Optimization of Experimental Conditions for the Supercritical Carbon Dioxide Extraction of Pesticide Residues from Grains

Abstract

The efficiency of a supercritical carbon dioxide extraction system was investigated for the extraction at different pressures and temperatures of fortified grain samples containing organochlorine, organophosphorus, and organonitrogen pesticides from grain matrixes. The extractor unit was constructed using a gas booster pump and a Florisil sorbent trap for extracting and isolating the residues of interest. Using 20 g samples, extractions were performed between 40° and 80° C with pressures from 2000 to 10 000 psig. In most cases, pesticide recoveries exceeding 80% were recorded over the above range of temperature and pressure. Excellent recoveries and precision were recorded for an incurred methyl chlorpyrifos residue at the 0.043 ppm level. An improved liquid chromatographic assay was also developed for the analysis of carbofuran in grain samples.