Identification of non-regulated polycyclic aromatic compounds and other markers of urban pollution in road tunnel particulate matter.

A combination of silicone rubber extraction and non-target and suspect screening by gas chromatography coupled to high-resolution time-of flight mass spectrometry was used for the identification of compounds in particulate matter (PM). Tunnel PM is a proxy for local road pollution that constitutes a hazard to the urban environment and human health. The use of silicone rubber for the extraction of PM allowed the pre-concentration of a wide range of compounds for non-target analysis while minimising the effects of the sample matrix. As expected, polycyclic aromatic compounds (PACs) constituted the major group of compounds identified, but only 5 of 50 PACs identified were amongst those regularly monitored and many of them were alkylated or contained a heteroatom. Urban markers of contamination such as organophosphate flame-retardants, phthalates, benzothiazoles, musk compounds and a plasticiser were also identified. The level of confidence for the identifications was high based on accurate mass, the pattern of fragmentation and retention. The unequivocal identification of 16 compounds, from all groups, was confirmed by co-chromatography with standards and the compounds semi-quantified. Most of the PACs identified are not regularly monitored, and the hazards they pose are therefore unknown. Some of these PACs are known to be more persistent and mobile in the environment than the EPA PAH16. Copyright Â