A NEW HIGH-PERFORMANCE INTERFACE FOR CAPILLARY ELECTROPHORESIS ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

A novel capillary electrophoresis electrospray ionization mass spectro metry (CE/ESI-MS) interface has been developed based upon an alternati ve means of establishing electrical contact at the CE capillary termin us. In this design, the terminus of the CE separation capillary and a short ESI emitter capillary are connected and sheathed by polysulphone micro-dialysis tubing. The electrical connection, to close the CE cir cuit and simultaneously establish the electrospray voltage, is provide d outside the membrane via an electrode in a small liquid reservoir. I n contrast to the sheath flow and liquid junction interfaces, the flow rate of liquid to the ESI source consists of the CE eluent and is not increased. The use of a 'micro-spray' type emitter produces a stable electrospray at the very low flow rates typical of CE, providing a hig hly sensitive, efficient interface. Post-separation acidification of a nalytes via the dialysis junction is also demonstrated.