Characterisation of reversed-phase liquid-chromatographic columns by chromatographic tests: Comparing column classification based on chromatographic parameters and column performance for the separation of acetylsalicylic acid and related compounds

Selection of RP-LC columns with suitable selectivity for a given analysis is difficult. For example, the European Pharmacopoeia (Ph. Eur.) and other official compendia for drug analysis only give a general description of the stationary phase in the operating procedure of a liquid chromatographic method. The need for a general test method to characterise RP-LC columns has been rising since the 1970s. A project to define a chromatographic procedure characterising RP-LC columns was started earlier. A procedure to measure test parameters was introduced and a classification of the columns, based on a minimal number of parameters, was obtained. This paper focuses on correlating the column classification with the selectivity obtained for a real separation. The separation of acetylsalicylic acid (aspirin) and related compounds was performed according to the Ph. Eur. monograph on the stationary phases previously characterised chromatographically. It was examined whether the classes of columns, determined using test parameter results, contain either suitable or unsuitable supports for the aspirin separation. The system suitability test prescribed by the Ph. Eur. in order to distinguish between suitable or unsuitable columns for this separation was also evaluated.