94. Solving a chemistry problem

10. For spectrophotometric determination of the amount of quinotilin in a sterile solution for injection, an accurately measured volume V, ml of the preparation solution (equivalent to the content of 0.002 g of quinotilin) ​​is taken, placed in a 100 ml volumetric flask, the volume of the solution is adjusted to the mark with water and mixed. Take 25 ml of the resulting solution, transfer to a 100 ml volumetric flask, dilute the volume of the solution with water to the mark and mix.
Measure the optical density A(X) of the resulting solution at 235 nm and the optical density A(st) of a standard solution of quinotiline with a concentration of c(st), g/ml at the same wavelength in a cuvette with the same thickness of the absorbing layer.
Derive the following formula to calculate the content of t quinotilin in grams in 1 ml of the initial injection solution:
m \u003d A (x) * c (st) * 100 * 100 / A (st) * V * 25