1、BRITISH STANDARD BS ISO 1279:1996 Essential Oils Determination of carbonyl value Potentiometric methods using hydroxylammonium chloride ICS 71.100.60; 71.040.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 1279:1996 This British Standard, having been prepared under th
2、e 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 38318 0 National foreword This British Standard reproduces verbatim ISO 1279:1996 and implements it as th
3、e 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-references The British Standards which
4、 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 Catalogue. A British Standard does not
5、 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; present to the responsible int
6、ernational/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, an inside front cover, the IS
7、O 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 1279 Third edition 1996-12-15 Essential oils
8、- Determination of carbonyl value - Potentiometric methods using hydroxylammonium chloride Huiles essentielles - Dgtermination de lindice de carbonyle - Mkthodes potentiom6triques au chlorure dhydroxylammonium Reference number IS0 1279:1996(E) IS0 1279:1996(E) IS0 (the International Organization for
9、 Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which . a technical committee has been established has th
10、e right to be represented on that committee. international organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft In
11、ternational Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard IS0 1279 was prepared by Technical Committee lSO/TC 54, Es
12、sential oils. This third edition cancels and replaces the second edition (IS0 1279:1984), which has been technically revised. 0 0SI 6991 llA sthgir .devreser sselnU esiwrehto ,deificeps on trap fo siht noitacilbup yam eb decudorper ro dezilitu ni yna mrof ro yb yna ,snaem cinortcele ro ,lacinahcem g
13、nidulcni gniypocotohp dna ,mliforcim tuohtiw noissimrep ni gnitirw morf eht .rehsilbup lanoitanretnI noitazinagrO rof noitazidradnatS esaC elatsop 65 l 1121-HC eveneG 02 l dnalreztiwS tenretnI lartnec hc.osi.scosi 004.x ;hc=c ;ten004=a ;osi=p ;scosi=o lartnec=s detnirP ni dnalreztiwS ii INTERNATIONA
14、L STANDARD 0SI IS0 1279:1996(E) Essential oils - Determination of carbonyl values - Potentiometric methods using hydroxylammonium chloride 1 SCOPE This International Standard specifies two methods for the potentiometric determination of the carbonyl value of essential oils which contain carbonyl com
15、pounds, either aldehydes or ketones. Method I (see clause 5), is based on a cold oximation reaction with hydroxylammonium chloride. It applies to essential oils whose main constituents are easily oximable aldehydes and ketones, with the exception of citronella1 which needs a low temperature to avoid
16、 cyclization phenomena and acetalization. NOTE 1 In the case of citronella1 the free hydroxylamine method described in IS0 1271 should be used. NOTE 2 Examples of essential oils concerned are lemongrass, hesperydus and rue. Method II (see clause 6), is based on a hot oximation reaction with hydroxyl
17、ammonium chloride. It applies to essential oils whose main constituents are ketones which are in general oximable only with difficulty. NOTE 3 Examples of essential oils concerned are vetiver, Dalmation sage and white artemisia which contain methylketones oximable only with difficulty. The Internati
18、onal Standard for a specific essential oil will specify the method to be used, whether this is the free hydroxylamine method described in IS0 1271 or another method. 2 NORMATIVE REFERENCES The following standards contain provisions which, through reference in this text, constitute provisions of this
19、 International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated
20、below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 212: 1973, Essential oils - Sampling. IS0 1279:1996(E) 0 0SI IS0 356:1996, Essential oils - Preparation of test sample. IS0 1271:1983, Essential oils - Determination of carbonyl value - Free hydroxylamin
21、e method. 3 DEFINITION For the purposes of this International Standard, the following definition applies. 3.1 carbonyl value (of an essential oil): Number of milligrams of potassium hydroxide, per gram of essential oil, required to neutralize the hydrochloric acid liberated in the oximation reaction
22、 with hydroxylammonium chloride. 4 SAMPLING Sampling shall be carried out in accordance with IS0 212. 5 METHOD I: METHOD OF COLD OXIMATION OF ALDEHYDES WITH HYDROXYL- AMMONIUM CHLORIDE 5.1 Principle Conversion of the carbonyl compounds to oximes by reaction with hydroxylammonium chloride. Potentiome
23、tric determination with standard potassium hydroxide solution of the hydrochloric acid liberated by this reaction. 5.2 Reagents 5.2.1 Potassium hydroxide, standard solution, c(KOH) - 0,5 mol/l in 95 % (V/l/) ethanol. 5.2.2 Potassium hydroxide, standard solution c(KOH) = 0,l mol/l in 95 % (V/V) ethan
24、ol. 5.2.3 Ethanol, 95 % (WV). 5.2.4 Bromophenol blue, 2 g/l solution. Heat 0,2 g of Bromophenol blue in 3 ml of ethanolic potassium hydroxide solution (5.2.2) and 10 ml of ethanol (5.2.3). After cooling, dilute to 100 ml with ethanol. 0 0SI IS0 1279:1996(E) 5.2.5 Hydroxylammonium chloride, 50 g/i so
25、lution. Dissolve 50 g of hydroxylammonium chloride in 100 ml of water and add about 800 ml of ethanol (5.2.3). Neutralize with the ethanolic potassium hydroxide solution(5.2.1) in the presence of 10 ml of the Bromophenol blue solution (5.2.4) to the mid-green endpoint of the indicator (equivalence p
26、oint of pH 3,4) and dilute to 1000 ml with ethanol. NOTE: The neutralized solution is stable for 1 week at least. 5.3 Apparatus Usual laboratory equipment and, in particular, the following. 5.3.1 Beaker, of capacity 100 ml, tall form. 5.3.2 Automatic burette 5.3.3 Recorder 5.3.4 pH-meter 5.3.5 Glass
27、 electrode 5.3.6 Printer 5.4 Procedure 5.4.1 Preparation of test sample See IS0 356. 5.4.2 Test portion Weigh, to the nearest 0,001 g, between 1 g and I,5 g of the essential oil. NOTE: If the test sample should be larger, this will be stated in the appropriate International Standard for the oil conc
28、erned. 5.4.3 Determination Add to the test portion (5.4.2) 25 ml of the hydroxylammonium chloride solution (5.2.5) and mix well. Add 3 drops of Bromophenol blue (5.2.4) and mix well. Dip the glass electrode (5.3.5) into the solution. Titrate with the potassium hydroxide solution (5.2.1) and mix the
29、contents until the pH is lower than 4,20. It is important that the pH value does not exceed 4,20 during the determination. 3 IS0 1279:1996(E) 0 0SI Allow to stand for 15 min. Titrate with potassium hydroxide solution (5.2-l) to the equivalence point the green to blue colour change of the Bromophenol
30、 blue (5.2.4). The equivalence point on pH is around a value of 3,4. 5.4.4 Expression of results 5.4.4.1 The content of carbonyl compounds, expressed as a percentage by mass, of the reference aldehyde specified is given by the formula: IM,xVxc IOm where M r is the relative molecular mass of the alde
31、hyde specified in the standard specific to the essential oil concerned; V is the volume, in millilitres, of potassium hydroxide solution (5.2.1) used in the titration; C is the exact concentration, in moles per litre, of the potassium hydroxide solution; m is the mass, in grams, of the test portion.
32、 5.4.4.2 The carbonyl value, expressed in milligrams of potassium hydroxide per gram of essential oil, is given by the formula: 56 1 Xc I- m where the symbols are as given in 5.4.4.1. 6 METHOD II: METHOD OF HOT OXIMATION OF KETONES WITH HYDROXYL-AMMONIUM CHLORIDE 6.1 Principle Conversion of the carb
33、onyl compounds to oximes by reaction with hydroxylammonium chloride. Determination with potassium hydroxide solution of the hydrochloric acid liberated by the reaction. 4 0 0SI IS0 1279:1996(E) 6.2 Reagents Use the reagents given in 5.2. 6.3 Apparatus Usual laboratory equipment and, in particular, t
34、he following. 6.3.1 Automatic burette, 50/O, l/B. 6.3.2 Beakers, of capacity 100 ml, tall form. 6.3.3 Flask, of capacity 100 ml, with reflux tube. 6.3.4 pH-meter 6.3.5 Glass electrode 6.3.6 Heater with magnetic stirrer 6.4 Procedure 6.4.1 Preparation of test sample See IS0 356. 6.4.2 Test portion We
35、igh, to the nearest 0,001 g, between 2 g and 2,5 g of the essential oil in the flask (6.3.3). See note to 5.4.2. 6.4.3 Determination Add to the test portion (6.4.2) 25 ml of the hydroxylammonium chloride solution (5.2.5). Insert the glass electrode (6.3.5). Titrate with potassium hydroxide (5.2.1) u
36、ntil the pH is lower than 4,2. Add the reflux tube to the flask. Place the flask on the heater (6.3.6)and heat with stirring to a temperature sufficient to keep a constant reflux. After 10 min, cool, add 3 drops of Bromophenol blue (5.2.4) and slowly titrate with the potassium hydroxide solution (5.
37、2.1) to a pH lower than 4,22. It is important that the pH value does not reach or exceed 4,22 during the determination. Stop when the colour begins to change. Put the flask back on the heater. Repeat this operation every 10 min, as many times as necessary, until the addition of a supplementary drop
38、of solution is enough to pass the equivalence point. IS0 1279:1996(E) 0 0SI NOTE: The determination time is usually 2 h, but for certain fragrances this is not enough. In this case, go on until the inflexion curve. 6.4.4 Expression of results Trace the pH curve as a function of the volume V of potas
39、sium hydroxide (5.2.1) used in the titration: pH = f(V) Note the equivalence point. Calcul Calcul 7 ate the content of carbonyl compounds using the formula given in 5.4.4.1. ate the carbonyl value using the formula given in 5.4.4.2. TEST REPORT The test report shall include the method used and the r
40、esults obtained. It shall also mention any operating details not specified in this International Standard or regarded as optional, together with details of any incidents which might have influenced the results. The test report shall include all details necessary for the complete identification of th
41、e sample. 6 BS ISO 1279:1996 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 international level. It is incorporated by Royal Charter
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