2. Solving a chemistry problem

51. To determine the content of the acid violet dye in the Rainbow ink, standard solutions were prepared: 0.50 1.00 2.00 3.00 ml of the standard dye solution (T = 0.0003) was placed in volumetric flasks with a capacity of 100.0 ml, brought to the mark with distilled water, measured the optical density and obtained the following data:
V, cm3 0.50 1.00 2.00 3.00
A 0.07 0.12 0.23 0.35
A sample of the analyzed ink solution with a volume of 0.004 ml was placed on chromatographic paper. After separation into red and violet components, the acid violet dye zone was excised, extracted, diluted in a volumetric flask with a capacity of 50.0 ml, and the optical density of the resulting solution was measured. Determine the concentration (mg/ml) of the dye in the test solution, if the value of the optical density Ax=0.28.