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

[F1 3. APPARATUS U.K.

The instructions given are for the usual equipment used for gas chromatography, employing capillary columns and a flame-ionisation detector.

3.1. Gas chromatograph U.K.

The gas chromatograph shall comprise the following elements.

3.1.1. Injection system U.K.

Use an injection system with capillary columns, in which case the injection system should be specially designed for use with such columns. It may be of the split type or the splitless on-column injector type.

3.1.2. Oven U.K.

The oven shall be capable of heating the capillary column to a temperature of at least 260 °C and of maintaining the desired temperature to within 0,1 °C. The last requirement is particularly important when a fused silica tube is used.

The use of temperature-programmed heating is recommended in all cases, and in particular for fatty acids with less than 16 carbon atoms.

3.1.3. Capillary column U.K.

3.1.3.1. Tube, made of a material inert to the substances to be analysed (usually glass or fused silica). The internal diameter shall be between 0,20 to 0,32 mm. The internal surface shall undergo an appropriate treatment (e.g. surface preparation, inactivation) before receiving the stationary phase coating. A length of 60 m is sufficient for fatty acid and cis and trans isomers of fatty acids. U.K.

3.1.3.2. Stationary phase, polar polysiloxane (cyanopropylsilicone) bonded (cross-linked) columns are suitable. U.K.

Note 2: There is a risk that polar polysiloxanes may give rise to difficulties in the identification and separation of linolenic acid and C ₂₀ acids. U.K.

The coatings shall be thin, i.e. 0,1 to 0,2 μm.

3.1.3.3. Assembly and conditioning of the column U.K.

Observe the normal precautions for assembling capillary columns, i.e. arrangement of the column in the oven (support), choice and assembly of joints (leak tightness), positioning of the ends of the column in the injector and the detector (reduction of dead-spaces). Place the column under a flow of carrier gas (e.g. 0,3 bar (30 kPa) for a column of length 25 m and internal diameter 0,3 mm).

Condition the column by temperature programming of the oven at 3 °C/min from ambient temperature to a temperature 10 °C below the decomposition limit of the stationary phase. Maintain the oven at this temperature for one hour until stabilisation of the baseline. Return it to 180 °C to work under isothermal conditions.

Note 3: Suitably pre-conditioned columns are available commercially. U.K.

3.1.4. Flame ionisation detector and converter-amplifier U.K.

3.2. Syringe U.K.

The syringe shall have a maximum capacity of 10 μl, graduated in 0,1 μl divisions.

3.3. Data acquisition system U.K.

Data acquisition system connected online with the detectors and employed with a software program suitable for peak integration and normalisation.]

Textual Amendments

F1 Substituted by Commission Implementing Regulation (EU) 2015/1833 of 12 October 2015 amending Regulation (EEC) No 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis.