Volatile Organic Compound Analysis in Activated Carbon

After collection, the samples were transported to the laboratory. Both the front and back sections of the activated carbon tube were transferred to different 2 mL vials. Samples were extracted, with 1 mL carbon disulfide (99.5%) (Merck Inc., Darmstadt, Germany) as eluent under ultrasonic waves for at least 30 min to complete extraction. Qualitative information about the predominant VOCs was obtained by gas chromatography-mass spectrometry (6890N/5973; Agilent, Palo Alto, Santa Clara, CA, USA). Analysis was performed using gas chromatography (GC 7890 Agilent, Santa Clara, CA, USA) equipped with a flame ionization detector (FID) using a capillary column (length = 30 m, internal diameter = 0.25 mm). Helium gas was used as a carrier gas, with a flow rate of 2 mL min⁻¹. The injection volume was 1 μL, and a split ratio of 5/1 was applied. The initial temperature of the column was 50 °C, which increased to 100 °C after 5 min. The injector was set at a temperature of 250 °C. Standard solutions of benzene, ethylbenzene, xylene, toluene, styrene, n-hexane, n-heptane, n-nonane, trichloroethylene, tetrachloroethylene, n-butyl acetate, n-octane, n-decane, dichlorofluoromethane, and acetone (Merck Inc., Darmstadt, Germany) were used to obtain the calibration curves.