High Pressure Liquid Chromatographic Determination of Brodifacoum in Formulations: Collaborative Study

A method is described for the determination of brodifacoum in technical and formulated material by high pressure liquid chromatography (HPLC). Samples of technical or formulation are dissolved in a solution of 1,3,5-triphenyl benzene in dichloromethane and methanol. The solution is injected into an HPLC system fitted with 25 cm Zorbax ODS column and an ultraviolet detector. The solution is eluted with a mixture of methanol, water, and acetic acid. Quantitative data are obtained by comparing peak areas of the compound and triphenyl benzene with those obtained by injecting a standard solution. Bait formulations are extracted into dichloromethane-formic acid, filtered, and concentrated by evaporation before chromatography. Nine collaborators made replicate determinations on 4 samples including technical material, a 0.1% powder, a 0.25% liquid, and a 0.005% pelleted bait formulation. They also carried out a recovery experiment on the bait product. Coefficient of variation (%) were 1.21 on the technical product, 13.49 on the powder, 2.40 on the liquid, and 11.06 on the bait. Insufficient data were generated to adequately quantitate the recovery factor. The method has been adopted official first action for the analysis of technical material, liquid, and bait formulations.