络合萃取-在线衍生气相色谱-质谱法检测土壤中酸性除草剂

摘要

以Na4-EDTA为络合剂、五氟苄基溴为衍生试剂,对土壤中酸性除草剂进行在线衍生络合萃取,采用负化学源质谱技术对衍生产物实现了快速、高灵敏检测.将10.0 g土壤样品、1.5 mL蒸馏水、0.50 g Na4-EDTA充分混合,加入过量衍生试剂,采用加速溶剂萃取仪,样品在100 ℃,10.3 Mpa压力下,10 min完成衍生及萃取过程,萃取液脱水并净化后进行检测.本方法在10-500 μg/kg范围内线性关系较好,相关系数r2> 0.990.方法的检出限为0.8-7.7 μg/kg;回收率为70%-130%;精密度2.0%-8.0%.%A rapid and sensitive method for the detection of acidic herbicides in soil was developed by in-situ derivatization complexing extraction with Na4-EDTA as complexing reagent and pentafluoro-benzyl bromide (PFBBr) as derivatization reagent combining with GC-negative ion chemical ionization (NCI)-MS. On the basis of sufficient mixture of 10. 0 g soil, 1. 5 mL H2O, and 0. 5 g Na4-EDTA, the derivatization and extraction was completed in 10 min, with elevated temperature (100 °C) and pressure (10. 3 Mpa) by accelerated solvent extractor (ASE) with excessive PFBBr in the extraction cell. The extract was detected after drying and clean-up. The correlation coefficient (r2) > 0. 990 in the samples concentration of 10-500 μg/kg, the MDL was 0. 8-7. 7 μg/kg, the recovery was 70% -130%, and the RSD was 2.0%-8.0%.