Hyphenation of fast gas chromatography to photo-ionisation mass spectrometry for comprehensive analysis of climate and health-relevant organic aerosol components from dynamic combustion processes

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Components of organic aerosol are known to have complex impacts on human health and climate. The investigation of dynamic changes in combustion processes, such as in log wood combustion or internal combustion engines at different loads, requires measurement techniques of appropriate time resolution to follow qualitative and quantitative changes of complex organic emissions. Single-photon (SPI) and resonance-enhanced multi-photon ionisation (REMPI) as soft ionisation techniques combined with time-of-flight mass spectrometry (TOFMS) fulfil these requirements. However, solely based on molecular mass no definite identifications of compounds can be carried out. The hyphenation of fast gas chromatography with a novel Peltier-modulator to SPI/REMPI-TOFMS can overcome this issue and separate isobaric species, while compounds of equal retention time but different molecular mass are separated by different peaks in the mass spectra. Hence, single volatile to semi-volatile compounds can be analysed with sufficient time resolution during dynamic combustion processes. The focus will be on alkylated polycyclic aromatic hydrocarbons (PAH) and phenolic species, which both can be analysed by SPI- and REMPI-TOFMS with low limits of detection. Alkylated PAHs, which are mainly emitted by combustion processes using fossil fuels, have recently moved towards the centre stage of PAH research, because it has been shown that they can exhibit significantly different toxicological properties than their unsubstituted basic structures. Phenolic species are known to be emitted by mainly biomass combustion and are discussed as mitigating toxicological effects of other compounds of the combustion aerosol. In addition to the toxicological assessment of emissions, the data can be valuable to predict possible conversion processes in ambient air, e.g. ozone formation potential or the formation of secondary organic aerosol. Finally, the Fast-GC-SPI/REMPI setup can be further utilised in an additional hyphenation to a thermal-optical carbon analyser to investigate particle-bound organic species , covering the full volatility range of organic aerosol emission.