The effect of sodium dodecyl sulphate on Furosemide - A cardiovascular drug in water-methanol at different temperature

Different kinds of interactions have been critically assessed in order to understand the effect of methanol (MeOH) on sodium dodecyl sulphate (SDS) containing different concentrations of Furosemide with the help of densimetric and conductometric methods. A number of physico-chemical parameters viz, apparent molar volume, apparent molar adiabatic compressibility, standard enthalpy of micellization, standard entropy of micellization and standard free energy of micellization have been calculated from experimentally measured density, velocity of sound and critical micelle concentration (CMC). The CMC has been calculated from conductivity studies. The behaviour of these parameters suggests hydrophobic hydration of the surfactant molecules in a pre-micellar region and their cooperative self-association in a micellar region. The application of the Lumry-Rajender enthalpy-entropy compensation model to the present thermodynamic parameters has also been done to calculate compensation temperature T-c, which lies in the range 270-300 K suggesting solvent induced synergistic behaviour. The plot of apparent molar volume (phi(v)) vs. (SDS) at different concentrations of Furosemide in 8.0 mol% aqueous solution of MeOH at 303 K is shown in Fig. (A) which clearly indicates the dominance of electrostatic interaction in the pre-micellar region. The data were found to be in qualitative accordance indicating the existence of intermolecular hydrophobic as well electrostatic interactions between the surfactant, MeOH and drug. (C) 2013 Published by Elsevier B.V.