Application of high-performance liquid chromatography in the kinetic study of α-methyldopa

摘要: Abstract A reversed-phase high-performance liquid chromatographic (HPLC) method was developed for use in kinetic studies of α-methylopa (MD). The proposed further applied to the determination MD sustained release capsules and presence its industrial impurity, 3-O-methylmethyldopa (MMD). detector response linear range 0.5–200 μg/ml MMD. Replicate injections both compounds gave relative standard deviations 0.54 0.62%, respectively. mean recoveries from raw material were 99.71–100.2% 99.5–100. 1%, HPLC used study kinetics degradation as a function temperature, pH, humidity exposure UV radiation. followed first-order relationship, agreement with Arrhenius theory, all incubation media studied. activation energy 93.36–105.92 kJ 1 mol −1 . disappearance pseudo-first-order buffered distilled water over experimental pH 2–13. Above 7.96, base-catalysed dominates, second-order rate constant 190.72 ± 14.51 day Below PH is independent 6.65 (± 1.07) · 10 −4 at 25°C. Degradation or ground beads not enhanced by 80% radiation 21 days.