Determination Of Organophosphorus Pesticides In Soil By Dispersive Liquid-liquid Microextraction Combined With ³¹P Quantitative Nuclear Magnetic Resonance

Sample pretreatment is one of the most effective procedures to improve the performance of analytical instruments,which enables separation,purification and enrichment of the components in the complex matrix.This paper demonstrated several sample pretreatment techniques of pesticide residues and their applications.Nowadays,sample pretreatment technology tends to be green,simple,fast and easy to be coupled with instrument detection,which has become an important researching field.Dispersive liquid phase microextraction(DLLME)is a new technology based on liquid-liquid extraction.This method integrates sampling,extraction and concentration.By dispersing the dispersant to small amount of organic solvent into the sample solution,DLLME can form dispersed phase/aqueous/organic phase in a turbid system.With high-speed centrifugation,the organic phase is deposited onto the lower layer,thus completing the separation and enrichment of objective.So far,SPME technology has been coupled with many analytical instruments and is well-applied in many analytic fields,for example,pesticide residues,environmental analysis and food safety.Quantitative NMR analysis can qualify and quantify samples at the same time.Simple and quick experimental operation,non-essential for high purity standard analytes and no damage to the samples ensures its wide application in drug analysis,food safety and metabonomics.In this experiment,quantitative 31P was used as the internal standard to quantify organic phosphorus pesticide by NMR.Using DLLME coupled NMR,we established a determination method for chlorpyrifos and methyl parathion in agricultural soil.The specific contents were as follows:(1)With optimized 31P-NMR parameters and DLLME conditions,the deuterated chloroform and Triphenylphosphate was used as solvent and internal standard,respectively.The effective content of chlorpyrifos TC was 86.68%and the relative standard deviation was 1.02%.In the DLLME system,300 μL of deuterated chloroform and 1 mL isopropyl alcohol was used as extraction agent and dispersant dispersion,respectively.The recovery rate quantification of established method toward chlorpyrifos pesticide residue in soil was 79.8%-93.1%,and the RSD%was 0.85%-1.31%.The deuterated chloroform and Triphenylphosphate was used as solvent and internal standard,respectively.The effective content of methyl parathion TC was 94.18%and the relative standard deviation was 1.09%.In a DLLME system,300 μL of deuterated chloroform and 0.5 mL acetone was used as extraction agent and dispersant dispersion,respectively.The recovery rate quantification of established method toward methyl parathion pesticide residue in soil was 87.2%-92.7%,and the RSD%was 0.9%-2.46%.