High-performance liquid chromatography of amino acids, peptides and proteins : XLVI. Selectivity effects of peptidic positional isomers and oligomers separated by reversed-phase high-performance liquid chromatography

Abstract

The reversed-phase chromatographic retention behaviour of selected peptide homologues on an octadecylsilica stationary phase has been investigated in isocratic elution experiments using low pH binary mobile phases composed of water and methanol or water and acetonitrile. Good correlation for linear relationships between the logarithmic capacity factor, ln k′, and the surface tension, γ, of the eluent were obtained from the experimental data over the organic solvent content range up to ψs 0.6. In accord with predictions based on solvophobic considerations, linearity was also observed in the plots of ln k′ versus residue number, nres, of the peptide oligomers over a wide range of ψs values. The retention behaviour of peptide positional isomers has also been examined with aqueous acetonitrile mobile phases and the selectivity differences which arise between isomer pairs discussed in terms of specific solvation processes.