INSTRUMENTATION FOR HIGH-PERFORMANCE CAPILLARY ELECTROPHORESIS MASS-SPECTROMETRY

An automated, commercially available capillary electrophoresis (CE) instrument was modified for interfacing with electrospray ionization mass spectrometry (ESI-MS). A Beckman P/ACE 2000 CE instrument with both electrokinetic and hydrostatic sample injection capabilities and efficient temperature control of the separation conditions was selected on the basis of these characteristics for this project. Modifications to it included extension of the fluid circulation path in an interface block extension and electrical modifications due to changes in electrophoresis current measurement capabilities. The capabilities for complete computer automation, capillary temperature control and on-line UV detection were retained. The minimum capillary length was increased by 35 cm due to the extension to the electrospray ionization-mass spectrometer interface. Initial results employing a laboratory-designed liquid sheath electrospray source are presented which show that very high separation efficiencies can be routinely obtained using the modified instrumentation. Capabilities for combined CE-MS are demonstrated for peptide and protein mixtures.