Suitability of microwave-assisted extraction for multiresidue pesticide analysis of produce

A systematic study of the microwave-assisted extraction of field-incurred pesticide residues from several crop matrices was conducted. Five crops consisting of beets, cucumbers, lettuce, peppers, and tomatoes were grown and treated in the field with seven pesticides, dacthal, chlorpyrifos, chlorothalonil, diazinon, permethrin, methoxychlor, and azinphos-methyl. Values were determined for the microwave extraction parameters, time and temperature, which resulted in efficient recovery over the selected pesticides and crops. The microwave settings were shown to be dependent on both crop matrix and pesticide. Recovery of the fungicide chlorothalonil was highly dependent on temperature, while the remaining pesticides tested were not so demanding. Using the selected microwave time and temperature values, pesticide recoveries from the microwave method were then compared with those of the conventional method. Statistical comparison of pesticide recoveries and method reproducibility of the microwave method versus the conventional blender extraction indicated that microwave extraction data compare favorably with conventional extraction data.