活体固相微萃取-气相色谱法测定小白菜中3种农药残留

Determination of three pesticides residue in pakchoi with in vivo solid-phase microextraction-gas chromatography

为指导小白菜合理施用农药、降低农药残留水平,采用采样速率法对活体固相微萃取技术进行定量校正,结合气相色谱法对小白菜中3种农药(百菌清、毒死蜱和氟虫腈)进行了活体采样和定量测定,研究小白菜中农药的吸收、富集和消解行为。结果显示:活体检测方法准确、灵敏、快速、便捷;光照和温度均能促进3种农药降解;施药方式会影响农药的吸收,叶面喷洒施药后,小白菜对3种农药的吸收速率更快;培养方式会影响农药降解,土培方式的小白菜中农药消解速率比水培方式更快;采后贮藏对农药的降解也有一定影响,贮藏温度对于百菌清的消解速率影响不大,而低温能够延缓毒死蜱和氟虫腈的消解。结果表明,3种农药中百菌清的稳定性最差,氟虫腈在4℃条件下的稳定性最好,毒死蜱在常温和4℃条件下均比较稳定。

Three pesticides including chlorothalonil,chlorpyrifos and fipronil in pakchoi were sampled and determined quantitatively by sampling rate calibrated in vivo solid-phase microextraction-gas chromatography.The environmental behavior of pesticides including absorption,enrichment and dissipation in pakchoi were studied.The results showed that the in vivo detection method was accurate,sensitive,fast and convenient.Both light and temperature promoted the degradation of three pesticides in pakchoi.The application method affected the absorption of pesticides,and the absorption rate of the three pesticides by foliar spraying of pakchoi was faster.The culture method affected the degradation of pesticides,and the rate of pesticide degradation in the soil-cultured pakchoi was faster than that of the pakchoi cultured in water.Postharvest storage had an effect on the degradation of pesticides.Storage temperature had little effect on the dissipation rate of chlorothalonil,while low temperature inhibited the dissipation of chlorpyrifos and fipronil.The results showed that among the three pesticides,chlorothalonil had the worst stability,fipronil had the best stability at 4℃,and chlorpyrifos was relatively stable at room temperature and 4℃.It will provide an analytical method for tracking pesticides in living plants and an insight into the environmental behavior in complex biological systems.It will be helpful to better understand the characteristics of pesticide residues in pakchoi and to reduce the potential health risks in human.