Multiresidue Analysis Of Organophosphorus Pesticides And Degradation Dynamics Rhythm Of Chlorpyriphos In Ramie

Ramie is one of traditional economical crops in China. Recently, feed exploitation of Ramie is becoming a research hotspot. The organophosphorus pesticides (OPPs) has been widely used in Ramie growth. Developed a method for determination of organophosphorous pesticides residues in Ramie is significant in guaranteeing Ramie quality safety and promoting the development of Ramie industry. Our research has developed the method for determination of organophosphorous pesticides residues in Ramie with Gas Chromatography (GC) and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and the degradation dynamics rhythm of Chlorpyriphos in Ramie was also studied. The results were as follows:1、A rapid analytical method for simultaneous determination of8organophosphorus pesticides in ramie and soil was established based on QuEChERS with GC-FPD. The samples were extracted by acetonitrile, and then purified by primary secondary amine (PSA) and graphitized carbon black (GCB). The8organophosphorus pesticides residues was analyzed by GC-FPD and quantified with external standard. The results showed that the average recoveries of the8pesticides in soil, ramie stem, ramie blade at three levels (0.05mg/kg,0.1mg/kg and0.5mg/kg) were in the range of71.1%～114.2%with relative standard deviations (RSD) ranged from2.2%～14.6%, The limits of detection (LOD) were0.006-0.016mg/kg.2、A rapid analytical method for simultaneous determination of16organophosphorus pesticides in ramie and soil was developed by UPLC-MS/MS. The samples was extracted with acetonitrile and cleaned-up by PSA and GCB. The analytes were quantified by UPLC-MS/MS in a positive ion multiple reaction mode (MRM). An excellent linear relationship for16organophosphorus pesticides residues was observed in the concentration range of10～1000μg/L with the regression coefficients of0.9936-0.9999. The average recovery rate of16organophosphorus pesticides residues at the spiked level of50-500μg/kg was in the range of71.2%～112.3%with relative standard deviation of2.0%～15.7%. This developed method revealed a detection limit range of0.18～9.69μg/kg.3、The residue dynamic and final residues of chlorpyrifos in ramie stem, ramie blade and soil were studied through the field experiment and gas chromatography analysis. The results showed that chlorpyrifos dissipated rapidly in ramie stem, ramie blade and soil, and the half-life of degradation for chlorpyrifos was7.8d,6.5d and11.3d respectively. When40%chlorpyrifos EC was applied once or twice at recommended concentration in ramie field, the final residues of chlorpyrifos in ramie stem, ramie blade and soil were all below0.1mg/kg that harvested more than21days after the last application.