Multi-residue analysis of avermectins in swine liver by immunoaffinity extraction and liquid chromatography-mass spectrometry

A multi-residue LC-MS method was developed to determine avermectin residues in swine liver. Abamectin and ivermectin (22,23-dihydroabamectin) were ext racted, and cleaned up by immunoaffinty columns with immobilized anti-averm ectin polyclonal antibodies. The cleaned samples were separated by high-per formance liquid chromatography (HPLC) with a C-8 column and determined by n egative-ion atmospheric pressure chemical ionization (APCI) mass spectromet ry (MS) using selective ion monitoring (SIM) of [M-H](-). Recoveries of aba mectin and ivermectin from fortified samples at 5-100 mug kg(-1) levels ran ged from 74 to 94% and from 65 to 87%, respectively. The limits of detectio n were 5 mug of abamectin or ivermectin in 1 kg sample. (C) 2001 Elsevier S cience B.V. All rights reserved.