Lead hydride generation in a lactic acid-potassium dichromate medium and its application to the determination of lead in fish, vegetable and drink samples

Abstract

The effect of different acids on the efficiency of lead hydride generation in potassium dichromate oxidant medium was investigated and lactic acid-potassium dichromate was found to give optimum lead hydride generation. Various parameters affecting sensitivity and the influence of interfering ions were studied. The sensitivity of the method (0.44 ng) is greater than published values for ammonium peroxodisulphate-nitric acid (20.0 hg) and hydrogen peroxide-nitric acid (10.0 ng). This could be because lactic acid stabilizes the Pb(IV) metastable compounds more effectively, acting as intermediate species in lead hydride formation. The method was applied to the determination of lead in liquids (tap water and wine) and fish and vegetable samples. The liquids were analysed directly without preconcentration or mineralization and the solids after wet digestion or slurry formation; these two sample preparation methods gave similar results.