Low-pressure helium microwave-induced plasma mass spectrometry for the detection of halogenated gas chromatographic effluents

A low-pressure helium microwave-induced plasma was interfaced to a mass spectrometer and the system was utilised as a detector for gas chromatography. The over-all system was optimised with respect to microwave power and the first-stage pressure of the mass spectrometer. The linear dynamic range for iodobenzene extended over three orders of magnitude starting at 1 pg. The absolute 3σ detection limit for iodine was 0.1 pg. The evaluation of the interface for the detection of bromine indicated an interference at mass 79 due to the formation of a polyatomic nickel species. A preliminary detection limit of 3.5 pg was calculated for bromine. A second interface design was used in a preliminary investigation of the backgrounds at masses 35 and 37. The background 35/37 ratio was correct, indicating a source of chlorine within the system. The detection limit for chlorine was 24 pg.