噻唑磷在甘蔗和土壤中的残留消解动态及风险评估

建立了噻唑磷在甘蔗和土壤中的残留分析方法，并在广东和广西2地进行了10%噻唑磷颗粒剂在甘蔗上残留的田间试验，研究了噻唑磷在甘蔗和土壤中的消解动态和最终残留量，并对甘蔗中噻唑磷可能产生的膳食摄入风险进行了评估。甘蔗样本用乙腈提取，氨基固相萃取小柱净化，采用气相色谱-火焰光度检测器 (GC-FPD) 检测。结果表明:在0.01、0.1和1 mg/kg添加水平下，噻唑磷在甘蔗中的平均回收率为83%～84%，相对标准偏差 (RSD) 为2.6%～3.4%；在土壤中的平均回收率为84%～86%，RSD为4.1%～6.7%。噻唑磷检出限 (LOD) 和定量限 (LOQ) 均为0.01 mg/kg。田间试验结果表明:10%噻唑磷颗粒剂在广东和广西甘蔗中的消解不符合一级反应动力学方程，没有显著的消解规律，呈现的特点是浓度由小到大再变小的趋势，施药后14～21 d甘蔗中噻唑磷的残留量达到最大值0.027 mg/kg；噻唑磷在土壤中消解符合一级反应动力学方程，半衰期为8.6～9.6 d，属易降解农药；噻唑磷在甘蔗和土壤中的最终残留量均小于0.01 mg/kg。膳食摄入风险评估结果表明:甘蔗中噻唑磷对人群的急性膳食摄入风险值为225%，急性膳食摄入风险较大，还需进一步结合噻唑磷在人体内的代谢行为等数据进行综合评估；慢性膳食摄入风险值为57%，表明按照推荐剂量施用10%噻唑磷颗粒剂，慢性膳食摄入风险较低，对消费者健康是安全的。

Residual dynamics and risk assessment of fosthiazate in sugar cane and soil

An effective method was developed for the determination of fosthiazate residue in sugar cane and soil. Field trials were designed to evaluate the dissipation and residue of fosthiazate in sugar cane and soil in Guangdong Province and Guangxi Province. The dietary exposure and risk assessment were also conducted. The samples were extracted by acetonitrile, cleaned up by NH₂-solid phase extraction and detected by GC-FPD. The results showed that, in terms of sugar cane samples, good average recoveries of 83%-84% with relative standard deviations of 2.6%-3.4% at the spiked level of 0.01, 0.1 and 1 mg/kg were achieved. As for soil samples, recoveries of 84%-86% with RSDs 4.1%-6.7% were obtained. The limit of detection (LOD) was 0.01 mg/kg and the limit of quantification (LOQ) was 0.01 mg/kg. The results demonstrated that residue of fosthiazate in sugar cane decreased first, then increased, and finally decreased again. The maximum concentration were 0.027 mg/kg which was detected 14-21 d after the application. Dissipation of fosthiazate in soil was in accordance with the first order kinetic equation with half-lives from 8.6 to 9.6 d. The terminal residue was below 0.01 mg/kg at harvest time. The acute dietary intake risk probability of fosthiazate was 225%, which was hazardous to people. It is necessary to combine the metabolic behavior data of fosthiazate in human body for comprehensive evaluation. The chronic dietary intake risk probability of fosthiazate was 57%, which was not hazardous to people.