DETERMINATION OF TOTAL AND LEACHABLE ARSENIC AND SELENIUM IN SOILS BY CONTINUOUS HYDRIDE GENERATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

A novel gas-liquid separator has been designed for continuous hydride generation inductively coupled plasma mass spectrometry, incorporating a water trap to remove solution droplets from the gas stream. The system has been applied to the determination of total and leachable arsenic and selenium in soils of the Western Cape region of South Africa. Samples were prepared by alkaline fusion for the determination of total concentrations, and leaching with 1 mol l-1 ammonium nitrate was used to determine the leachable content. Use of the hydride generation system confers a 40-fold increase in sensitivity over conventional nebulization, and eliminates argon chloride interferences. Detection limits were in the range 0.2-1.0 mug l-1. Certified reference materials were analysed, and good agreement was obtained.