21. Solving a chemistry problem

Thin layer chromatography was used to determine dioxydiphenylmethane in food products. For standard samples, the following data were obtained:
Dioxydiphenylmethane concentration, µg/0.02 cm3 5.0 10.0 15.0 35.0
Spot area, mm2 7.94 12.59 15.85 27.10
To construct a calibration graph, the lgS-f(lgC) dependence was used. A sample of vegetables weighing 250 g was treated with 100 cm3 of alcohol, which was then evaporated to 5.00 cm3. A 0.02 cm3 aliquot was chromatographed by thin layer chromatography to give a spot of 38 mm2. Determine the concentration of dioxydiphenylmethane in vegetables (mg/kg).