Liquid Chromatographic Determination of Dopamine, Methyldopa, L-dopa and Tyrosine in pharmaceutical preparations using 4- Dimethylaminebenzalaldehyde as a Derivatizing Reagent

Abstract

Analytical procedure has been developed for the determination of Dopamine (DA) methyl dopa (MD) L-dopa (LD) and Tyrosine (TY) by High Performance Liquid Chromatography using 4- Dimethylaminebenzalaldehyde as precolumn derivatizing reagent, The separation was achieved from Phenomenex C – 18, 5 µm (150×4.6mm id) column when eluted isocritically with methanol-acetonitrile-water (58;3;39v/v/v with a flow rate of 1ml/min. The detection by UV was at 280 nm. The linear calibration curves were obtained within the range of 2-10 µg/ml with limit of detection within 0.065- 0.098, 0.062-0.075 and 0.081 µg/ml for each of the compound. The derivatization , separation and quantitation was repeatable with relative standard deviations (RSDs) within2.3-3.8%(n=5).The method was applied for the determination of dopamine methyldopa, L-dopa and tyrosine from pharmaceutical preparations with RSDs within2.4-4.1% (n=3) and the results agreed with labeled values. The pharmaceutical preparations were also analyzed by standard addition and recovery of analytes was calculated within 95-98% with RSD 4.1%. The pharmaceutical additives did not affect the determination.