Determination of Gibberellin A₃ solubility in different solvents based on mathematical models, solvent effect and thermodynamic analysis

For gibberellin A₃, one of the important phytohormones, solubility parameters and characterisation are the basis of data for its isolation and purification. In this work, the solubility of GA₃ was determined in twelve pure solvents (ethanol, isopropanol, 1-butanol, n-hexane, n-heptane, trichloromethane, ethyl acetate, acetone, xylene, tetrahydrofuran, dimethylsulfoxide and acetonitrile) and three binary mixed solvents (trichloromethane + ethanol, acetonitrile + ethanol and n-hexane + ethanol) at temperatures ranging from 278.15 K to 323.15 K. The experimental results showed that the solubility of GA₃ in various solvents was positively correlated with the temperature, with better solubility in ethanol. The measured data were fitted with the modified Apelblat model, the Buchowski-Ksiazaczak λh model, the CNIBS/R-K model and the Jouyban-Acree model. Then, the solvent effect was analyzed using the KAT-LSER model, which showed that the dipole polarisation rate of the solvent had the greatest effect on the solubility of GA₃. In addition, the dissolution thermodynamic properties of GA₃ were studied with the van't-Hoff equation, concluding that the dissolution of GA₃ was an entropy-driven heat absorption process. The data obtained from this research will contribute to improve the purity of GA₃ in the recrystallisation process, and ensure its efficacy and stability, thereby playing a certain guiding role in the industrial production of GA₃.