Proton Transfer Reaction-Mass Spectrometry measurements of propylene glycol and diethylene glycol: preliminary results

Atmospheric volatile organic compounds (VOCs) are precursors of fine particulate matter anground-level ozone, both of which threaten the public health and are regulated by the U.S. EPA.. Due to the decrease in emissions from traditional transportation vehicles and power plants in the last four decades, volatile chemical products (VCPs) have become an emerging contributor to VOC emissions in urban atmosphere. These VCPs are typically found in household products as inactive ingredients, including cleaning agents, aerosol sprays, personal/hygienic care products, printer ink, pesticides, etc. Once these products are used, the VCPs volatilize and participate in reactions that form ground-level ozone and fine particulate matter. Despite their prevalence in our daily lives, these VCPs and their contribution to VOC emissions remain understudied and uncharacterized. This study aims to develop analytical methods for measuring and quantifying two VCPs using a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS). PTR-ToF-MS can provide real time VOC concentration measurements in ambient air. The quantification of VCPs and their mass analogues will allow for their detection in these ambient air samples. We focus on characterizing measurements of propylene glycol and diethylene glycol, which are commonly found in VCPs and have some of the highest chemical production volumes. We will present the preliminary results for their instrument sensitivities, fragmentation pathways, potential interferences, and humidity dependencies. We will discuss how altering various instrument parameters can improve these sensitivities and explore the optimal conditions for the atmospheric measurements of these species using PTR-ToF-MS