Fast atom bombardment mass spectrometry of alkali metal fluorides and chlorides; a comparison of the solid salt and glycerol matrix spectra

Abstract

AbstractThe Fast Atom Bombardment (FAB) mass spectra of the alkali metal chlorides (Na, K, Cs) and fluorides (Na, K, Rb, Cs) were obtained from solids and a glycerol matrix, using a fast atom bombardment source. From solids the fluorides exhibited an ion abundance enhancement of the well‐known [M(MF)4]+ cluster, which decreased with increasing cation size. A gradual decrease in the n=4 enhancement was observed as the salt was diluted with glycerol. In the chlorides only sodium chloride showed the n=4 relative enhancement. The mass spectra of the salts from a glycerol matrix at molar ratios of 1:1 to 1:10 showed that the spectra of the 1:1 solutions were similar to those from the solids, while glycerol adducts were found to increase with increasing glycerol concentration. A [M(MX)n(gly)]+ species that featured successive losses of HX was observed. It has not been established whether HX losses take place in solution, in the surface/vacuum interface and/or whether gas phase reactions might be responsible for the observation of the [M(MX)n(gly)–y HX]− species in the mass spectra of the MX/glycerol system.