1、BRITISH STANDARD BS ISO 3794:1976 Essential Oils (containing tertiary alcohols) Estimation of free alcohols content by determination of ester value after acetylation ICS 71.100.60; 71.040.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 3794:1976 This British Standard,
2、 having been prepared under the direction of the Consumer Products and Services Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 September 2001 BSI 08-2001 ISBN 0 580 38371 7 National foreword This British Standard reproduces verbatim ISO 379
3、4:1976 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee AW/54, Essential Oils, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-referenc
4、es The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogu
5、e. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text;
6、present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover,
7、 an inside front cover, the ISO title page, the ISO foreword page, pages 1 and 2, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsINTERNATIONAL STANDARD 379
8、4 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION l MEXAYHAPOAHAJI OPTAHM3AUMX no CTAHAAPTZ13AUMWORGANISATION INTERNATtONALE DE NORMALISATON Essential oils (containing tertiary alcohols) - Estimation of free alcohols content by determination of ester value after acetylation Huiles essentielles (con t
9、enan t des alcools tertiaires) - haiuation de Ia teneur en alcools libres par dbtermination de / indice d es ter aprk ack tyla tion t First edition - 1976-12-15 UDC 668.5 : 543.85 Ref. No. ISO 3794-1976 (E) Descriptors : essential oils, Chemical analysis, determination of content, alcohols, ester nu
10、mber ecirP desab no 2 segap FOREWORD ISO (the International Organization for Standardization) is a worldwide federation of national Standards institutes (ISO Member Bodies). The work of deveioping International Standards is carried out through ISO Technical Committees. Every Member Body interested i
11、n a subject for which a Technical Committee has been set up has the right to be represented on that Committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the Technical Ccmmittees are circul
12、ated to the Member Bodies for approval before their acceptance as International Standards by the ISO Council. International Standard ISO 3794 was drawn up by Technical Committee ISO/TC 54, Essential oils, and was circulated to the Member Bodies in February 1975. lt has been approved by the Member Bo
13、dies of the following countries : Belgium Italy Canada Netherlands France Portugal Germany South Africa, Rep. of India Spain Sri Lanka Turkey Yugoslavia No Member Body expressed disapproval of the document. lanoitanretnI noitaknagrO rof ,noitakdradnatS 6791 l detnirP ni dnalreztiwS INTERNATIONAL STA
14、NDARD ISO 3794-1976 (E) Essential oils (containing tertiary alcohols) - Estimation of free alcohols content by determination of ester value after acetylation 1 SCOPE AND FIELD OF APPLICATION This International Standard specifies a method for estimat- ing the free alcohols content of essential oils,
15、by determi- nation of ester value after acetylation.1) This method is applicable to essential oils containing an appreciable Proportion of tertiary alcohols, namely of linalol and terpineol, ISO/R 1241 not being applicable to those oils. This method is not applicable to essential oils containing app
16、reciable proportions of phenols, anthranilates, lactones and aldehydes, as stated in ISO/R 1241. 2 REFERENCES ISO 2 12, Essential oils - Sampling. ISO 356, Essential oils - Prepara tion 0 f test Sample. ISO/R 709, Determination of ester value and calculation of ester con ten t 0 f essential oils. IS
17、OIR 124 1, Essential oils - Estimation of free alcohols content by determination of ester value after acetylation. 3 DEFINITION ester value after acetylation : The number of milligrams of potassium hydroxide which are required to neutralize the acids liberated by the hydrolysis of the esters contain
18、ed in 1 g of the acetylated Oil. 4 PRINCIPLE Acetylation of the essential oil by acetyl chloride and acetic anhydride, in the presence of dimethylaniline. Isolation and drying of the acetylated Oil. Determination of the ester value after acetylation. Calculation of the free alcohols content taking i
19、nto account the ester value of the Same but non-acetylated essential Oil. 5 REAGENTS During the analysis, use only reagents of recognized ana- lytical grade, and only distilled water or water of equivalent purity. 5.1 Acetyl chloride. 5.2 Dimethylaniline, freshly distilled and free from monomethylan
20、iline and aniline. 5.3 Acetic anhydride, concentration not less than 98 %. 5.4 Anhydrous magnesium sulphate or sodium sulphate, recently desiccated and powdered. 5.5 Sodium sulphate (Na,SO,), 100 g/l solution. 5.6 Hydrochlorit acid Solution. Dilute 5 Parts of hydrochloric acid (pZc 1,19 g/ml) to 100
21、 Parts by volume with the sodium sulphate Solution (5.5). 5.7 Sodium hydrogen carbonate Solution. Dissolve 50 g of sodium hydrogen carbonate in 1 I of the sodium sulphate Solution (5.5). 5.8 Potassium hydroxide, 0,l N aqueous Solution. 5.9 Potassium hydroxide, 0,5 N Standard volumetric Solution in 9
22、5 % (WV) ethanol. 5.10 Hydrochlorit acid, 0,5 N Standard volumetric Solution. 5.11 Litmus Paper. 5.12 Phenolphthalein, 2 g/l Solution in 95 % (WV) ethanol. 6 APPARATUS Ordinary laboratory equipment, and 6.1 Acetylation apparatus, comprising a 100 ml round- bottomed acetylation flask connected by a g
23、round glass joint to a glass tube at least 1 m long and with an inside diameter of about IO mm, to act as an air condenser, and a ground glass stopper to fit the flask. Both the round-bottomed flask and the condenser shall be carefully dried before use. 1) This method is usually known as the “Fiore
24、method”. ISO 3794-1976 (E) c) twice with 25 ml of the sodium hydrogen carbonate Solution (5.7); d) twice with 25 ml of the sodium sulphate Solution (5.5); 6.2 Measuring cylinders, capacity 10 ml. 6.3 Measuring cylinders, capacity 50 ml. 6.4 Melting ice bath. After each addition, Shake vigorously for
25、 30 s and allow to settle until the two layers are clearly separated. During the last separating Operation, check the neutral condition of the aqueous layer with the Iitmus Paper (5.11). 6.5 Water bath, set at 40 + 1 “C. 6.6 Boiling water bath. Transfer the oily layer into a flask, dry over anhydrou
26、s magnesium sulphate or sodium sulphate (5.4) and fil ter. 6.7 Separating funnel, capacity at least 250 ml. 8.4 Determination of ester value after acetylation 6.8 Saponification flask, capacity 250 ml, made of alkali- resistant glass and to which tan be fitted a reflux condenser. Determine the ester
27、 value in accordance with ISO/R 709. 6.9 Calibrated burettes, capacity 50 ml, graduated in 0,l ml. 9 EXPRESSION OF RESULTS The free alcohols content, expressed as a percentage by mass, is given by the formula 7 SAMPLING See ISO 212. M (E.V., - E.V., ) 561 - 0,42 E.V., 8 PROCEDURE 8.1 Preparation of
28、test Sample See ISO 356. The combined alcohols content, expressed as a percentage by mass, tan be calculated from the ester value, using the formula 8.2 Determination of ester value before acetylation M x E.V., 561 , Determine the ester value before acetylation in accordance with lSO/R 709. The tota
29、l alcoho Is Conte nt, expressed as a percentage by mass, is obtained by add ing the two p revi ous percentages. 8.3 Acetylation In the above formulas, Measure, with a cylinder (6.2) 10 ml of the test Sample and pour into the round-bottomed flask (6.1). Add 20 ml of the dimethylaniline (5.2), mix tho
30、roughly and cool in the melting ice bath (6.4). M is the molecular mass of the reference alcohol speci- fied in the International Standard for the essential oil being tested; Then add, keeping the round-bottomed flask in the melting ice bath, 8 ml of the acetyl chloride (5.1) and 5 ml of the acetic
31、anhydride (5.3). Remove the round-bottomed flask from the melting ice bath and allow it to stand at room temperature for 30 min. Place the flask in the water bath (6.5) at a temperature of 40 + 1 “C and let it remain for 16 h. E.V., is the ester value of the oil before acetylation (8.2), determined
32、according to lSO/R 709; E.V., is the ester value of the oil after acetylation (8.4), determined according to ISO/R 709. IO TEST REPORT Cool to room temperature and pour the liquid into the separating funnel (6.7), then wash the acetylated oil as follows : The test report shall state the method used
33、and the result obtained. lt shall also mention any operating conditions not specified in this International Standard, or regarded as optional, as weil as any circumstances that might have influenced the result. a) twice with 75 ml of the sodium sulphate Solution (5.5); b) at least five times with 50
34、 ml portions of the hydrochloric acid Solution (5.6), until the washings are free from dimethylanilinel 1; The test report complete identif shall include all deta catio n of the Sample. ils required for the i 1) Test as follows for the absence of dimethylaniline : add to 15 ml of the hydrochloric wa
35、shing 2 drops of permanganate. Shake vigorously. If an orange-yellow colour appears in less than 15 s, dimethylaniline is presen a saturated Solution of potassium 2 BS ISO 3794:1976 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body respon
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