138. Solving a chemistry problem

To determine dioxydiphenylmethane in food products, the method of thin layer chromatography was used. The following data were obtained for standard samples:
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 plot the calibration graph, the lgS-f (lgC) dependence was used. A 250 g sample of vegetables was treated with 100 cm3 of alcohol, which was then evaporated to 5.00 cm3. An aliquot of 0.02 cm3 in volume was chromatographed by thin layer chromatography to obtain a 26.55 mm2 spot. Determine the concentration of dioxydiphenylmethane in vegetables (mg / kg).