Quantitative relationship between the retention of peptides on a reversed-phase alumina support and their physicochemical parameters

Chromatography of amino acids and short peptides. New advances

The newest results in the application of various chromatographic methods (gas-liquid chromatography, liquid chromatographic techniques, electrically driven systems) for the separation and quantitative determination of amino acids and short peptides in pure state and in complicated matrices are compiled. The results are concisely described and critically evaluated. The future trends of the chromatographic analysis of amino acids and short peptides are briefly discussed.

Chemometric evaluation of relationships between retention and physicochemical parameters in terms of multidimensional liquid chromatography of peptides

Statistical evaluation of relationships between chromatographic retention and physicochemical descriptors of peptides was performed. The relationships describing retention were derived for a set of 98 structurally diversified peptides chromatographed on HPLC columns using acetonitrile and water with the addition of 0.1% trifluoroacetic acid as the mobile phase. It was found with the aid of multivariate principal component analysis (PCA) and factor analysis that the retention contributions of the amino acids comprising the individual peptide and the physicochemical parameters describing the bulkiness properties of peptides have the greatest influence on the retention of peptides, independent of the stationary phase used. Retention data were determined on six physicochemically different HPLC columns with the aid of experiments performed with various gradient times and column temperatures. Moreover, PCA permitted differentiation of the RP-HPLC columns used in terms of their similarities and dissimilarities in respect of peptide separations.

Behavior of peptides and computer-assisted optimization of peptides separations in a normal-phase thin-layer chromatography system with and without the addition of ionic liquid in the eluent

The addition of an ionic liquid into the mobile phase appeared to be useful in optimization of chromatographic separation of peptides. Different behavior of peptides in thin-layer chromatography (TLC) was observed after addition of 1-ethyl-3-methylimidazolium tetra fluoroborate to the eluent in comparison to the system without the ionic liquid. Nonlinear dependence of the retention coefficient, R(M), of peptides on the volume percentage of acetonitrile in the eluent was found in normal-phase TLC with and without immidazolium tetra fluoroborate in the mobile phase. In general, R(M) increased with increasing concentration of acetonitrile. In TLC systems without the ionic liquid, R(M) can be described well with a quadratic function. On the other hand, in a TLC system with an ionic liquid as the additive to the mobile phase, the retention behavior is better described with a third-degree polynomial function. The potential usefulness of ionic liquids for optimization of separation of peptides was demonstrated. Optimization of the separation conditions was supported by a commercially available computer program.