SESI and ESI (Electro-Spary Ionization) have been linked since the initial development of ESI. Fenn and colleagues already noted that gas-phase species in the counterflow gas were also ionized by the spray. Still today, the routine calibration of mass spectral data relies on ubiquitous plasticizes and other contaminants (i.e. polydimethylcyclosiloxanes, phthalates) that are ionized in regular ESI via Secondary Electrospray Ionization mechanisms.
As you probably already know, current VOC MS analyzers can detect high volatile species, even when they are present in very low concentrations. For instance, in 2009 P. Spanel and D. Smith measured the concentration of ammonia, acetone, methanol, ethanol, and isoprene in human breath using Selected Ion Flow Tube Mass Spectrometry (SIFT-MS)  .