SOLID-LIQUID EXTRACTION FOR THE DETERMINATION OF IMPURITIES IN HIGH-PURITY LEAD BY ATOMIC-ABSORPTION SPECTROMETRY WITH ELECTROTHERMAL ATOMIZATION

After dissolving a lead sample in 4.5 mol l(-1) nitric acid, the solution was evaporated to dryness. The trace impurities were extracted from lead nitrate crystals with an ethanolic solvent, that is, a 99 + 1 mixture of ethanol (99.5% v/v) and 15 mol l(-1) aqueous ammonia (for silver) or a 99 + 1 mixture of ethanol (99.5% v/v) and 12 mol l(-1) hydrochloric acid (for iron, copper and cadmium). The desired trace metals were recovered in >93% yields and determined by electrothermal atomic absorption spectrometry. The separation factor for the lead matrix was about 10(-3) The proposed method was applied to the determination of impurities at ng g(-1) levels in high-purity lead metal.