Analysis of pesticide residues in matrices with high lipid contents by membrane separation coupled on-line to a high-performance liquid chromatography system

Separation through membranes coupled to an HPLC system was used as a technique for the analysis of pesticide multiresidues in samples with high lipid contents. As well as the usual procedure, in the proposed system it is possible to recirculate the sample through the membrane cell, which permits the extraction system to be applied to cases in which only a very small volume of sample is available. A procedure for pesticide multiresidue analysis in egg samples was developed as a representative example of the applicability of the proposed method. To accomplish this, the analytes (dichlorvos, dimethoate, propoxur, paraoxon, pirimicarb, atrazine, ametryne, terbutryne, azinphos-methyl, folpet) were subjected to prior extraction in a Soxhlet system, after which the extract was introduced into the membrane separation device coupled to the HPLC system. This procedure afforded clean chromatograms, hence considerably facilitating determination, and at the same time was efficient in removing macromolecular compounds. For egg samples, spiked at a concentration level of 0.750 mg/kg, recoveries ranged from 60 to 98%. The detection limits varied from 0.018 mg/kg for dichlorvos to 0.002 mg/kg for atrazine.