Abstract
This paper investigates the hydrolysis kinetics of levodopa methyl ester in 0.05–1.5 M HCl between 37 and 75°C. An isocratic HPLC assay was developed for simultaneous determination of levodopa methyl ester and levodopa in the hydrolysate of levodopa methyl ester. A series of hydrolysis rate constants were obtained and the effects of hydrogen ion concentration and temperature on the reaction were evaluated. It was found that pH was a key factor at low temperature, but that when the temperature was raised, temperature became in turn the most influent factor on the hydrolysis. From the measured pseudo-first order reaction rate constants, the activation energy for levodopa methyl ester hydrolysis in 0.5, 1.0 and 1.5 M HCl were calculated to be 71.24, 74.32 and 76.57 kJ mol−1, respectively.
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Revised: 24 May and 15 August 2005
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Wang, J., Zhou, Y. & Fang, Y.Z. Studies of the Rate Constant of Levodopa Methyl Ester Hydrolysis by LC. Chroma 62, 423–428 (2005). https://doi.org/10.1365/s10337-005-0643-3
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DOI: https://doi.org/10.1365/s10337-005-0643-3