RESUMO
A rapid spectrophotometric procedure for the determination of isoprenaline salts, levodopa, dopamine hydrochloride, and dobutamine hydrochloride, either in the drug substances or in pharmaceutical formulations, is described. The method is based on the development of orange, red, or violet products with sodium metaperiodate in an aqueous alcoholic medium. The reaction is suggested to proceed via oxidative cyclization of the catecholamine to form an aminochrome. The wavelengths of maximum absorption range from 465 to 520 nm. The structure of the cyclization product was confirmed by ultraviolet, infrared, and nuclear magnetic resonance spectroscopy and microanalysis data.
Assuntos
Catecolaminas/análise , Epinefrina/análise , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Ácido Periódico , Pós , Soluções , Solventes , Espectrofotometria Infravermelho , Espectrofotometria Ultravioleta , ComprimidosRESUMO
A simple and accurate spectrophotometric method is described for the determination of epinephrine (EP), norepinephrine (NE) and their bitartrate salts. The method is based on the development of a red colour (lambda(max) 490 nm) with sodium periodate in aqueous alcoholic medium. The colour is stable for at least 1 hr. The molar reacting ratio of EP or NE to periodate is 1:2. The proposed method is particularly suitable for routine analysis of EP and NE injections. The interference due to the sodium metabisulphite normally used as antioxidant can be overcome by addition of acetone. Results for analysis of bulk drugs and injections agree well with those of official methods.
