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.