DETERMINATION OF LEAD AND BISMUTH IN NICKEL-BASE ALLOYS BY GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY USING CONTINUUM SOURCE BACKGROUND CORRECTION

The analysis of trace lead and bismuth in nickel-base alloys using the stabilized temperature platform furnace atomic absorption spectrometr y (AAS) with deuterium background correction was investigated. The pea k times of lead and bismuth were different in different matrices. Lead was determined directly without any chemical modifier since the backg round absorption caused by the alloy matrix was compensated by the con tinuum background corrector. Aqueous standards were used to construct the calibration curves. The high background absorption encountered in the determination of bismuth could not be eliminated by chemical modif iers, neither palladium nor ethylenediaminetetraacetic acid (EDTA). Ba ckground absorption was effectively reduced when trace bismuth was sep arated from the major matrix by coprecipitation with the addition of a mmonium before determination by AAS. Hence, subnanogram levels of lead and bismuth in the aqueous solutions of nickel-base alloys were deter mined precisely with the optimum instrumental conditions established i n this work. The accuracy and precision of the proposed methods were e valuated through the analysis of standard reference materials of nicke l-base alloys. The experimental results agreed closely with the certif ied values and the reference values.