The atmospheric oxidation of monoterpenes leads to the formation of secondary organic aerosol (SOA). While numerous works have been carried out in the past to characterise SOA at a molecular level, the structural elucidation of SOA compounds remains challenging owing to the lack of authentic standard compounds. In this work, the structures of α-pinene originating dimeric esters in SOA with m/z 357 (C17 H25 O8- ) and m/z 367 (C19 H27 O7- ) were characterised using UPLC/ ESI(-)IMS-TOFMS2 (ultra-performance liquid chromatography coupled to ion mobility spectrometry tandem time-of-flight mass spectrometry). The measured collision cross-section (ΩN2 ) values were compared to theoretically calculated ΩN2 values. Selected product ions of dimeric compounds and the authentic standard compounds of product ions were subjected to CO2-IMS-TOFMS for more detailed structural characterisation. Our results were consistent with previously reported subunits of the m/z 357 (terpenylic acid and cis-pinic acid), and the m/z 367 (10-hydroxy-cis-pinonic acid and cis-pinic acid) ions. The measured and calculated ΩN2 values of m/z 367 ions further support the conclusion of earlier structural characterisation; however, the structure of the m/z 357 ion remains vague and requires further characterisation studies with a synthesised reference compound.
CITATION STYLE
Iinuma, Y., Ramasamy, S., Sato, K., Kołodziejczyk, A., & Szmigielski, R. (2021). Structural characterisation of dimeric esters in α-pinene secondary organic aerosol using n2 and co2 ion mobility mass spectrometry. Atmosphere, 12(1), 1–15. https://doi.org/10.3390/atmos12010017
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