Investigation of intermolecular interactions of anionic surfactant SDS and rutin: A physico-chemical approach for pharmaceutical application

The thermodynamic, acoustic and H-1 NMR studies between rutin trihydrate and sodium dodecyl sulfate (SDS) were carried out to investigate the flavonoid-surfactant interactions. Four different hydro-ethanolic concentrations (aqueous, 30% v/v, 70% v/v and absolute ethanol) at five different temperatures (20-40 degrees C with a difference of 5 degrees C) were selected for the study. The critical micelle concentration (CMC) values were calculated using conductivity (kappa) parameter to further compute the change in standard enthalpy (Delta H-m(o)), standard entropy (Delta S-m(o)) and standard Gibbs free energy (Delta G(m)(o)) of micellization. Other thermoacoustic parameters, i.e., apparent molar volume (phi v) and apparent molar compressibility (phi k) were calculated employing the density (rho) and ultrasonic sound velocity (l) studies. In addition to these, the relative viscosity (eta r) for all the concentrations was also determined to understand the flow properties. The introduction of surfactant into the system increased the diffusion properties of rutin trihydrate. The acoustic studies highlighted the existence of hydrophobic and electrostatic interactions within the system. The intermolecular interactions between SDS and rutin trihydrate were also established from the chemical shifts observed for H-1 NMR spectra in DMSO d(6). The obtained parameters play a vital role in optimizing the thermo-physically stable concentration which might prove useful in formulation development. (C) 2021 Elsevier B.V. All rights reserved.