Planar chromatography for screening of ivermectin residues in swine and cattle tissues

A method was developed for qualitative detection of ivermectin residues. It involves extraction of 1 g tissue sample with 5 mL acetonitrile and C-18 solid-phase extraction. After derivatization with trifluoroacetic anhydride, the extract is purified again on the same but previously reconditioned C-18 column. The eluate is evaporated, and the residue is diluted in methanol. The method allows detection of residues in swine and cattle meat, liver, and fat at levels as low as 5 mu g/kg.