Online Aerosol Chemical Characterization by Extractive Electrospray Ionization − Ultrahigh-Resolution Mass Spectrometry (EESI-Orbitrap)

<p>These datasets are the raw data presented in the presented work of &quot;Online Aerosol Chemical Characterization by Extractive Electrospray Ionization &minus; Ultrahigh-Resolution Mass Spectrometry (EESI-Orbitrap)&quot; in <em>Environmental Science &amp; Technology Journal</em>, doi:10.1021/acs.est.9b07090.</p> <p>Abstract:&nbsp;Current mass spectrometry techniques for the online&nbsp;measurement of organic aerosol (OA) composition are subjected to either&nbsp;thermal/ionization-induced artifacts or limited mass resolving power,&nbsp;hindering accurate molecular characterization. Here, we combined the soft&nbsp;ionization capability of extractive electrospray ionization (EESI) and the&nbsp;ultrahigh mass resolution of Orbitrap for real-time, near-molecular&nbsp;characterization of OAs. Detection limits as low as tens of ng m^&minus;3 with&nbsp;linearity up to hundreds of &mu;g m^&minus;3 at 0.2 Hz time resolution were&nbsp;observed for single- and mixed-component calibrations. The performance of the EESI-Orbitrap system was further evaluated with laboratory-generated secondary OAs (SOAs) and filter extracts of ambient particulate&nbsp;matter. The high mass accuracy and resolution (140 000 at <em>m/z</em> 200) of&nbsp;the EESI-Orbitrap system enable unambiguous identification of the&nbsp;aerosol components&rsquo; molecular composition and allow a clear separation&nbsp;between adjacent peaks, which would be significantly overlapping if a medium-resolution (20 000) mass analyzer was used.&nbsp;Furthermore, the tandem mass spectrometry (MS²) capability provides valuable insights into the compound structure. For instance,&nbsp;the MS² analysis of ambient OA samples and lab-generated biogenic SOAs points to specific SOA precursors in ambient air among a&nbsp;range of possible isomers based on fingerprint fragment ions. Overall, this newly developed and characterized EESI-Orbitrap system&nbsp;will advance our understanding of the formation and evolution of atmospheric aerosols.</p> <p>Structure of the datasets: The raw data are separated into individual file of&nbsp;excel format for the figures. Simulation data from Figure 4 can be generated using the matlab code named <em>Figure4PeakSimulation.m.</em>&nbsp;</p>