Concurrent Quantification of Emerging Chemicals of Health Concern in e-Cigarette Liquids by High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Emerging chemicals of concern (ECCs), including phthalate plasticizers, flame retardants, and phenolic compounds, are likely present in electronic nicotine delivery system (ENDS) replacement solutions (e-liquids) which are often packaged, stored in, and/or can contact with, plastic, glass, and metal materials. Developing and validating an efficient analytical method for concurrent quantification of ECCs in e-liquids are thus needed to inform evidence-based safety evaluation of ENDS products. In this study, we developed and validated a "dilute-and-shoot" method using high-performance liquid chromatography coupled with tandem mass spectrometry to simultaneously measure organophosphate flame retardants (OPFRs), phthalate plasticizers, and tetrabromobisphenol A (TBBPA) in e-liquids. We analyzed samples in positive electrospray ionization mode (ESI+) for OPFRs and phthalates and negative ESI- for TBBPA. The method has a total runtime of 10 min. The optimized procedure was able to deliver broad dynamic linearity ranges with coefficients of determination (R2) above 0.995, limits of detection ranging from 0.020 to 10 ng/mL, average accuracy within ±15%, and imprecision ≤ 15.0% for all analytes. To our knowledge, this is the first multianalysis method for measuring ECCs in e-liquid samples, and the validation results show that it is sensitive, accurate, precise, and efficient.