Determination of 4 Odor Substances in Drinking Water by Gas Chromatography-Mass Spectrometry with Trap Headspace

A method for the determination of 4 odor substances in drinking water, including dimethyl disulfide, dimethyl trisulfide, 2-methylisocamphenol, and soil odor, was proposed by gas chromatography-mass spectrometry with trap headspace. 10.0 mL of water sample was taken and placed in a headspace bottle, and 3.0 g of sodium chloride was added quickly. The mixture was heated and equilibrated at 0.276 MPa and 70 ℃ for 15 min, and separated on a DB-624 chromatographic column according to the column heating program after the trap was cycled 4 times. Multiple reaction monitoring (MRM) mode was adopted in mass spectrometry analysis, and the external standard method was used for quantitative analysis. As shown by the results, linear relationships between the corresponding peak areas and mass concentrations of 4 odor substances were found in the range of 5.0—100.0 ng·L⁻¹, with detection limits (3S/N) in the range of 0.6—2.5 ng·L⁻¹. Test for recovery was made by the standard addition method, giving results in the range of 95.0%—107%, with RSDs (n=6) of the determined values less than 5.0%. This method was used for the analysis of 10 samples of drinking water, and dimethyl disulfide in 2 samples was detected, with detection amouts of 4.7 ng·L⁻¹ and 2.4 ng·L⁻¹, while the remaining 3 odor substances were not detected.