| Picoxystrobin is a highly effective,low-toxicity,broad-spectrum strobilurin fungicides.In this study,two preparations of picoxystrobin and the original drug were used as the research objects.A general analytical method was established for the determination of the active ingredient content in two preparations under the same liquid chromatographic conditions.The residual determination of picoxystrobin in soil was studied and three different types of soil surface photodegradation of picoxystrobin were studied using high performance liquid chromatography and mass.Finally it was analyzed and compared using computer-assisted profiling(ACD/MS Fragment)software.1.A general analytical method was developed for the determination of the active ingredient content in picoxystrobin suspension concentrate and water dispersible granule under the same liquid chromatographic conditions.The samples were dissolved in acetonitrile and analyzed by RP-HPLC using acetonitrile and water as mobile phases in the ratio of 80:20,with a mobile phase flow rate of 1.0 m L/min and an injection volume of 5?L.The separation was carried out on a waters symmetry-C18column with a diode array detector at 220 nm.In addition,a diode array detector was used to check the peak purity and to validate different laboratory methods.The linear range of the method was between 100.1 and 1000.8 mg/L with the linear correlation coefficient R~2 of 0.9993.The mean recoveries of the spiked suspensions and aqueous dispersions were 100.64%and 99.74%with the relative standard deviations(RSDs)of1.31%and 0.69%,respectively.The relative standard deviations(RSDs)of the results were 1.31%and 0.69%for suspension and water dispersible granules,respectively.The precision,accuracy and peak purity of the method were in accordance with the requirements of the analytical methods for pesticides,and were suitable for the determination of picoxystrobin in suspension concentrate and water dispersible granule.It has the advantages of time saving,high sensitivity,good accuracy and reproducibility,etc.2.The method was optimized for the determination of picoxystrobin residues in soil samples by high performance liquid chromatography(HPLC),using a modified QuEChERS.Diatomite was used as an auxiliary in the pretreatment.and the filter agent reduces the soil matrix effect.An efficient and sensitive detection method for picoxystrobin residues in soil was established.When using the method,the linear range of the method was 0.3?10 mg/L.The recoveries were 95.8%?103.3%with RSDs of0.67%-1.63%in Xerosols,85.5%?106.4%with RSDs of 0.71%-1.80%in Yermosols,and the recoveries in Jilin soil ranged from 78.4%to 95.7%with RSDs of1.19%-4.46%,which met the requirements of the residue analysis method of the pesticide residue.3.The photochemical degradation of picoxystrobin fungicide on the surface of three soils(Xerosols,Yermosols and Chernozem)was measured in batches at regular intervals.The measurement results were in accordance with the first-order kinetic equation.The half-lives of Xerosols,Yermosols soil and Chernozem were 3.80 d,4.29d and 3.80 d,respectively.The initial photodegradation concentration of picoxystrobin was 10 mg/kg.The terminal residues of picoxystrobin were 2.665,4.275 and 2.675mg/kg,respectively;the dissipation dynamics of picoxystrobin on the soil surface photodegradation was obtained.Full scan mass spectrometry of picoxystrobin and secondary MS mass spectrometry with m/z 205.15,205.17 and 205.14 as parent ions.The dissipation dynamics of the photodegradation of picoxystrobin on the soil surface were obtained.Two possible degradation pathways for the photodegradation of picoxystrobin on the surface of three soils were obtained by simulating the fragment ions that could be obtained from the cleavage of picoxystrobin by computer-aided spectral analysis(ACD/MS Fragment)software and comparing them with the ions optimised in the secondary mass spectra obtained by the mass spectrometry workstation. |
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