High-performance liquid chromatographic determination of amantadine in urine after micelle-mediated pre-column derivatization with 1-fluoro-2,4-dinitrobenzene.

Cationic micelles have been used for the derivatization of the anti-Parkinson drug amantadine with the chromophore 1-fluoro-2,4-dinitrobenzene in urine. In the presence of 90 mM cetyltrimethylammonium bromide (CTAB), the conversion of amantadine into its derivative is complete within 4 min at 60 degrees C and pH 11. Such a short reaction time allows a fully automated pre-column derivatization of amantadine in an on-line combination with reversed-phase high-performance liquid chromatography. This cannot be attained when using purely aqueous derivatization mixtures because then the reaction takes some 20 min at the same temperature. Without the use of an internal standard, the repeatability of the automated determination at the 0.5 microgram ml-1 level is ca. 6%, whilst the detection limit is 75 ng ml-1 (S/N = 3). The present study clearly demonstrates that micellar systems can be beneficially used for the on-line precolumn derivatization of amines in urine.