Comparison of Extraction Methods by Soxhlet, Sonicator, and Microwave in the Screening of Pesticide Residues from Solid Matrices

Three types of solvent extraction methods (by soxhlet, sonicator and microwave) for pesticide recoveries in solid matrices were compared and evaluated using the standard addition method. Variables (solvent and extraction time) for the optimization of microwave assisted extraction (MAE) were also studied. Three organochlorine pesticides (BHC, DDE, and Dildrin) were chosen for this particular study because of their great presence in the soil where the samples were collected and their positive association with the risk of breast cancer. Comparison of the results obtained indicates that the efficiency of extraction varies, depending on the matrices and the pesticides analyzed. The study focused on the variation in the extraction quantities of different methods in different matrices. The extraction conditions were optimized for MAE with a single matrix (bark) and applied to the rest in order to study the variability in results. Gas chromatography with an electron capture detector (GC–ECD) was used for analysis of the extracts. The results show that even though the use of MAE improved extraction in some of the matrices studied, the extraction method must be optimized whenever a new matrix is evaluated. A statistical comparison indicated that pesticide recoveries and method reproducibility of microwave extraction compared less favorably with the conventional soxhlet method in some of the matrices, whereas the sonicator method was not found to be as efficient as the others.