O. Trapp, E. W. Pearce, J. R. Kimmel, O. K. Yoon, I. A. Zuleta and R. N. Zare, “A Soft On-Column Metal Coating Procedure for Robust Sheathless Electrospray Emitters Used in Capillary Electrophoresis/Mass Spectrometry,” Electrophoresis 26, 1358-1365 (2005).