Measurements for the solid solubilities of antipyrine, 4-aminoantipyrine and 4-dimethylaminoantipyrine in supercritical carbon dioxide

The solid solubilities of three active pharmaceutical ingredients (APIs) of antipyrine, 4-aminoantipyrine and 4-dimethylaminoantipyrine in supercritical carbon dioxide were measured by a semi-flow apparatus. The experiments were taken at 308.2, 318.2 and 328.2 K. The pressure range was from 10 to 22 MPa. These experimental results were correlated by the semi-empirical models of Mendez–Santiago–Teja and Chrastil. A solution model was also employed to fit the measured data. The average absolute relative deviation in solid solubility from semi-empirical models was 4–6%, and that from the solution model was 5–8%. The measured data satisfied the self-consistency test, and the parameters in the semi-empirical models are feasible for data extrapolation.