The α-dicarbonyl compounds glyoxal (GLY, CH(O)CHO) and methylglyoxal (MGLY, CH3C(O)CHO)) are ubiquitous intermediates formed in the photooxidation of a wide range of anthropogenic and biogenic volatile organic compounds (VOCs). The global glyoxal source from land ranges from between 50 and 108 Tg yr-1. However, only about half of this terrestrial source is currently accounted for. Recent measurements demonstrate the large uncertainties in the amount of glyoxal formed from isoprene photooxidation. In addition, a-dicarbonyls are known secondary organic aerosol (SOA) precursors and can potentially form a significant fraction of the missing global SOA in atmospheric models. However, the exact role of such dicarbonyl compunds is still not well established. One of the main reasons for such uncertainties over the role of these compounds as products in different photochemical atmospheric processes and in particle formation and growth is the difficulty in measuring them, as they are very reactive and ‘sticky’ (i.e. difficult to handle experimentally).

In order to elucidate both the chemical and instrumental issues related to the quantitative measurement of these compounds, a short experimental chamber campaign in EUPHORE was proposed where a number of techniques (both optical and spectrometric) has been intercompared.


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