33. Solving a chemistry problem

For the determination of iron in waste water, 25 ml of a colored solution was obtained from 100 ml of water after evaporation and treatment with o-phenanthralin. The optical density of this solution at a layer thickness of 1 cm turned out to be 0.45. Determine the iron content of industrial water (in mg/l) if the molar absorption coefficient of this colored compound is 1100.