AQESHOW - Abstract

Abstract Information :

Emerging contaminants, particularly Per- and polyfluoroalkyl substances (PFAS), pose significant environmental and health risks due to their prevalence in manufacturing and detectable toxicity. Despite their widespread detection in environments and human serum, understanding PFAS behavior and degradation remains limited by traditional analytical methods lacking temporal resolution. Time-of-flight chemical ionization mass spectrometry (ToF-CIMS) presents an efficient solution, capable of high-resolution, sub-part-per-trillion (ppt) level measurements of atmospherically relevant PFAS. Recent validations of ToF-CIMS underscore its potential for real-time PFAS detection and in-depth environmental monitoring, highlighting the urgent need for research and regulatory action to address the public health concerns associated with PFAS exposure. Here, we report measurements of key atmospheric PFAS classes, particularly perfluoroalkyl carboxylic acids (PFCAs) and fluorotelomer alcohols (FTOHs), utilizing our newly developed AIM chemical ionization reactor. Operating at a medium pressure of 50 mbar, the AIM reactor is optimized for adduct-ion chemistry, ensuring minimal fragmentation. It employs VUV lamps as ionization sources, capable of generating both positive and negative reagent ions. We focus on establishing a strong calibration approach, analyzing the sensitivity in diverse sampling scenarios, and assessing the effectiveness of different reagent ions. PFAS samples were prepared by first diluting a standard solution to a specific volume, then evaporating this solution in a controlled volume of clean air, which was achieved by passing it through a heated tube. Utilizing iodide as the ion-adduct, we have performed an extensive analysis of sensitivity for two fluorotelomer alcohols (FTOHs) and eleven perfluoroalkyl carboxylic acids (PFCAs). The measured sensitivities were in the range of 1-10 cps/ppt, with the biggest of the PFCAs having the lowest sensitivities, while LODs were as low as 1 ppt. In addition, using three different solvents (methanol, ethyl acetate and dichloromethane), effects of the used solvent were evaluated with sensitivities being within 20% between all solvents. Our finding demonstrates the AIM reactor’s efficacy in ambient environmental analysis, extending its capabilities to a spectrum of emerging pollutants beyond conventional volatile organic compounds (VOCs) and inorganic acids at sub-ppt concentrations. The reactor's enhanced selectivity, facilitated by the application of various reagent ions, significantly reinforces its value for environmental monitoring initiatives.