Highly robust stainless steel tips as micro electro spray emitters

Tapered stainless steel spray tips for sheathless microelectrospray ionization (muESI) have been developed. The fabrication procedure for the tapered stainless steel tips was optimized using an electropolishing technique followed by removal of the burr. Using the tip as the muESI emitter, a stable ESI spray was obtained at a flow rate of 20 nL/min. The sensitivity of the muESI system was almost two orders greater than that of the conventional ion spray system. The tip was highly stable, and was successfully used for over 1000 h. Moreover, these stainless steel tips were suitable for use with sheathless capillary electrophoresis/mass spectrometry (CE/MS) and capillary liquid chromatography/mass spectrometry (LC/MS) for routine analysis in proteomic and pharmaceutical applications. Copyright (C) 2002 John Wiley Sons, Ltd.