Direct non-target analysis of dissolved organic matter and disinfection by-products in drinking water with nano-LC-FT-ICR-MS

Abstract

Non-target analysis of drinking water often requires solid-phase extraction (SPE) as a sample pretreatment to enrich the dissolved organic matter (DOM) and remove salts. However, highly polar and mobile DOM fractions are extracted with only low yield. This limits the deeper understanding of drinking water treatment processes, such as disinfection, resulting in an incomplete picture of the formation of disinfection by-products (DBPs). In this study, we present a nano-LC-FT-ICR-MS method to directly analyze DOM and DBPs in drinking water, shedding light on the previously inaccessible polar fraction of DOM and DBPs. With only 1 μL injection volume, 19 856 and 21 095 DOM compounds were detected across nano-LC elution profiles in samples with and without SPE pretreatment, respectively. Three times as many highly polar DOM compounds were detected in the non-extracted (2269 compounds) as compared to the SPE processed sample (817 compounds). Likewise, 15% more nitrogenous DOM compounds were detected without extraction (8716 compounds) compared to the SPE processed sample (7556 compounds). After disinfection, 2136 and 2225 non-halogenated nitrogenous DBPs were detected in samples from two drinking water treatment plants. The successful direct analysis of dissolved organics in drinking water using nano-LC-FT-ICR-MS enables a more complete picture of DOM and DBPs in drinking water treatment processes.