APPLICATION OF MICRODIALYSIS FOR ONLINE COUPLING OF CAPILLARY ISOELECTRIC-FOCUSING WITH ELECTROSPRAY MASS-SPECTROMETRY ON A MAGNETIC-SECTORINSTRUMENT

The on-line coupling of capillary isoelectric focusing (CIEF) with ele ctrospray mass spectrometry (MS) by means of microdialysis (MD) for ap plication to three carbonic anhydrase isozymes is described. The dialy sis device consisted of a donor and an acceptor compartment that were separated by a flat membrane, and served to clear the CIEF effluent th at was directed to the mass spectrometer from ampholytes that were nec essary for the establishment of a pH gradient in the IEF capillary. In addition to single-ion monitoring and full-scan experiments, a positi on-and time-resolved ion counting (PATRIC) detector was used in the st atic array mode. For CIEF/MD/MS of unknown proteins the minimum amount of analyte required for the analysis was estimated to be in the mid-f emtomole range using full-scan MS data acquisition. (C) 1998 John Wile y & Sons, Ltd.