Investigation into reversed phase chromatography peptide separation systems part III: Establishing a column characterisation database.

The Peptide RPC Column Characterisation Protocol was applied to 38 stationary phases, varying in ligand chemistry, base silica, end capping and pore size, which are suitable for the analysis of peptides. The protocol at low and intermediate pH is based on measuring retention time differences between peptides of different functionality to calculate selectivity delta values. The characterisation was designed to explore increases / decreases in positive or negative charge (deamidation), steric effect (i.e. racemisation / switch in amino acid order), oxidation and addition / removal of aromatic moieties. The necessity of developing a characterisation protocol specifically for peptide analysis was highlighted by the fact that the small molecule databases (Snyder's Hydrophobic Subtraction Model and the extended Tanaka protocol) failed to correlate with the Peptide RPC Column Characterisation Protocol. Principal Component Analysis was used to demonstrate that the protocol could be used to identify columns with similar or dissimilar chromatographic selectivity for the purpose of selectivity back-up or method development columns respectively. This was validated using peptide fragments derived from the tryptic digest of bovine insulin and carbonic anhydrase. It was also demonstrated that the presence of positively charged functional groups on the stationary phase was advantageous as it yielded very different chromatographic selectivity and improved peak shape.