对氯苯氧乙酸钠在荔枝和土壤中的残留行为

建立了对氯苯氧乙酸钠在荔枝和土壤中的残留分析方法，并在广州和南宁进行了8%对氯苯氧乙酸钠可溶性粉剂在荔枝上残留的田间试验，研究了对氯苯氧乙酸钠在荔枝和土壤中的消解动态和最终残留量。样品用碱溶液提取，盐酸调节pH值至2.5后乙酸乙酯萃取，采用高效液相色谱二极管阵列紫外检测器(HPLC-PDA)检测。结果表明:在0.01、0.1和1 mg/kg 3个添加水平下，对氯苯氧乙酸钠在荔枝和土壤中的平均回收率为81%~85%，相对标准偏差(RSD)为1.9%~4.6%，检出限(LOD)为0.005 mg/kg，定量限(LOQ)为0.01 mg/kg。田间试验结果表明:8%对氯苯氧乙酸钠可溶性粉剂在荔枝和土壤中的半衰期分别为3.2~5.9 d和15.2~20.6 d，属易降解农药。最终残留量测定结果显示:8%对氯苯氧乙酸钠可溶性粉剂按有效成分20和30 mg/L分别施药2次，广州和南宁两地收获期荔枝中对氯苯氧乙酸钠的残留量均＜0.01 mg/kg。

Residue behavior of sodium 4-chlorophenxyacetate in litchi and soil

An effective method was developed for the determination of sodium 4-chlorophenxyacetate residue in litchi. Field trials were designed to evaluate the dissipation and residue of sodium 4-chlorophenxyacetate in litchi at two locations:Guangdong and Guangxi. Samples were extracted by solution of sodium hydroxide, and further distributed by ethyl acetate after adjusting pH value into 2.5 by HCl and detected by high performance liquid chromatography with photo-diode array. The results showed that average recoveries ranged from 81% to 85% with relative standard deviations of 1.9%-4.6% at the spiked level of 0.01, 0.1 and 1 mg/kg. The limit of detection was 0.005 mg/kg and the limit of quantification was 0.01 mg/kg. Half-lives of sodium 4-chlorophenxyacetate ranged from 3.2 to 5.9 days in litchi and from 15.2 to 20.6 days in soil, respectively. The terminal residues of sodium 4-chlorophenxyacetate in litchi were below 0.01 mg/kg.