Multi-residue analysis of eight anticoagulant rodenticides in animal plasma and liver using liquid chromatography combined with heated electrospray ionization tandem mass spectrometry

A sensitive method for the simultaneous quantification of eight anticoagulant rodenticides (brodifacoum, bromadiolone, chlorophacinone, coumatetralyl, difenacoum, difethialone, flocoumafen and warfarin) in animal plasma and liver using liquid chromatography combined with heated electrospray ionization tandem mass spectrometry (LC-HESI-MS/MS) is described. The sample preparation includes a liquid–liquid extraction with acetone. The compound 7-acetoxy-6-(2,3-dibromopropyl)-4,8-dimethylcoumarin is used as an internal standard. Chromatographic separation was achieved using a Nucleodur C18 gravity column. Good linearity was observed up to 750 ng mL−1 for chlorophacinone and up to 500 ng mL−1 for the other compounds in plasma. In liver, good linearity was seen up to 500 ng g−1 for brodifacoum, chlorophacinone, difenacoum and difethialone and up to 750 ng g−1 for the other compounds. Depending on the compound, a level of 1 or 5 ng mL−1 could be quantified fulfilling the criteria for accuracy and precision and was therefore set as limit of quantification of the method in plasma. In liver, the limit of quantification was set at 250 ng g−1 for coumatetralyl and warfarin and at 100 ng g−1 for the other compounds. In plasma, the limit of detection varied from 0.07 ng mL−1 for flocoumafen to 3.21 ng mL−1 for brodifacoum. In liver, the limit of detection varied from 0.37 ng g−1 for warfarin to 4.64 ng g−1 for chlorophacinone. The method was shown to be of use in a pharmacokinetic study after single oral administration to mice and in the confirmation of suspected poisoning cases in domestic animals.