Novel chlorinated disinfection byproducts from tannic acid: nontargeted identification, formation pathways, and computationally predicted toxicity

Tannic acid is ubiquitously present in various simulated and real water sources and in wastewater. Various chlorinated disinfection byproducts (Cl-DBPs) are generated via reactions with tannic acid during disinfection with chlorine. We used high-resolution mass spectrometry in combination with our self-developed halogen extraction code to selectively identify Cl-DBPs. Our strategy enabled successful detection of 35 Cl-DBP formulas formed by chlorination of tannic acid, and we identified 26 of these structures. The structures of 17 novel Cl-DBPs are firstly reported here. The reaction pathways of these Cl-DBPs were tentatively proposed. These Cl-DBPs are likely to be generated during chlorination at various chlorine doses, from 0.0 to 10.0 mg-Cl/L, and 14 of the 26 Cl-DBPs were detected in simulated drinking water, which implies a relatively high probability of incidence. Quantitative structure-activity relationship toxicity analyses predicted that most of these Cl-DBPs would exhibit much higher acute toxicity than the common DBPs trichloromethane and monochloroacetic acid and that some of these compounds would induce developmental toxicity and be mutagenic, which further emphasizes that these Cl-DBPs should raise concerns. This study broadens our understanding of the Cl-DBPs formed from tannic acid and should prompt wider application of our analytical strategy in environmental matrices.