Immunoaffinity column cleanup and liquid chromatographic method for determining ivermectin in sheep serum

A simple and sensitive method was developed for determining ivermectin in sheep serum. The sample is cleaned up on an immunoaffinity column and determined by liquid chromatography with detection at 245 nm. Recoveries ranged from 90.3 to 98.8% (93.9 +/- 4.3%) for samples fortified with 2.0-50 ng ivermectin/mL. Coefficients of variation were 3.2-11.0%. The limit of detection was 1 ng/mL in 5.0 mL serum.