Thermal Stability of Ginkgolic Acids and Thermal Decomposition Kinetics of Ginkgolic Acid C15:1

Thermal stability of ginkgolic acids and thermal decomposition kinetics ginkgolic acid C15:1 were investigated. Ginkgolic acid was heated at 70 ℃ for 30 d, a small amount of ginkgols were determined by liquid chromatography electrospray spray ionization mass spectrometry (LC-ESI-MS). The thermal decomposition behavior and kinetics of ginkgolic acid C15:1 were investigated by thermogravimetric analysis (TG) under the static air atmosphere at the heating rates of 5.0, 10.0, 15.0 and 20.0 ℃·min⁻¹. The thermogravimetric differential scanning curve of ginkgolic acid C15:1 was recorded and the thermal decomposition parameters were calculated by Ozawa-Flynn-Wall, Friedman, Šatava-Šesták and Coats-Redfern methods. The most obvious weight loss on the TG curves of ginkgolic acid C15:1 occurred in the first weight loss stage, the peak temperature was 243 ℃, and the weight loss rate was 14.37%, which was the decarboxylation reaction of ginkgolic acid C15:1. The calculated activation energy using Ozawa-Flynn-Wall and Friedman method was 67.44 kJ·mol⁻¹. The dynamic model function of ginkgolic acid C15:1 decarboxylation was Avrami-Erofeev equation, its integral form was G(α)=−ln(1−α)^1/2, and the decomposition mechanism was random nucleation and subsequent growth, and the reaction order was n=1/2. This study would provide help for the control of silver apricot acid content in ginkgo products.