Fatty acid composition—
Place about 1 g of Corn Oil in a small conical flask fitted with a reflux attachment. Add 10 mL of methanol and 0.5 mL of 1 N methanolic potassium hydroxide solution prepared by dissolving 34 g of potassium hydroxide in sufficient methanol to produce 500 mL, allow it to settle for 24 hours, and decant the clear solution. Reflux the mixture for 10 minutes, cool, transfer to a separator with the aid of 15 mL of
n-heptane, shake with 10 mL of saturated sodium chloride solution, and allow to separate. Transfer the lower layer to another separator, and shake it with 10 mL of
n-heptane. Wash the combined organic layers with 10 mL of water, dry over anhydrous sodium sulfate, and filter. Introduce a suitable portion of the filtrate into a gas chromatograph equipped with a flame-ionization detector and a 4-mm × 1.8-m column, preferably glass, packed with 10% liquid phase G4 on support S1A, maintained at a temperature of 175
. The carrier gas is nitrogen. Measure the five main peak areas of the methyl esters of the fatty acids. The order of elution is palmitate, stearate, oleate, linoleate, and linolenate, and their relative areas, expressed as percentages of the total area of the 5 main peaks, are in the ranges 8 to 19, 1 to 4, 19 to 50, 34 to 62, and 1 to 2, respectively.
841
:
between 0.914 and 0.921.