Rapid determination of abamectin in lettuce and cucumber by high-performance liquid chromatography.

A rapid, sensitive and reliable method is presented for the determination of trace amounts of abamectin in lettuce and cucumber. Abamectin consists of greater than or equal to 80% avermectin B1a and less than or equal to 20% avermectin Bb. Vegetables were extracted with ethyl acetate and the extract was purified by solid-phase extraction using Sep-Pak silica cartridges. The purified extracts were analysed by high-performance liquid chromatography with a 5 microm Zorbax ODS column and UV detection under isocratic conditions. The method yields recoveries for avermectin B1a and B1b of 76-109% in the 0.054-0.54 ng/kg range. The limit of detection of the method is 40 microgram/kg each of avermectin B1a and B1b in vegetables.