Determination of ivermectin in medicated swine feeds at the 2 ppm concentration level.

An analytical method has been developed that is applicable to the determination of Ivermectin in medicated feeds at the 2 ppm concentration level. It is based upon liquid chromatographic analysis with a reverse-phase column and ultraviolet detection. After the drug is extracted from the feed into methanol, an analytical sample is prepared by the consecutive use of column chromatography on alumina and solid-phase extraction on Sep-Pak C18 and silica cartridges. This procedure has been applied to the concentration range 0.50-3.0 ppm of Ivermectin in feed with an accuracy of +/- 2% mean relative error and a precision of +/- 2% relative standard deviation at the 2 ppm concentration level.