Design and performance of a low-flow capillary electrophoresis-electrospray-mass spectrometry interface using an emitter with dual beveled edge

A low-flow electrophoresis-mass spectrometry (CE-MS) interface has been developed for interfacing capillary zone electrophoresis (CZE) with electrospray- ionization-mass spectrometry (ESI-MS). The interface consists of two parallel capillary columns (a separation column and a makeup column), and an emitter with a dual beveled edge. While maintaining a relatively low optimum flow rate, the dual-beveled-edge ESI emitter allows the use of a tip with larger orifice. Therefore, this interface is less prone to column blocking in comparison with a flat tip. Primarily attributed to low sample dilution and smaller initial droplet, the interface showed better sensitivity than a conventional sheath liquid interface. Furthermore, the interface was found to be more resistant to the presence of nonvolatile salts. By using 40 mM borate and 20 mM alpha-cyclodextrin (alpha-CD) as the running buffer, four major forms of gangliosides were detected by CE-MS.