NEW METHODS AND INSTRUMENTATION IN TANDEM MASS SPECTROMETRY (BEQQ, SCANS, FAQQQ)
Abstract
The research presented herein is concerned with developing new methods and instrumentation in the area of tandem mass spectrometry (MS/MS). First, a hybrid BEQQ mass spectrometer is described. The BEQQ is used to demonstrate several new types of MS/MS scans, including combinations of parent, daughter, and neutral loss scans. The new scans are shown to provide information inaccessible by conventional MS/MS experiments. Second, a method of generating ions from thermally labile systems using a continuous wave CO(,2) laser and a triple quadrupole mass spectrometer is described. Laser desorption is used in combination with a glycerol and alkali carbonate salt matrix to generate cationized sugar ions in high yields. Daughter spectra reveal that lithium reacts differently to other alkali ions in that it can catalyze ring opening. Selectivity of the sugar molecules is also exhibited by the substrate. Third, a flowing afterglow triple quadrupole (FAQQQ) mass spectrometer is described. Experiments are described which highlight the unique features of the FAQQQ for studying gas phase ion molecule chemistry. For example, while FA experiments generally rely upon ion molecule reactions for structural information, the FAQQQ adds a powerful new dimension of product characterization via MS/MS. The chemical versatility and well defined conditions of the FA likewise add a new dimension to the MS/MS experiment which traditionally employs a static ion source. Finally, a kinetic method of ordering gas phase acidities and basicities based upon the competitive dissociations of loosely-bound cluster ions is described. Application of the method to the ordering of D(A('-)-H('+)) values for a set of carboxylic acids and to the ordering of gas phase basicities of amines is described.
Degree
Ph.D.
Subject Area
Analytical chemistry
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