Determination of avermectin B1 in biological samples by immunoaffinity column cleanup and liquid chromatography with UV detection.

A simple and specific procedure for determination of avermectin B1 in biological samples is described. A specific anti-avermectin B1 immunosorbent was developed. Avermectin B1 was extracted from cattle plasma, cattle meat, and pear samples. The extracts were cleaned up on a solid-phase extraction column (C18) and an immunoaffinity column. Avermectin B1 was determined by reversed-phase liquid chromatography with UV detection at 245 nm. Recoveries of avermectin B1 from samples spiked at levels of 6 and 60 parts per billion (ppb) ranged from 80 to 86%, with coefficients of variation of 5-14%. The limit of detection was 2 ppb. The procedure provides a simple and sensitive method for monitoring avermectin B1 residues in biological matrixes.