A comparison of ultrasonication and soxhlet methods for DDT extraction from soil

The goal of this study was to determine the efficacy of ultrason/cation extraction of 1,1,1trichloro-2,2-bis[p-chlorophenyljethane (DDT), 1,1-dichloro-2,2-b\s[p-chlorophenyl]ethane (ODD), and2,2-bls[p-ch!orophenyl]1,1-dichloroethylene (DDE) residues in soil for the purposes of saving time, minimizing generation of hazardous solvent wastes, and reducing costs associated with monitoring contaminant concentrations at remediation sites. An ultrasonic extraction method was developed for DOT, ODD, and DDE residues in soil, and the efficiency of extraction using an ultrasonic cavitator was compared to the traditional soxhlet method by GC-MS. Uncontaminatedsoil was spiked with analytes DDT, ODD, and DDE at 0.1,1.0,10.0, and 100.0 mg/ kg. Experiments were performed in triplicate, and recoveries of analytes were determined and statistically compared. Results indicate that ultrasonic extraction is a suitable preparatory method for analysis of DDT, ODD, and DDE residues in soil. For spike concentrations of 1 mg/kg to 100 mg/kg, ultrason/cation extraction resulted in recoveries in excess of 80% in all but one case. Most recoveries obtained by ultrason/cation extraction were statistically indistinguishable from or slightly lower than recoveries obtained by soxhlet extraction. In addition, the lower temperatures employed in ultrasonication extraction may have reduced the amount of thermal degradation of DDT to DDE, a phenomenon that could occur during soxhlet extraction.