BS ISO 709-2001 en_9897 Essential oils - Determination of ester value《香精油.酯化值的测定》.pdf

1、BRITISH STANDARD BS ISO 709:2001 Incorporating Corrigendum No. 1 Essential oils Determination of ester value ICS 71.100.60 BS ISO 709:2001 This British Standard, having been prepared under the direction of the Consumer Products and Services Sector Policy and Strategy Committee, was published under t

2、he authority of the Standards Policy and Strategy Committee on 8 November 2001 BSI 16 February 2005 ISBN 0 580 38667 8 National foreword This British Standard reproduces verbatim ISO 709:2001 and implements it as the UK national standard. It supersedes DD ISO 709:1980 which is withdrawn. The UK part

3、icipation 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-references The British Standards which implement international or Europea

4、n publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all

5、the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on

6、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, an inside front cover, an ISO title page, pages ii and iii, a blank page, pa

7、ges 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 Comments 15557 Corrigendum No. 1 9 February 2005 See national forewordReference number ISO 709:2001(E) I

8、NTERNATIONAL STANDARD ISO 709 Second edition 2001-09-01 Essential oils Determination of ester value Huiles essentielles Dtermination de lindice desterISO 709:2001(E) DPF dlcsiremia ihTs PDF file mya ctnoain emdeddeb tyfepcaes. In acccnadroe with Aebods licnesign lopic,y this file may be pirntde ro i

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13、pothgiso.ch eWb www.iso.ch ii ISO 709:2001(E) iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each

14、 member body interested in a subject for which a technical committee has been established 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. ISO collaborates closely with the Internationa

15、l Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for

16、voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifyi

17、ng any or all such patent rights. International Standard ISO 709 was prepared by Technical Committee ISO/TC 54, Essential oils. This second edition cancels and replaces the first edition (ISO 709:1980), which has been technically revised. Annex A of this International Standard is for information onl

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21、iven below. ISO 2001 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs memb

22、er body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch ii INTERNATIONAL STANDARD ISO 709:2001(E) 1 Essential oils Determination of ester value 1 Scope This International Standa

23、rd specifies a method for the determination of the ester value of an essential oil. This method is not applicable to essential oils containing lactones or an appreciable proportion of aldehydes. 2 Normative references The following normative documents contain provisions which, through reference in t

24、his text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the m

25、ost recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 356, Essential oils Preparation of test samples ISO 385-

26、1, Laboratory glassware Burettes Part 1: General requirements ISO 1242, Essential oils Determination of acid value 3 Term and definition For the purposes of this International Standard, the following term and definition applies. 3.1 ester value EV number of milligrams of potassium hydroxide required

27、 to neutralize the acids liberated by the hydrolysis of esters present in 1 g of the essential oil 4P r i n c i p l e The esters present in the essential oil are hydrolysed by heating under specified conditions with an excess of a standard volumetric ethanolic potassium hydroxide solution. The exces

28、s alkali is determined by back titration with a standard solution of hydrochloric acid. 5 Reagents During the analysis, use only reagents of recognized analytical grade and distilled or demineralized water or water of equivalent purity. 5.1 Ethanol, 95 % (volume fraction) at 20 C, freshly neutralize

29、d with the potassium hydroxide solution (5.2), in the presence of the coloured indicator (5.4) used for the determination.ISO 709:2001(E) 2 5.2 Potassium hydroxide, standard volumetric ethanolic solution, c(KOH) = 0,5 mol/l at 20 C, freshly restandardized before each series of tests. 5.3 Hydrochlori

30、c acid, standard volumetric solution, c(HCI) = 0,5 mol/l at 20 C. It is important that the reagent be taken at the specified temperature of 20 C, particularly the ethanolic solution of potassium hydroxide, as the volume varies greatly with temperature. 5.4 Coloured indicator. Use phenolphthalein, 2

31、g/l solution in ethanol (5.1), or phenol red, 0,4 g/l solution in ethanol, 20 % (volume fraction), if the essential oil has components that contain phenol groups. NOTE This particular case will be specified in the specific standard for the essential oil concerned. 6 Apparatus Usual laboratory appara

32、tus and, in particular, the following. 6.1 Saponification flask, with ground glass neck, of alkali-resistant glass, of capacity 100 ml to 250 ml, to which can be fitted a ground glass air condenser at least 1 m in length with 1 cm to 1,5 cm internal diameter. If necessary, and particularly for the e

33、ssential oils with high light fractions and depending on the time placed in the boiling water bath, the glass tube may be replaced by a water-cooled reflux condenser. 6.2 Test tubes, of capacity 5 ml. 6.3 Burettes, of capacity 25 ml, graduated in 0,05 ml, complying with the requirements of ISO 385-1

34、, class B. 6.4 Boiling water bath. 6.5 Analytical balance, accurate to the nearest 0,001 g. 6.6 Potentiometer. 7 Sampling Sampling is not included in the method specified in this International Standard. A recommended sampling method i sg iv eninIS O21 2 1) . It is important that the laboratory recei

35、ve a representative sample, not damaged or modified during transport or storage before the arrival at the laboratory. 8 Preparation of test sample The test sample shall be prepared according to ISO 356. 1) ISO 212, Essential oils Sampling.ISO 709:2001(E) 3 9 Procedure 9.1 Test portion Weigh, to the

36、nearest 0,005 g, 2 g of the test sample. The test portion may be different from this, if so specified in the specific standard for the essential oil concerned. 9.2 Blank test Carry out a blank test, in parallel with the determination (9.3), under the same conditions and using the same reagents. (See

37、 9.3.3.) 9.3 Determination 9.3.1 Introduce the test portion (9.1) into the saponification flask (6.1). Add from the burette (6.3) 25 ml of the potassium hydroxide solution (5.2) (see note) and fragments of pumice stone or porcelain. NOTE If the test portion has been retained from the determination o

38、f the acid value, it will not be necessary to neutralize it before adding the potassium hydroxide. For oils with a high ester value, increase the volume of the potassium hydroxide solution (5.2) used so that (V 0 V 1 ) (see clause 10) is at least equal to 10 ml. For oils with a low ester value, incr

39、ease the mass of the test portion used. Attach the air condenser or water-cooled reflux condenser, and place the flask in the boiling water bath (6.4) for a time depending on the essential oil analysed. This time is mentioned in the specification for the oil to be tested. Allow to cool and remove th

40、e tube. Add 20 ml of water and 5 drops of the phenolphthalein solution, or of the phenol red solution (5.4) if the essential oil contains phenols or compounds with phenolic groups. 9.3.2 Titrate the excess potassium hydroxide with the hydrochloric acid (5.3). 9.3.3 This determination may be carried

41、out with the solution resulting from the determination of the acid value, which can be used as the blank test, by adding 5 ml of ethanol (5.1) in this blank test before the addition of the 25 ml of potassium hydroxide solution (this volume corresponds to the volume introduced during the determinatio

42、n of the acid value). 9.4 Potentiometry Potentiometry may be used for all the essential oils, but it is particularly recommended for highly coloured essential oils for which it is difficult to appreciate the endpoint of the coloured indicator (e.g. vetiver oil). In this case, the same reagents and a

43、pparatus shall be used. NOTE These special cases will be established in the specific standards for the essential oils concerned.ISO 709:2001(E) 4 10 Expression of results 10.1 Calculation 10.1.1 Ester value The ester value (EV) is given by the formula 01 28,05 EV AV VV m where V 0 is the volume, in

44、millilitres, of hydrochloric acid (5.3) used for the blank test (9.2); V 1 is the volume, in millilitres, of hydrochloric acid (5.3) used for the determination (9.3.2); m is the mass, in grams, of the test portion; AV is the acid value determined according to ISO 1242. The mass fraction of ester, w,

45、 as a percentage, with respect to a stated ester, is given by the formula r EV 561 M w where M r is the relative molecular mass of the ester used to express the results conventionally; EV is the ester value calculated as above. Express the ester value to two significant figures when it is less than

46、100, and to three significant figures when it is 100 or more. 10.1.2 Ester value determined after the acid value When the determination is carried out on the solution resulting from the determination of the acid value, the ester value (EV) is obtained by the formula 01 28,05 EV ( ) VV m where V 1 is

47、 the volume, in millilitres, of hydrochloric acid (5.3) used in the new determination.ISO 709:2001(E) 5 11 Test report The test report shall state: all information necessary for the complete identification of the sample; the sampling method used, if known; the test method used, with reference to thi

48、s International Standard; all operating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test result(s); the test result(s) obtained.ISO 709:2001(E) 6 Annex A (informative) Precision A.1 General At the

49、 time of publication of this International Standard, precision values for this test method have not been established. Nevertheless, taking into account the data available at present, it was considered useful for the users of this International Standard to include some indications of the values obtained for repeatability and reproducibility, and it is expected to be able to specify definitive values in the next revision of this International Stan