储藏和加工方式对稻谷中毒死蜱和三唑磷残留量的影响

Effect of Storage and Processing Methods on Residues of Chlorpyrifos and Triazophos in Paddy

[目的]了解稻谷加工方式和储藏方式对稻米中毒死蜱和三唑磷残留动态的影响机制。[方法]采用液相色谱-三重四极杆质谱法同时检测稻米中的毒死蜱及其代谢物3,5,6-三氯-2-吡啶酚(3,5,6-Trichloro-2-pyridinol,TCP)和三唑磷残留,分析碾磨、蒸煮、发芽加工以及储藏温度(37和4℃)对毒死蜱和三唑磷残留量的影响。[结果]毒死蜱及其代谢物TCP、三唑磷等农药残留多数分布在米糠层;短时间的蒸煮无法明显降低稻谷中毒死蜱的残留量;发芽稻谷中毒死蜱及其代谢物TCP、三唑磷的残留量显著低于未发芽稻谷;在37℃储藏条件下,毒死蜱的降解方程为C=0.899e^(-0.005t)(R^2=0.855 6),半衰期为138.6 d;三唑磷降解方程C=0.768e-0.009t(R^2=0.822 8),半衰期77.0 d,近似满足一级动力学模型方程;在4℃低温储藏条件下,稻谷中毒死蜱和三唑磷的残留量变化不大。[结论]碾磨和发芽加工有利于降低稻谷的农药残留量,低温储藏稻谷不利于残留农药的降解。研究可为稻米加工过程的风险评估以及开发稻米中农药残留的消解技术提供参考。

[ Objective ] To investigate the effect of rice processing and storage methods on the residual dynamics of chlorpyrifos and triazophos in paddy. [ Method] The residues of chlorpyrifos and their metabolites 3,5,6-Trichloro-2-pyridinol（TCP） and triazophos were detected by liquid chromatography-triple quadrupole mass spectrometry. The effect of milling, cooking, germination and storage temperatures （ 37 and 4 ℃ ） on the residues of chlorpyrifos and triazophos were investigated in the present research. [ Result] The results showed that the pesticide residues such as chlorpyrifos and their metabolites TCP and triazophos were mostly distributed in the rice bran layer. Short-term cooking could not sig- nificantly reduce the residues of chlorpyrifos in paddy. The residues of chlorpyrifos and their metabolites TCP and triazophos in sprouted paddy were significantly lower than that of unsprouted paddy. The degradation equation of chlorpyrifos was C = O. 899e-~＇~＇（R2 = 0. 855 6）, the half-life period was 138.6 d, while the triazophos degraded equation was C = 0.768e^-0.009 （R^2 = 0. 822 8） and the half-life period was 77. 0 d, which satisfies the first-order kinetic model equation. Under the condition of 4 ℃ low temperature storage, the residues of chlorpyrifos and tfiazophos in paddy did not significantly degraded. [ Conclusion] The milling processing and germination processing are beneficial to re- duce the pesticide residues in the paddy. Low temperature storage of paddy is not conducive to the degradation of residual pesticides. The resuits of this study can provide a reference for the risk assessment of paddy processing and the development of technologies to reduce pesticide residues in paddy.