Chemical mass shifts in quadrupole ion traps, miniature cylindrical ion trap and chiral analysis of amino acids using ESI-mass spectrometry
Abstract
Chemical mass shifts are the result of compound-dependent collisional modification of the ejection delay produced by field faults near the endcap electrode apertures in a quadrupole ion trap operated in the mass selective instability mode. Both dissociative and non-dissociative collisions can occur but dissociative collisions make the predominant contribution to the chemical mass shifts. In other words, chemical mass shifts are compound-dependent and compounds which are easier to fragment generally give relatively large chemical mass shifts. The large chemical mass shifts associated with the nitro-aromatic compounds could serve as a diagnostic for identifying this class of compounds in mixtures and a simple method of implementing this test is described based on the effect of non-linear resonance on the chemical mass shifts. The kinetic method provides an alternative to current methods of chiral analysis of amino acids. This mass spectrometry-based chiral analysis technique has been applied successfully to the enantiomeric determination of all pure amino acids of interest, giving accurate quantitative results with a relative standard deviation of less than 3% when tested individually using optimized experimental conditions. A general mass spectrometric procedure was established for chiral analysis of both standard mixtures and permafrost extracts. The approach presented in this thesis therefore serves as a rapid and direct method of enantiomeric quantification of amino acids in a complex mixture using the kinetic method.
Degree
Ph.D.
Advisors
Cooks, Purdue University.
Subject Area
Analytical chemistry
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