Exploration of a Causative Substance of Fishy-Smell in Raw Water for Taps by Combining a LC-HRMS, a GC-O-HRMS, and Multivariate Analyses

摘要

Off-flavor events in raw waters for taps have been reported from various regions of Japan. Especially, a causative substance of fishy smell has not yet been unrevealed to the best of our knowledge. Identification of the causative compound of fishy smell may make the outbreak mechanism uncovered, water quality measurements simpler and more accurate, and removal technology much better. Thus, in the present study, raw water samples and cultured media with Uroglena americana were analyzed by LC-HRMS, GC-O-HRMS, and multivariate analysis to explore a mass peak(s) of the causative compound. A combination of LC-HRMS and MVA resulted in the selection of one ion as a possible candidate and its formula was determined to be C_(13) H_(20) O_3 based on its accurate mass and isotopic pattern. The candidate underwent GC-O-HRMS analyses and milk-like smell was detected at around its retention time. Although the detected smell was different from fishy smell, it is expected that fishy-smell may be caused by multiple substances and the candidate is one of them. The first generation product ion spectra of the candidate suggested that it may contain a hydroxyl group, a methoxy-substituted cyclohexene, and an enol moiety.