| As the raw material of wine,grape(Vitis Vinifera L.)is vulnerable to various fungi and pests during the planting process.Thus,pesticides are widely used.The pesticide residuesremaining in the wine will not only affect the quality of wine,but also have adverse effects on the environment and human health.However,the conventional extraction method involves many kinds of organic extraction solvents,which need large reagent consume amount and long time-consuming.In this study,QuEChERS(Quick,Easy,Cheap,Effective,Rugged and Safe)method modified with ultrasonic-assisted extraction from intact grape berries(Vitis Vinifera L.)was optimized for determination of 43 pesticides residues by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS).The change of pesticide residues in the ripening process of grape is studied by using the method of UPLC-MS;the distribution of pesticide residues in 103 commercial wines from different regions and the changes of pesticide residues in wine during fermentation were studied by using the traditional QuEChERS method and UPLC-MS analysis method to find key control point of fermentation.The main results are as follows:(1)The distribution of pesticide residues in 103 wine samples sold in domestic and abroad.The results showed that 28 pesticide residues were detected in 96%of the wine samples.The top three pesticide residues were imidacloprid(76.7%),thiamethoxam(57.3%)and triadimefon(55.3%).The main kind of pesticide residues in domestic wine were triazole(0.23?g/L?198.93?g/L),benzimidazole(1.08?g/L?176.83?g/L)and pyridylamide pesticide(7.94?g/L?170.87?g/L)while nicotine(0.18?g/L?59.61?g/L),triazole(61.85?g/L?65.70?g/L)and anilinepyrimidine(2.26?g/L?87.20?g/L)pesticide were more easily find in domestic white wine.The content of nicotine(0.70?g/L?28.95?g/L),triazole(0.23?g/L?16.91?g/L)and anilinepyrimidine(0.39?g/L?5.95?g/L)pesticides were the main pesticide residues in foreign red wine,and nicotine(1.79?g/L?16.45?g/L)triazole(0.31?g/L?25.42?g/L)pesticides were higher in white wine.Risk assessment results of all wine samples showed that there was no harm to human health.(2)An optimized QuEChERS method was established for extraction of pesticide followed by UPLC-MS in this study.According to the traditional QuEChERS method,the effects of the grape condition,the extraction mode,the extraction solvent,the extraction solvent volume and the extraction time in the responses of selected analytes were carefully investigated.10 mL acetonitrile was added into 10g(±0.05g)intact grape berries.After ultrasonic treatment for 2 min,the mixture was centrifuged at 3700 r/min for 5 min.Fill up the QuEChERS purification pipe with 1.8mL supernatant.After vortex oscillation for 2 min and centrifugation for 3 min at the speed of 7000 r/min,the supernatant was taken to determine 43 pesticide residues in grapes by UPLC-MS.Under the modified QuEChERS method,a good linearity was obtained from 0.01 to 200 ?g/kg.The results showed that the linear relationship was good in the range,the determination coefficient was 0.9963-0.9999.The detection limit(LOD)and the quantitative limit(LOQ)were 0.005-0.2 ?g/kg and 0.10-10?g/kg respectively.The recoveries of 43 pesticides were in a range from 80.63%to 119.71%with the range of RSD from 0.02%to 9.92%for all analytes.The results of the intra-day and inter-day precision for 43 pesticides showed RSDs were 3.391-9.92%and 2.39-9.48%,respectively.The method is stable,accurate and reliable,and satisfies the requirements of quantitative analysis.(3)Changes of pesticide residues in grape ripeness processing.The pesticide residues of four kinds of grapes in three regions were studied during the ripeness.In Region I,the contents of carbendazine,thiophanate-methyl,cyazofamid and fludioxonil in Pinot Noir were decreased by 19.3%,82.2%,89.5%and 34.8%,respectively.The contents of carbendazine,thiophanate-methyl and cyazofamid in Merlot decreased by 87.9%,81.2%and 100%,respectively,There was no significant change in the content of buprofezin in Pinot Noir and Merlot(p>0.05).There was no significant change in the content of mefenacet and buprofezin in Region ? either(p>0.05).In Region ?,the content of thiamethoxam and dimethomorph was decreased by 94.1%and 61.8%.However,the content of pyraclostrobin and difenoconazole was increased by 3609.8%and 363.9%,while the content of buprofezin remained unchanged(p>0.05).The results showed that the content decreased with the change of time.Buprofezin was used in the early stage,and the degradation was completed at maturity,so the content did not change.(4)Changes of pesticide residues during wine fermentation.The results showed that the content of carbendazim and pyrazoxystrobin in Pinot Noir decreased by 31.2%and 64.4%,and the content of dimethomorph and pyrimethanil increased by 10.4%and 126.9%.The content of Carbendazim and pyrazoxystrobin in Merlot decreased by 53.8%and 75.6%respectively,and the content of Dimethomorph increased by 67.4%.The contents of imidacloprid,acetamiprid and azoxystrobin in Cabernet Sauvignon decreased by 90.7%,80.8%and 59.1%,while the contents of dimethomorph,pyrimethanil and pyrazoxystrobin increased by 14.5%,10.1%and 291.3%,respectively.The content of pyrazoxystrobin,difenoconazole and dimethomorph in Chardonnay decreased by 37.9%,50.0%and 19.1%,and the content of thiamethoxam increased by 2.07%.The content of pesticide residues increased in the late stage of fermentation.(5)The key control point of pesticide residue during fermentation.Six pesticide residues,including imidacloprid,thiophanate-methyl,boscalid,pyrimethanil,pyraclostrobin and difenoconazole,were detected in both Pinot Noir and Merlot wine.Pesticides in Pinot Noir wine decreased by 49.0%?91.2%.In Merlot wine,except thiophanate methyl and pyrimethanil,which increased by 15.7%,the remaining pesticide residues decreased by 59.9%-95.1%.The key control point of pesticide residue in brewing process is affected by grape varieties.Alcohol fermentation is the key control point of Pinot Noir wine,and the separation is the key control point of Merlot wine. |
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