PART I: FORMATION OF COMPLEXES WITH DIVALENT CATIONS IN FIELD DESORPTION MASS SPECTROMETRY. PART II: POLYHYDROXYL MATRICES IN FIELD DESORPTION MASS SPECTROMETRY OF SODIUM SALTS OF ORGANIC ACIDS.

摘要

Part I. Sugars and other polar molecules are shown to form doubly-charged complexes with divalent ions which are detected by field desorption mass spectrometry (FDMS) with reasonable intensities. Cationization of sucrose, raffinose, and stachyose with Ba(u272+) ions generates a series of doubly-charged complex ions, including {M + Ba}(u272+). Similar treatment of several polyether mixtures with Ca(u272+) gives abundant {M + Ca}(u272+) ions which show approximately the molecular weight distribution of the oligomers. Such doubly-charged ions have the advantage of extending the effective mass scale of conventional mass spectrometers without inherent loss of sensitivity. Part II. Field desorption (FD) mass spectra of the sodium salts of several organic acids have been improved with the addition of polyhydroxyl compounds such as pentaerythritol and cis-inositol. The presence of the additives as a matrix leads to a smoother desorption process, higher ionization intensity, and lower abundance of Na(u27+). Hydrogen and alkyl exchange are also demonstrated in the FD mass spectra of sodium acetate, sodium propionate, labelled analogs, and various mixtures of these compounds. Both exchange processes are shown to be significant even at low desorption temperature where decomposition products are minimized. A simple mechanistic scheme was not found for these complex intermolecular reactions. Throughout this work, pentaerythritol was used as a matrix to improve the reproducibility of minor ions in the FD spectra. Source: Dissertation Abstracts International, Volume: 42-08, Section: B, page: 3274. Thesis (Ph.D.)--University of Windsor (Canada), 1981.