio also shows effects attributed to severe discrimination against the lighter fragment at pressures exceeding the limit for single collisions. These discrimination effects are most pronounced at low collision energy and are not observed (for argon target gas) at the higher energies.