HPLC OF ANTIPHLOGISTIC ACIDS ON SILICA DYNAMICALLY MODIFIED WITH CETYLPYRIDINIUM CHLORIDE

The cetylpyridinium chloride (CPC) which contains an aromatic ring and a hydrophobic cetyl group differs in its structure from the generally used cationic counter ions. Thirteen of antiphlogistic acids and their derivatives were investigated. Silica as a stationary phase and an eluent containing CPC were used. The conclusion can be drawn that CPC functions as an ion pairing agent and its use in the aqueous eluent results in the formation of a `'dynamically modified'' silica surface. The adsorption isotherm for CPC on the bare silica also was determined. Comparative data are shown on the retention of several antiphlogistic acids with CPC and cetrimide containing aqueous eluents.