Capillary zone electrophoresis with electrospray condensation particle counting detection.

A new sheath flow microelectrospray interface combines capillary electrophoretic separation of protein standards with condensation particle counting detection. Protein separations are performed in both coated and uncoated fused-silica columns. The electrospray needle utilizes a sheath flow rate between 0 and a few microL/min. Typically, the makeup flow is equal to or less than the electroosmotic flow from the separation capillary; thus there is minimal dilution while still providing pH adjustment and solid electrical contact with the separation capillary. While there are some inherent restrictions to a condensation particle counting detector, the microelectrospray needle performs well and has direct application to electrospray mass spectrometry.