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 (3 σ ) 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.