Th12 - Detection of fluorine anions using the liquid sampling - atmospheric pressure glow discharge / Orbitrap coupling

Fluoride detection plays a crucial role across multiple disciplines, including environmental monitoring, drinking water analysis, and nuclear forensics. In PFAS analysis, a topic of major concern in the environmental community, detection of fluoride anions can be useful for determining total F levels. Water sources within communities are commonly fluorinated for the purpose of preventing cavities, with studies showing that water fluoridation alone decreased cavity counts by 27%. However, there are dangers caused by exposure to excessive levels of fluoride with increased potential for dental and skeletal fluorosis. In nuclear forensics the detection of fluoride can be used to monitor the age of UO₂F₂ particles that are formed when highly reactive UF₆ from the enrichment process is exposed to the atmosphere, therefore allowing contamination timeframes to be monitored. Techniques such as gas chromatography – mass spectrometry (GC-MS), inductively coupled plasma – mass spectrometry (ICP-MS), molecular absorption spectroscopy (MAS), and fluorescence spectroscopy are commonly employed to identify and characterize fluoride residues in samples. These methods are successful for detecting fluoride but require lengthy sample preparation/derivatization processes, poor sensitivity, inability to perform negative ion mode MS analysis, potential for isobaric interferences, poor limits of detection, or the inability to quantify fluoride levels. To address these limitations, we propose using the liquid sampling - atmospheric pressure glow discharge / orbitrap coupling to produce spectra of fluorine anions from simple salt solutions. This application uses the high-resolution capabilities offered by the orbitrap and FTMS Booster X2T data acquisition systems to resolve isobaric interferences at resolutions of 70,000 or higher. Analysis was performed on fluoride complexes since the fluoride anion F^- falls below the orbitrap mass detection range. We produced the most simplified forms of these complexes using optimized in-source collision induced dissociation, higher energy collisional dissociation, and plasma operating conditions. Once the highest level of reduction occurred, we performed validation of the method with response curves, reproducibility assessments, and salt studies to observe the effect of different salt forms on the method’s efficiency.