Characterization of the microdialysis junction interface fcr capillary electrophoresis microelectrospray ionization mass spectrometry

A capillary electrophoresis/electrospray ionization mass spectrometry (CE/ESI-MS) interface, based on an electric circuit across a microdialysis membrane surrounding a short capillary segment closely connected to the separation capillary terminus, is demonstrated to be sensitive, efficient, and rugged, A microspray type ionization emitter produces a stable electrospray at the low now rates provided by CE and thus avoids both the need for a makeup liquid now provided by liquid junction or sheath now interfaces and the subsequent dilution and reduction in sensitivity. Reproducibility studies and comparisons with CE/UV and the CE/sheath now interface with ESI-MS are presented. Additionally, postrun acidification via the microdialysis junction interface is demonstrated and shown to be capable of denaturing the holomyoglobin protein noncovalent complex while maintaining separation efficiency.