The Preparation And Application Of Chlorpyrifos-D₁₀ Reference Material

The objective of this work aims to prepare Chlorpyrifos-D₁₀0 reference material in acetone,to explore the application of it as isotope internal standard in the insecticides multi-residue detection and to verify its role in the detection of quality control.At present,there's no reports of Chlorpyrifos-D₁₀0 reference material preparation in China.The results of this work fill the blank of the reference material in our country and provide a scientific basis for the selection of internal standard in the determination of insecticides which can ensure the accuracy of detecting results.1.Chlorpyrifos-D₁₀0 in acetone reference material was prepared using purity stable isotope material.The homogeneity and stability of it were examined by F test and t test respectively.The expanded uncertainty of the preparation method was calculated.The results showed that the homogeneity of the material was good;the reference material could stay stable for at least 1 year,and the best temperature for storage was 4?;it could stay stable for at least 1 month in the process of transportation at even 45?;the stability kept good at the low concentration of2.0mg/L for 3 months.The concentration and expanded uncertainty of the Chlorpyrifos-D₁₀0 in acetone reference material was?100±1.4?mg/L?k=2?.2.A method for the simultaneous determination of 14 insecticides residues in honey was developed using ultra high performance liquid chromatography-tandem mass spectrometry?UPLC-MS/MS?with Chlorpyrifos-D₁₀0 as isotope internal standard.The honey samples were extracted with acetonitrile,and the extracts were cleaned up with solid phase extraction?SPE?using LC-NH₂ purification column.The qualitative and quantitative analysis for the analytes were carried out under the multi-reaction monitoring?MRM?mode with positive mode.Chlorpyrifos,Propargite,Hexythiazox,Fenthion,Phosalone,Chlorpyrifos-methyl and Pirimiphos-methyl were proved to be suitable quantitified with Chlorpyrifos-D₁₀0 as internal standard;while Coumaphos,Tebufenpyrad,Pyridaben,Spirodiclofen,Etoxazole,Fenpyroximate and Fenitrothion were quantitified with matrix-matched standard method.The response of each pesticide showed a good linearity in the range of 1²00?g/L with r>0.999.The limits of quantitation?LOQs?were 0.1⁰.5?g/kg for 14 insecticides.The blank honey samples were spiked at three concentration levels of 10,50,100?g/kg,the recoveries ranged from 81.9%to 118.9%with the relative standard deviations less than 11.0%.And the method was proved to be suitable for several common kinds of honey in the detection.3.The quality control role of Chlorpyrifos-D₁₀0 in the determination was verified by destructive tests.In the destructive tests,the extracting solvent was lost with varying degrees,different volume of solvent was used in the volume step,extracting solvent and purification column were replaced comparing to the original method.The results showed that Chlorpyrifos-D₁₀0 used as internal standard in the determination could reduce the differences of recovery caused by the pretreatment process,could eliminate the matrix effects and could adjust the instability of the instrument response to ensure the accuracy of the testing results.