Determination of brodifacoum in commercial rodenticides by using high-performance liquid chromatography with fluorescence detection

Abstract

Consumer samples such as food and drugs contaminated with small amounts of green-coloured particles are frequently submitted to the Forensic Chemistry Center for analysis. Based on the green colour of the contaminant, and the history of the sample, it has been suggested that the particles may be present due to commercially available rodenticides. As the commonly used active ingredient of such rodenticides is the superwarfarin brodifacoum {3-[3-(4′-bromobiphenyl-4-yl)-1,2,3,4-tetrahydro-1-naphthyl]-4-hydroxycoumarin}, a simple method for the determination of brodifacoum in wheat-based commercial rodenticides in samples as small as 2 mg has been developed. A small amount of the green particulate material is sonicated in a methanol–methanoic acid mixture for 15 min and analysed by reversed-phase HPLC with a fluorescence detector. The selective and sensitive nature of the fluorescence detector makes it possible to determine brodifacoum without extensive sample clean-up and preconcentration. The estimated detection limit is 4 pg of brodifacoum injected into the column and recoveries are 86 and 99% for two popular commercial brands.