HPLC studies of peptides. The effect of the mobile phase system in reversed-phase chromatography

Summary

The retention of four small peptides with different functionalities was investigated using various mobile phase systems, including different concentrations of an organic modifier and counterions and different pH values. The four peptides are: the dipeptide Ala-Phe, the acidic tripeptide Ala-Phe-Asp, the basic tripeptide His-Ala-Phe and the tetrapeptide His-Ala-Phe-Asp which contains both an acidic and a basic amino acid moieties. It is shown that the concentration of an organic modifier not only affects the capacity factor, but also the selectivity of separation. The four peptides have their own characteristic retention relationship in mobile phase with different pH. The presence of a certain counterion in the mobile phase also plays an important role on their retention, depending both on the nature of the counterion and the peptide. The above results had been applied to check the retention characteristic of a synthetic biologically active peptide DSIP (delta sleep-inducing peptide).