Determination of brodifacoum and bromadiolone residues in rodent and canine liver

Abstract

SUMMARY A method to determine residue concentrations of anticoagulant rodenticides, brodifacoum ( bf ) and bromadiolone ( bd ) in liver was developed, using gas chromatography/mass spectrometry. Nine dogs were given 1.1 mg of bf /kg of body weight, po , in polyethylene glycol 400, one time. Rats were fed bf or bd (via commercial baits) in amounts from 0.28 to 11.25 mg/kg over 1- to 4-day periods. Fresh liver samples were collected at necropsy from all rats and 3 dogs, ground with Na 2 S0 4 , and extracted with CHCl 3 :MeOH (9:1). After evaporation and silica cartridge purification were performed, residues were oxidized with a 0.16 M chromic acid solution, and an oxidation product (4-bromobenzoic acid) was partitioned into CHCl 3 . The methylated derivative (port derivatization with trimethylanilinium hydroxide) was assayed, using gas chromatography/mass spectrometry. Bromadiolone was detected in livers from rats given > 6 mg of bd /kg of body weight, but not in livers of rats given 1.25 mg of bd /kg. In contrast, bf was detected (with one exception) in livers from dogs (given 1.1 mg of bf /kg) and from rats given high (11.25 mg of bf /kg) and low (0.28 mg of bf / kg) doses. This protocol, which does not differentiate between bf and bd because of the formation of a common product after chromic acid oxidation, was used to diagnose anticoagulant toxicosis in 3 dogs, 1 human being and 1 llama naturally poisoned.