Non-Targeted Screening and Identification of Chlorination Products in Reclaimed Water

摘要

In recent years, total water demand and threats to natural water resources have driven interest in sustainable water practices, such as the reclamation and reuse of wastewater. The reclamation process can produce novel transformation products with limited structural or toxicological data. The application of high-resolution mass spectrometry and non-targeted screening techniques can be used to elucidate these unknown products of water reclamation as a step towards understanding the environmental impacts of reclaimed water usage. In this work, water obtained from wastewater treatment effluent, pre- and post- chlorination at North Carolina wastewater facilities, were examined using non-targeted analysis (NTA) approaches to identify novel products formed during the reclamation process. Concentrated water extracts were analyzed by liquid chromatography (LC) coupled to high resolution mass spectrometry (MS). Molecular features, consisting of accurate mass and chromatographic peaks resolved using MS vendor processing software, in these samples were isolated, and then filtered using a statistical data processing workflow in R. The remaining features were assigned tentative molecular formulae and searched against known compounds in the EPA's CompTox Chemistry Dashboard (https://comptox.epa.gov/dashboard). Assignments were confirmed using a semi-untargeted data-dependent MS/MS and independent targeted MS/MS characterization was carried out for compounds with no positive matches in the database. The identification of these unknown products is an important first step for future explorations of potential human exposure effects.