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

Abstract

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.