... ions on the basis of mass-to-charge ratios,281 HPLC for Pharmaceutical Scientists, Edited by Yuri Kazakevich and Rosario LoBruttoCopyright © 2007 by John Wiley & Sons, Inc.low-polarity ... the most widely used systems for analysis of large bio-molecules. For a continuous ion source, the ions can be stored for a shortperiod of time and pulsed out for analysis. In the case of ESI, ... structures of analytes. For basic compounds (i.e., amines), apositive ion mode can be used to form a protonated or cationized molecule. For acidic compounds, a deprotonated molecule is formed in the negative...