Compound mass spectral database establishment and suspect screening of lithium-ion battery-related...

Cyclotriphosphazenes (CTPs) are widely used as multifunctional electrolyte additives in lithium-ion batteries (LIBs). However, their environmental occurrence remains largely uncharacterized due to the limitations of targeted analysis. In this study, a mass spectral database of 3003 CTPs was constructed, expanding the structural landscape considered beyond the six congeners previously reported in environmental matrices. A customized structural classification framework was further developed to map the CTP chemical space, highlighting the narrow structural scope of previously monitored organic congeners. A suspected screening list of 2716 candidates was derived based on the mass range covered by the analytical method. The list guided retrospective analysis of archived ultra-high performance liquid chromatography coupled with quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) data from 23 surface sediment samples collected in Taihu Lake, China. This approach detected 29 suspected molecular formulas, of which 10 exhibited detection frequencies (DF) exceeding 30% and were prioritized for structural elucidation. Through diagnostic fragmentation analysis, four high-priority CTPs were identified. Hexaphenoxycyclotriphosphazene (HPCTP; DF: 95.7%, CL 1) was unequivocally confirmed via reference standard comparison. Three novel analogues (C₁₄H₂₉N₈OP₃, C₁₂H₂₇F₃N₃P₃, and C₁₆H₃₆N₉P₃) were tentatively identified at CL 3, representing their first report in the environment. No records were found for these proposed structures in the CAS Registry, CompTox Chemicals Dashboard, or Inventory of Existing Chemical Substances of China. These findings provide a 2019 occurrence baseline and mass spectrometric evidence for future CTP contamination surveys, while suggesting a blind spot between industrial chemical innovation and existing environmental monitoring frameworks.