Determination of 21 Phenolic Compounds in Soil by Gas Chromatography-Mass Spectrometry after Accelerated Solvent Extraction Combined with Gel Chromatography Purification

A method for simultaneous determination of 21 phenolic compounds in soil by gas chromatography-mass spectrometry after accelerated solvent extraction combined with gel chromatography purification was proposed. 10 g of the finely sieved soil sample (moisture content of 15%-20%) was taken, and 6 g of diatomite was added. The mixture was mixed uniform and placed in the extraction tank, extracted with a mixed solution of dichloromethane and n-hexane at the volume ratio of 2∶1 at 120 ℃ by accelerated solvent extraction. Anhydrous sodium sulfate was used to dehydrate the extract, and then thoroughly rinsed with dichloromethane. All organic phases were combined and concentrated to 1 mL. The concentrated solution was purified by gel chromatography, and the effluent of 9-18 min was collected, then concentrated to 1 mL. The 21 phenolic compounds in the solution were separated on a HP-5MS column according to the column heating program, and SCAN mode was adopted in mass spectrometry analysis. As shown by the results, linear relationships between the corresponding peak areas and mass concentrations of 21 phenolic compounds were found in the range of 2.50-50.0 mg·L⁻¹, with detection limits (3.143s) in the range of 0.02-0.07 mg·kg⁻¹. Test for recovery was made by the standard addition method, giving results in the range of 73.4%-107%, with RSDs (n=6) of the determined values not more than 17%. This method was used for the analysis of 2 soil samples, and 21 phenolic compounds were not detected. This method was used for the analysis of soil quality control sample, and the determined values of 21 phenolic compounds were all within the uncertainty ranges of the certified values.