Modified method for the determination of ivermectin residues in animal tissues

A simple, reliable method for determining residues of ivermectin in animal tissues is described combining existing sample cleanup procedures for muscle and for feed. Sample extracts are purified on alumina, C18, and silica solid-phase extraction cartridges, and ivermectin is determined by liquid chromatography with fluorescence detection. The average recovery of ivermectin from cattle, swine, and sheep muscle and liver was 87%, in the range of 5-25 ppb. Recovery from fish muscle was 77%, in the range of 5-30 ppb. The detection limit in tissue is 2 ppb.