ISO 18609:2000 PDF

Overview

ISO 18609:2000 specifies a laboratory method for determining the unsaponifiable matter content of animal and vegetable fats and oils using a three-stage hexane extraction. The method covers saponification with ethanolic potassium hydroxide, extraction of non-saponifiable components by hexane (or light petroleum), evaporation of solvent and gravimetric determination of the residue after drying. Note: the method is applicable to fats and oils but not to waxes, and it gives results that are systematically lower than the diethyl-ether method in ISO 3596.

Keywords: ISO 18609:2000, unsaponifiable matter, hexane extraction, animal and vegetable fats and oils, fat analysis, quality control

Key topics and technical requirements

• Scope: Determination of unsaponifiable matter in all fats and oils except waxes.
• Principle: Boil sample with ethanolic KOH to saponify; extract unsaponifiables with hexane; evaporate and weigh residue.
• Reagents: Analytical-grade n-hexane (or light petroleum 40–60 °C), ethanolic KOH (≈1 mol/L), ethanol wash solution, phenolphthalein indicator.
• Apparatus: 250 ml round-bottom flask with reflux condenser, 250 ml PTFE-stopcock separating funnels, boiling water bath, oven at 103 ± 2 °C (or vacuum drying).
• Procedure highlights:
  • Use ~5 g test portion; saponify 1 h under reflux.
  • Perform three successive 50 ml hexane extractions; combine extracts.
  • Wash extracts with ethanolic solution until neutral (phenolphthalein).
  • Evaporate solvent, dry residue at 103 °C and weigh to constant mass (repeat drying until mass change