Simultaneous Determination of 51 Odorous Substances in Water by Headspace-Solid Phase Microextraction-Gas Chromatography/Triple Quadrupole Mass Spectrometry

A method of headspace-solid-phase microextraction-gas chromatography/triple quadrupole mass spectrometry was established for simultaneous determination of 10 types of 51 odorous substances in water. The effects of extraction head, extraction temperature, extraction time, salt content, desorption time and split ratio on detection results were investigated with optimized gas chromatography-mass spectrometry parameters using the multiple reaction monitoring (MRM) mode for triple quadrupole mass spectrometry. The results showed that the optimized conditions were polydimethylsiloxane/divinylbenzene as extraction head, 55 ℃ as extraction temperature, 20 min as extraction time, 300 g/L NaCl as salt content, desorption time of 0.5 min and the split ratio of 10∶1. The detection limits of 51 odorous substances ranged from 0.4 to 183 ng/L, and the linear correlation coefficients were greater than 0.995. The detection limits of indicator substances, such as geosmin, 2-methylisothiol, anisole, dimethyl disulfide, and dimethyl trisulfide were 0.4, 0.9, 1.9, 3.5, 1.7 ng/L, respectively, which met the limit requirement of “Standard for Drinking Water Quality (GB 5749—2022)” of China. The spiked recoveries of the low, medium and high concentration levels were 76.2%-118%, 78.9%-119% and 82.0%-119%, and the relative standard deviations were 2.9%-19.4%, 1.8%-13.4% and 0.9%-13.2%, respectively. This method was used to detect the odorous substances in 29 surface waters, in which 12 odorous substances such as methyl mercaptan, dimethyl sulfide, and DL-sec-butyl acetate were detected with the concentration range of 2.2~1 651 ng/L. There were no apparent interferences in the MRM channels for the detected odorous substances. This method has the characteristics of simple pretreatment, good reproducibility and high accuracy, which is suitable for simultaneous and rapid screening of various types of odorous substances in water bodies.