An analytical method was developed and validated for the simultaneous determination of four macrocyclic
lactones (ML) (abamectin, doramectin, ivermectin and moxidectin) in butter, using liquid chromatography
with fluorescence detection. The method employed heated liquid–liquid extraction and a mixture
of acetonitrile, ethyl acetate and water, with preconcentration and derivatization, to produce stable fluorescent
derivatives. The chromatographic run time was