温湿度对VC片剂变色反应的影响

Effects of Temperature and Humidity on Discoloration of Vitamin C Tablets

报道了在密封避光条件下 ,采用恒温恒湿加速试验法 ,研究温度与湿度对VC片剂变色反应动力学的影响 .VC片剂表面颜色变化用漫反射光谱监测 ,在相对湿度 (RH)低于临界相对湿度 (CRH)时 ,表观变色反应速度常数kc 与温度和相对湿度间具有定量关系 :kc=k′exp( -Ea/T)exp(m′RH) ,式中k′、m′为常数 ,表观变色反应活化能Ea 为 98.36kJ·mol-1.在相同实验温度、湿度范围 ,VC片剂表面反射率 (R)与其溶液透光率 (T0 )间亦存在定量关系 :log( 1 0 0T0 - 1 ) =L +slogR 。

The effects of temperature and humidity on discoloration kinetics of Vitamin C tablets were studied by accelerated test under isothermal and constant humidity conditions.The changes of color of the Vitamin C tablets were monitored by Diffuse Reflectance Spectroscopy (DRS).When relative humidity (RH) is less than the critical relative humidity (CRH),the apparent rate constant of discoloration of the Vitamin C tablets is k c=k′ exp( - Ea/T-1 )exp(m′RH),where k′and m′ are constants,and the activation eergy E a is 98 36kJ/mol.Under the same experimental conditions,it was found that the reflective ratio R of the Vitamin C tablets is related with the transparency T 0 of this tablets's olution:log(100/ T 0-1)=L+s log R ,where L and s are all constants.$$$$