Extraction solvent selection in environmental analysis.
A method for the prediction of a suitable solvent for the extraction of pesticides is outlined. The procedure is based on the Hildebrand solubility parameter, delta(t). The solubility parameter is broken down into three individual components, which are calculated by the addition of group contributions. To demonstrate the applicability of the approach pressurized fluid extraction was used to extract 4,4'-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] and its metabolites, 4,4'-DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethane] and 4,4'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], from an historically contaminated soil from the United States and pentachlorophenol from a certified reference material (CRM524) using various solvents. Visual representation of the individual parameters predicted the ideal extraction solvent to be DCM for 4,4'-DDT and its metabolites and a mixture of acetonitrile and dichloromethane (1:1, v/v) for PCP. These findings were confirmed by the experimental results.