BACKGROUNDIn 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.

OBJECTIVESTo establish a method to determine 19 phenolic pollutants in reclaimed land.

METHODSBased 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.

RESULTSThe 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.

CONCLUSIONSThis method can be used effectively to avoid matrix interference and provide reference for trace determination of phenolic pollutants in soil samples with complex matrix.