Characterizing disinfection byproduct precursors through organic matter fractionation and correlation analysis using nontargeted screening analysis with Orbitrap mass spectrometry.

Disinfection byproducts (DBPs) are formed from a wide range of dissolved organic matter (DOM) precursors during water chlorination. Since the molecular characteristics of DBPs are complex and understudied, this study proposes a novel method to investigate DBP precursors by partially removing DOM using different dosages of styrene-divinyl benzene polymer (PPL) sorbent. Nontargeted screening analysis revealed that increasing PPL doses reduced the intensity of DOM features, resulting in differences in the intensity of the remaining precursors. Following chlorination, the remaining precursors reacted with chlorine to produce various DBP features. More than half of the CHO and CHON features observed had high correlation coefficients (>0.95) with either CHOCl or CHONCl features. Features with high correlations (751 of 1372 CHO and 364 of 635 CHON features) were considered to be DBP precursors. The weighted average molecular characteristics of these precursors showed higher molecular weights, greater unsaturation, and lower oxidation levels than average CHO and CHON features. Trihalomethane precursors also shared these characteristics. Additionally, PPL solvent preferentially removed the molecules exhibiting these characteristics. In summary, combining partial removal using PPL sorbents and correlation analysis was demonstrated to be effective for investigating DBP precursors.