Solubility of drugs in aqueous solutions. Part 5. Thermodynamic consistency test for the solubility data.
This paper is devoted to the verification of the quality of experimental data regarding the solubility of sparingly soluble solids, such as drugs, environmentally important substances, etc. in mixed solvents. A thermodynamic consistency test based on the Gibbs-Duhem equation for ternary mixtures is suggested. This test has the form of an equation, which connects the solubilities of the solid, and the activity coefficients of the constituents of the solute-free mixed solvent in two mixed solvents of close compositions. The experimental data regarding the solubility of sparingly soluble substances can be verified with the suggested test if accurate data for the activity coefficients of the constituents of the solute-free mixed solvent are available. The test was applied to a number of systems representing the solubilities of sparingly soluble substances in mixed solvents. First, the test was scrutinized for four nonaqueous systems for which accurate solubility data were available. Second, the suggested test was applied to a number of systems representing experimental data regarding the solubility of sparingly soluble substances in aqueous mixed solvents.
Ruckenstein
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Department of Chemical and Biological Engineering, State University of New York at Buffalo, Amherst, NY 14260, USA. feaeliru@acsu.buffalo.edu
Shulgin
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D000873:Anthracenes / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003510:Cyclohexanes / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D008722:Methods; D009281:Naphthalenes / Q000737:chemistry; D020005:Propanols / Q000737:chemistry; D012995:Solubility / Q000187:drug effects*; D012996:Solutions / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water
D000873:Anthracenes; D003510:Cyclohexanes; D009281:Naphthalenes; D020005:Propanols; D012996:Solutions; D014867:Water; D000431:Ethanol; C007229:decalin; C034020:anthracene