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

Abstract

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 alpha-, beta-, gamma- and delta-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 CO2, extraction pressure 15 MPa, extraction temperature 60 degrees 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.