A quantification method for methylglyoxal oligomers and its application on 1,3,5- trimethylbenzene SOA
Other literature type
(issn: 1680-7324, eissn: 1680-7324)
Methylglyoxal is often described to form oligomeric compounds in the aqueous particle phase which might have a significant contribution to the formation of aqueous secondary organic aerosol (aqSOA). Thus-far, no suitable method for the quantification of methylglyoxal oligomers is available despite the great effort spent for structure elucidation. In the present study a simplified method was developed to quantify methylglyoxal oligomers as a sum parameter. The method is based on the thermal decomposition of oligomers into methylglyoxal monomers. Formed methylglyoxal monomers were detected using PFBHA (o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride) derivatisation and gas chromatography/mass spectrometry (GC/MS) analysis. The method development was focused on the heating time (varied between 15 and 48 hours), pH during the heating process (pH = 1 − 7), and heating temperature (50 °C, 100 °C) and optimised values for these conditional parameters are presented.
The developed method was applied to quantify methylglyoxal oligomers formed during the OH-radical oxidation of 1,3,5-TMB in the Leipziger aerosol chamber (LEAK). Oligomer formation was investigated as a function of seed particle acidity and relative humidity. A fraction of methylglyoxal oligomers of up to 8 % of the produced organic particle mass was found, highlighting the importance of those oligomers formed solely by methylglyoxal for SOA formation. Overall, the present study provides a new and suitable method for quantification of methylglyoxal oligomers in the aqueous particle phase.