Determination Of Pesticides Residues In Soil Based On Trichlorfon-D₆

Since 1980s,many countries in the world,especially developed countries,had made and carried out the plan of soil pollution control and remediation.Therefore,a new soil remediation industry had been emerged.The bulletin of a national soil pollution survey published in 2014 showed the soil environment was generally not optimistic,and close to one fifth of the country's arable land was polluted with around 3%suffering either moderate or serious pollution.Excessive use of chemical fertilizers,pesticides and other toxic dust related to air pollution had caused irreversible pollution to the soil.In face of the severe situation of soil pollution,the state accelerated the legislative process.It had become a top priority to carry out pesticides residues detection and establish a rapid,efficient and low-cost method for pesticides detection in soil.This thesis focused on different soil samples with complex matrix,combined orthogonal experiment and uniform design to investigate the influence of the sample speed,elution volume,elution speed on the extraction rate of trichlorfon,optimized pretreatment conditions,and established the internal standard method of liquid chromatography tandem mass spectrometry?LC-MS/MS?and external standard method of ultra high performance liquid chromatography?UPLC?for the trichlorfon in soil.The main conclusions are as follows:1?The trichlorfon-D₆ labeled by deuterium was developed by Shanghai Research Institute of Chemical Industry Co.,Ltd and its chemical purity and isotope abundance were respectively characterized by UPLC and MS.The results showed that the chemical purity of97.7%and the abundance of 95.9 atom%D met the requirements of isotope internal standard reagent.2?The ultrasonic extraction combined with solid phase extraction purification was applied to pretreatment,and the pretreatment conditions of soil samples were optimized by orthogonal experiment and uniform design.The main factors affecting the extraction of trichlorfon were obtained by orthogonal experiment,and on the basis of this,the best conditions of the sample flow rate 3 mL/min,elution volume 12 mL,elution velocity 3mL/min were determined by uniform design.The method of LC-MS/MS is able to meet the analysis requirements of pesticides residues.3?A method for the determination of pesticides residues in soil was developed by LC-MS/MS with self-prepared trichlorfon-D₆ as internal standard.The linear range was 0.1¹0?g/mL with correlation coefficient R²=1,recovery rates 95.9%¹02.9%,limit of detection 0.05 mg/kg,and relative standard deviation?RSD?1.0%².7%.4?A method for the determination of pesticides residues in soil was developed by UPLC.The linear range was 5⁵00?g/mL with correlation coefficient R²=0.9999,recovery rates77.8%⁸5.4%,limit of detection 7.24 mg/kg,and relative standard deviation?RSD?0.32%⁰.67%.The recovery rate was lower and limit of detection was higher when compared with LC-MS/MS.The method of UPLC is unable to meet the trace analysis of trichlorfon residues in soil.