A Demonstration of Mass-spectrometric Exploration of Organic Ecotoxicants from Simulated Sewage-treatment-plant Effluents

Abstract

From three different sewage treatment plants, three effluent samples were collected to demonstrate applicability of a non-targeted mass spectrometric analysis for exploration and identification of organic ecotoxicants in the samples. Five known organic ecotoxicants were added to these samples to simulate toxic samples. The non-targeted analyses of the simulated samples were conducted with a liquid chromatograph-high resolution mass spectrometer. The whole effluent toxicity tests were conducted by using Raphidocelis subcapitata as the test organism. The number of components detected by the analyses was 3,427. Relationships between peak volumes of these detected components and the samples’ toxicities were analyzed by the orthogonal projections to latent structure-regression analysis, the correlation analysis and the multiple regression analysis. An ion of m/z 286.9436 was found as a possible monoisotopic ion of the added toxicant. A molecular formula of the ion was determined by its accurate mass and natural isotopic pattern. The determined molecular formula was searched in an advanced mass spectral database. The database suggested that the found toxicant is triclosan (an antibacterial and antifungal agent). It was identified as triclosan by a co-chromatography using a reference standard reagent. Because a dominant toxicant was triclosan among the added five toxicants, the applicability was successfully demonstrated.