Extraction and clean-up methods for the determination of organochlorine pesticide residues in medicinal plants

The application of various extraction solvents with an Ultra-Turrax system and ultrasonication with a probe and solid-phase extraction (SPE) with octadecyl (C-18)-bonded silica and Florisil cartridges to linden samples for the gas chromatography-electron capture detection (GC-ECD) of alpha-hexachlorocyclohexane (alpha-HCH), beta-HCH, gamma-HCH, hexachlorobenzene (HCB), heptachlor and its epoxide, p,p'DDE, p,p'DDD, o,p'DDT, p,p'DDT, alpha-endosulfan, beta-endosulfan, endosulfan-sulfate, aldrin, dieldrin and endrin is described. Better results were obtained using ultrasonication with n-hexane and SPE Florisil cartridges. Limits of quantification ranged from 1 mu g/kg for alpha-HCH to 10 mu g/kg for endrin. An attempt to apply this methodology to other medicinal plants such as senna, common balm, german camomile, high mallow and orange flowers revealed that the SPE Florisil clean-up was not enough on its own and it was necessary to use 2 g of 3% deactivated Florisil.