Effects of lipids on analysis of residue pesticides in herbal medicines

Serious problems in residue analysis of acetamipirid, chlorpyrifos, and bifenthrin caused by lipids present in herbal medicines, platycodon root, safflower, and persicae semen have been found during the pesticide residue analysis using a currently used analytical method. Particularly, recovery tests for artificially spiked pesticides showed poor recoveries for bifenthrin in persicae semen, which may be due to the low polarity of the pesticide and high lipid content in the matrix. An unclear layer separation between water and organic solvent, methylene chloride, has been also observed during the liquid-liquid partitioning process, which favors modification of the liquid-liquid partitioning by replacement with acetonitrile and a macroporous diatomaceous earth column, respectively. The effectiveness of newly modified methods was evaluated based on the recoveries of three pesticides in the herbal medicines at two fortification levels (1.0 and 4.0 mg/kg). The modified methods increased recoveries to 81.8-98.9%, suggesting those methods could be effective and feasible alternatives to determine acetamiprid, bifenthrin, and chlorpyrifos in lipidic samples.