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‐µm diameter emitter tip and a 1‐mm spacing between the separation capillary tip and the emitter tip. Under these conditions, mass detection limits (3σ) 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 µM 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 © 2010 John Wiley & Sons, Ltd.