RESUMO
<p><b>OBJECTIVE</b>To study the optimum process of removing cadmium irons from extracts of Gentianae Radix et Rhizoma with gamma-mercaptopropyl-modified silica gel (MPS) and assess its cadmium ion-removing property.</p><p><b>METHOD</b>Static and dynamic adsorptions were adopted to detect the cadmium-removing rate. MPS' cadmium ion-removing property was assessed with such indicators as the cadmium-removing rate, the solid content and the HPLC fingerprint.</p><p><b>RESULT</b>The process parameters of the static adsorption were as follows: 0.20 g x mL(-1) of concentration of extracts, 120 minutes of adsorption time and 15:1 between raw materials and MPS. The process parameters of the dynamic adsorption were as follows: 1:3.5 times between diameter and height, 0.20 g x mL(-1) of concentration of extracts, 0.9 mL x min(-1) of flow rate of the extracts and 50:1 between raw materials and MPS. Before and after the cadmium ion-removing process, the extracts showed no notable difference in solid content and HPLC fingerprint.</p><p><b>CONCLUSION</b>gamma-mercaptopropyl-modified silica gel (MPS) can effectively remove cadmium ion from the extracts of Gentianae Radix et Rhizoma with an excellent cadmium ion-removing property.</p>