Molecular Characterization of Alkyl Nitrates in Atmospheric Aerosols by Ion Mobility Mass Spectrometry

Xuan Zhang, Haofei Zhang, Wen Xu, Geoffrey S. Tyndall, John J. Orlando, John T. Jayne, Douglas R. Worsnop, Manjula R. Canagaratna
2019 Atmospheric Measurement Techniques Discussions  
<p><strong>Abstract.</strong> We demonstrate the capability of the Ion Mobility Mass Spectrometry (IMS-MS) for molecular characterization of reactive and short-lived alkyl nitrates (ANs) in atmospheric aerosols. We show significantly enhanced production of ion adducts from a selection of alkyl nitrates by clustering with inorganic anions such as chloride and nitrate during negative electrospray, a special chemical ionization mechanism in the condensed phase. This approach enables the detection
more » ... bles the detection of ANs that have low tendency to form molecular ions on their own by electrospray ionization. Molecular identity of each AN adduct is well constrained by the developed collision cross section vs. mass to charge ratio correlation, which provides a two-dimensional separation of the &amp;ndash;ONO<sub>2</sub> containing compounds on the basis of their molecular size and geometry. Structural information of AN molecules is further probed by the identification of characteristic fragments produced from the collision induced dissociation of parent AN adducts. Application of the IMS-MS technique is exemplified by the identification of hydroxy nitrates in secondary organic aerosols produced from isoprene photochemistry.</p>
doi:10.5194/amt-2019-184 fatcat:7ml37jqj7rd7bjnl6p7upzafxm