RESUMO
A sensitive and selective colorimetric assay has been developed for the determination of dihydralazine. The method is based on the interaction of dihydralazine with an ethanolic solution of 2-hydroxy-1-naphthaldehyde to yield a water-insoluble yellow product, 1,4-bis[(2-hydroxy-1-naphthyl)methylene hydrazine]phthazine. This colour can be quantified spectrophotometrically at 420 nm. The calibration curve was linear between 0.4 and 8 micrograms ml-1 of dihydralazine. The molar absorptivity at 420 nm is 24000 l mol-1 cm-1. The method was successfully applied to the determination of dihydralazine in mixtures containing other drugs (reserpine, hydrochlorothiazide, oxprenolol, xanthinol, rutoside, chlorthalidone and bietaserpine).
Assuntos
Química Farmacêutica/métodos , Di-Hidralazina/análise , Naftalenos/química , Di-Hidralazina/análogos & derivados , Di-Hidralazina/química , Etanol/química , Concentração de Íons de Hidrogênio , Concentração Osmolar , Espectrofotometria UltravioletaRESUMO
A new extraction-spectrophotometric method for the determination of hydralazine, based on its reaction with 2-hydroxy-1-naphthaldehyde at 25 degrees C, is described. The calibration curve was linear between 0.4 and 6 mg/mL of hydralazine. The molar absorbtivity of the product at 408 nm is 40,900 L.mol-1.cm-1. The method described was applied to the analysis of hydralazine in pharmaceutical preparations containing reserpine, hydrochlorothiazide, bendrofluorthiazine, propranolol, and other substances. The agreement with the U.S.P. XXI method was satisfactory for tablets and injections, but not for pellets.