Studies On The National Standard Method For Residue Analysis Of Esfenvalerate In Corn

Esfenvalerate is a pesticide used to control a wide variety of harmful insects. It is used on corn,vegetables, cotton , fruits, tea and so on. The residual analytical method of this pesticide is singularly reported; its national standard method has also not been established.In this research,Gas chromatography was optimized for analysis of esfenvalerate, In order to improve the accuracy ,precision and reproducibility the sample pretreatment procedures were also optimized .The pretreatments include the extraction system and cleaned-up system.. The optimal method was surging method,extracted solvent is petroleum ether.,extracted times is 2 times. The optimal extracted time were respectively 60min, the optimal volume of extracted solvent is 60ml. The optimal adsorbent is 4.5g 5%(hydrous quality) neutral Al2O3 and 0.01g active carbon. TheCleaned-up solvent is 60ml petroleum ether / ethyl acetate(9:1,v/v). The method was validated in corn. Generally the method was validated on matrices for each esfenvalerate-related at fortification levels, the fortification levels were 0.05 mg/kg, 0.20 mg/kg, and 0.50mg/kg.Using the established method, the average recoveries from spiked corn with fortified level 0.05mg/kg, 0.2mg/kg and 0.5mg/kg were respectively 78.55%, 89.47% and 86.38% .The results are all according with the requirement of residual analysis.Using the established method, the tests of matrix-adaptability in the other matrix such as wheat and rice were performance.Using the established method, the recoveries of esfenvalerate in freash corn wheat and rice at level 0.20mg/kg were respectively 85.62%,76.80% and 83.55%, The results are all according with the requirement of residual analysis.The validity and the precision of the established method were evaluated by put up the quality-controlled .Agilient 6890 GC:LOQ is 0.02ng and the minimum detected concentration is 0.005mg/kg.The stability of esfenvalerate in different stored condition was studied.The standard solution of esfenvalerate at 1×10-6 g/ml can be stored 6 months at 4℃; Esfenvalerate in extracted solution of corn can be stored 15 days at -20℃and 4℃; Esfenvalerate added in corn matrix can be stored 10 days at 4℃and -20℃, Esfenvalerate in extracted solution of corn and esfenvalerate added in corn matrix can be stored excess 5 days at 25℃.The author put up the quality-controlled to the validity and the precision of the analytical method with the results of that the validity-analysis and the precision-analysis were both in the controlled condition and the analytical data were available.