Abstract: Objective To establish the determination Methods of related substances and to investigate the stabilitiy of calcipotriol raw materials. Methods High performance liquid chromatography (HPLC) was used for the determination of related substances in calcipotriol. The column was Kromasil 100-5 C18 and the column temperature was 35 ℃. The mobile phase was acetonitrile- methanol - 0.01 mol·L^-1 phosphate buffer solution (pH 6.0 ± 0.1) (20:50:30) with the flow rate of 1.0 mL·min^-1. The detection wavelength was 264 nm. Moreover, the effects of light, heat, acid, alkali and oxidation on calcipotriol were investigated. Results The resolution and reproducibility of the principal component peak and impurity peaks of calcipotriol is good. It showed a good linear relationship in the concentration range of 0.138 5~37.221 8 µg·mL^-1, and the linear equation was Y=120 000X+2 969.5, R=0.999 4. The limit of quantitation of the method was 0.14 µg·mL^-1. Destructive test Results showed that calcipotriol was sensitive to light, heat, acid, alkali and oxidation. Conclusion The method is simple, accurate, with high sensitivity, high precision and good reproducibility, which can be used for the separation and analysis of the related substances in calcipotriol raw materials. Light, heat, acid, alkali, as well as the impact of oxidation should be avoided in the process of production and storage of the calcipotriol raw materials and its preparations.

Key words: HPLC, calcipotriol, related substance, destructive test