Thermodynamic Properties of Matrine in Ethanol

In this paper, the enthalpies of dissolution of matrine in ethanol (EtOH) were measured using a RD496-2000 Calvet microcalorimeter at 309.65 K under atmospheric pressure. The differential enthalpy (Δ_dif H _m) and molar enthalpy (Δ_sol H _m) of dissolution of matrine in ethanol were determined. And the relationship between heat and the amount of solute was also established. Based on the thermodynamic and kinetic knowledge, the corresponding kinetic equation that described the dissolution process was determined to be \fracdadt=2.36×10^-4(1-a)^1.09{\frac{{\rm d}\alpha}{{\rm d}t}=2.36\times 10^{-4}(1-\alpha )^{1.09}} . Moreover, the half-life, t _1/2 = 48.89 min, Δ_sol H _m = −12.40 kJ · mol⁻¹, Δ_sol S _m = −354.7 J · mol⁻¹ · K⁻¹, and Δ _sol G _m =  97.43  kJ · mol⁻¹ of the dissolution process were also obtained. The results show that this work not only provides a simple method for the determination of the half-life for a drug but also offers a theoretical reference for the clinical application of matrine.