Figure 2.

Solubility of theophylline at 25 °C, expressed as its mole fraction, x_T, in binary solvents comprising water and five different organic solvents in varying compositions. On the ordinate, $x_2^{*}$ represents the mole fractions of organic solvent in solute-free binary solutions. The values of Theophylline solubility in aqueous methanolic solutions published by Cárdenas et al. [85] were marked with grey crosses and are anhydrous. Additionally, monohydrate and anhydrate theophylline solubilities measured by Liu et al. [86] were plotted as open diamonds and triangles.