DIFFERENT SAMPLE INTRODUCTION SYSTEMS FOR THE SIMULTANEOUS DETERMINATION OF AS, SB AND SE BY MICROWAVE-INDUCED PLASMA ATOMIC EMISSION-SPECTROMETRY

The determination of hydride-forming elements using different sample introduction procedures into microwave-induced plasmas (MIPs) has been studied. For the determination of As, Sb and Se analyte introduction was accomplished with a pneumatic concentric glass nebulizer, a graphite furnace, or with hydride generation followed by cold-trapping or hot-trapping in a graphite furnace. The detection limits obtained with different types of low power MIPs (toroidal, 1 or 3 filament MIPs) operated in a TM010 cavity according to Beenakker also were investigated. The construction of the flow system used for preconcentration and the effects of reagent concentration, gas flow rates as well as other experimental conditions were described in detail. Suitable conditions for multielement determination with MIP-atomic emission spectrometry (AES) were investigated. The trapping of the hydrides followed by their vaporization showed substantial advantages over the other introduction systems investigated, especially with respect to power of detection. Further, mutual interferences being a big problem in atomic absorption spectrometry are widely absent in MIP-AES. Under compromise operating conditions the detection limits for As, Sb and Se are 0.4; 0.35; 0.25 ng ml-1 respectively, while the sample volume can be varied from 0.05 ml up to several millilitres.