Determination of six pyridine pesticide residues in agricultural soil by pressurized liquid extraction-automatic SPE-UPLC-MS/MS method
A pressurized liquid extraction method was established to extract six pyridine pesticides from the samples,including picoxystrobin,fluridone,imidacloprid,boscalid,fluopicolide,and acetamiprid.The method,takes agricultural soil as the research object,which was enriched and purified by automatic solid phase extraction,and quantitated by ultra-performance liquid chromatography-mass spectrometry(UPLC-MS/MS).Agricultural soil samples were taken,dried and crushed,and passed through a 120-mesh sieve.10 g of the screened sample was accurately weighed to the extraction tank,20 g diatomite was added,methanol and acetone solvent(V∶V=1∶1)was selected as extract solution.500 mg/12 mL HLB solid phase extraction column was put into automatic solid phase extraction instrument.After activation,the program was set,the above extraction solution was passed through the solid phase extraction column at a flow rate of 20 mL/min,and finally eluted with 20 mL methanol-acetonitrile(V∶V =1∶1).The eluent was collected and blown to nearly dry by nitrogen.The residue was dissolved by 1 mL methanol and volexed,then qualitatively and quantitatively detected on UPLC-MS/MS.Picoxystrobin,fluridone,imidacloprid,boscalid,fluopicolide and acetamiprid showed good linear relationships in the concentration ranges of 0.001 to 5.0 μg/mL,with correlation coefficients all greater than 0.995.Detection limits were 0.012,0.009,0.024,0.007,0.013,0.005 μg/L,respectively.Average recoveries in 3 concentration levels were 84.4%-105.2%.Relative standard deviation(RSD)of repeatability(n=6)were 2.0%,3.1%,2.3%,2.2%,1.9%and 2.3%.The experimental results showed that the method was accurate,sensitive and suitable for the determination of trace pyridine pesticide residues in agricultural soil.
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