Pressurised fluid extraction (PFE) as an alternative general method for the determination of pesticide residues in rape seed

Abstract

A pressurised fluid extraction (PFE) multi-method has been developed for the determination of pesticide residues in rape seed. The method was validated for 25 different pesticides and metabolites. The reliability and efficiency of PFE for extracting pesticide residues from rape seed was investigated. The traditional extraction solvent, hexane saturated with acetonitrile, was used at elevated temperature and pressure. With increased temperature, the extraction kinetics were improved but at the same time more co-extractives were obtained in the form of lipids. When 1 g of rape seed was extracted at temperatures from 60 °C to 150 °C, the lipid content extracted was found to be as high as 17–26%. An additional clean-up step was therefore required and lipid co-extractives were effectively removed by gel permeation chromatography. The interpretation of the chromatograms and the quantification of the results were satisfactorily improved by the removal of interfering lipids. The developed method was used to extract vinclozolin and iprodione from incurred samples, resulting in a concentration in accordance with the results using conventional liquid–liquid extraction (LLE) between hexane and acetonitrile and also supercritical fluid extraction (SFE) using carbon dioxide. The results of the present study suggest that PFE is a good alternative extraction technique for the determination of pesticide residues in oil seed. Despite the necessity for a lipid-removal clean-up step, the PFE technique facilitated the extraction process by faster extractions and the possibility of automated analysis.