AOAC Official Method 933.08 Residue (Unsaponifiable) of Oils and Fats
Ether Extraction Method
First Action 1933
Final Action
Accurately weigh 2–2.5 g fat into saponification flask (200 mL Erlenmeyer with standard taper 24/40 outer joint is recommended). Add 25 mL alcohol and 1.5 mL KOH solution (3 + 2). Saponify by boiling, with occasional swirling, on steam bath 30 min under reflux air condenser. (No loss of alcohol should occur during saponification.) Transfer alcoholic soap solution while still warm to 250 mL separator, using total of 50 mL H2O. Rinse saponification flask with 50 mL ether and add ether to separator. Shake vigorously, and let layers separate and clarify. Drain lower layer and pour ether
layer through top into second separator containing 20 mL H2O. Rinse pouring edge with ether, adding rinsings to second separator. Extract soap solution with two 50mLportions ether in same manner. Make total of 4 extractions for marine oils or other oils of high unsaponifiable content.
