Commission Regulation (EEC) No 2568/91Dangos y teitl llawn

[F1 5. REAGENTS U.K.

All reagents should be of analytical grade unless otherwise specified. The water used should be distilled water, or water of at least equivalent purity.

[F2 5.1. Hexane or mixture of alkanes of b.p. interval 65 to 70 °C, distilled with rectifying column. Hexane may be replaced by iso-octane (2,2,4-trimethyl pentane in chromatography grade), provided that comparable precision values are achieved. The residue after evaporation of 100 ml of solvent may be controlled. Solvents with higher boiling point than n-hexane take longer to evaporate. However, they are preferred due to the toxicity of hexane.] U.K.

Textual Amendments

F2 Substituted by Commission Implementing Regulation (EU) 2019/1604 of 27 September 2019 amending Regulation (EEC) No 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis.

5.2. 96 v/v ethanol. U.K.

5.3. Anhydrous sodium sulphate. U.K.

5.4. Alcoholic potassium hydroxide solution at 10 %. Add 10 ml of water to 50 g potassium hydroxide, stir, and then dissolve the mixture in ethanol to 500 ml. U.K.

Note 3: U.K.

Alcoholic potash turns brown on standing. It should be prepared freshly each day and kept in well stoppered dark glass bottles. U.K.

5.5. Silica gel 60 for column chromatography, 70 to 230 mesh, (Merck, reference 7734 or similar). U.K.

Note 4: U.K.

Usually, silica gel can be used directly from the container without any treatment. However, some batches of silica gel may show low activity resulting in bad chromatographic separations. Under this circumstance, the silica gel should be treated in the following way: Activate the silica gel by heating for a minimum of four hours at 550 °C. After heating, place the silica gel in a desiccator while the gel is cooling and then transfer the silica gel to a stoppered flask. Add 2 % of water and shake until no lumps can be seen and the powder flows freely. U.K.

If batches of silica gel result in chromatograms with interfering peaks, the silica gel should be treated as above. An alternative could be the use of extra pure silica gel 60 (Merck, reference 7754).

5.6. Stock solution (200 ppm) of cholesta-3,5-diene (Sigma, 99 % purity) in hexane (10 mg in 50 ml). U.K.

5.7. Standard solution of cholesta-3,5-diene hexane at concentration of 20 ppm, obtained by dilution of above solution. U.K.

Note 5: U.K.

The solutions 5.6 and 5.7 are stable for a period of at least four months if kept at less than 4 °C. U.K.

5.8. Solution of n-nonacosane in hexane at concentration of approximately 100 ppm. U.K.

5.9. Carrier gas for chromatography: helium or hydrogen of 99,9990 % purity. U.K.

5.10. Auxiliary gases for flame ionization detector: hydrogen of 99,9990 % purity and purified air.] U.K.

Textual Amendments

F1 Inserted by Commission Regulation (EC) No 656/95 of 28 March 1995 amending Regulation (EEC) No 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis and Council Regulation (EEC) No 2658/87 on the tariff and statistical nomenclature and on the Common Customs Tariff.