Interaction of ciprofloxacin hydrochloride with sodium dodecyl sulfate in aqueous/electrolytes solution at different temperatures and compositions

Interactions of ciprofloxacin hydrochloride (CPFH) with sodium dodecyl sulfate (SDS) were investigated by conductivity measurement in H2O/electrolyte solutions (NaCl, Na2SO4 & Na3PO4) over 298.15–318.15 K temperature range (with 5 K interval) considering the human body temperature. In all cases, two critical micelle concentrations (c⁎) were observed which are increased in the presence of drug and decreased in the presence of salts enunciating the presence of interaction amongst the studied components. For (CPFH+SDS) system in the presence of salt, the c⁎ values at 303.15 K and I = 0.50 mmol·kg−1 followed the order: CNaCl > CNa2SO4 > CNa3PO4. The G01,m and ∆G02,m values are found to be negative for all systems that show that the micellization process is thermodynamically spontaneous. For (CPFH+SDS) system in water, the ∆H0m &∆S0mvalues reveal that the micellization processes is both entropy dominated in almost all cases. In the occurrence of electrolytes, ∆H0m and ∆S0m values indicate that micellization processes are both entropy & enthalpy restricted at upper temperature but it becomes totally entropy dependent at higher temperature. The higher positive ∆S0m values indicate the enhanced hydrophobic interaction in presence of salts. The enthalpy-entropy compensation was determined from the linear relationship between ∆H0m and ∆S0m values in every state. Different transfer energies as well as compensation temperature and intrinsic enthalpy were also evaluated and the behaviors were comparable to other biological system. •The interaction between SDS and CPFH drug has been studied.•The cmc of SDS enhances in the presence of CPFH while reduces in the presence of salts.•The negative values of ∆Gm0 in entire cases reveal the spontaneity of the micellization.•Micellization is both enthalpy and entropy controlled process.•Transfer energies, compensation temperature and intrinsic enthalpy were also evaluated.