COLORIMETRIC DETERMINATION OF GUANETHIDINE SULFATE, GUANOXAN SULFATE, AND AMILORIDE HYDROCHLORIDE IN TABLETS

Simple colorimetric methods for the determination of guanethidine sulfate (I), guanoxan sulfate (II), and amiloride hydrochloride (III) are described. These methods are based on the reaction of each drug with 9,10-phenanthraquinone in the presence of either 1-naphthol, resorcinol, or 3,5-dihydroxybenzoic acid with 3 M potassium hydroxide aqueous solution. Green to blue colors were obtained with maximum absorptions at 648, 590, and 615 nm, respectively. Conditions for maximum color development with respect to reagent concentrations, reaction times, color stabilities, and the suitable concentration of potassium hydroxide solution were studied. Concentration ranges for I are 12-22, 4-24, and 6-14 mug/ml; for II they are 4-14, 4-16, and 4-16 mug/ml; and for III they are 10-24 and 14-30 mug/ml. With an application of this proposed method, the above three drugs in tablets were estimated within a relative standard deviation of less than 2%. (C) 1994 Academic Press, Inc.