Modified method for the determination of unsaponifiable matter in oils and fats

Abstract

An inversion of the existing methods for the determination of unsaponifiable matter in oils and fats is proposed. The modified procedure consists in saponifying a 2–2.5 g sample of oil or fat with 2 mol l^–1 ethanolic potassium hydroxide solution, dissolving the resultant mixture in 50 ml of pure cyclohexane, removing the soap by addition of 25 ml of water containing 0.5 g of sodium hydrogencarbonate and extracting the separated soap layer with 25 ml of cyclohexane. The combined cyclohexane layers are washed twice with 25 ml portions of 50% aqueous ethanol, cyclohexane is evaporated and the residue is dried in vacuo at 80 °C. Results obtained with the above procedure in the determination of the unsaponifiable matter in four different vegetable oils were in agreement with those given by the IUPAC standard hexane method II.D.5 with economy of solvents and operational time.