Liu S C, Yin G K, Ma B Z, Sun Y
School of Pharmacy, West China University of Medical Sciences, Chengdu.
Yao Xue Xue Bao. 1993;28(5):389-96.
The effect of temperature and humidity on the rate of discoloration and degradation of vitamin K3 powder was studied via accelerated test under isothermal, constant humidity and dark conditions. The photodegradation of vitamin K3 powder was studied under room temperature and constant humidity. The changes of color and concentration of vitamin K3 were monitored by diffuse reflectance spectroscopy and high performance liquid chromatography, respectively. At temperatures 50-90 degrees C and relative humidities 50-93%, the rate equation of discoloration is -dR/dt = KRR, that of degradation is d(c(o)-c)/dt = kc (c(o)-c)1/2, and that of photodegradation is -dR/dt = kp (Ro-R)-1, where Ro and R are initial relative reflectance and relative reflectance at time t, respectively, c(o) and c are initial concentration and concentration at time t, respectively, kR, kc and kP are apparent rate constants of discoloration, degradation and photodegradation, respectively. The general equation of the relationship between the apparent rate constant k, absolute temperature T and relative humidity RH is k = k' exp (-Ea/RT) exp (m' RH), where Ea is apparent activation energy, k' and m' are constants. Within the ranges of experimental temperatures and humidities, the average apparent activation energies of discoloration and degradation are 105.51 and 130.72 kJ/mol, respectively.
通过在等温、恒湿和黑暗条件下的加速试验，研究了温度和湿度对维生素K3粉末变色和降解速率的影响。在室温及恒湿条件下研究了维生素K3粉末的光降解。分别采用漫反射光谱法和高效液相色谱法监测维生素K3的颜色变化和浓度变化。在温度50 - 90℃和相对湿度50 - 93%条件下，变色速率方程为 -dR/dt = KRR，降解速率方程为d(c(o)-c)/dt = kc (c(o)-c)1/2，光降解速率方程为 -dR/dt = kp (Ro-R)-1，其中Ro和R分别为初始相对反射率和时间t时的相对反射率，c(o)和c分别为初始浓度和时间t时的浓度，kR、kc和kP分别为变色、降解和光降解的表观速率常数。表观速率常数k、绝对温度T和相对湿度RH之间关系的通式为k = k' exp (-Ea/RT) exp (m' RH)，其中Ea为表观活化能，k'和m'为常数。在实验温度和湿度范围内，变色和降解的平均表观活化能分别为105.51和130.72 kJ/mol。
