Iodide-assisted total lead measurement and determination of different lead fractions in drinking water samples

Abstract

Lead and its compounds are toxic and can harm human health, especially the intelligence development in children. Accurate measurement of total lead present in drinking water is crucial in determining the extent of lead contamination and human exposure due to drinking water consumption. The USEPA method for total lead measurement (no. 200.8) is often used to analyze lead levels in drinking water. However, in the presence of high concentration of the tetravalent lead corrosion product PbO2, the USEPA method was not able to fully recover particulate lead due to incomplete dissolution of PbO2 particles during strong acid digestion. In this study, a new procedure that integrates membrane separation, iodometric PbO2 measurement, strong acid digestion and ICP-MS measurement was proposed and evaluated for accurate total lead measurement and quantification of different lead fractions including soluble Pb2+, particulate Pb(ii) carbonate and PbO2 in drinking water samples. The proposed procedure was evaluated using drinking water reconstituted with spiked Pb2+, spiked particulate Pb(ii) carbonate and in situ formed or spiked PbO2. Recovery tests showed that the proposed procedure and the USEPA method can achieve 93-112% and 86-103% recoveries respectively for samples containing low PbO2 concentrations (0.018-0.076 mg Pb per L). For samples containing higher concentrations of PbO2 (0.089-1.316 mg Pb per L), the USEPA method failed to meet the recovery requirement for total lead (85-115%) while the proposed method can achieve satisfactory recoveries (91-111%) and differentiate the soluble Pb2+, particulate Pb(ii) carbonate and PbO2. © 2012 The Royal Society of Chemistry.