Simplified capillary electrophoresis nanospray sheath-flow interface for high efficiency and sensitive peptide analysis

We report a simple nanospray sheath-flow interface for capillary electrophoresis. This interface relies on electrokinetic flow to drive both the separation and the electrospray; no mechanical pump is used for the sheath flow. This system was interfaced with an LCQ mass spectrometer. The best results were observed with a 2-mu m diameter emitter tip and a 1-mm spacing between the separation capillary tip and the emitter tip. Under these conditions, mass detection limits (3 sigma) of 100 amol were obtained for insulin receptor fragment 1142-1153. The separation efficiency exceeded 200,000 plates for this compound. The relative standard deviation generated during continual infusion of a 50 mu M solution of angiotensin II was 2% for the total ion count and 3% for the extracted ion count over a 40-min period. Finally, the interface was also demonstrated for negative ion mode. Copyright (C) 2010 John Wiley & Sons, Ltd.