维生素AD胶丸中VitA的含量测定.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,The Assay of Vitamin A Soft Capsules,Purpose,1.To study the principles and procedures of multi-wavelength spectropho-tometric assay method.,2.To exercise on the spectrophotometric assay of Vitamin A.,Procedures and methods,Vitamin A Soft Capsules contain a solution of vitamin A in refined vegetable oil(remove the solid fat at 0),the concentration of which has been adjusted appropriately.Each capsule contains not less than 90.0%and not more than 120.0%of the labelled amount of Vitamin A activity.,Method 1,(,Vitamin A in Ester Form A,)preparation not directly soluble in cyclohexane may be fractionated by extraction or other means not involving saponification.If this is not possible the preparation is dealt with as described below under Other Vitamin A,Method 2,(Other Vitamin A)Mix a quantity of the preparation being examined containing not less than 500 Units of vitamin A and not more than 1 g of fat with 30 ml of absolute ethanol and 3 ml of a 50%w/w solution of potassium hydroxide.Boil gently under a reflux condenser in a current of oxygen-free nitrogen for 30 minutes,cool rapidly and add 30 ml of water.Transfer the hydrolysate to a separating funnel using three 50-ml quantities of ether and extract the vitamin A by shaking for 1 minute.After complete separation discard the aqueous layer and wash the extract with four 50-ml quantities of water,mixing very cautiously during the first two washes to avoid the formation of emulsions.Evaporate the separated extract to about 5 ml and remove the remaining solvent in a current of oxygen-free nitrogen without the application of heat.Dissolve the residue in sufficient propan-2-ol to produce a solution containing 9 to 15 Units per ml and measure the absorbance at 300,310,325 and 334 nm.Determine the wavelength of maximum absorption.,Discussions,1.Why are the spectrophotometric assay method used for the assay of Vitamin A in all the pharmacopoeias,2.Figure out all the equations for the calculation of the content of Vitamin A.,。