Technology

Things you didn't know about SESI and ESI (Electro-Spray ionization)

Things you didn't know about SESI and ESI (Electro-Spray ionization)

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.

The relevant role of humidity in Secondary Electrospray Ionization (SESI)

The relevant role of humidity in Secondary Electrospray Ionization (SESI)

Rising the humidity level of the gas introduced through the sample line accelerates the charge transfer reaction rate in Secondary Electrospray Ionization (SESI). It is hypothesized that larger clusters transfer their charge more efficiently than smaller clusters or even bare ions.

The difficulty of detecting low volatility species for VOC analysis technologies

The difficulty of detecting low volatility species for VOC analysis technologies

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) [1] .

Differences between SESI and APCI ambient ionization techniques

Differences between SESI and APCI ambient ionization techniques

In the equilibrium, both Secondary Electro Spray Ionization (SESI) and Atmospheric Pressure Chemical Ionization (APCI) generate charged water clusters that act as charging agents. What are the differences bewtween these ionization techniques?