Determination of organochlorine compounds in fatty matrices: application of rapid off-line normal-phase liquid chromatographic clean-up.

A clean-up method for organochlorine compounds in fatty samples based on normal-phase liquid chromatography (NPLC) is described. To this end, an existing clean-up procedure which uses column switching for the separation of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) from the fat matrix was simplified to a single silica LC column procedure. The use of an LC column packed with 3 μm silica enables complete fat/OCP separation in a total fraction volume of 12 ml, and results in a fully automated clean-up procedure that takes only 32 min per sample. The method showed average recoveries of 80-110% in the concentration range of 1-510 μg/kg, with relative standard deviations of less than 10%. Limits of determination were in the range of 0.5-50 μg/kg. The simplified approach has shown its potential for a variety of samples, such as milk, pork fat, animal feed and cod liver oil, showing its general applicability to fatty samples.