Diverse actions of added alkanols on the binding of dibucaine cation to an anionic polymer
The binding of dibucaine cation to a polyanion [poly(acrylamide 2-methylpropane sulfonate)] in the presence of various alkanols(C1C3, C5, and C7) is measured by using an electrode responsive to dibucaine cation. The binding is characteristic of cooperative interaction. The binding affinity is enhanced by added pentanol and heptanol, and is well correlated with thermodynamic activities of these alkanols. In contrast, methanol and ethanol reduce the binding affinity, which is well correlated with the free energy of transfer of dibucaine cation from water to mixed solvent. The effect of added propanol lies between the medium- and the small-chain alkanols. The significance of the present results is briefly referred to in relation with the solution state of dibucaine in a body fluid.
KeywordsDibucaine Selective electrode Anionic polymer Binding isotherm Alkanols
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