HG-AAS Determination of Lead in Chinese Herbal Medicines

Sample of Chinese herbal medicine was digested with HNO3-H2O2 and oxidized by K3Fe(CN)6, to transform Pb(Ⅱ) into Pb(Ⅳ). Lead was then determined by flow injection-hydride generation-atomic absorption spectroscopy (FI-HG-AAS) with KBH4 as reducing reagent and HCl as carrying solution. Linear relationship between values of absorbance and mass concentration of lead were obtained in the range of 0.50-20 μg·L-1, with detection limit (3S/N) of 0.067 μg·L-1. Four samples of Chinese herbal medicines were analyzed by the proposed method, values of RSD′s (n=5) obtained were in the range of 3.2%-4.8%, and values of recovery found by standard addition method were in the range of 95.6%-103%.