Calculation of the amino acid hydrophilicity index for retention of peptides separation in a normal-phase LC

Abstract

It was reported in a previous paper that the separation of peptides took place in normal-phase liquid chromatography on amide, diol and silica columns. In this study, the contribution of individual amino acid residues to the retention of peptides was evaluated in order to clarify the mechanism of peptide separation. This paper lists the "hydrophilicity retention coefficients". The retentions of 121 peptides were measured through normal-phase liquid chromatography on the amide, diol and silica columns using an acetonitrile-water mixed solution containing 0.2% trifluoroacetic acid + 0.2% triethylamine as the mobile phase in a linear gradient elution system. For the silica column, the best-fit hydrophilicity retention coefficients could be calculated by a linear-regression analysis. For the amide and diol columns, the best-fit hydrophilicity retention coefficients could be calculated by a non-linear regression analysis. A set of the hydrophilicity retention coefficients on each column successfully explained the contribution degree of retention on each column.