QuEChERS-高效液相色谱法分析稻田水及土壤中五氟磺草胺残留及其消解动态研究

目的建立稻田水及土壤中五氟磺草胺残留分析方法,研究其消解动态和残留水平。方法在安徽、黑龙江及河南三地进行农药残留田间试验。样品采用乙腈提取并净化浓缩,再经QuEChERS前处理净化,Agilent HC-C_(18)色谱柱分离,以乙腈-0.4%磷酸水为流动相进行梯度洗脱,利用高效液相色谱(high performance liquid chromatography,HPLC)检测。结果在0.02~5mg/kg的添加水平下,五氟磺草胺在稻田水中的平均回收率为88.8%~95.2%,相对标准偏差为4.0%~7.3%,最低检出浓度为0.02mg/kg;在0.02~2mg/kg的添加水平下,五氟磺草胺在土壤中的平均回收率为77.2%~90.0%,相对标准偏差为2.8%~7.5%,最低检出浓度为0.02mg/kg。实验三地的消解动态均符合一级动力学方程,五氟磺草胺在稻田水和土壤中的半衰期分别为1.9~12d和3.5~18d;8%五氟磺草胺油悬浮剂在三地水稻上以其推荐剂量的高值及其1.5倍剂量喷雾施药1次,在水稻收获期采样时测得稻田土壤中的最终残留量平均值均低于0.02mg/kg。结论由于气候、土壤类型等的不同,五氟磺草胺在安徽及黑龙江的消解半衰期存在一定差异,该研究为五氟磺草胺在水稻上的安全使用提供了科学依据。

Residue analysis and degradation dynamics of penoxsulam in water and soil of rice field by QuEChERS-high performance liquid chromatography

Objective To establish a method for penoxsulam residue analysis in water and soil of rice field, and study the degradation dynamics and residue level. Methods Residual trials of penoxsulam were carried out in Anhui, Heilongjiang and Henan Provinces. After extraction with acetonitrile and purification enrichment, the extract was purified by QuEChERS method, separated by an Agilent HC-C18 column using acetonitrile and 0.4% phosphoric acid water as mobile phase for gradient elution, and then detected by high performance liquid chromatography (HPLC). Results The average recoveries of penoxsulam in field water were 88.8%~95.2% spiked at the levels of 0.02~5 mg/kg with RSDs of 4.0%~7.3%, and the limit of quantitation (LOQ) was 0.02 mg/kg. At the levels of 0.02~2 mg/kg, average recoveries of penoxsulam in soil were 77.2%~90.0% with RSDs of 2.8%~7.5% and LOQ of 0.02 mg/kg. Degradation dynamic equations all fitted the first order reaction dynamic equations with half-lives of 1.9~12 d for field water and 3.5~18 d for soil. Final residues average values obtained in harvest time in rice filed soil were below 0.02 mg/kg after spray pesticide with 1 and 1.5 times of recommended dose of 8% penoxsulam oil suspension for 1 time. Conclusions The degradation dynamics of penoxsulam in water and soil of rice field in Anhui and Heilongjiang provinces were different due to different climates and soil types, which can provide scientific basis for safe use of penoxsulam in rice.