Spacer performance in the cationic isotachophoresis of proteins

Performance of narrow range ampholytes and a discrete spacer mixture is evaluated for improved protein separations by cationic isotachophoresis. A spacer mixture containing 22 cations is developed and relative step heights of components are presented. Different ampholytes and the discrete spacer give unique results for test mixtures of model proteins. While no spacer mixture can be universally recommended, discrete spacers offer the possibility of optimizing separations based on component selection. An example of optimizing a separation of five model proteins is presented.