Characterization and formation of high molecular weight disinfection byproducts in drinking water: an integrated SEC-DAD-FLD-OCD approach

Abstract

High molecular weight disinfection byproducts (HMW DBPs, MW > 500 Da) significantly contribute to drinking water toxicity yet remain inadequately characterized. This study provides a comprehensive perspective on HMW DBPs through a systematically optimized size exclusion chromatography with diode array detection, fluorescence detection and organic carbon (SEC-DAD-FLD-OCD) approach, enabling a holistic mapping of their multi-dimensional evolution. Results showed chlorination induced oxidative fragmentation of humic substances (HS, 1.2–5 kDa) into building blocks (BB, 0.45–1.2 kDa) and low molecular weight substances (LMWS, < 0.45 kDa). In real drinking water samples, distinct protein-like fluorescence indicated nitrogenous or microbial precursors absent in simulated samples. Parallel factor analysis (PARAFAC) of SEC-DAD chromatograms identified four components: C1 (100–800 Da) correlated with fast-forming LMWS/BB; C2 (800–1200 Da) as BB intermediates; C3 (1.2–4 kDa) and C4 (2–5 kDa) representing persistent HS precursors. Two-dimensional correlation spectroscopy (2D-COS) revealed the relative formation rates followed the order: fulvic-like acids > LMWS > 0 > humic-like acids > BB. Integrated chromatographic peak areas demonstrated rapid HS degradation (52.7% reduction) and LMWS accumulation (117% increase), alongside significant protein-like material accumulation (450%) after 72 h chlorination. This work established SEC-DAD-FLD-OCD as a robust platform for characterizing HMW DBPs, supporting improved water treatment strategies.

Graphical abstract

Keywords

High molecular weight / Disinfection byproducts / Drinking water / SEC / Formation

Highlight

	● An optimized SEC-DAD-FLD-OCD approach for characterizing HMW DBPs was developed.
	● Chlorination oxidatively fragmented HS into BB and LMWS.
	● Distinct protein-like fluorescence was found in real drinking water samples.
	● Four components were identified by SEC-DAD-PARAFAC modeling.
	● Relative formation rates: fulvic-like acids > LMWS > 0 > humic-like acids > BB.

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