Performance of micellar mobile phases in reversed-phase chromatography for the analysis of pharmaceuticals containing beta-blockers and other antihypertensive drugs.

A rapid and simple reversed-phase micellar liquid chromatographic procedure for the simultaneous determination of the beta-blockers atenolol, metoprolol and oxprenolol, the diuretics amiloride, bendroflumethiazide, chlorthalidone and hydrochlorothiazide and the vasodilator hydralazine in pharmaceuticals, is proposed. An interpretive optimization procedure, which uses the chromatographic data for only five mobile phases, was applied to select a suitable micellar mobile phase. A comparative study was also made of the performance of micellar and aqueous-organic mobile phases in the analysis of pharmaceuticals that combine beta-blockers and diuretics. The determination of all the drugs could be made with a micellar mobile phase of 0.15 mol l-1 sodium dodecyl sulfate and 7% propanol in 0.01 mol l-1 phosphate buffer at pH 3, with retention times below 20 min, whereas two different aqueous-organic mobile phases were needed to make the same analyses.