CHARACTERIZATION OF STATIONARY PHASES USED IN REVERSED-PHASE AND HYDROPHOBIC INTERACTION CHROMATOGRAPHY

Nine prepacked columns used in reversed-phase and in hydrophobic interaction chromatography were studied. The stationary phases investigated were widely different with respect not only to the type and surface concentration of the ligands but also to the material and geometry of the support and the extent of previous usage. In order to characterize the columns, measurements were made under isocratic conditions with three different homologous series. From the retention behaviour of the components some descriptors were calculated according to four characterization methods described in the literature. On the basis of the intercept of the In k-methanol content relationship, a rough estimate of the hydrophobicity of the stationary phases could be given. More realistic results were obtained with the polar-apolar characterization suggested by Hetem and co-workers, but some discrepancies were also found. The use of the isopotential eluent composition as a descriptor resulted in the most acceptable characterization. Two-dimensional mapping along the parameters of the slope-intercept relationships summarizes the results obtained with the other techniques.