Collection, speciation and aerosol modelling for volatile organic compounds

Volatile organic compounds (VOCs) are collected on the integrated organic gas and particle sampler (IOGAPS) to measure particle loss and collection efficiency. Particle loss increases with increasing flow rate while collection efficiency is a function of alkane volatility. Unresolved complex mixtures (UCMs) are then analyzed and quantified using the novel technique supersonic molecular beam gas chromatography/mass spectrometry (SMB-GC/MS), to develop accurate inputs in modelling the formation of secondary organic aerosol (SOA). Alkanes were segregated by carbon number (NC), number of double bond equivalents (NDBE), and chemical structure. With the most explicit compositional knowledge to date, these mixtures were modelled for their affinity towards formation of SOA. Unsaturated alkanes formed the most and relatively equal amounts of aerosol based on their degree of unsaturation while branched species formed the least. Increasing specificity in chemical structure led to increased computational demands while only general structural motifs were needed to form an accurate picture of aerosol formation.