Determination of organophosphorus pesticides in stomach contents of postmortem animals by QuEChERS and gas chromatography.

The quick, easy, cheap, effective, rugged and safe (QuEChERS) method for sample preparation was applied to determine seven organophosphorus pesticides (OPs) in stomach contents of poisoned postmortem animals. The pesticides consisted of diazinon, edifenphos, ethyl p-nitrophenyl phenylphosphonothioate, fenitrothion, monocrotophos, parathion and phosphamindon, and tested samples included stomach contents from postmortem animals of cattle, goat, dog, cat, birds, deer and rabbit. The pesticides were spiked into the samples which were found to be negative through previous pesticide poisoning analysis, and the pesticides were extracted and cleaned up based on the QuEChERS process and then they were analyzed using gas chromatography (GC)-flame photometric detector (FPD) or GC-nitrogen-phosphorus detector (NPD) with a DB-5 column. Limits of detection ranged from 0.27 to 0.41 mg/kg for the seven pesticides. The mean recoveries ranged from 80 to 99% in GC-FPD and 83 to 90% in GC-NPD. The coefficients of variation were <10% for all analytes and sample matrix combinations except for phosphamidon and edifenphos in dog stomach contents. This study demonstrated that the method using QuEChERS and GC-FPD and/or GC-NPD is very effective to analyze the OPs in the stomach contents of postmortem animals.