Optimisation of an atmospheric pressure helium microwave-induced plasma coupled with capillary gas chromatography for the determination of alkyllead and alkylmercury compounds

This paper describes the optimisation of a microwave-induced plasma (MIP) spectrometer for the determination and speciation of organometallic compounds. The MIP was interfaced to a gas chromatograph by threading a capillary column down a heated transfer line directly into the plasma torch. Both simplex and univariate search methods were investigated for the optimisation of the system for the organometallic compounds. For both the mercury and lead compounds the most critical parameter was found to be the plasma gas flow-rate. The calibration graphs obtained for liquid standards of these compounds were linear over three orders of magnitude and detection limits of about 1 pg were obtained without background correction or the use of scavenger gases.