Single Sweeping Oscillopolarographic Determination of Lead and Cadmium in Chinese Herbal Medicines

In a base solution of 6×10-3mol·L-1 HCl containing ascorbic acid,potassium iodide,sodium potassium tartrate and poly-ethylene glycol (PEG) 400,trace amounts of lead and cadmium in 5 kinds of Chinese herbal medicines were determined successively by the single-sweeping oscillopolarography.Linear relationships between the peak current (I″p) and the concentration of lead and cadmium were obtained in the ranges of 0.004-0.50 mg·L-1 (r=0.998 0) and 0.003-0.40 mg·L-1 (r=0.999 4) respectively.Precision was tested at different concentration levels of both element,and values of RSD′s (n=7) obtained were in the ranges of 1.2%-4.5% (for Pb) and 1.6%-4.1% (for Cd).Results of recovery test were in the ranges of 94.0%-100.5% (for Pb) and 97.0%-103.0% (for Cd).In the analysis of 5 kinds of Chinese herbal medicines,results obtained checked quite well with the results found by GF-AAS methods.