Mass transport techniques as a tool for a better understanding of the structure of l-Dopa in aqueous solutions

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• 作者：Marisa C.F. Barros^a ; ^c ; ^{marisa.barros@gmail.com} ; Ana C.F. Ribeiro^a ; ^{anacfrib@ci.uc.pt} ; Artur J.M. Valente^a ; ^{avalente@ci.uc.pt} ; Victor M.M. Lobo^a ; ^{vlobo@ci.uc.pt} ; Ana M.T.D.P.V. Cabral^b ; ^{acabral@ff.uc.pt} ; Francisco J.B. Veiga^b ; ^{fveiga@ci.uc.pt} ; Carmen Teijeiro^c ; ^{carmen.teijeiro@uah.es} ; Miguel A. Esteso^c ; ^{miguel.esteso@uah.es}
• 关键词：Parkinson disease ; Levodopa ; Diffusion coefficients ; Transport properties ; Solutions
• 刊名：International Journal of Pharmaceutics
• 出版年：2013
• 出版时间：15 April, 2013
• 年：2013
• 卷：447
• 期：1-2
• 页码：293-297
• 全文大小：302 K

文摘

Mutual diffusion coefficients, D, densities, ¦Ñ, and viscosities, ¦Ç, are reported for aqueous solutions of l-3,4-dihydroxyphenylalanine (l-Dopa) at 298.15 K and 310.15 K at concentrations from (0.00025 to 0.0075) mol dm^?3. The aim of this study is to contribute to a better understanding of the structure of these systems and the thermodynamic behaviour of l-Dopa in solution. Thus, from these experimental data it was possible to estimate some parameters, such as the hydrodynamic radius, R_h, apparent molar volumes, ?_V, and diffusion coefficients at infinitesimal concentration, D⁰, essential for a better understanding of disperse systems. From the measured diffusion coefficients, activity coefficients, ¦Ã, for aqueous l-Dopa solutions were also estimated by using Nernst-Hartley equation. The effect of the viscosity on the estimated hydrodynamic radius was also studied.