RESUMEN
A reversed-phage high-performance liquid chromatographic procedure with UV detection at 280 mm is presented for the determination of 6-hydroxydopa, tyrosine, 3-O-methyldopa, and other trace amino acid impurities in levodopa preparations. The method is fast and sufficiently sensitive to determine trace impurities at 0.1% of the levodopa concentration with a relative standard deviation of 4-6%. The trace impurities can be estimated at less than or equal to 0.01%.
Asunto(s)
Aminoácidos/análisis , Levodopa/análisis , Cromatografía Líquida de Alta Presión , Contaminación de MedicamentosRESUMEN
A reversed-phase high-performance liquid chromatographic procedure with UV detection at 280 nm is presented for levodopa determination in pharmaceutical preparations. The method is fast and specific for levodopa in the presence of its most likely impurities and degradation products.
Asunto(s)
Levodopa/análisis , Aminoácidos/análisis , Cromatografía Líquida de Alta Presión , Métodos , Comprimidos , Xantinas/análisisRESUMEN
An isothermal chromatographic (GC) method employing an SE-30 column and flame-ionization detection has been developed for the simultaneous assay of methyl, ethyl, propyl, and butyl 4-hydroxybenzoates and 4-hydroxybenzoic acid in liquid antacid formulations. The method, which uses a silica column chromatographic cleanup step prior to GC, is specific for the compounds with respect to possible degradation products, impurities, and excipients.
Asunto(s)
Antiácidos/análisis , Hidroxibenzoatos/análisis , Cromatografía de Gases/métodos , Estabilidad de Medicamentos , Conservadores Farmacéuticos/análisisRESUMEN
An impurity present in all commercial guaifenesin-containing dosage forms examined was isolated and identified as 2-(2-methoxyphenoxy) 1,3-propanediol (VI). The eluant of a previously developed stability-indicating liquid chromatographic method for phenylephrine hydrochloride (I), phenylpropanolamine hydrochloride (II), and guaifenesin (III) was modified to yield a better separation between phenylpropanolamine and the impurity. The method was expanded to include sodium benzoate (IV), a preservative found in some liquid formulations.
Asunto(s)
Guaifenesina/análisis , Benzoatos/análisis , Ácido Benzoico , Cápsulas , Cromatografía de Gases , Cromatografía Líquida de Alta Presión , Contaminación de Medicamentos , Estabilidad de Medicamentos , Fenilefrina/análisis , Fenilpropanolamina/análisisRESUMEN
Reversed-phase high-performance liquid chromatography with differential pulse polarographic detection at a dropping mercury electrode provides a high degree of specificity for stability-indicating assays of drugs in animal feed. The selectivity of this detection system is demonstrated in the assay of diacetolol in feed at concentrations down to 50 microgram/g.