Pulsed Desorption Electrospray Ionization Mass Spectrometry
Pittcon Conference and Expo / McCormick Place, Chicago, IL, USA
Biological samples, Imaging, Instrumentation, Mass Spectrometry
Desorption electrospray ionization mass spectrometry (DESI-MS) is a powerful method for generating ions at ambient conditions without the need for sample preparation or pretreatment. In DESI-MS, a continuous stream of charged microdroplets impacts a surface containing a sample (cDESI-MS). Upon impact, analyte molecules are extracted from the surface into secondary microdroplets, from which gas-phase ions are eventually formed. We have developed a pulsed DESI-MS source (pDESI-MS) that demonstrates higher sensitivity. In addition, the pDESI-MS source is designed so that desorption only occurs during ion accumulation time (IT) of an ion trap mass spectrometer, increasing the sampling efficiency (SE) closer to 100%. This capability is particularly advantageous for high-resolution instruments such as the LTQOrbitrap hybrid mass spectrometers that require significant transient acquisition times after ion accumulation (e.g. for IT = 0.5 s and m/z-resolution = 100,000, and scan time = ~2.3 s, the SE increases by a factor of ~5 from 22% to 100%). In addition, pulsing the primary microdroplet spray reduces the total volume of deposited solvent per m/z scan, which minimizes the ‘washing effect’ reported for cDESI-MS on surfaces such as glass or Teflon®. The ability to control the amount of deposited solvent by varying the pulse widths offer the potential for improved spatial resolution in imaging mode. These results demonstrate that pDESI-MS offers the potential to transform current approaches for implementing spray-based ambient ionization techniques in chemical analysis and imaging.
Comi, Troy J. and Perry, Richard H., "Pulsed Desorption Electrospray Ionization Mass Spectrometry" (2014). Chemistry and Physics Faculty Proceedings, Presentations, Speeches, Lectures. 209.