Passive air sampling and nontargeted analysis for screening POP-like chemicals in the atmosphere: Opportunities and challenges
Xianming Zhang, Amandeep Saini, Chunyan Hao, Tom Harner
Abstract
Hundreds of thousands of organic chemicals are present as a complex mixture in the atmosphere. While well-known contaminants such as persistent organic pollutants (POPs) have been studied and characterized, environmental risks and impacts from lesser-known POP-like chemicals are not yet understood. In this study, we conducted a literature review and a pilot study to explore the opportunities and challenges of using passive air samplers and nontargeted analysis for improving our understanding of contaminant mixtures in air. In our approach, nontargeted analysis using gas chromatography coupled with atmospheric pressure chemical ionization and quadrupole time-of-flight mass spectrometry analysis for chlorinated and brominated semi-volatile compounds in passive air samplers deployed with different source contributions using gas chromatography coupled with atmospheric pressure chemical ionization and quadrupole time-of-flight mass spectrometry. Data from the instrumental analysis were processed and analyzed via suspect screening, mass defect and isotope filterings, and in silico fragment predictions. Some lesser-known monocyclic aromatic compounds containing chlorine or bromine were tentatively identified. Chemical space analysis based on predicted physicochemical properties suggests some of the prioritized compounds have POP-like properties such as long-range transport and bioaccumulation potential and deserve more detailed assessment of their contributions to the overall risk of atmospheric chemical mixtures. Information gained from this study will guide further explorations of complex chemical mixtures in air using passive air samplers and nontargeted analysis.