Comprehensive Analysis beyond Traditional Organophosphate Esters (OPEs) Uncovers the Prevalence of Novel OPEs and Related Compounds in River Waters

This study aims to comprehensively characterize the occurrence and potential risks of organophosphate esters (OPEs), especially the novel OPEs and related compounds present in river waters. Using high-resolution mass spectrometry, we conducted a comprehensive analysis of OPE-related compounds in water samples (n = 90) from the Chaobai River in Beijing, China. Target screening detected 16 traditional OPEs with cumulative concentrations of 0.69–1315 ng/L in spring and 1.5–1218 ng/L in autumn water samples. Suspect and nontarget screening further identified 42 novel OPEs and related compounds, including 12 organophosphate triesters, 11 organophosphate diesters, 7 organophosphonates, 8 organothiophosphate esters, and 4 others. The semiquantified concentrations of these novel compounds make up, on average, 36% of all OPE-related compounds. Thereinto, 36 novel compounds were discovered in surface water for the first time. Downstream samples exhibited more complex OPE profiles and higher concentrations compared to upstream and reservoir samples, associated with varied watershed characteristics. Hazard assessment and risk-based prioritization revealed significant environmental concerns regarding certain chlorinated OPEs and novel compounds, such as bis((5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl) methyl phosphonate P,P’-dioxide, 2-ethylhexyl hydrogen (2-ethylhexyl)phosphonate, and dihexyl hydrogen phosphate. This study underscores the importance of a comprehensive analysis in understanding OPE-related contamination and risks in surface water.