Determination of Heavy Metal Ions in Chinese Herbal Medicine by Microwave Digestion and RP-HPLC with UV-Vis Detection

摘要

A new method for the simultaneous determination of heavy metal ions in Chinese herbal medicine by microwave digestion and reversed-phase high-performance liquid chromatography (RP-HPLC) has been developed.The Chinese herbal medicine samples were digested by microwave digestion.Lead,cadmium,mercury,nickel,copper,zinc,and tin ions in the digested samples were pre-column derivatized with tetra-(4-chlorophenyl)-porphyrin (T_4-CPP) to form the colored chelates which were then enriched by solid phase extraction with C_(18) cartridge and eluted from the cartridge with tetrahydrofuran (THF).The chelates were separated on a Waters Xterra RP_(18) column by gradient elution with methanol (containing 0.05 mol L~(-1) pyrrolidine-acetic acid buffer salt,pH=10.0) and THF (containing 0.05 mol L~(-1) pyrrolidine-acetic acid buffer salt,pH=10.0) as mobile phase at a flow rate of 0.5 mL min~(-1) and detected with a photodiode array detector in the range of 350-600 nm.In the original samples the detection limits of lead,cadmium,mercury,nickel,copper,zinc and tin are 4 ng L~(-1),3 ng L~(-1),6 ng L~(-1),5 ng L~(-1),2 ng L~(-1),6ngL~(-1),and 4 ng L~(-1),respectively.This method was applied to the determination of lead,cadmium,mercury,nickel,copper,zinc and tin in Chinese herbal medicine samples with good results.