嘧菌酯在杨梅中的残留行为及膳食暴露风险评估

Residue behavior and dietary exposure risk assessment of azoxystrobin in waxberry

建立嘧菌酯在杨梅中的残留分析方法,考察嘧菌酯在杨梅中的储藏稳定性,通过开展50%嘧菌酯水分散粒剂在杨梅树上1年(2018年)6地的田间试验,明确嘧菌酯在杨梅上的残留特征及膳食风险。杨梅样品中嘧菌酯经乙腈提取,碱性氧化铝净化,超高效液相色谱串联质谱(UPLC-MS/MS)检测,外标法定量。结果表明,在0.001~0.05 mg·L^(-1)范围内,嘧菌酯在溶剂及基质中的峰面积与其对应的质量浓度间线性关系均良好,R 2≥0.9991。当添加质量分数为0.01~30.0 mg·kg^(-1)时,嘧菌酯在杨梅中添加回收率为90%~98%,相对标准偏差(RSD)为1.8%~7.9%,定量限(LOQ)为0.01 mg·kg^(-1),该方法能用于检测嘧菌酯在杨梅中的残留量。杨梅中嘧菌酯在冷冻储藏条件下较为稳定,在≤-18℃储藏条件下杨梅样品储藏650 d,其降解率低于14.3%。田间试验结果表明,嘧菌酯在杨梅上降解较快,其消解符合一级动力学方程,半衰期为2.2~5.0 d。按照300 mg·kg^(-1)(制剂用药量:1667倍液)对杨梅树施用50%嘧菌酯水分散粒剂2次,施药间隔10 d,最后一次施药后20、25、30 d,杨梅中嘧菌酯的残留量分别为0.012~0.57、<0.010~0.52、<0.010~0.28 mg·kg^(-1)。嘧菌酯的普通人群国家估算每日摄入量(national estimated daily intake,NEDI)是6.1114 mg,风险商(risk quotient,RQ)为48.5%,对一般人群健康风险较低。

In order to clarify the residual characteristic and dietary risk of azoxystrobin in waxberry,an analytical method was developed for the determination of azoxystrobin residues in waxberry by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),and the storage stability of azoxystrobin in waxberry was also investigated.The field trials of 50%water dispersible granule of azoxystrobin were conducted in six provinces in the year of 2018.The samples were extracted by acetonitrile,purified by alkaline alumina and quantified by external standard method.The results showed that the calibration curve with good linearity was obtained in the concentration range from 0.001 to 0.05 mg·L^(-1),with correlation coefficients(R 2)not less than 0.9991.At the spiked levels of 0.01 to 30.0 mg·kg^(-1),the average recovery of azoxystrobin in waxberry was 90%-98%with relative standard deviations(RSD)of 1.8%-7.9%.The limit of quantitation(LOQ)of azoxystrobin in waxberry matrix was 0.01 mg·kg^(-1).The degradation rates of azoxystrobin in waxberry samples with initial concentration of 5 mg·kg^(-1)were lower than 14.3%at no more than-18℃,indicating that azoxystrobin can be steadily stored for at least 650 days in waxberry samples.The dissipation dynamics of azoxystrobin was fitted to the first-order kinetics equation,and the half-lives of azoxystrobin in waxberry were 2.2-5.0 d,indicating azoxystrobin was an easily degradable pesticide(T 1/2<30 d).50%azoxystrobin water dispersible granule was sprayed twice with an interval of 10 d at the recommended high dosage(300 mg·kg^(-1))in the waxberry.The final residues of azoxystrobin in the waxberry were 0.012-0.57,<0.010-0.52,<0.010-0.28 mg·kg^(-1)at day 20,25 and 30 after application,respectively,which were lower than the maximum residue limits of azoxystrobin in berry and other small fruits.The long-term dietary intake risk assessment indicated that the national estimated daily intake(NEDI)of azoxystrobin was 6.1114 mg,with a risk quotient(RQ)of 48.5%.The results showed that the residual levels of azoxystrobin in waxberry did not pose unacceptable risks to the general population.