Separation and estimation of seven vasodilators using packed column supercritical fluid chromatography

This paper reports a method for an isocratic separation and simultaneous estimation of seven vasodilators: isosorbide mononitrate (ISMN), isosorbide dinitrate (ISDN), cyclandelate, nimodipine, amlodipine, pentifylline and pentoxifylline using packed column supercritical fluid chromatography (SFC). An arbitrary choice of vasodilatory compounds with respect to their chemical structures was made to examine the viability of this technique for analysis of drugs and pharmaceuticals. Elution was performed on a RP-C,, column. SFC offers several degrees of freedom: temperature, pressure and modifier concentration to attain optimum resolution and sensitivity. The effects of these parameters on retention time have been studied using methanol modified carbon dioxide. The analytes were identified and measured by UV-detection. The chromatographic points of merit have been listed. Detection limits appear to be similar to those found in liquid chromatography. Modifier concentration does generally make major changes in retention and selectivity. A full scale validation for the seven vasodilators has been attempted and the statistical quality evaluated. (C) 1998 Elsevier Science B.V. All rights reserved.