固相萃取-高效液相色谱法同时检测土壤中4种咪唑啉酮类除草剂残留

建立了一种以SAX固相小柱萃取和高效液相色谱(HPLC)法同时检测土壤中咪唑烟酸、甲基咪草烟、咪草酸甲酯和咪唑乙烟酸4种咪唑啉酮类除草剂残留的方法。考察了不同提取剂、pH、固相萃取(SPE)小柱和淋洗液体积等因素对回收率的影响。结果表明:采用SAX固相萃取小柱,以V(乙腈)∶V(水)=5∶3混合溶液为提取剂,6 mL甲醇为淋洗液时,在pH=3条件下,样品的提取及净化效果较好。淋出液浓缩后用甲醇定容,过滤膜后经HPLC检测。添加回收试验结果表明:在0.02~0.5 mg/kg添加水平下,4种除草剂的平均回收率在86%~109%之间,相对标准偏差(RSD)≤3.3%(n=5)。咪唑烟酸、甲基咪草烟和咪唑乙烟酸在土壤中的定量限(LOQ)均为0.01 mg/kg,咪草酸甲酯的LOQ为0.02 mg/kg。

Determination of four imidazolinone herbicide residues insoils by solid-phase extraction-high performance liquid chromatography

A new method for determining residues of imazapyr, imazapic, imazamethabenz-methyl and imazethapyr in soil was developed by solid-phase extraction (SPE) cleanup and high performance liquid chromatography(HPLC) detection. Various extraction reagents, solvents at different pH values, various type of SPE and the elution volumes were compared. Extraction with V(acetonitrile):V(water)=5:3 at pH 3, with SAX cartridge SPE purification of the extracts were found to be the most suitable conditions. Determination was done with HPLC coupled with diode array detector(DAD). Mean recoveries of four imidazolinone herbicides at fortification levels of 0.02-0.5mg/kg were between 86%-109% (RSD≤3.3%, n=5). Under the optimal conditions, limits of quantification in soil were 0.01 mg/kg for imazapyr, imazapic and imazethapyr, and 0.02 mg/kg for imazamethabenz-methyl (S/N=3).