# Commission Regulation (EEC) No 2568/91 of 11 July 1991 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis, Division 2: PRINCIPLE

Extent: E+W+S+N.I.

The oils, with added α-cholestanol and 1-eicosanol as internal standards, are saponified with potassium hydroxide in ethanolic solution and the unsaponifiable matter is then extracted with ethyl ether.
The different alcoholic compounds fractions are separated from the unsaponifiable matter either by thin-layer chromatography on a basic silica gel plate (reference method) or by HPLC with a silica gel column. The fraction recovered from the silica gel separation is transformed into trimethylsilyl ethers and then analysed by capillary column gas chromatography.

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Source: https://www.legislation.gov.uk/eur/1991/2568/annex/XIX/division/1/division/2 (the official version)
Page: https://openlegislation.uk/eu-regulation-1991-2568/annex-XIX/division-1/division-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.