Simultaneous multi-sample supercritical-fluid extraction of food products for lipids and pesticide residue analysis

Abstract

Sample preparation for food analysis has traditionally involved the processing of a large number of samples simultaneously. A supercritical-fluid extraction (SFE) apparatus has been designed and tested to facilitate a similar approach, using SC-C0 2 as the extraction fluid. The prototype extractor was constructed to allow the extraction of six samples simultaneously, as well as the regulation and balancing of the fluid flow through each of the individual extraction vessels. In addition, procedures were developed to eliminate contamination from the apparatus and the extraction fluid which could interfere with electron capture detection of pesticide residues in meat samples. Rapid extraction of lipid phases from food products (soybeans, frankfurters, poultry) could be achieved within 15 minutes using extraction pressures of 5,000–10,000 psi at 60 °C and accompanying CO 2 flow rates of 5–10 L min -1 (ambient conditions). Simultaneous multi-extraction of dispersed fat and soybean flake samples yielded lipid recoveries of 98 and 95%, respectively. Initial experiments on spiked frankfurter samples yielded analyte recoveries of 87–118% for a mixture of eight chlorinated pesticides. Additional studies on the coextraction of incurred organo-chlorine pesticide residues from poultry adipose tissue, resulted in 96% or better recoveries of endrin, heptachlor epoxide, and dieldrin, at the 1–3 ppm level in the extracted fat.