衍生化气相色谱-质谱法测定复垦土地样品中19种酚类污染物

Determination of 19 Phenolic Pollutants in Reclaimed Land Samples by Derivation Gas Chromatography-Mass Spectrometry

近年来国家对自然环境的保护愈加重视,更多被破坏或污染的土地需要进行复垦整治。在评价效果时,需要检测酚类等多项污染物指标。采用气相色谱与气相色谱-质谱联用等方法对酚类化合物直接测定时,存在色谱响应值低、稳定性差、检出限高等问题。本文针对复垦土地样品基质复杂、干扰因素多、前处理困难等特点,对该类样品的提取与净化方法进行筛选优化。根据酚类污染物检测中浓度范围大、重现性差等问题,对衍生化与非衍生化效果进行对比确定了提取和净化方法,结合衍生化条件的优化、实际样品测定结果等方面的综合研究,建立了复垦土地样品19种酚类污染物(其中2,4,6-三氯苯酚和2,4,5-三氯苯酚,以及2,3,4,5-四氯酚和2,3,5,6-四氯酚,因无法分离而合并计算)的衍生化气相色谱-质谱检测方法。该方法采用加速溶剂萃取仪,以正己烷-丙酮(体积比1∶1)提取样品,提取液经浓缩、净化后,由五氟苄基溴衍生化,气相色谱-质谱联用仪测定。该方法基质加标回收率为73.3%~107.0%,检出限为0.67~3.95μg/kg,相比非衍生化方法的检出限(10~80μg/kg)显著降低;并且衍生物的稳定性更好,色谱响应值更高,各组分表现在色谱图上的峰高(峰面积)更均衡,对于低浓度样品的测定结果更加准确。该方法能有效去除基质干扰,可为复杂基质土壤样品中的酚类污染物痕量检测提供参考。

BACKGROUND:In recent years,more attention has been paid to the protection of the environment in China.More damaged or polluted land needs to be reclaimed.When evaluating the effect,it is necessary to detect several pollutant indexes for phenolic pollutants.In the direct determination of phenolic compounds by gas chromatography(GC)and gas chromatography-mass spectrometry(GC-MS),there are challenges such as low chromatographic response,poor stability and high detection limit.OBJECTIVES:To establish a method to determine 19 phenolic pollutants in reclaimed land.METHODS:Based on the characteristics of complex matrix,multiple interference factors,and difficult pre-processing of reclaimed land samples,the extraction and purification methods of this type of sample were screened and optimized.The extraction and purification methods were determined by comparing the effects of derivatization and non-derivatization,combined with comprehensive research on the optimization of derivatization conditions and the measurement results of actual samples.A derivatized gas chromatography-mass spectrometry method for detecting 19 phenolic pollutants in reclaimed land samples was established(Among them,2,4,6-trichlorophenol and 2,4,5-trichlorophenol,2,3,4,5-tetrachlorophenol and 2,3,5,6-tetrachlorophenol were combined because of could not be separated).The samples were extracted with n-hexane and acetone(1∶1,V/V)by ASE.The extract was concentrated,purified and derivatized by pentafluorobenzyl bromide.Finally,it was determined by GC-MS internal standard method.RESULTS:The standard-addition recoveries were 73.3%-107.0%.The method detection limits of phenolic compounds in soil were 0.67-3.95μg/kg,which was significantly lower than nonderivative method(10-80μg/kg).The derivatives had better stability and higher chromatographic response,the groups were more even in peak height(area)on the chromatogram.The derivatization method had better reproducibility and the results of low-concentration samples were more accurate.CONCLUSIONS:This method can be used effectively to avoid matrix interference and provide reference for trace determination of phenolic pollutants in soil samples with complex matrix.