Factor analysis and experiment design in high-performance liquid chromatography : VII. Classification of 23 reversed-phase high-performance liquid chromatographic packings and identification of factors governing selectivity

Abstract

The chromatographic behaviour of 63 solutes was investigated in reversed- phase high-performance liquid chromatographic (RP-HPLC) systems with the same mobil phase and 23 different commercially available packings. The results provide a new insight into variations of selectivity with column type. The factors affecting solute selectivity in RP-HPLC systems, emerging from correspondence factor analysis (CFA), are grouped into types: hydrophobic factor and chemical and/or steric factors. The relative importance of these factors is considered. Physical and chemical properties of packings, expected to affect the solute selectivity, such as the nature of the organic ligand, carbon loading, end-capping procedure, shape of silica, monomeric or polymeric layer and compression technique, are compared. It is shown that only the three first influence the selectivity. The CFA results also permit a classification of the packings on a relative scale of “hydophobicity”. To position any ne RP-HPLC packing on this scale and to estimate its “hydrophobicity”, a test with sets of only four or five test compounds is proposed.