Quaternary ammonium compounds (QACs) have raised concerns due to their widespread use in disinfectants and unknown bioaccumulation behavior. However, conventional bioaccumulation assessments are costly, time-consuming, and low-throughput, limiting their utility for screening the growing array of emerging QACs. In this study, we developed a protein affinity ultrafiltration mass spectrometry (PA-UF-MS) strategy using human serum albumin (HSA) as a molecular bait to selectively isolate bioaccumulative QACs from disinfectants. We identified 12 traditional and emerging QACs, including several silanol alkyltrimethylammonium compounds (silanol-ATMACs), with strong HSA binding affinities fold changes (FCs): 10.1-60.0. Five silanol-ATMACs (C10-C18) were further structurally elucidated by MS/MS characterization and confirmed via a hydrolysis-based transformation experiment. In silico toxicokinetic modeling and in vivo rat experiments revealed longer elimination half-lives for silanol-ATMACs compared to ATMACs, indicating their bioaccumulation potential. These silanol-ATMACs were mainly detected in medical disinfectants with a median total concentration (∑silanol-ATMAC) of 779 mg/L. While detected at modest levels in indoor dust (median: 8.04 ng/g), silanol-ATMACs exhibited elevated concentrations in human serum, comparable to those of 18 traditional QACs (medians: 10.6 and 13.9 ng/mL, respectively). Our findings demonstrate the application of PA-UF-MS for prioritizing emerging bioaccumulative contaminants and highlight the need for further toxicological evaluation and human exposure assessment of silanol-ATMACs.
Cheng et al. (Wed,) studied this question.