The multi-residue determination of coumarin-based anticoagulant rodenticides in animal materials by high-performance liquid chromatography.

The rodenticides brodifacoum, difenacoum, coumatetralyl and warfarin are determined in animal relicta by high-performance exclusion chromatography on porous silica. The first three compounds are not separated, but are subsequently differentiated by adsorption or reversed-phase high-performance liquid chromatography of the appropriate eluate fraction collected from the exclusion column. The method is rapid, and clean-up (on Sep-Pak silica cartridges) is simple. Mean recoveries from spiked substrates were generally above 80% at levels of 0.1-1.0 mg/kg. Routine limits of determination are about 0.05-0.1 mg/kg for warfarin and about 0.02 mg/kg for the other compounds. If analysis for warfarin is not required, the latter limit can be lowered to about 1 microgram/kg by a slight modification to the clean-up step.

Determination of pentachlorophenol and related compounds in animal materials by high-performance liquid chromatography and gas chromatography.

The rapid determination of pentachlorophenol and tetrachlorophenols in animal materials by high-performance liquid chromatography (HPLC) on porous silica is described. Non-fatty substrates are digested in alkali and the chlorophenols extracted as ion pairs. Fatty materials are extracted with ethyl acetate-hexane after acidification. Extracts are cleaned up on "Sep-Pak" silica or Florisil cartridges. Penta- and tetrachloroanisoles are recovered by the extraction procedures and can be determined by gas chromatography if required. Mean recoveries of the chlorophenols were 73-108% at fortification levels of 0.1-10 mg/kg. A concentration of 0.1 mg/kg can readily be determined and the method can be adapted to reach about 1 microgram/kg. Identities can be confirmed by ion-pair HPLC on a reversed-phase column.

Determination of the rodenticide difenacoum in biological materials by high-pressure liquid chromatography with confirmation of identity by mass spectrometry.

A method for determining difenacoum in liver, plasma, urine and feedingstuffs by high-pressure liquid chromatography is described. Samples are cleaned up by molecular exclusion chromatography on porous glass. In some cases this also serves for determination; if not, the separated difenacoum is determined on an adsorption column. Identity is confirmed by chemical ionisation mass spectrometry. Recoveries at levels of 0.025-5 ppm from plasma were 101-113% by exclusion chromatography alone and 93-101% after adsorption chromatography. Recoveries from liver after both chromatographic steps were 62-86%. Reasons for the lower recoveries from liver are suggested.

Determination of warfarin in animal relicta and feedingstuffs by high-pressure liquid chromatography with confirmation of identity by mass spectrometry.

The determination of warfarin in liver, blood, urine and feedingstuffs by high-pressure liquid chromatography (HPLC) is described. Clean-up is simple and the lower limit of determination is about 0.025 ppm. Recoveries from liver are about 85% over the range 0.025-1.0 ppm; recoveries from blood range from about 67 to 90%. Chemical ionisation mass spectrometry can be used to confirm identity and, by specific ion monitoring, to detect warfarin in HPLC eluates at levels below the sensitivity of the HPLC detector.