Solubility modeling of Levofloxactin hemihydrate in supercritical CO2 green solvent using Soave-Redlich-Kwong EoS and density-based models

Abstract

Solubility of solid components such pharmaceuticals in green solvents like supercritical carbon dioxide (SC-CO2) should be measured in order to develop the supercritical fluid (SCF) technology for their reduction size. This is a crucial procedure in assessing the required processes in this type of technology. A statistical technique was applied to measure the Levofloxactin hemihydrate (LH) drug solubility. The measurements of drug solubility at various operating conditions were performed by UV-vis investigation. Present study, for the first time, investigates LH solubility in the SC-CO2 at pressures and temperatures ranging from 120-270 bar and 308-338 K. The obtained results showed that the LH solubility is in (3.91-20.01)×10-7 range. Both temperature and pressure affected drug solubility and pressure indicated direct effect, however, in the case of temperature a cross-over point was detected. Modeling was also performed by SRK EoS and eight density-based models. All equations have presented acceptable agreements with solubility data. Among density-based models, Sung-Shim with AARD=%5.65 was better one. Eventually, the enthalpies of the LH/SC-CO2 system were obtained by Bartle et al., KJ and Chrastil correlations.