Multiresidue Determination of Abamectin, Doramectin, Ivermectin, and Moxidectin in Milk Using Liquid Chromatography and Fluorescence Detection

Abamectin, doramectin, ivermectin, and moxidectin are macrocyclic lactones derived from soil dwelling actinomycetes, and are very effective against nematode, insect, and arthropod infestations. These compounds, known as endectocides, have been approved for use in beef cattle in the United States; however, they are currently not approved for use in dairy cattle. Abamectin, doramectin, ivermectin, and moxidectin residues were isolated from milk by a series of liquid-liquid extraction steps, derivatized with trifluoroacetic anhydride, and determined by liquid chromatography with fluorescence detection. Recovery studies were performed in 2 laboratories. Recoveries of > 80% (1-30 ng/mL) were achieved for all 4 compounds.