Application of a column classification method in a selectivity study involving caffeine and its related impurities

In this paper a comparative study of RP-LC column selectivity as obtained by the classification method of the Katholieke Universiteit Leuven (KUL method) and the selectivity obtained in real pharmaceutical analysis is reported. The separation of caffeine and its respective impurities was performed on 35 brands of stationary phases in accordance with the method prescribed in the European Pharmacopoeia (Ph. Eur.). Evaluation concerned the probability of appropriate column selection related to the selection of two different stationary phases for reference. The comparison was based on the traditional correlation of the F-values with the results of a system suitability test (SST) for the columns, as well as an application of a factor analysis (FA) for graphical visualisation of the differences and similarities between the stationary phases established against four test chromatographic parameters provided by the KUL method and the retention parameters of the compounds of interest describing the column performance test. The obtained results confirmed that the class of the stationary phases selected according to the chromatographic test parameters gave comparable separation for caffeine and its impurities.