Trace metals in traditional Chinese medicine: A preliminary study using ICP-MS for metal determination and as speciation

The metal content in several TCM drugs was determined by ICP-MS. The effici encies of different sample digestion methods were compared. Since one of th e products studied is known to contain arsenic sulfides as a main ingredien t, a solvent fractionation scheme was developed and applied to speciate As in the product. The metal content in the same TCM drug produced by differen t manufacturers was compared. The concentration of some metals such as Pb a nd Cd differs widely with different manufacturers, suggesting that their or igin is primarily from external contamination. The high sensitivity and pre cision of the ICP-MS technique offers considerable advantages over conventi onal ICP-OES techniques for the analysis of complex samples such as TCM mat erials. Standardized analytic protocols based on ICP-MS are being developed fur the determination and characterization of metals and trace elements in TCM materials for product quality assessment.