Hydride generation atomic absorption determination of tellurium and bismuth with in situ concentration in a graphite furnace

Abstract

Tellurium and bismuth are determined in the parts per trillion range by a combination of hydride generation, modified graphite furnace trapping, and atomic absorption detection. The metalloid elements are reduced by sodium borohydride to their hydrides, stripped from solution by nitrogen gas stream, and collected onto a porous graphite disc in a graphite furnace. They are then atomized by increasing the graphite furnace temperature and detected by an atomic absorption spectrophotometer. The present method involves a batch process for speciation of Te(Ⅳ), Te(Ⅵ), and total Te and a continuous flow injection process with a Teflon membrane gas/liquid separator for rapid bismuth determination. The absolute detection limits are found to be 3 pg of tellurium and 2 pg of bismuth. The precisions of the measurements are 5.1% for 20 pg and 2.5% for 200 pg of tellurium, and 3.1% for 100 pg and 1.9% for 1,000 pg of bismuth, respectively. Analyses of USGS rock standards show quantitative recovery. Analytical results obtained by the method are presented for natural waters, aerosol particles, geological and biological materials.