Determination of trace lead by hydride generation–inductively coupled plasma–mass spectrometry

Abstract

A newly developed hydride generation–inductively coupled plasma–mass spectrometry (HG–ICP–MS) system was employed to determine trace amounts of lead in geological and biological samples. Laboratory-made single-stage and double-stage gas–liquid separators (GLSs) were investigated in order to replace the consumable membrane-GLS. Possible reasons were given why double-stage GLSs were superior over the single-stage ones according to the factors such as GLS volume and configuration, carrier gas inlet mode and flow rate. Interferences in liquid and vapor phase from concomitant ions and their products were investigated employing different flow mani-folds. Memory effects contributed to the blank values, but could be reduced employing a special wash protocol. Internal and external standardization were combined to improve the accuracy of the method, with bismuth as the internal standard according to its similarity with lead in the HG–ICP–MS system. Compared with ICP–MS and hydride generation–atomic fluorescence spectrometry (HG–AFS) methods, the system performance of HG–ICP–MS was characterized with improved detection limit to 0.002 ng/ml and acceptable short- and long-term stabilities. The linear dynamic range of this method was up to 50 ng/ml lead. Three Chinese national certified reference materials: poplar leaves, human hair and copper ore, were analyzed for method validation, and the results agreed well with the certified values. At last, the method was also employed to determine wide range of lead concentrations in lightweight limestone and nervous tissue samples from infants of albino rats with recoveries between 95 and 105% ( n=10).