Design of an Active Sampler for Characterization of Total Ionic Per- and Polyfluoroalkyl Substances (PFAS) in Indoor Air

MARGOT FRANCINI, Naomi Chang, Barbara Turpin, UNC-Chapel Hill

     Abstract Number: 177
     Working Group: Chemicals of Emerging Concern in Indoor and Outdoor Aerosol: Sources, Vectors, Reactivity, and Impacts

Abstract
Per- and polyfluoroalkyl substances (PFAS) are ubiquitous indoors. Despite this, their fate and transport are not well characterized due to limitations in air sampling methodology, particularly for ionic PFAS. To address this knowledge gap, low-cost, accurate collection of gas- and particle-phase ionic PFAS is necessary. The goal of this study was to design a novel integrated air sampler that accurately measures the total concentration (particle- and gas-phase) of ionic PFAS species in indoor air, guided by evidence that quartz fiber filters (QFFs) adsorb ionic PFAS gases, in addition to collecting particles. We found that six QFFs in series effectively captured the 13 perfluoroalkyl carboxylic acids (PFCAs) we measured with <15% breakthrough when sampling indoors at 10 L min^-1 over a six-day period. Notably, results revealed that there are more ionic PFAS in the gas phase than widely recognized, in agreement with a modest number of previously reported outdoor denuder measurements. Additionally, the proportion of gas-phase breakthrough across backup QFFs relative to front filter loading varied by ionic PFAS class, suggesting that physicochemical properties have a complex influence on gas-particle interactions and filter partitioning. To further optimize sample collection, we provide a second-generation prototype sampler design and initiate consideration of alternative front filter materials with smaller (or zero) PFAS adsorption artifacts and low PFAS background values. This work aids the development of low-cost, accurate, and separate particle- and gas-phase measurements, lending critical evidence to more comprehensive human exposure assessments for ionic PFAS.