Development of new targeted and non-targeted analysis methods for residential airborne contaminants

Indoor environments are a major contributor to human exposure to volatile and semi-volatile organic compounds (VOCs and SVOCs), many of which originate from building materials, consumer products and occupant activities. However, comprehensive characterization of residential airborne contaminants remains challenging due to the broad chemical diversity, low ambient concentrations, and limited availability of rapid and mobile sampling approaches.

In this study, we revisited and validated legacy sampling methods involving personal pumps and sorbent tubes, and analyzed the samples with newly developed data analysis approaches. To maximize our chemical space, multiple sorbents (low-cost XAD-2, polyurethane foam and DNPH-treated silica gel) were selected. Following 150-minute sampling periods, the analytes were desorbed through solvent extraction and analyzed by offline liquid chromatography–high resolution mass spectrometry (LC–HRMS).

For targeted analysis, our parallel reaction monitoring (PRM) method enabled sensitive and accurate quantification for common sVOCs such as phthalates, organophosphate esters (OPEs) and benzophenones. Key performance metrics demonstrated method detection limits (MDLs) as low as sub-ng/m³, good precision (RSD < 10%), and 70–110% recoveries for most analytes. In parallel, a non-targeted analysis workflow was established to identify compounds beyond the predefined list. Our methods combined mass spectral library searches with newly identified diagnostic fragmentation evidence used as “molecular fingerprints”. In particular, neutral loss scanning and data-dependent acquisition (DDA) were incorporated simultaneously to enhance characterization of volatile aldehydes following DNPH derivatization. Lastly, a major analytical challenge we encountered was the high background levels of selected sVOCs, due to their ubiquitous presence in environments., Here we discuss our strategies to mitigate this issue including blank preparations (solvent, extraction and field blanks) and instrumental background reduction approaches through data acquisition settings and mobile phase compositions.