SIMULTANEOUS DETERMINATION OF SE AND AS BY HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY WITH ANALYTE CONCENTRATION IN A GRAPHITE-FURNACE COATED WITH ZIRCONIUM

Conditions for the simultaneous determination of selenium and arsenic at ng 1(-1) level were developed. Simultaneous determination of these elements was possible through the multielement capabilities of hydride generation, with in situ trapping and atomization in a graphite tube coated with zirconium and measurements using a dual channel atomic abs orption spectrophotometer. The zirconium coating employed in this work was relatively stable; once formed it could stand approximate to 80 f irings without any significant change in the efficiency of hydride col lection. This appears to be an advantage over the palladium coating, w hich is usually formed individually before each measurement because of its thermal instability during the atomization step of the furnace te mperature programme. As a result, two determinations of the two elemen ts could be performed in 2.5 min. Under the optimized conditions, conc entration detection limits of 17 and 13 ng 1(-1) for a 7.1 ml sample v olume were obtained for selenium and arsenic, respectively (absolute d etection limits 120 and 92 pg for Se and As).