High-sensitive protein analysis by FESI-CE-MALDI-MS.

Capillary zone electrophoresis (CZE) and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) are two techniques highly suitable for the separation and detection of intact proteins. Herein, based on the use of a recently introduced iontophoretic fraction collection interface for the coupling of CE and MALDI-MS, the potential of the combination of both techniques for the analysis of intact proteins is assessed. To further provide a bioanalytical platform with high-sensitivity capabilities, field-enhanced sample injection is integrated as on online preconcentration strategy upstream from the electrokinetic separation. Under optimized conditions, more than 3200- and 4800-fold improvement, respectively in terms of peak height and peak area, as well as LODs ranging from 5 to 10 nM, has been achieved.