2.4. Chemical stability study
The stability of R. kordesii extract over time and the influence of temperature on the degradation of R. kordesii extract gel without and in the presence of antioxidant were investigated.Gel formulations were stored in well-closed 10 g dark glass flasks under different conditions: 5, 25 and 45 C (1 C). The amount of crude extract in samples was quantitatively determined at 3e4 months stability studies. Briefly, 1.0 ml of distilled water and 10 ml of hexane were added to 50 mg of the samples. A fraction of the hexane layer was evaporated under nitrogen, dissolved in ethanol and analyzed by HPLC with
electrochemical detection.1