Diffusion coefficients of the ternary system (2-hydroxypropyl-β-cyclodextrin + caffeine + water) at T = 298.15 K

• Published in: The Journal of chemical thermodynamics 2009-12, Vol.41 (12), p.1324-1328
• Main Authors: Ribeiro, Ana C.F., Santos, Cecilia I.A.V., Lobo, Victor M.M., Cabral, Ana M.T.D.P.V., Veiga, Francisco J.B., Esteso, Miguel A.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Caffeine solutions; Complexes; Diffusion coefficient; General pharmacology; Medical sciences; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Taylor dispersion; Transport properties
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2009.06.005

Ternary mutual diffusion coefficients measured by Taylor dispersion method ( D 11, D 22, D 12, and D 21) are reported for aqueous solutions of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) + caffeine at T = 298.15 K at carrier concentrations from (0.000 to 0.010) mol · dm −3, for each solute, respectively. These diffusion coefficients have been measured having in mind a better understanding of the structure of these systems and thermodynamic behaviour of caffeine and 2-hydroxypropyl-β-cyclodextrin in solution. For example, from these data it will be possible to estimate some parameters, such as the fraction of associated species HP-β-CD ( X 1) and caffeine ( X 2) in this complex, the monomer and dimer fractions, X 2 M and X 2 D , respectively, and the limiting diffusion coefficients of the HP-β-CD, D HPBCD ∘ , of the dimers caffeine entities, D D ∘ , and of those complexes (1:1), D complex ∘ .