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

• Published in: The Journal of supercritical fluids 2016-01, Vol.107, p.400-407
• Main Authors: Banchero, Mauro, Manna, Luigi
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Correlation; Drug; Empirical and semi-empirical models; Semi-flow method; Solubility
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2015.10.008

•New solubility data of niflumic and tolfenamic acid in supercritical CO2.•A continuous solvent-washing step of the depressurization line was adopted.•Comparison with literature reveals that solubility data underestimation is avoided.•Data correlation performances of fourteen empirical models were compared.•Adachi–Lu and del Valle–Aguilera models provided the best data fit. New experimental solubility data of niflumic and tolfenamic acid in supercritical CO2 have been measured at temperatures between 313 and 343K and pressures of 16–40MPa. 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.