Residue Analysis Of Pyraclostrobin In Potato And Soil

Pyraclostrobin is a fungicide with a broadspectrum,high-effect,and the characteristic of long-lasting effect,it has a good control effect on potato late blight,and it was commonly used in potato production.The resulting residues problem has attracted attention.In this study,a High performance liquid chromatography tandem mass spectrometry?HPLC-MS/MS?analytical method was established for the determination of pyraclostrobin residues in soil,potato plants,and potato tubers.And applied on degradation dynamics and final residue of 1%pyraclostrobin granules on potato and soil,and provided a reference point for safe use of of pyraclostrobin in potato.The specific results are as follows:1.HPLC-MS/MS method for the determination of pyraclostrobin was established.The soil samples were extracted with water:acetonitrile?V:V=1:4?by vortex,salted out with NaCl and cleaned up by magnesium sulfate anhydrous?MgSO₄?/N-propyl ethylenediamine?PSA?,and determined by HPLC-MS/MS.In the range of 0.001⁰.2 mg·L^-1,the linear equation of pyraclostrobin in soil matrix was y=16397151.1551 x+4957.1129,with the correlation coefficient of 0.9999,the spiked levels of 0.005⁰.2mg·kg^-1,recoveries were ranged from 90.37%¹07.38%with the relative standard deviations?RSD?0.82%¹.86%.The potato plants samples were extracted with acetonitrile by shaking for 1 hour,salted out with NaCl and cleaned up by MgSO₄/PSA/octadecyl bonded silica(C₁₈),determined by HPLC-MS/MS.In the range of 0.001⁰.2 mg·L^-1,the linear equation of pyraclostrobin in plant matrix was y=19036623.7624 x+5477.6172,with the correlation coefficient of 0.9992,the spiked levels of 0.005⁰.2mg·kg^-1,recoveries were ranged from86.37%¹08.23%with RSD 0.96%².94%.Potato tubers were extracted by vortex with acetonitrile,salted out with NaCl and cleaned up by MgSO₄/PSA/C₁₈,determined by HPLC-MS/MS.In the range of 0.001⁰.2 mg·L^-1,the linear equation of pyraclostrobin in tubers matrix was y=16738254.1254 x-1591.8350,with the correlation coefficient of0.9996,the spiked levels of 0.005⁰.2mg·kg^-1,recoveries were ranged from87.41%⁹6.59%with RSD 1.04%².63%.The limit of detection?LOD?was 3.8×10^-4ng in soil,plant and potato samples,and the limit of quantification?LOQ?of the method was 0.005mg·kg^-1.The accuracy,precision and sensitivity of this method all meet the requirements of pesticide residue detection.2.The residual digestion dynamics and final residue of 1%pyraclostrobin granules in soil and potato were determined.The half-lives of pyraclostrobin in Baoding,hebei and Guiyang,guizhou soil used pyraclostrobin were 12.5d and 11.7d,respectively,and the degradation curve equations were C=0.6656 e^-0.0550t and C=0.4158 e^-0.0593.1%pyraclostrobin granules were applied once at the recommended high dose?225 g a.i/ha?and 1.5 times the recommended high dose?337.5 g a.i/ha?.The final residue in potato tuber,was less than 0.005mg·kg^-1,and in soil was 0.015-0.070 mg·kg^-1during the harvest period.