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PART I. ANALYTICAL APPLICATIONS OF MASS SPECTROMETRY/MASS SPECTROMETRY (MS/MS). PART II. INVESTIGATIONS OF ION-MOLECULE REACTIONS PRODUCTS BY MS/MS. PART III. THE QUESTION OF TAUTOMERISM OF ALKYLNITRILE AND ISONITRILE RADICAL CATIONS
Abstract
Part I. We describe the design of a unique high resolution mass spectrometry/mass spectrometry (ms/ms) instrument having the configuration electrostatic analyzer, magnetic sector, and electrostatic analyzer (EBE). Suitable experiments are reported which evaluate the instrument in terms of the requirements for analytical ms/ms applications: high resolution mass selection, high dynamic range, and good transmission for collision-induced decomposition (CID) fragments. The unique capability of triple-sector instruments to monitor consecutive collision-induced reactions is applied to the analysis of mixtures of ions which are isobaric and isomeric, respectively. In addition, a method for the analysis of tetrachlorodibenzo-p-dioxin (TCDD) suitable for use with double or triple sector instruments is described in which the loss of COCl from the molecular ion is monitored. The precision, quality of calibration, and detection limit are evaluated directly, and the accuracy and specificity are tested by comparing the results of an analysis of soil samples with those obtained using GC/HRMS. Part II. We employ ms/ms techniques to study the ion-molecule reaction products created and collisionally-stabilized in a high-pressure ion source. By comparison of unimolecular and collision-induced dissociation spectra, it is demonstrated that the stabilized collision complex from the reaction of {o-quinodimethane}('+) and styrene is shown to have the structure of 2-phenyltetralin, the anticipated product of a {4+2}-cycloaddition mechanism. The stabilized complex from the reaction of {styrene}('+) and neutral styrene is shown not to have the structure of 1-phenyltetralin, and we offer evidence in favor of a formal {4+2}-cycloaddition mechanism. The stabilized complexes of {1,3-butadiene}('+) and olefins are shown not to possess the structures expected for a {4+2}-cycloaddition mechanism. Part III. We use unimolecular and collision-induced dissociations to establish that the isomeric pairs {CH(,3)CN}('+) and {CH(,2)CNH}('+) and {CH(,3)NC}('+) and {CH(,2)NCH}('+) are stable, noninterconverting structures, even when activated to decompose. The same conclusion pertains to the ions {CH(,3)CH(,2)CN}('+) and {CH(,3)CHCNH}('+) and for {NCCH(,2)CH(,2)CN}('+), {NCCH(,2)CHCNH}('+), and {HNCCHCHCNH}('+). The energy barrier of a {1,3}-hydrogen shift, a possible isomerization mechanism, is determined to be at least 76 kcal mol('-1) for the {CH(,3)CN}('+) and {CH(,2)CNH}('+) pair.
Subject Area
Analytical chemistry
Recommended Citation
CHESS, EDWARD KELLEY, "PART I. ANALYTICAL APPLICATIONS OF MASS SPECTROMETRY/MASS SPECTROMETRY (MS/MS). PART II. INVESTIGATIONS OF ION-MOLECULE REACTIONS PRODUCTS BY MS/MS. PART III. THE QUESTION OF TAUTOMERISM OF ALKYLNITRILE AND ISONITRILE RADICAL CATIONS" (1982). ETD collection for University of Nebraska-Lincoln. AAI8220643.
https://digitalcommons.unl.edu/dissertations/AAI8220643