Determining Sublimation Pressure of Ibuprofen from Solubility Data in Supercritical Carbon Dioxide

Solvent effects in the calculation of the sublimation pressure of pure ibuprofen using high pressure solubility data are discussed. The solubility of ibuprofen in supercritical carbon dioxide was measured using a dynamic apparatus in the pressure between 80 and 130 bar and at three temperatures, 308.15, 313.15 and 318.15 K. With this experimental region, the mole fraction of ibuprofen in fluid phase was in the range from 0.015 × 10-3 - 3.261 × 10-3. The sublimation pressure PSub of the solid drug is considered as a parameter to be determined by regression analysis of experimental solubility data (TPy), using four equations of state along with two mixing rules. The equations of state are Redlich-Kwong (RK), Soave-Redlich-Kwong (SRK), Peng-Robinson (PR) and Pazuki and some others. Mixing rules are van der Waals-1 parameter (vdW1) and van der Waals-2 parameter (vdW2). Correlations were compared and discussed on the basis of the employed equations-of-state, mixing/combining rules, the results show that the determination of sublimation pressure using high pressure solubility data is reliable and all systems lead to very good fit results, with almost identical values of AARD (Changing from 4.71% to 17.98%).