21. Solution to Chemistry Problem

4. Calculate the cyanocobalamin concentration as a percentage.
Determination method. Dissolve about 0.1 g (exact mass) of the preparation in water in a 500 ml measuring flask and bring the volume to the mark with water. Transfer 25 ml of this solution to a 250 ml measuring flask and bring the volume to the mark with water. Determine the optical density of the resulting solution using a spectrophotometer at a wavelength of 361 nm in a cuvette with a layer thickness of 10 mm. The comparison solution is water.
E1%1cm} = 207.
The cyanocobalamin content is recalculated for dry matter. Its moisture content is 12.0%, optical density is 0.341, the exact mass of the preparation is 0.1000 g.