毒死蜱在大豆和土壤中的消解动态与最终残留研究

Dissipation Dynamic and Terminal Residue of Chlorpyrifos in Soybean and Soil

为阐明毒死蜱在防治大豆食心虫过程中的残留消解特性,评估其使用安全风险,本研究利用超高效液相色谱-串联质谱仪(UPLC-MS/MS)分析了毒死蜱在大豆植株、全豆或大豆籽粒和土壤中的消解动态与最终残留。结果表明:在2 250 g·hm^(-2)×1次和1 500 g·hm^(-2)×2次的试验剂量条件下,毒死蜱在大豆植株中的原始沉积量达17.24~19.69 mg·kg^(-1),残留消解曲线分别为C_(t)=17.403 0e^(-0.165t)和C_(t)=12.039 0e^(-0.122 t),半衰期分别为3.5和2.7 d。毒死蜱在全豆中原始沉积量较低,为1.78~2.98 mg·kg^(-1),药后1~3 d消解平缓,5~10 d消解较快,10 d后又趋于平缓,2 250 g·hm^(-2)×1次、1 500 g·hm^(-2)×2次试验剂量条件下的残留消解曲线分别为C_(t)=2.136 3^(e-0.217 t)和C_(t)=2.684 7e-0.199 t,半衰期分别为4.0和3.0 d,比在植株中的半衰期长0.3~0.5 d。药后0~21 d全豆中毒死蜱残留量均超过0.02 mg·kg^(-1)的国家限量标准,此时间段内采摘菜豆食用具有潜在食用安全风险。毒死蜱在土壤中的原始沉积量虽然较低,但其消解速度较慢,特别是在超推荐剂量情况下使用,药后28 d仍然有较高的残留。按照推荐剂量在大豆上施药2次,药后14,21,28 d大豆籽粒中均未检出毒死蜱残留,表明毒死蜱可用于大豆的安全生产。

In order to clarify the residual digestion properity, evaluate the security risks of chlorpyrifos in the control of Leguminivora glycinivorella(Mats.), this study analyzed the dissipation dynamics and terminal residues of chlorpyrifos in soybean plants, whole beans or soybean seeds and soil by ultra high performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS). The results showed that the original deposition of chlorpyrifos in soybean plants was 17.24-19.69 mg·kg^(-1). The residual digestion curves under the conditions of two test doses of 2 250 g·ha^(-1)once and 1 500 g·ha^(-1)twice were C_(t)= 17.403 0 ^(e-0.165 t), C_(t)= 12.039 0 ^(e-0.122 t), and the half-life was 3.5 d and 2.7 d, respectively. The original deposition of chlorpyrifos in whole beans was low, up to 1.78-2.98 mg·kg^(-1). The dissipation was gentle 1-3 days after treatment, rapid 5-10 days after treatment, and tended to be gentle again 10 days later. The residue digestion curves under the two test doses of 2 250 g·ha^(-1)once and 1 500 g·ha^(-1)twice were C_(t)= 2.136 3 e^(-0.217 t), C_(t)= 2.684 7 e^(-0.199 t), and the half-life was 4.0 d and 3.0 d, respectively, which was 0.3-0.5 d longer than that in plants. The residues of chlorpyrifos in whole beans from 0 to 21 days after treatment exceed the national limit standard of 0.02 mg·kg^(-1). There is a potential risk of picking soybeans as kidney beans during this period. Although the original deposition amount of chlorpyrifos in the soil was low, its digestion speed was slow, especially when it was used in excess of the recommended dose, there was still a high residue 28 days after treatment. The terminal residues were not detected in soybean seeds 14, 21 and 28 days after the application of chlorpyrifos on soybean twice according to the recommended dose, indicating that chlorpyrifos is safe for the production of soybean.