Abstract: A novel method for the determination of representative toxaphene congeners in traditional Chinese herbal medicines was developed. Ginseng and Milkvetch Root were selected as the samples and seven toxaphene congeners were selected as the monitoring objects. The samples were extracted by accelerated solvent extraction with cyclohexane-acetone (9:1, v/v), then cleaned-up by Florisil solid phase extraction with hexane as the eluent and the residues were detected by gas chromatography-electron ionization tandem mass spectrometry (GC-EI-MS/MS) in multiple reaction monitoring (MRM) mode. The performance was demonstrated by the analysis of Ginseng and Milkvetch Root samples spiked with toxaphene congeners at three concentration levels of 0.005, 0.01 and 0.1 mg/kg. The recoveries ranged from 72.4% to 105% with the relative standard deviations (RSDs) of 0.96%~10.4%. The limits of detection (LODs) were 0.2~1.7 μg/kg. This method is sensitive and efficient in the aspect of extraction, and can be applied to monitor the residue of toxaphene congeners in Ginseng and Milkvetch Root.

Key words: Ginseng, Milkvetch Root, residue, toxaphene, traditional Chinese herbal medicine, gas chromatography-electron ionization tandem mass spectrometry(GC-EI-MS/MS)