紫外分光光度法直接测定AD钙盐中维生素A的含量

AD钙盐中的维生素A是以其乙酸酯的形态加入，而后者不溶于水。根据此性质，将AD钙盐试样用水浸取即可使维生素A与基体组分离，将不溶物分出，溶于乙醇中并定客为10mL，随即可在此试样乙醇溶液中用UV-分光光度法测定维生素A。在维生素A的吸收峰325nm波长处，用1cm石英吸收皿以乙醇作参比液测得其吸光度。用高纯度的维生素A乙醇酯（纯度99．9％）作标准制作标准曲线，得其线性回归方程为CVC=16．899A＋0．059，r=0．9996，方法的回收率在97．7％至100．1％之间。此方法远较国家标准方法和药典方法简单、可行。

DIRECT UV-SPECTROPHOTOMETRIC DETERMINATION OF VITAMIN A IN AD CALCIUM SALT

Vitamin A is added in the AD calcium salt in the form of ethyl ester,which is insoluble in water.Based on this fact,vitamin A was separated from the matrix by extraction with water.The insoluble substance was collected and dissolved in ethanol and diluted to 10 mL quantitatively.Vitamin A in the sample solution was then determined by UV-spectrophotometry. Its absorbance was measured at its absorption maxima of 325 nm,with 1 cm quartz absorption cell using ethanol as reference solution.High purity(99.9%) ethyl ester of vitamin A was used as standard in the preparation of standard curve,the linearity of which was given by the regression equation c_(VA)=(16.899 A)+0.059(r=0.999 6).Results of recovery test obtained were in the range from 97.7% to 100.1%.This method was proved to be much simpler than the method given in GB standard and in pharmacopoeia.