CHARACTERIZATION OF REVERSED PHASES BY CHEMOMETRIC METHODS

The characterization of stationary phases by empirically selected test solutes is compared with chemometric methods. Cluster, principal component, correspondence factor and discriminant analysis were applied to a data set consisting of capacity factors, selectivities and asymmetry factors. Commercially available RP-8 and RP-18 columns from German distributors with various specifications, and laboratory-prepared polymer-coated stationary phases were chosen. The different chemometric methods showed a uniform picture of the multi-dimensional data set. However, factor and correspondence factor analysis provide the most useful information. Factor analysis confirmed the pragmatic finding that the elution behaviour of aniline and phenol is well suited for the characterization of polar and toluene and ethylbenzene for that of hydrophobic phase properties. Correspondence factor analysis indicated similarity within some groups of the investigated stationary phases and emphasized the importance of proper selection of the test solutes. The deviation of some columns from the typical trend observed for RP-8, RP-18 or polymeric columns was detected by either of the chemometric methods and can be explained by their extreme physico-chemical properties.