改进QuEChERS-气相色谱-质谱法快速分析测定农用土壤中多环芳烃

Rapid determination of polycyclic aromatic hydrocarbons in farmland soils by GC-MS coupled with modified QuEChERS

建立农用土壤中16种多环芳烃的改进QuEChERS快速提取净化方法及气相色谱-质谱检测方法,并通过对西安市周边农用土壤样品的分析,调查土壤中多环芳烃的污染情况。土壤样品用KOH饱和的甲醇碱化处理后,用丙酮-正己烷(1+1)为提取溶剂,涡旋混匀后超声提取,提取液按改进QuEChERS方法加入无水MgSO4、硅胶及正丙基乙二胺(PSA)进行净化,检测时选用DB-5MS(30 m×0.25 mm×0.25μm)色谱柱分离,EI电离源及离子监测模式检测,16种多环芳烃的测定低限0.7～3.2μg/kg,加标回收率79.8%～109.6%,相对标准偏差均低于9.4%。检测的农用土壤样品中均检出有不同程度的多环芳烃残留,约16.7%的土壤样品为轻度污染。

A rapid analytical method based on modified QuEChERS sample preparation and GC-MS for the analysis of 16 polycyclic aromatic hydrocarbons（PAHs） residues in farmland soils has been developed.In order to evaluate farmland soil contamination around Xi＇an city,the concentrations of 16 PAHs were determined.Soil samples were treated by saturated methanolic potassium hydroxide solution,and extracted with acetone-hexane（1：1） by ultrasound method.The extract solution was purified by using modified QuEChERs method with anhydrous magnesium sulfate,silica gel and primary secondary amine（PSA）.The samples were analyzed by GC-MS with DB-5MS（30 m × 0.25 mm× 0.25 μm） and EI source in selective ion monitoring mode.With the analytical method developed in this study,the detection limits for PAHs ranged from 0.7 μg/kg to 3.2 μg/kg.The recoveries for PAHs varied from 79.8 % to 109.6 % and precisions（RSDs） were lower than 9.4 %.The determination result shows that all the farmland soil samples around Xi＇an city contain PAHs,and about 16.7 % of the soil samples pollute slightly.