The Extraction and Analysis for the Resi due of ThreePyrethroid Pesticides in Medicinal Herbs Isatis indigotica Fort.

A method for determination of three pyrethroid pesticides, cypermethrin, fenvale rate and deltamethrin in medicinal herbs， Isatis indigotica Fort, by gas chr omatography was developed. The samples were extracted by ultrasonic, Soxhlet and Shake extraction. The supernatant was re-extracted with acetone/0.05 mol/L CaC l2. The extract was cleaned up on a florisil column and followed by analysis w ith GC/ECD. The linear range of the method was 0.4×10-10～4×10-10g . When the fortified concentration were 0.04～1.0 mg/kg, the average recover ies of the pyrethroid pesticides were 81.1%～126.3%, 80.2%～98.5% and 80.0%～10 1.7% for Soxhlet, ultrasonic and Shake extraction, respectively. The minimum det ec tive concentration of cypermethrin, fenvalerate and deltamethrin were 5.0×1 0-3、5.0×10-3 and 2.0×10-3 mg/kg, respectively. Auth or s suggest that the ultrasonic extraction is the best method for extraction of th e pyrethroid pesticides residue in Isatis indigotica Fort.