Quantitative Analysis of Pesticides in Postconsumer Recycled Plastics Using Off-Line Supercritical Fluid Extraction/GC-ECD

The supercritical fluid extraction (SFE) of several organochlorine and organophosphorus pesticides and two metabolites, o, p -DDE and 4,4‘-dichlorobenzophenone, from recycled plastics was studied. The recycled plastics, used as agricultural soil covers, were a mixture of low-density polyethylene (∼90% w/w) and ethylene−vinyl acetate copolymer (∼10% w/w). The SFE was optimized and compared to the classical sonication and total dissolution extraction methods. The plastic was extracted with supercritical CO 2 at different extraction conditions, depending on the physical matrix characteristics. Average recoveries of the 11 chemicals under study ranged from values greater than 90% with an overall relative standard deviation of 4.3% for plastic film to values lower than 40% with an overall standard deviation of 7.2% for plastic pellets. The variables affecting the whole extraction process, and the results obtained in the comparison between the three extraction methods were discussed.