戊唑醇和吡唑醚菌酯在苹果中的残留行为及膳食暴露风险评估

Residues behavior and dietary exposure risk assessment of tebuconazole and pyraclostrobin in apple

[目的]建立同时检测不同地区苹果中戊唑醇和吡唑醚菌酯的残留分析方法,通过苹果树1年12地的田间试验,监测了2种农药在苹果主要产区的消解态势,并评估不同人群对其膳食暴露风险。[方法]QuEChERS-HPLC-MS/MS法的建立,用于检测苹果中的戊唑醇和吡唑醚菌酯的残留,并且分析2种农药在苹果中的最终残留和消解动态,计算6类典型人群国家估算每日摄入量(National Estimated Daily Intake,NEDI)和风险指数(Risk Index,RI)。[结果]根据戊唑醇和吡唑醚菌酯在苹果中的消解动态,可知2种农药在苹果中的半衰期分别为9.4~21.7 d和10.3~23.8 d。戊唑醇和吡唑醚菌酯在苹果鲜果中膳食暴露RI值均小于100%,膳食暴露风险处于可接受水平,针对6类典型人群进行膳食暴露风险评估,膳食暴露量随年龄的增加逐渐降低。[结论]采用QuEChERS-HPLC-MS/MS法可同时快速检测戊唑醇和吡唑醚菌酯,2种农药在不同年龄段和不同性别人群对于苹果鲜果的膳食暴露风险处于可接受水平,对于农药安全使用和膳食摄入评估具有重要意义。

[Objective]The residue and degradation dynamics of tebuconazole and pyraclostrobin in apple were studied at twelve sites in one year.And the dietary exposure risk assessment concerning two compounds were estimated.[Methods]QuEChERS-HPLC-MS/MS method was established to detect tebuconazole and pyraclostrobin in apple fruits.The purification of sample was adjusted to the proportion of purifying agent.Samples were extracted by acetonitrile(Compared with methanol,acetonitrile was more efficient and safer as extraction solvent),and purified by a traditional purifying agent(20 mg graphitized carbon black(GCB)+40 mg primary secondary amine(PSA)and 150 mg anhydrous magnesium sulfate).Both compounds were optimized for separating under conditions of chromatography and mass spectrometry.The national estimated daily intake(NEDI)and risk index(RI)of six typical populations were calculated.[Results]The method established in this study greatly decreased the sample pretreatment time and the separation efficiency of the two pesticides,the operation was practical,the peak shape was symmetrical,the response value was high and the reproducibility was perfect.In order to achieve efficient purification effect,PSA,PSA+GCB and multi-walled carbon nanotubes(MWCNTs)were investigated in the process of screening out different proportions of purification agents.The amount of purification agent was optimized for obtaining higher recovery.The extraction and purification of apple samples from different regions and varieties could achieve good purification effect.Through addition and recovery test,under three levels of addition(0.005,0.5 and 2 mg·kg-1),the average inter-day recovery of tebuconazole in apple matrix was between 87%and 101%,the relative standard deviation(RSDs)(n=5)was between 0.6%and 7.9%,the intra-day average recovery was 91%-100%,RSDs(n=15)were 1.0%-6.6%;the inter-day average recovery of pyraclostrobin in apple matrix was 87%-103%,RSDs(n=5)were 1.3%-7.0%,the average recovery was 93%-101%and RSDs(n=15)were less than 6.7%.Compared with other methods,the analytical method established in this study had higher recovery rate and versatility.In practical application group,it could realize rapid detection for a large number of samples from different regions.Moreover,the limit of quantitation about tebuconazole and pyraclostrobin in apple matrix was 0.005 mg·kg-1,which could be used to detect the distribution of two pesticides at low residue level.In this study,the effects of climate conditions and varieties were comprehensively considered.The results of degradation dynamics showed that the half-life period of the two fungicides in apple were faster(In the digestion test plots,the half-life periods of tebuconazole and pyraclostrobin were 9.4-21.7 d and 10.3-23.8 d,respectively),which were easily degradable pesticides(T1/2<30 d).The half-life periods of tebuconazole and pyraclostrobin in apple matrix were influenced by the climate conditions.At the same time,the adhesion of different varieties on apple directly affected the original deposition amount of pesticides,which was one of the important factors affecting pesticide residue behavior.The results of final residue test showed that the residues of tebuconazole and pyrazoxystrobin in apple were 0.010-0.191 mg·kg-1 and 0.005-0.115 mg·kg-1,respectively,28 d and 35 d after the last application,which were lower than the maximum residue limits of two pesticides in apple.In addition,according to the final residue data from 12 places in one year,the dietary exposure risk of tebuconazole and pyraclostrobin in fresh apple fruits were calculated.The results showed that the dietary exposure risk index of tebuconazole and pyraclostrobin in fresh apple fruits were less than 100%,and the dietary exposure risk was at an acceptable level.In this study,12 experimental sites were selected,including main production areas in China.The varieties were local dominant varieties,and the results were more realistic and universal.[Conclusion]QuEChERS-HPLC-MS/MS method can be used to detect tebuconazole and pyraclostrobin rapidly at the same time.It had prospects applied in the control of raw materials of fresh and processed apples,pesticide residue detection of intermediate processing bodies,spot check of market food quality and national quarantine of imported and exported food.The results showed that the dietary exposure risk of fresh apple was acceptable in six different population,but age and gender had little effect on the overall exposure risk.In different age groups,the dietary exposure risk of 2-4-year-old children was significantly higher than that of additonal two groups,which was 3.3-5.6 times and 4.5-5.6 times of the other two groups,respectively.Therefore,in the future food risk assessment,we should take good care of individuals,such as children,women and pregnant women.This study focused on the detection of residues in primary agricultural products,not the processing food.Cleaning,peeling,condensing,sterilization,fermentation and other processes involved in the processing of apple products could be used as the influencing factors of food residues.Therefore,if the processing factors were considered before the assessment of pesticide dietary exposure,more accurate risk assessment would be obtained.The results of this study had reference significance for guiding 40%pyraclostrobin·tebuconazole SC to determine the reasonable safety interval,and was important for the safety of fungicide application and dietary intake evaluation.