Objective: To evaluate the feasibility of removing heavy metal ions from the extract of Chinese herbal medicines containing alkaloids by γ-mercaptopropyl-modified silica gel(MPS). Method: Some influence factors on removal of cadmium ion in the aqueous extract of Coptidis Rhizoma were studied

such as the amount of MPS

flow velocity

ratio of column diameter to height and temperature. The chemical changes were evaluated by the HPLC fingerprint profiles and dried extract content

before and after the removal of cadmium ion. Result: The optimum parameters were as follows:the ratio of medicinal herb to MPS 40: 1

1: 3 of ratio of diameter to height

10 BV · h-1 flow velocity

and the room temperature. The removing rate of cadmium ion and copper ion reached 81.3% and 35.9%

respectively. The content of magnesium and zinc ion hardly changed. Dried extract content of aqueous solution of Coptidis Rhizoma decreased by 1.3%

and the similarity of HPLC fingerprint profiles was 0.99. Conclusion: MPS can remove efficiently heavy metal ions and there was no significant change on the chemical components of aqueous solution of Coptidis Rhizoma.