Detection of Gaseous Dimethylamine Using Vocus Proton-Transfer Reaction Time-of-Flight Mass Spectrometry
Gaseous amines, due to acid-base nucleation, significantly enhance new particle formation in the atmosphere. Sources of amines include industry, livestock, degradation of ocean organics, biomass burning, and many others. Highly time-resolved measurements of gaseous amines are analytically challenging because sample pretreatment is often required, they have only a trace presence in the atmosphere (commonly in the range of pptV), and they are easily lost to instrumentation inlets and other surfaces. With proper parameter tunings, the Vocus PTR-TOF is able to overcome these analytical challenges, while still measuring many other VOCs in the environment.
Prof. Lin WANG’s group in Fudan University has conducted pioneering research into the role of atmospheric amines in both urban and remote contexts. Their dataset acquired during their first field campaign using the first Vocus 2R PTR-TOF in China was published in the journal Atmospheric Environment. The Vocus 2R PTR-TOF, deployed at a suburban site in Northern China in December 2018, was optimized for measuring dimethylamine, which is believed to strongly enhance the formation of new aerosols in the ambient environment. The market-leading Vocus 2R PTR-TOF delivered comparable sensitivity factor to Ethanol CIMS, a fast instrument response time, a detection limit of ~1.5 pptV, and essentially no humidity dependence, all of which are critical to catch the rapid changing profile of atmospheric amines often present in the concentration range of tens of pptV or lower.
Strong of diurnal variations of C2-amines (dimethylamine and ethylamine) were clearly observed during the WangDu campaign, hinting at highly reactive physiochemical processes with a substantial involvement of C2-amines. Meanwhile, air samples were collected and analyzed by offline GC-MS for an inter-comparison. In the case of benzene and toluene, agreement between two techniques was established. More inter-comparison results are expected to appear soon in a second publication by the same authors. They are also planning to extend the list of atmospheric amines to be quantified by the Vocus PTR-TOF.