Off-Flavour Analysis of Polluted River Water Based on Gas Chromatography-Mass Spectrometry/Olfactory Synchronous Analysis Method after Solid Phase Extraction with Stirring Rod

The polluted river water sample in Shanghai was analyzed by gas chromatography-mass spectrometry/olfactory synchronous analysis method with stirring rod solid phase extraction. The compounds separated by chromatography were qualitatively analyzed based on the NIST spectrum library. The relative contents of these compounds were semi quantitatively analyzed using peak area normalization method. The odor source was determined based on olfactory identification results (olfactory identification time, odor types and odor intensities). It was shown that the chemical oxygen demand in polluted river water samples was relatively high, indicating high contents of organic pollutants in the water samples. However, the water samples did not contain common volatile and semi volatile organic pollutants, mainly derived from alcohols and ethers with relatively high content. However, these two substances did not have a significant odor. Based on the comprehensive analysis of gas chromatography-mass spectrometry results and olfactory identification results, it was concluded that the foul odor in water was the result of the comprehensive action of sulfur compounds (thiols, thiophenes), nitrogen compounds (indoles, pyridines), hydrocarbons (alkanes, olefins and aromatics), and oxygen organic compounds (alcohols, ketones and ethers) with relative content less than 1.00%.