1、BRITISH STANDARD BS ISO 1241:1996 Essential Oils Determination of ester values, before and after acetylation, and evaluation of the contents of free and total alcohols ICS 71.100.60; 71.040.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 1241:1996 This British Standar
2、d, 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 38321 0 National foreword This British Standard reproduces verbatim ISO 1
3、241:1996 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-refere
4、nces 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 Catalo
5、gue. 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 cove
7、r, an inside front cover, the ISO title page, page ii, pages 1 to 6, 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 IS0 1241 Second
8、edition 1996-12-15 Essential oils - Determination of ester values, before and after acetylation, and evaluation of the contents of free and total alcohols Huiles essen tie/es - Dgtermination de lindice dester, avant et aprks achc=c ;ten004=a ;osi=p ;scosi=o lartnec=s detnirP ni dnalreztiwS ii INTERN
9、ATIONAL STANDARD IS0 IS0 1241:1996(E) Essential oils - Determination of ester values, before and after acetylation, and evaluation of the contents of free and total alcohols 1 SCOPE This International Standard specifies a method to evaluate the con* alcohols in essential oils by determination of est
10、er values before anhydride in the presence of sodium acetate. The method is not applicable to essential oils containing appreciabl (for example linalol and terpineols), which would not be completely tents of free alcohols and total and after acetylation by acetic e quantities of tertiary alcohols ac
11、etylated. NOTE: For these essential oils the method given in IS0 3794l) should be used. The method is not applicable to essential oils containing appreciable quantities of phenols, Id be acetyl( ated in addition to free alcohols. lactones, aldehydes or enolysable ketones, which wou 2 NORMATIVE REFER
12、ENCES -PI r .I . . . - . . . I l I 1 ne tollowrng standards contain provrsrons wnicn, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements
13、based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 2 12: 1973, Essential oils - Sampling. IS0 356: 1996, Es
14、sential oils - Preparation of test sample. IS0 385-1:1984, Laboratory glassware - Burettes - Part I: General requirements. IS0 709: 1980, Essential oils - Determination of ester value. I) IS0 3794:1976, Essential oils (containing tertiary alcohols) - Estimation of free alcohols content by determinat
15、ion of ester value after acetylation. 1 IS0 1241:1996(E) 0 0SI 3 DEFINITIONS For the purposes of this International Standard, the following definitions apply. 3.1 ester value: Number of milliligrams of potassium hydroxide which are required to neutralize the acids liberated by the hydrolysis of the
16、esters contained in 1 g of the oil. 3.2 ester value after acetylation: Number of milligrams of potassium hydroxide which are required to neutralize the acids liberated by the hydrolysis of the esters contained in 1 g of the acetylated oil. 4 PRINCIPLE 4.1 Determination of ester value in accordance w
17、ith IS0 709. 4.2 Acetylation of the essential oil by acetic anhydride in the presence of sodium acetate. Isolation and drying of the acetylated oil, and determination of its ester value in accordance with IS0 709. 4.3 Calculation of the free, combined and total alcohol contents from the ester values
18、 before and after acetylation. 5 REAGENTS Use only reagents of recognized analytical grade and distilled water or water of equivalent purity. 5.1 Reagents for determination of ester value 5.1.1 Ethanol, 95 % (V/v) at 2O”C, freshly neutralized by the potassium hydroxide solution (5.1.2) in the presen
19、ce of the coloured indicator (5.1.4) used for the determination. 5.1.2 Potassium hydroxide, standard ethanolic solution, c(KOH) = 0,5 mol/l. 5.1.3 Hydrochloric acid, standard solution, c(HCI) = 0,5 mol/l. 5.1.4 Coloured indicator: phenophthalein, 2 g/l solution in ethanol 95 % (V/v) or, if the essen
20、tial oil contains phenolic groups, phenol red, 0,4 g/l solution in ethanol 20 % (V/V). 5.2 Reagents for acetylation 5.2.1 Acetic anhydride, not less than 98 %. 5.2.2 Sodium acetate, anhydrous, freshly melted and powdered. 2 0 0SI IS0 1241:1996(E) 5.2.3 Sodium chloride, saturated solution. 5.2.4 Sodi
21、um carbonate/sodium chloride, 20 g/i solution of anhydrous sodium carbonate saturated with sodium chloride. 5.2.5 Magnesium sulfate, anhydrous, or sodium sulfate, anhydrous, freshly dried and powdered. 5.2.6 Litmus paper. 6 APPARATUS Usual laboratory apparatus and, in particular, the following. 6.1
22、Acetylation apparatus, including an acetylation flask of capacity 100 ml to 250 ml, with a ground glass neck, provided with a glass tube to act as a reflux condenser, at least 1 m in length and of at least 10 mm internal diameter. The flask and the condenser shall be carefully dried before use. 6.2
23、Measuring cylinders, of capacity 10 ml, graduated in 0,l ml. 6.3 Measuring cylinders, of capacity 50 ml, graduated in 1 ml. 6.4 Water bath, capable of being maintained at between 40 “C and 50 “C. 6.5 Suitable heating device, for boiling acetic anhydride without local overheating. 6.6 Separating funn
24、el, of capacity at least 250 ml. 6.7 Saponification apparatus, including an alkali-resistant glass flask, of capacity 100 ml to 250 ml, to which can be fitted a reflux condenser, at least 1 m in length and of at least 10 mm iinternal diameter. 6.8 Burette, of capacity 50 ml, graduated in 0,l ml, con
25、forming to the requirements of IS0 385-l. 6.9 Analytical balance. 7 SAMPLING Sampling shall be carried out in accordance with IS0 212. 3 IS0 1241:1996(E) 0 0SI 8 PROCEDURE 8.1 Preparation of test sample The test sample shall be prepared in accordance with IS0 356. 8.2 Determination of ester value be
26、fore acetylation Determine the ester value before acetylation in accordance with the method given inIS 709. 8.3 Acetylation Mix approximately 10 ml of the test sample (8.1), 10 ml of the acetic anhydride (5.2.1) and 2 g of the anhydrous sodium acetate (5.2.2) in the acetylation flask (6.1). Add frag
27、ments of pumice stone or porcelain and fit the reflux condenser to the flask. Heat the flask by means of the heating device (6.5) and maintain the liquid at moderate boiling for 2 h or for the time given in the International Standard for the essential oil being analysed. At the end of this period, a
28、llow the liquid to cool. Add 50 ml of distilled water and heat on the water bath (6.4), set at between 40 “C and 50 OC, for 15 min, shaking frequently. Allow to cool to room temperature, remove the reflux tube and transfer the liquid to the separating funnel (6.6). Wash the flask twice with 10 ml of
29、 water and collect the washing in the separating funnel. Wait until separation of the phase is complete, then draw off and reject the aqueous phase. Wash the oil by shaking successively with a) 50 ml of the sodium chloride solution (5.2.3), b) 50 ml of the sodium carbonate/sodium chloride solution (
30、5.2.4), c) 50 ml of the sodium chloride solution (5.2.3), and d) 20ml of water. If the washing have been properly conducted, they will be neutral to the litmus paper (5.2.6). Run the oil phase into a dry tube and shake several times over 15 min with at least 3 g of the magnesium or sodium sulfate (5
31、.2.5). Filter. Repeat the contact and shaking with further 3 g portions of magnesium or sodium sulfate until the acetylated oil is free of water. 8.4 Determination of ester value after acetylation Determine the ester value of the acetylated oil (8.3), in accordance with the requirements of IS0 709,
32、by using approximately 2 g, weighed to the nearest 0,05 g, of the acetylated oil and 50 ml of the potassium hydroxide solution (5.1.2). 4 0 0SI IS0 1241:1996(E) 9 EXPRESSION OF RESULTS 9.1 The ester value after acetylation is given by the formula: E2 =?j?(“() -“f,) 9.2 The free alcohols content, exp
33、ressed as a percentage by mass with respect to a given alcohol, is given by the formula: NOTE: This formula takes into account the increase in mass of the test portion during acetylation. 9.3 The combined alcohols content, expressed as a percentage by mass, with respect to a given alcohol, is given
34、by the formula: M, XEl 561 9.4 The total alcohols content, expressed as a percentage by mass with respect to a given alcohol, is obtained by adding the two percentages obtained in 9.2 and 9.3. In the above formulae: m is the mass, in grams, of the test sample of the acetylated oil; V, is the volume,
35、 in millilitres, of the hydrochloric acid solution (5.1.3) used for the blank test; VI is the volume, in millilitres, of the hydrochloric acid solution (5.1.3) used for the determination of the ester value after acetylation ; M, is the relative molecular mass of the alcohol used to express results c
36、onventionally and which is given in the International Standard for the essential oil being analysed; El is the ester value of the oil before acetylation (8.2) calculated in accordance witt E2 is the ester value of the oil after acetylation (8.4), calculated in accordance with I 5 IS0 1241:1996(E) 0
37、0SI 10 TEST REPORT The test report shall state the method used and the results obtained. It shall also mention any operating conditions not specified in this International Standard, or regarded as optional, as well as any details that may have influenced the results. The test report shall include al
38、l details required for the complete identification of the sample. 6 BS ISO 1241:1996 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the
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