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 cVA=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.