甲基硫菌灵及其代谢物多菌灵在猕猴桃上的残留及安全性评价

Residue and safety evaluation of thiophanate-methyl and its metabolite carbendazim in kiwi fruit

为了评估甲基硫菌灵在猕猴桃上使用的安全性,采用QuEChERS-超高效液相色谱-串联质谱分析方法,对甲基硫菌灵及其代谢物多菌灵在猕猴桃上的残留量进行了分析,明确了其消解规律及半衰期,通过进行膳食摄入风险评估,以推荐甲基硫菌灵在猕猴桃上的最大残留限量(MRL),并对其代谢物多菌灵的残留量进行了安全性评价。结果表明:在0.01、0.1和1.0 mg/kg 3个添加水平下,甲基硫菌灵的回收率为85%~102%,相对标准偏差(RSD)为1.0%~7.1%;多菌灵的回收率为86%~101%,RSD为2.1%~5.2%;两者的定量限均为0.01 mg/kg。甲基硫菌灵在猕猴桃上的消解符合一级反应动力学方程,半衰期为10.1~10.5 d,属易消解农药。70%甲基硫菌灵可湿性粉剂在猕猴桃上按照推荐剂量及1.5倍推荐剂量(875和1166.7 mg/kg)分别施药3次和4次,推荐采收间隔期为21 d,膳食风险商为78.7%,推荐MRL值为5 mg/kg,该结果通常不会对一般人群健康产生不可接受的风险。依据GB 2763多菌灵在猕猴桃上的MRL值0.5 mg/kg,代谢物多菌灵存在较大的超标风险。建议有关部门制定甲基硫菌灵在猕猴桃上的MRL值,并重新评估多菌灵在猕猴桃上的MRL值。

To evaluate the safety of thiophanate-methyl in kiwi fruit,the QuEChERS-ultra high performance liquid chromatography-tandem mass spectrometry(QuEChERS-UPLC-MS/MS)analysis method was used to analyze the residues of thiophanate-methyl and its metabolite carbendazim in kiwi fruit.The kinetic equation and half-life of thiophanate-methyl residues in kiwi fruit were calculated.The dietary intake risk assessment was conducted.The maximum residue limit(MRL)of thiophanatemethyl in kiwi fruit was recommended and the safety of its metabolite carbendazim was evaluated.The results showed that the recovery rates of thiophanate-methyl and carbendazim were 85%-102%and 86%-101%,respectively,and their relative standard deviations(RSD)were 1.0%-7.1%and 2.1%-5.2%,respectively,at the spiked levels of 0.01,0.1 and 1.0 mg/kg.The limits of quantitation(LOQ)of two pesticides on kiwi fruit were both 0.01 mg/kg.The regulation of thiophanate-methyl residues in kiwi fruit conformed to the first-order reaction kinetic equation,with the half-life of 10.1-10.5 d.When the recommended dosage and 1.5 times of the recommended dosage(875 mg/kg,1166.7 mg/kg)of thiophanate-methyl(70%WP)were sprayed for 3-4 times and the harvest interval was 21 days,the dietary risk quotient(RQ)was calculated as 78.7%.The result was acceptable to the general population and a MRL valaue of 5 mg/kg was recommended.The metabolite carbendazim had a greater risk of exceeding the standard of 0.5 mg/kg according to GB 2763.The MRL valaue of thiophanate-methyl should be established in kiwi fruit,while the MRL value of carbendazim should be reevaluated.