The potential of a modified rf glow discharge source for enhanced elemental speciation studies

Abstract

Radio frequency glow discharge source mass spectrometry (rf GDMS) was employed for determination of tetramethyltin (TMT) with axial sample introduction via capillary gas chromatography (GC). The axial cell design provided homogenous sampling independent of the transfer line capillary position by eliminating discharge asymmetry. Sensitivity value for TMT of 2237 counts pg^–1 was achieved with the current setup, a nearly three-fold improvement from a previous study (681 counts pg^–1). The ¹²⁰Sn⁺ ion signal increased with pressure and decreased with rf power. TMT mass spectra with fragment ion signals comparable in intensity to the ¹²⁰Sn⁺ ion signal were obtained. The ion signal ratio (¹²⁰Sn⁺ ion intensity/fragment ion intensity) was monitored as a function of expansion stage pressure of the mass spectrometer to access the extent of molecular fragmentation with variable plasma conditions.