Step 4

We have established that your compound is a hydrophobic zwitterion. Below is an example of a separation of a similar compound. This example can be used a starting condition in your method development.

Hydrophobic zwitterionic compounds can be analyzed on any Primesep column in reverse mode. Different Primesep columns give different selectivity and degree of retention. For zwitterions with carboxylic acid, lowering the pH of the mobile phase leads to suppression of ionization of carboxylic acid and creating an excess of positive charge which will work against retention with anion-exchange columns and will increase retention on cation-exchange columns. Although hydrophobicity is similar for all Primesep columns, the resulting retention is different due to additional electrostatic attraction or repulsion.