Determination of macrocyclic lactones in food and feed.

A confirmatory high-performance liquid chromatography method with fluorescence detection (HPLC-FLD) was developed and validated for the simultaneous determination of the following anti-parasitic veterinary drugs in foodstuffs (liver, muscle and milk) and feed: abamectin, doramectin, emamectin, eprinomectin, ivermectin and moxidectin. Samples were extracted, purified and analysed by HPLC-FLD after prior derivatisation of analytes with N-methylimidazole, trifluoracetic anhydride and acetic acid to produce stable fluorescent derivatives. Recoveries were in the range of 73-98% (liver), 82-93% (muscle), 77-84% (milk), and 93-110% (feed). In all matrices the coefficients of variation for repeatability and intra-laboratory reproducibility were satisfactory. For emamectin in liver the worst method performance was observed. As this multi-analyte method fully met the required criteria and applicability both to food and feed, it has been successfully applied in National Control Plans in food and feed.