A standard solution containing cholesterol 1.29 10-5 M and 5--cholestane 5.0 10-6M, as an internal standard, originated peaks of area 390 and 486 units, respectively, in phase chromatography. 0.5 g of milk were treated by saponification and extraction in 2 mL of hexane containing 5--cholestane 5.0 10-6 M, and obtained by GC under identical experimental conditions as for the dissolution standard, a chromatogram with peak areas of 245 and 503 units for cholesterol and the internal standard, respectively. Considering that there was no matrix effect in the sample Calculate the concentration of cholesterol in the milk sample. Weight molecular cholesterol=386.65 g/mol. (Sol. 12.12 g/g).