A multiresidue method using gas chromatography (GC) and gas chromatography/ mass spectrometry (GC/MS) was developed for the determination of several organochlorine pesticides in three crude drugs: Astragali Radix (sic)\ Zizyphi Sativae Fructus (sic)\ and Zingiberis Rhizoma (sic). The pesticides including alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, 2,4'-DDE, 4,4'-DDE, 2,4'-DDT and 4,4'-DDT were determined using a modified extraction and refining procedure, separated by a capillary column (DB-1, 0.25 mu m, 0.25 mm x 30 M), observed with an electron capture detector (ECD), and confirmed by GC/MS if necessary. The precision and accuracy were satisfactory. Calibration graphs of eight pesticides were constructed in the range of 0.25 - 2.0 mu g/ml and their correlation coefficients (r) were in the range of 0.995 - 0.998. Recovery studies were performed at the 1.0 ppm spike level of each pesticide in these three crude drugs. Recovery rates were 66.4 - 98.0% for Astragali Radix, 36.7 - 86.9% for Zizyphi Sativae Fructus, and 31.1 - 109.7% for Zingiberis Rhizoma. Coefficients of variation were between 2.3 and 4.9%. The estimated limits of detection of the pesticides were all below the 0.06 ppm level. Coefficients of variation ranged between 6.3 and 10.2%. This analysis method could be also applied to concentrated Chinese medicines.
