Determination of 8 Phenolic Pollutants in Wastewater by Gas Chromatography-Mass Spectrometry Coupled with Ultrasound-Assisted Emulsion Extraction

By optimizing extraction and chromatographic conditions, the title method was proposed to determine 8 phenolic pollutants in wastewater, including phenol, o-chlorophenol, o-cresol, p-cresol, 2,5-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, and quinoline. After settling and filtering the wastewater sample, 20 mL of the sample was taken. Then 4.0 g of sodium chloride was added, and the mixture was shaken for 2 min. After 20 mL of dichloromethanen was added, ultrasonic emulsification extraction was performed for 5 min. The mixed solution was placed into a separating funnel to settle for 5 min. The organic phase was taken, and concentrated to 2-3 mL at 10 ℃. The concentrated solution was diluted to 5 mL by dichloromethane, and 1 g of anhydrous sodium sulfate was added. The mixture was settled for 10 h to remove the moisture, and the resulting solution was introduced into the gas chromatograph-mass spectrometer. Program temperature separation of 8 phenolic pollutants in the sample solution was conducted on the Agilent DB-VRX chromatographic column (30 mm×0.25 mm, 1.4 μm). Qualitative and quantitative analysis was performed by full scan (SCAN) and selective ion monitoring (SIM) modes, respectively. It was shown that linear relationships between values of the mass concentration and peak area of 8 phenolic pollutants were kept in the range of 0.50-500.00 μg·L⁻¹, with detection limits (3S/N) in the range of 0.02-0.07 μg·L⁻¹. Test for recovery was made according to the standard addition method, giving recoveries in the range of 76.8%-114%, and RSDs (n=6) of the determined values not more than 10%. The proposed method was used for the analysis of surface water and coal chemical wastewater samples, 2.40 μg·L⁻¹ phenol and 1.3 μg·L⁻¹p-cresol were detected in surface water, and 8 phenolic pollutants were detected in coal chemical wastewater with detection amounts in the range of 1.21-30.63 μg·L⁻¹.