Comparative study of test methods for reversed-phase columns for high-performance liquid chromatography

Column selection in reversed-phase liquid chromatography (RPLC) is still not a straightforward process. A number of tests to characterise and classify RPLC columns have been suggested. Several tests are already applied in laboratory practice, while others are under development. The results of the various tests, however, are not always qualified to describe the properties of columns for RPLC. In this study different tests for RPLC-columns are studied and compared, viz. the Engelhardt, Tanaka, Galushko and Walters tests. The column descriptors hydrophobicity and silanol activity are investigated in particular. The tests are studied using approximately 20 silica, alumina and polymer based C8- and C18-columns. Hydrophobicity data from the tests generally were good and interchangeable between the tests resulting in a column classification that is independent of the applied test. It appears that buffering of the eluent is mandatory for adequate testing of column silanol activity. In contrast with the high-quality hydrophobicity data, the silanol activity results of the various tests differ significantly. As a consequence column classification with respect to silanol activity depends considerably on the applied test method.