Solubility of fenamate drugs in supercritical carbon dioxide by using a semi-flow apparatus with a continuous solvent-washing step in the depressurization line

New experimental solubility data of niflumic and tolfenamic acid in supercritical CO2 have been measured at temperatures between 313 and 343 K and pressures of 16-40 MPa. The use of a continuous solvent-washing step in the depressurization line avoids the solubility data to be underestimated, which may occur when a discontinuous solvent-washing step is used. This was confirmed by comparison with previous literature work that obtained values up to 57-105% smaller than those reported here. Results were fitted with fourteen different correlation methods and showed that the Chrastil-modified approaches provided the best results. The best fit was obtained with the Adachi-Lu model for niflumic acid (AARD%=5.8) and the del Valle-Aguilera model for tolfenamic acid (AARD% = 5.5) while the original Chrastil model provided only slightly higher deviations. Correlation parameters of the Chrastil, Kumar-Johnston and Bartle models allowed the CO2-solute solvation and drug sublimation enthalpies to be estimated. (C) 2015 Elsevier B.V. All rights reserved.