Commission regulation (EC) No 1623/2000 of 25 July 2000 laying down detailed rules for implementing Regulation (EC) No 1493/1999 on the common organisation of the market in wine with regard to market mechanisms (repealed) (c. 1623)

[F1 ANNEX IV U.K. COMMUNITY ANALYSIS METHOD FOR NEUTRAL ALCOHOL

Textual Amendments

F1 Substituted by Commission Regulation (EC) No 625/2003 of 2 April 2003 amending Regulation (EC) No 1623/2000 laying down detailed rules for implementing Council Regulation (EC) No 1493/1999 on the common organisation of the market in wine with regard to market mechanisms.

II. METHODS U.K.

Method 7: Determination of esters U.K.

1. SCOPE AND FIELD OF APPLICATION U.K.

The method determines esters, expressed as ethyl acetate, in neutral alcohol.

2. DEFINITION U.K.

The ester content: the content of esters, expressed as ethyl acetate, as determined by the method specified.

3. PRINCIPLE U.K.

Esters react quantitatively with hydroxylamine hydrochloride in alkaline solution to form hydroxylamic acids. These then form coloured complexes with ferric ions in acid solution. The optical densities of these complexes are measures at 525 nm.

4. REAGENTS U.K.

4.1. Hydrochloric acid 4 mol/l. U.K.

4.2. Ferric chloride solution, 0,37 mol/l in 1 mol/l hydrochloric acid. U.K.

4.3. Hydroxylamine Hydrochloride, 2 mol/l. Store in a refrigerator. U.K.

4.4. Sodium hydroxide solution, 3,5 mol/l. U.K.

4.5. Ethyl acetate standard solutions containing 0,0, 0,2, 0,4, 0,6, 0,8 and 1,0 g ethyl acetate per hl ester-free ethanol at 96 % vol. U.K.

5. APPARATUS U.K.

5.1. Spectrophotometer with 50 mm pathlength cuvettes. U.K.

6. PROCEDURE U.K.

6.1. Calibration curve U.K.

• Weigh accurately 1,0 g ethyl acetate on an analytical balance,

• add ester-free alcohol in a 1 000  ml volumetric flask and make up to the mark at 20  ^o C,

• prepare dilution series in two stages to produce 20 reference solutions containing 0,1 to 2,0 mg ethyl acetate per 100 ml solution,

• determine absorbence values for the reference solution in accordance with 6.2 and construct a graph.

6.2. Determination of ester content U.K.

• Pipette 10 ml of the sample into test-tubes fitted with ground-glass stoppers,

• add 2 ml hydroxylamine hydrochloride solution,

• at the same time prepare a blank using 10 ml ester-free ethanol at 96 % vol and 2 ml hydroxylamine hydrochloride solution,

• then add 2 ml sodium hydroxide to each solution, close the tubes with ground-glass stoppers and shake well,

• keep for 15 minutes at 20  ^o C in a water bath,

• add 2 ml hydrochloric acid to each tube, shake briefly,

• add 2 ml ferric chloride solution, mix well,

• pour contents into cuvettes,

• Determine absorbence values at 525 nm.

7. EXPRESSION OF RESULTS U.K.

7.1. Formula and method of calculation U.K.

Plot the optical densities of the standards against their concentrations.

The ester content (expressed as ethyl acetate = A) corresponding to the absorbence value is read off on the graph and calculated according to the formula:

and given in 9 per hl ethanol at 100 % vol,

where T

=

alcohol content of the sample in % vol determination as described in method 1.

7.2. Repeatability U.K.

The difference between the results of two determinations, carried out simultaneously or in rapid succession, by the same analyst, on the same sample, under the same conditions, should not exceed 0,1 g esters, as ethyl acetate, per hl ethanol at 100 % vol.]