Recent applications of mass spectrometry in the analysis of transformation products of emerging contaminants in PM_2.5

Ambient pollution correlated to fine particulate matter (PM2.5) is a worldwide environmental issue as it is highly associated with human health and eco-environmental safety. A significant part regarding the toxicity of PM2.5 is attributed to its bonded contaminants. Appreciable efforts have been performed to study the occurrence, exposure, and toxicological properties of chemicals of emerging concerns in PM2.5. Recent works indicated a broad environmental transformation of emerging contaminants in the atmospheric environment and highlighted the significance of PM2.5 bonded transformation products, which may exhibit higher environmental concentrations and toxicities compared to their parent compounds. Among these studies, mass spectrometry has been widely applied for the analysis of transformation products of emerging contaminants in PM2.5 on the aspects of suspect/non-target screening, structure elucidation, concentration profiling, and toxicity determination. This review describes key mass spectrometry-based analytical strategies and applications for determining transformation products in PM2.5 and presents outlooks for their analysis.