Comparison of Four Different Sample Treatment Methods in the Analysis of 31 Pesticide Residues in Buckwheat Tea By Gas Chromatography-electron Capture Detector

Purpose Four sample treatment methodsSPE(florisil)、SPE(NH2-Carb)、GPC、d-SPE(PSA+C18) were developed for the simultaneous determining of 31 pesticide residues in Buckwheat tea by gas chromatography-electron capture detector. The 31 pesticide analytes contained organochlorine and pyrethroid pesticide residues.Method Comparison of the four treatment methods was investigated and on performances including the effect of purification on blank matrix, matrix effect, and the recoveries of different level.Results The florisil solid phase extraction cartridge method gave the less interference of blank matrix, weakest matrix effect, best stability and this method could guarantee recoveries in the range of 70% and 120% for most of the pesticides except fluoride and its metabolites. The NH2-Carb solid phase extraction cartridge could guarantee recoveries in the range of 70% and 120% for most of the pesticides including fluoride and its metabolites, which was suitable for analysis and detection of multi-pesticide residues, but this method was unfriendly to the environment. The stability of GPC was weak. d-SPE (PSA+C18) method was a simple and fast method, but the recoveries was too high which would be improved by using internal standard or change the amount of dispersed solid phase extraction agent.Conclusion The studies provided data support for how to choose a suitable method which could be used to detect 31 pesticide residues in buckwheat tea.