| Jilin Province is a major province of maize production in China.The occurrence of maize diseases,pests and weeds seriously affects the yield and the quality of maize.Among them,chemical control is one of the most important prevention and control measures in maize diseases,pests and weeds prevention and control system.In view of the current gap of residue analysis of chemical pesticides in Jilin Province,in this paper,UHPLC-MS/MS and GC-MS/MS methods were used to analyze 11 common pesticide residues in maize in Jilin province.A residue analysis method was developed for the simultaneous determination of 7 pesticide residues in maize by UHPLC-MS/MS.In this study,the mobile phase and mass spectrometry conditions were optimized.At the same time,the extraction solvents and purification conditions in the pretreatment conditions were optimized,and the matrix effect was eliminated by using the matrix-matched calibration standard curves.Finally,the samples were extracted with acetonitrile,purified by Cleanert Pesticarb/NH2 SPE cartridge and using dichloromethane∶methanol as70∶30（V/V）mixed eluent leaching,detected by UHPLC-MS/MS in scheduled multiple reaction monitoring（Scheduled MRM）mode.The results showed that the calibration curves of seven pesticides were linear in the range of 0.0050.2 mg/L,with the correlation coefficients between 0.9934 and 1.0000.At three spiked levels of 0.01,0.1 and 0.5 mg/kg,the average recoveries of 7 pesticides in green maize and maize were 79.0%99.3%and 78.8%104.2%,respectively.And the relative standard deviations were 0.9%13.0%and 1.0%11.9%,respectively.Finally,ten of green maize and ten maize samples from supermarket and different planting areas in Jilin Province were tested by this method,none of the seven pesticides was detected.A residue analysis method for GC-MS/MS of atrazine,acetochlor,metolachlor and2,4-D-ethylhexyl in maize was established.In this study,the instrument conditions,extraction solvents and purification conditions were compared and optimized,and the matrix effect was eliminated by using the matrix-matched calibration standard curves.Finally,the samples were extracted with acetonitrile,purified by Cleanert Pesticarb SPE cartridge and using n-hexane∶ethyl acetate as 80∶20（V/V）mixed eluent leaching,detected by GC-MS/MS in multiple reaction monitoring（MRM）mode.The results showed that the calibration curves of four pesticides were linear in the range of 0.0051.0 mg/L,with the correlation coefficients between0.9991 and 0.9999.At three spiked levels of 0.01,0.1 and 0.5 mg/kg,the average recoveries of 4pesticides in green maize and maize were 92.8%105.1%and 91.9%100.0%,respectively.And the relative standard deviations were 0.8%3.1%and 1.3%11.0%,respectively.Finally,ten of green maize and ten maize samples from supermarket and different planting areas in Jilin Province were tested by this method,none of the four herbicides was detected. |
