Column Classification/Characterisation of Strong Cation Exchange Phases for the Liquid Chromatographic Analysis of Small Molecular Weight Bases

A simple, rapid and robust protocol for the characterisation of strong cation exchange columns for the analysis of small molecular weight bases is described. A range of ten different phases were characterised, and the resultant selectivity and retention factors analysed using Principal Component Analysis. The score plots for the first and second principal components described 83% of the variability within the dataset. Score plots highlighted the large chromatographic differences observed between the phases, the validity of which was established using a larger range of bases. All the strong cation exchange materials demonstrated a synergistic mixed mode (i.e. ion exchange and hydrophobic) retention mechanism. Principal Component Analysis also highlighted the potential difficulty in locating suitable strong cation exchange “ back - up ” columns for the analysis of small molecular weight bases in that the characterised columns all displayed very different selectivities. The robustness of the protocol was confirmed by a factorial design experiment.