联苯菊酯、噻虫嗪及其代谢物噻虫胺在小麦上的残留及膳食风险评估

Residue behavior and dietary risk assessment of bifenthrin,thiamethoxam and clothianidin in wheat

建立了小麦及其秸秆中联苯菊酯、噻虫嗪和代谢物噻虫胺残留量的分析方法。样品经乙酸-乙腈提取,无水硫酸镁、N-丙基乙二胺(PSA)及GCB净化,超高效液相色谱-三重四极杆串联质谱仪(UPLC-MS/MS)检测。结果表明:在0.002 5~0.1 mg/L范围内,联苯菊酯、噻虫嗪和噻虫胺的峰面积与其质量浓度间呈良好线性关系,R^(2)均大于0.99。麦粒样品在0.01、0.1和0.5 mg/kg,秸秆样品在0.05、0.5和3 mg/kg添加水平下,联苯菊酯、噻虫嗪和噻虫胺在小麦及其秸秆中的添加回收率分别在93%~98%、87%~98%和87%~98%之间,相对标准偏差(RSD)分别在0.8%~4.8%、0.6%~4.1%和1.0%~3.3%之间。按照《农作物中农药残留试验准则》在全国12个小麦主产区开展规范残留试验,采用35%联苯菊酯·噻虫嗪悬浮剂,以制剂用量150 g/hm^(2)(有效成分52.5 g/hm^(2))的剂量,于小麦蚜虫始盛时期施药1次,施药后间隔14 d和21 d采集的麦粒中联苯菊酯、噻虫嗪和噻虫胺的残留量结果验证了相关残留限量(MRL)值的适用性,且多点试验的结果具有更高的可靠性。长期及短期膳食暴露风险评估结果表明,小麦中联苯菊酯、噻虫嗪和噻虫胺残留量对1~6岁儿童和普通人群产生的膳食暴露风险在可接受范围内。

A high efficient and simple method for residue analysis of bifenthrin, thiamethoxam and its metabolite clothianidin in wheat and straw was developed. The samples were extracted with acetic acidacetonitrile, purified with anhydrous magnesium sulfate, primary secondary amine(PSA) and GCB, and detected by ultra-performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-MS/MS). The results showed that there was a good linear relationship between the peak areas of bifenthrin, thiamethoxam and clothianidin and their mass concentrations in the range of 0.002 5-0.1 mg/L, with R^(2) greater than 0.99. The recoveries of bifenthrin, thiamethoxam and clothianidin in wheat and straw were 93%-98%, 87%-98% and 87%-98%, respectively, and the relative standard deviations(RSDs) were 0.8%-4.8%, 0.6%-4.1% and 1.0%-3.3%, respectively, when the spiked levels were 0.01, 0.1, 0.5 mg/kg for wheat grain and 0.05, 0.5, 3 mg/kg for straw. The supervised residue trials were carried out in 12 main wheat producing areas in China according to "guideline for the testing of pesticide residues in crops". The 35% suspension concentrate of bifenthrin and thiamethoxam was sprayed once at the dosage of 150 g/hm^(2)(active ingredient 52.5 g/hm^(2)) at the beginning of wheat aphids bloom. The residual amounts of bifenthrin, thiamethoxam and clothianidin in wheat grains collected on day 14 and 21 after application verified the applicability of the MRL values, and the results of multipoint tests had higher reliability. The results of long-term and short-term dietary exposure risk assessment showed that the dietary exposure risks of bifenthrin, thiamethoxam and clothianidin residues in wheat were acceptable for children aged 1-6 years and the general population.