Decontamination of organochlorine pesticides in Radix Codonopsis by supercritical fluid extractions and determination by gas chromatography

A method involving depuration of 12 organochlorine pesticides (OCPs) from Radix codonopsis was developed using supercritical fluid extraction (SFE). The pesticides investigated in the study included α ‐, β ‐, γ ‐ and δ ‐benzene hexachloride, PCNB (pentachloro‐nitrobenzene), PCA (pentachloroaniline), HEPT (heptachlor), MPCPS (methyl‐pentachlorophenyl sulfide), pp ′‐DDE [1,1‐dichloro‐2, 2‐bis( p ‐chlorophenyl) ethylene], op ′‐DDT [1,1,1‐trichloro‐2‐( o ‐chlorophenyl)‐2‐( p ‐chlorophenyl)ethane], pp ′‐DDD [1,1‐dichloro‐2‐2‐bis( p ‐chlorophenyl)ethane] and pp ′‐DDT [1,1,1‐trichloro‐2,2‐bis( p ‐chlorophenyl)ethane]. A series of experiments was conducted to optimize the final extraction conditions as follows: pure CO 2 , extraction pressure 15 MPa, extraction temperature 60°C, extraction time 20 min and flow rate 55 mL/h. A GC method with electron capture detection was employed for the determination of the OCPs in Radix codonopsis . An HPLC method was developed for the quantitative determination of active constituents. SFE was used to remove the organochlorine pesticide from Radix codonopsis . The results showed that at least 93.5% of the organochlorine pesticide residues in the herb sample were removed by SPE, while 95.0% of the active constituent marker (atractylenoide III) remained. Copyright © 2006 John Wiley & Sons, Ltd.