人工牛黄的光解

人工牛黄是广泛用于中成药配方的中药代用品。本文用漫反射光谱法研究了人工牛黄样品在人工光源照射下发生颜色变化的光解规律:在三种光源下,其光解均属二步表观一级反应动力学,即光解曲线是由两段斜率不同的直线组成,初期的光解速度较其后的快2倍左右;不同光源下,紫外灯光解速度最快,荧光高压汞灯次之,碘钨灯最慢;表观光解常数与光波长有关,但基本不随光强度和照射时间乘积改变。而光解时间则与光强度成反比。从得到的动力学方程可预测不同条件下的褪色时间。研究表明,人工牛黄复方中,发生光解的主要成分是胆红素,其余成分不发生引起颜色变化的光解,但在第二步反应中对胆红素的光解有明显影响。

PHOTODECOMPOSITION OF ARTIFICIAL CALCULUS BOVIS

Artificial calculus bovis (ACB) is widely used in dispensing Chinese Traditional Patent Medicine as a substitute for Calculus bovis. Photodecomposition rule of ACB sample irradiated with three different light sources was studied by diffuse reflectance spectrophotometry (DRS) in this paper. The results show that, the photodecomposition rate curves of the ACB sample irradiated by all three light sources are composed of two straight lines of different slopes, indicating that they are of two-step apparent first order reaction, the apparent photodecomposition constants in the first steps are about twice as high as those in the second steps. The ACB sample has the fastest photodecomposition rate when irradiated with the UV mercury-arc lamp and the second with the fluorescent mercury-arc lamp and slowest with the iodine-tungsten lamp. In these three light sources apparent photodecomposition constants of ACB sample are respectively: K1, 2.7629 x 10(-5), 4.4132 x 10(-6); k2, 1.2176 x 10(-5), 2.0684 x 10(-6), 1.4357 x 10(-6) (lx-1.h-1). The apparent constants are independent of the product of the radiation intensity and the irradiation time, but the irradiation time is in inverse ratio of the radiation intensity to get the same proportion of the sample photodecomposition. The fading time of the ACB sample under different radiation intensity can be predicted with the kinetic equations reported. The fading time of ACB sample if directly exposed to light in bright room is 1.6 days.(ABSTRACT TRUNCATED AT 250 WORDS)