Comprehensive Screening of Air Pollutants using Enhanced Chromatography with High-Resolution Time-of-Flight Mass Spectrometry

An understanding of emerging particulate air pollution, such as microplastic additives as well as adsorbed pollutants, will strengthen preventative measures to protect public health. Here we demonstrate the development of a non-target method using two-dimensional gas chromatography and high-performance time of flight mass spectrometry for the annotation of known and emerging semi-volatile, and non-volatile airborne pollutants, i.e., plastic materials, which may facilitate routine chemical analysis of airborne particulate matter samples. Air samples were obtained using active samplers and quartz filters (PM2.5). Punched-out filter subsamples were placed into quartz-fritted liners and inserted into an inlet capable of both Thermal Desorption and Pyrolysis. Desorbed compounds and pyrolytic decomposition products were chromatographically separated and detected using comprehensive two-dimensional gas chromatography with high-resolution time-of-flight mass spectrometry (GCxGC-HRTOFMS). Electron Ionization (EI) data were utilized to annotate compounds through untargeted processing including peak finding and MS database searches. Additional compound characterization was facilitated with complementary chemical ionization using a multi-mode source (MMS), and formula determinations using the accurate mass of adducts, molecular ions, and fragments. The analyses resulted in the annotation of several chemical compound classes, including persistent organic pollutants. In addition, several types of plastic materials were annotated through the characterization of their pyrolytic markers. Rich, high-quality data with exceptional peak alignment between ionization modes, and improved S/N increased the number of annotated compounds. Chemical compounds annotated included terpenes, fatty acids, esters, substituted heterocyclic compounds, and numerous polymer additives. Polycyclic aromatic hydrocarbons and heteroatomic polyaromatic compounds were also characterized in these samples.