HPLC-fluorescence method for the determination of eprinomectin marker residue in edible bovine tissue

A method was developed and validated to determine eprinomectin marker residue in bovine liver, kidney, muscle, and fat. The overall percent recovery (+/- CV) was 93 +/- 12% (n = 66) for liver, 100 +/- 13% (n = 34) for muscle, 87 +/- 13% (n = 42) for kidney, and 95 +/- 11% (n = 42) for fat. The Limit of detection was 1 ng/g, the lower limit of quantitation was 2 ng/g, and the upper limit of quantitation was 5000 ng/g (mu g/kg). Accuracy, precision, Linearity, selectivity, and ruggedness were demonstrated. For the determination, tissue is mixed with sodium sulfate, homogenized, and extracted. The reconstituted extract is loaded onto an aminopropyl cartridge. After solvent exchange, a portion of the eluate is derivatized precolumn via automated addition of TFAA in acetonitrile and analyzed using fluorescence detection. The method is rapid, sensitive, and selective and provides for determination of eprinomectin marker residue in edible bovine tissue from the low parts per billion (ng/g) level to the parts per million level. The method has been successfully performed by several different analysts.