Microelectrospray interface with coaxial sheath flow for high-resolution capillary electrophoresis/mass spectrometry separation.

We have fabricated a coaxial sheath liquid flow microelectrospray ionization (microESI) interface for capillary electrophoresis coupled with mass spectrometry (CE/MS). The ESI interface, which features a reduced probe diameter (130 microm i.d. x 174 microm o.d.) with a nebulizer-free format, can relatively easily electrospray a large amount of make-up sheath liquid (5-10 microL/min) over the long term (more than 80 runs) with a high degree of stability. The interface also provides higher separation qualities and improved detection sensitivities compared with a conventional ion spray (IS) interface.