维生素K_3粉末降解动力学

STUDY ON THE DEGRADATION KINETICS OF VITAMIN K_3 POWDER

在温度为50～90℃,相对湿度为50～93%范围内,维生素K_3的变色速率方程为—dR/dt=k_RR,降解速率方程为d(C_o—c)/dt=k_c(c_o—c)^(1/2),光解速率方程为—dR/dt=k_P(R_o—R)^(-1)。k_R和_c与热力学温度T和相对湿度RH的关系通式为k=k′exp(—E_a/RT)exp(m′RH)。在实验温度和湿度范围内,变色和降解的表观活化能平均值分别为105.51和130.72 kJ/mol。

The effect of temperature and humidity on the rate of discoloration and degradation of vitamin K_3 powder was studied via accelerated test under isothermal, constant humidity and dark conditions. The photodegradation of vitamin K_3 powder was studied under room temperature and constant humidity. The changes of color and concentration of vitamin K_3 were monitored by diffuse reflectance spectroscopy and high performance liquid chromatography, respectively. At temperatures 50～90℃ and relative humidities 50～93%, the rate equation of discoloration is—dR/dt=k_RR, that of degradation is d (c_o—c)/dt=k_c (c_o—c)^(1/2), and that of photodegradation is—dR/dt=k_p(R_o—R)^(-1), where R_o, 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, k_R, k_c and k_p 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 (—E_a/RT)exp (m′RH), where E_a 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.