Dilute acid digestion procedure for the determination of lead, copper and mercury in traditional Chinese medicines by atomic absorption spectrometry

Abstract

A sample preparation procedure using 10% v/v HNO₃ was successfully applied to the determination of Pb, Cu and Hg in traditional Chinese medicines. It provides good recoveries of Pb, Cu and Hg, requires small volumes of concentrated acid and is free from reagent and procedural blank problems. A number of Chinese medicines were analysed using the proposed method. The results obtained were comparable to those obtained by other standard procedures. Using a 3 g sample, the detection limit for Pb was about 4 µg g^–1, for Cu about 0.2 µg g^–1 and for Hg about 0.03 µg g^–1. The precision of the method, obtained by calculation of the relative standard deviations for six replicate measurements, was 0.7% for Pb, 0.7% for Cu and 6.5% for Hg.