Multi-residue analysis of 18 organochlorine pesticides in 10 traditional Chinese medicines by gas chromatography (GC)

A rapid and simple method for the simultaneous analysis of 18 pesticides (alpha-(C6H6Cl6)-Benzene hexachloride, beta-BHC, gamma-BHC, delta-BHC, heptachlor, heptachlor epoxide, tecnazene, pentachloronitrobenzene (PCNB), hexachlorobenzene, aldrin, methyl pentachlorophenyl sulphide (MPCPS), alpha-endosulfan, trans-chlorodane, cis-chlorodane, p,p'-(C14H8Cl4)-Dichlorodiphenyl dichloroethylene, o,p'-(C14H9Cl5)Dichlorodiphenyl trichloroethane, p,p'-(C14H10Cl4)-Dichlorodiphenyl dichloeoethane, p,p'-DDT) by gas chromatography (GC) in 10 Traditional Chinese Medicines (TCMs) has been developed. The limit of detection was found to be 1.2 x 10(-13) to 9.0 x 10(-13) g with the recoveries ranging from 72.9 to 114.5% and Relative Standard Deviation being less than 17.5%. In addition, the assay was applied to monitor the residues in 10 TCMs, amongst which at least one of the above pesticides were found in 67 samples. The results showed that alpha-BHC was the most frequently detected with a presence of 44.6% in the tested samples, whilst heptachlor epoxide, trans-chlorodane, cis-chlorodane and p,p'-DDD were not detected at all. Nonetheless, none of pesticides in all samples appeared to exceed the maximum residue limits (MRLs) seen in the Chinese regulations.