Capillary electrophoresis - electrospray ionization mass spectrometry, CE-ESI-MS – University of Copenhagen


Capillary electrophoresis - electrospray ionization mass spectrometry, CE-ESI-MS

Capillary electrophoresis (CE) has many advantages compared to other separation techniques with regard to separation performance, analysis speed and low consumption of sample and separation buffer. For a typical CE separation less than 50 nL of the sample is consumed from the sample vial.

The standard detector for CE instrumentation is UV absorbance but UV detection in CE has a very low sensitivity as a result of the small injection volumes combined with the short optical path length of the UV detection cell. The lack of sensitivity has been one of the main drawbacks of CE to date.

Being able to use mass spectrometry (MS) as the detector will solve the sensitivity problem of CE since MS works as a concentration dependent detector not influenced by the flow rate of sample delivered to the detector. Coupling CE to ESI-MS is however not an easy task since the interface should provide both electric contact for the CE separation and the electrospray ionization (ESI) as well as provide a stable spray at low flow rates.

Recently we developed a new and robust CE-ESI-MS interface that provide stable electric contact for CE separations as well stable electrospray and MS signal even in the nano flow range.

CE-ME interface

This research project pursues:

  • Characterisation and optimization of the novel CE-ESI-MS interface
  • Two-dimensional (2D) separations of complex bio-samples by coupling the CE-ESI-MS with HPLC. Precise and repeated injections of the eluent from the HPLC into the CE-MS separation capillary can be automated by a programmable power supply. Since the separation method in CE are orthogonal the HPLC, analytes not fully separated by HPLC may then be separated in the second dimension thereby increasing the overall peak capacity. The separations in the given CE-MS setup can be achieved extremely fast and each peak eluting from the HPLC may therefore be probed several places.