All measurements were compared to a USP reference standard of Cimetidine, obtained from the U.S. Cimetidine was obtained commercially from the Aldrich Chemical Company and concentration measurements were generally made by UV-vis spectrophotometry, unless samples had very low solubility in which case the analysis was performed by high pressure liquid chromatography (HPLC). The solubility of Cimetidine in a range of pure and mixed solvents is presented in. there are no solid solutions present, then = 1 and
Where terms in square brackets represent concentrations.Īssuming that the solid phase is pure, i.e. The solubility product K sp is defined by: Solid – Liquid equilibria is represented in Aspen Properties 2004 by the solubility product function, located in the Chemistry folder and defined as follows:įor the equilibrium reaction: Solid ⇔ Dissolved Solid Numerous Excel templates are available for data analysis and design calculations, based on the NRTL-SAC model. The template is distributed with an Excel interface to simplify the data regression process and is suitable for non-expert users of Aspen Properties.
The Aspen Properties implementation of the NRLT-SAC method is available as a template *.aprbkp file to license holders of Aspen Properties or Aspen Plus release 12.1 or above, by contacting Aspen's support centre or regional sales offices. The solvent parameters and binary interaction values used in this example are given in Tables 2 and 13. The parameter tables are likely to change as new equilibrium data and solvents are added to improve its accuracy and functionality. The NRTL-SAC model was first published in 2004 and is still being developed by the authors. Acetylsalicylic acid is used as a convenient basis for new drug molecules in the Aspen template, because it includes data for all of the necessary thermodynamic methods to satisfy the simulation engine and avoid run time errors. The first step in building a solubility model in Aspen Properties is to define the solute as a new component in two instances, one for the solid phase and the other for the liquid phase. Peter Crafts, in Computer Aided Chemical Engineering, 2007 2.6.1 Using the NRTL-SAC model in Aspen Properties