Microdialysis membrane-based cathodic cell

Zhou and Johnston [55] reported protein characterization by capillary isoelectric focussing (CIEF) on-hne coupled to RPLC-MS. Direct coupling of CIEF to ESl-MS is limited by interferences by the ampholytes. Inserting RPLC in-between can help removing these interferences. CIEF is performed in combination with a microdialysis membrane-based cathodic cell to remove the ampholyte and to collect protein fractions by stop-and-go CIEF prior to transfer to a 5><0.3-pm-ID C,8 trapping colunm and RPLC separation on a 50><0.3-pm-ID C4 column. The separation is performed using an acetonitrile-water gradient (0.1% acetic acid). ESI-MS is performed on a quadrupole-TOF hybrid (Q-TOF) instrument. 

Figure 5.1 shows a schematic of the microdialysis membrane-based cathodic cell for CIEF. The cathodic cell is built around a PEEK tee (Valeo, Houston, TX, USA). One collinear port is coimected to a 55-cm CIEF capillary (50 pm i.d., 375 pm o.d.). The opposite collinear port is connected to a 20-cm fused-silica capillary that leads to a waste vial. The perpendicular... 

Figure 5.1 Diagram of the microdialysis membrane-based cathodic cell. Reprinted with permission from F. Zhou and M. Johnston, Analytical Chemistry, 76, 2734—2740, Copyright 2004 American Chemical Society...

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