Achieving 50% Ionization Efficiency in Subambient Pressure Ionization with Nanoelectrospray Ioan Marginean, Jason S. Page, Aleksey V. Tolmachev, Keqi Tang, and Richard D. Smith* Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States Anal. Chem., 2010, 82 (22), pp 9344-9349