Sample Extraction Methods for Determining Trace Carbamate and Triazole Pesticides in Soil

QuEChERS method, Accelerated Solvent Extraction(ASE) and Ultrasound Extraction(UE) were used for sample extraction and are reported in this paper. Combined with liquid chromatograph coupled with mass spectrometry, these extraction methods were used to determine eighteen kinds of trace carbamate and triazole pesticides in soil with strong polarity and poor thermal stability. Results show that the standard addition recoveries of the QuEChERS method range from 76.3% to 121.0% with the exception of aldicarb(27.5%), whereas those of UE ranged from 71.0% to 100.0% with the exception of aldicarb(4.7%) and aldicarb sulfoxide(137.8%). The recoveries of ASE are mostly below 70%, but methiocarb, aldicarb and triadimenol are almost not recovered. Therefore, the QuEChERS method was eventually chosen as the sample extraction method for determining carbamate and triazole pesticides. The low recovery of aldicarb and high recovery of aldicarb sulfoxide were related to the heating effect of the extraction method, whereas the recoveries of fenobucarb and carbaryl were related to soil types.