BS ISO 12871-2010 Olive oils and olive-pomace oils - Determination of aliphatic alcohols content by capillary gas chromatography《橄榄油和橄榄果渣油 毛细管气相色谱法测定脂肪醇含量》.pdf

1、BS ISO12871:2010ICS 67.200.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDOlive oils and olive-pomace oils Determination ofaliphatic alcoholscontent by capillarygas chromatographyThis British Standardwas published under theauthority of the StandardsPolicy and

2、 StrategyCommittee on 30 June2010 BSI 2010ISBN 978 0 580 63954 8Amendments/corrigenda issued since publicationDate CommentsBS ISO 12871:2010National forewordThis British Standard is the UK implementation of ISO 12871:2010.The UK participation in its preparation was entrusted to TechnicalCommittee AW

3、/307, Oil seeds, animal and vegetable fats and oils andtheir by products.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct appl

4、ication.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 12871:2010Reference numberISO 12871:2010(E)ISO 2010INTERNATIONAL STANDARD ISO12871First edition2010-05-01Olive oils and olive-pomace oils Determination of aliphatic alcohols content by capillary gas chroma

5、tographyHuiles dolive et huiles de grignons dolive Dtermination de la teneur en alcools aliphatiques par chromatographie en phase gazeuse sur colonne capillaire BS ISO 12871:2010ISO 12871:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy,

6、 this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Sec

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8、nsure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2010 All rights reserved. Unless otherwise specified, no part of this publica

9、tion 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 member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva

10、20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reservedBS ISO 12871:2010ISO 12871:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and def

11、initions .1 4 Principle1 5 Reagents.1 6 Apparatus.2 7 Sampling.3 8 Preparation of the test sample.3 9 Procedure.4 9.1 Preparation of the unsaponifiable matter .4 9.2 Separation of alcoholic fractions.4 9.3 Preparation of the trimethylsilyl ethers.5 9.4 Gas chromatographic analysis 6 10 Precision.7 1

12、0.1 Interlaboratory test7 10.2 Repeatability 7 10.3 Reproducibility 7 11 Test report8 Annex A (informative) Determination of the linear velocity of the gas .9 Annex B (informative) Results of an interlaboratory test .10 Bibliography11 BS ISO 12871:2010ISO 12871:2010(E) iv ISO 2010 All rights reserve

13、dForeword 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 member body interested in a subject for which a

14、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 International Electrotechnical Commission (IEC) on all matter

15、s of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulat

16、ed to the member bodies for 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 document may be the subject of patent rights. ISO shall not be held responsible

17、 for identifying any or all such patent rights. ISO 12871 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. BS ISO 12871:2010ISO 12871:2010(E) ISO 2010 All rights reserved vIntroduction As part of the Trade standard applying to oliv

18、e oils and olive-pomace oils, the International Olive Oil Council (IOOC) now known as the International Olive Council (IOC) published COI/T.20/Doc. 26:20034. COI/T.20/Doc. 26 was applicable to olive and olive-pomace oils and was used to distinguish between lampante virgin olive oils and crude olive-

19、pomace oils. Olive pomace is the residual paste which still contains a variable amount of water and oil after pressing or centrifuging. In 2008, the IOC submitted the document to ISO/TC 34/SC 11 for adoption as an International Standard. BS ISO 12871:2010BS ISO 12871:2010INTERNATIONAL STANDARD ISO 1

20、2871:2010(E) ISO 2010 All rights reserved 1Olive oils and olive-pomace oils Determination of aliphatic alcohols content by capillary gas chromatography 1 Scope This International Standard specifies a procedure for the determination of the content, as a mass fraction expressed as milligrams per kilog

21、ram, of aliphatic alcohols in olive oils and olive-pomace oils. NOTE This International Standard is based on COI/T.20/Doc. 26:20034. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies.

22、 For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 aliphatic alcoho

23、ls content sum of the aliphatic alcohols with carbon number C22, C24, C26, and C28, as a mass fraction, determined according to the method specified in this International Standard 4 Principle The oil, to which 1-eicosanol has been added as an internal standard, is saponified with ethanolic potassium

24、 hydroxide and the unsaponifiable matter extracted with diethyl ether. The alcoholic fraction is separated from the unsaponifiable matter by chromatography on a basic silica gel plate; the alcohols recovered from the silica gel are transformed into trimethylsilyl ethers (TMSE) and analysed by capill

25、ary gas chromatography. 5 Reagents WARNING Comply with any local regulations which specify the handling of hazardous substances. Technical, organizational and personal safety measures shall be followed. During the analysis, unless otherwise stated, use only reagents of recognized analytical grade, a

26、nd distilled or demineralized water or water of equivalent purity. 5.1 Potassium hydroxide, ethanolic solution, c(KOH) 2 mol/l. Dissolve, while cooling, 130 g potassium hydroxide w(KOH) = 85 % mass fraction minimum in 200 ml water and make up to 1 l with ethanol. Store the solution in a well-stopper

27、ed opaque glass bottle. BS ISO 12871:2010ISO 12871:2010(E) 2 ISO 2010 All rights reserved5.2 Potassium hydroxide, ethanolic solution, c (KOH) 0,2 mol/l. Dissolve 13 g potassium hydroxide in 20 ml water and make up to 1 l with ethanol. 5.3 Diethyl ether. 5.4 Anhydrous sodium sulfate. 5.5 Glass plates

28、, coated with silica gel, without fluorescence indicator, 0,25 mm thick. Suitable ready-for-use products are available commercially. 5.6 Benzene, chromatography grade. 5.7 Acetone, chromatography grade. 5.8 Hexane, chromatography grade. 5.9 Diethyl ether, chromatography grade. 5.10 Chloroform, chrom

29、atography grade. 5.11 Reference solution for thin-layer chromatography: 1-eicosanol, 0,5 g/100 ml solution in chloroform, or a fraction of alcohols obtained as indicated in 9.2 from the unsaponifiable matter of an olive-pomace oil. 5.12 2,7-Dichlorofluorescein in ethanol, 0,2 g/100 ml solution. Make

30、 slightly basic by adding a few drops of alcoholic potassium hydroxide solution (5.1). 5.13 Anhydrous pyridine, chromatography grade. 5.14 Hexamethyldisilazane (HMDS). 5.15 Trimethylchlorosilane (TMCS). 5.16 Standard solutions of trimethylsilyl ethers (TMSE), of aliphatic alcohols from C20to C28. Pr

31、epare from mixtures of pure alcohols immediately prior to use. 5.17 Internal standard solution: solution of 1-eicosanol in chloroform, mass concentration 0,1 g/100 ml. 5.18 Carrier gas: hydrogen or helium, gas chromatography grade. 5.19 Auxiliary gas: nitrogen, gas chromatography grade. 6 Apparatus

32、Usual laboratory equipment and in particular the following. 6.1 Round-bottomed flask, of capacity 250 ml, fitted with a reflux condenser having ground-glass joints. 6.2 Separating funnel, of capacity 500 ml. 6.3 Round-bottomed flasks, of capacity 250 ml. 6.4 Chromatographic chamber for thin-layer ch

33、romatography, suitable for glass plates of dimensions 20 cm 20 cm. 6.5 Ultraviolet lamp, of wavelength 366 nm or 254 nm. BS ISO 12871:2010ISO 12871:2010(E) ISO 2010 All rights reserved 36.6 Microsyringes, of capacities 100 l and 500 l. 6.7 Cylindrical filter funnel with a G3 porous septum (porosity

34、15 m to 40 m), of approximate dimensions: diameter 2 cm and depth 5 cm, with an attachment suitable for filtration under vacuum and a 12/21 male ground-glass joint. 6.8 Vacuum conical flask, of capacity 50 ml, with a 12/21 female ground-glass joint which can be fitted to the filter funnel (6.7). 6.9

35、 Test-tube, of capacity 10 ml, with a tapering bottom and a sealing stopper. 6.10 Gas chromatograph, suitable for use with capillary columns, equipped with the components specified in 6.10.1 to 6.10.4. 6.10.1 Column oven, capable of maintaining a temperature to within 1 C. 6.10.2 Split injection uni

36、t, temperature-adjustable, with a persilylated glass vaporizing element, or an on-column unit. 6.10.3 Flame ionization detector. 6.10.4 Integration system. 6.11 Fused silica capillary column, of length 20 m to 30 m, internal diameter 0,25 mm to 0,32 mm, with SE-52 or SE-541)liquid phase or equivalen

37、t, with a film thickness between 0,10 m and 0,30 m. 6.12 Microsyringe for gas chromatography, of capacity 10 l, with hardened needle. 6.13 Analytical balance, sensitive to 1 mg (with 0,1 mg display). 6.14 Desiccator, with calcium chloride as desiccant. 6.15 Drying oven. 7 Sampling Sampling is not pa

38、rt of the method specified in this International Standard. A recommended sampling method is given in ISO 55551. It is important that the laboratory receive a truly representative sample which has not been damaged or changed during transport or storage. 8 Preparation of the test sample Prepare the te

39、st sample in accordance with ISO 661. 1) SE-52 and SE-54 are examples of suitable products available commercially. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of these products. BS ISO 12871:2010ISO 12871:2010(E) 4 ISO 2010 Al

40、l rights reserved9 Procedure 9.1 Preparation of the unsaponifiable matter 9.1.1 Using a 500 l microsyringe (6.6), transfer to a 250 ml round-bottomed flask (6.1) a volume of internal standard solution (5.17) containing a quantity of 1-eicosanol approximately equal to 10 % of the content of aliphatic

41、 alcohols in the test portion. For example, to 5 g of sample, add 250 l of the internal standard solution for olive oil and 1 500 l for olive-pomace oil. Evaporate to dryness under a stream of nitrogen, then weigh (6.13) accurately 5,000 g of the dry filtered sample into the same flask. 9.1.2 Add 50

42、 ml of 2 mol/l ethanolic potassium hydroxide solution (5.1), fit the reflux condenser and boil gently on a steam bath, stirring continuously throughout the heating process until saponification has taken place, i.e. until the solution becomes clear. Continue heating for a further 20 min and then add

43、50 ml of water through the condenser. The condenser is then disconnected and the flask cooled to approximately 30 C. 9.1.3 Transfer the contents of the flask quantitatively to a 500 ml separating funnel (6.2), progressively adding portions of about 50 ml water. Add approximately 80 ml of diethyl eth

44、er (5.9), shake vigorously for approximately 30 s, and allow to settle. NOTE Emulsions are broken by spraying small quantities of diethyl ether or methanol into the funnel. Separate off the lower aqueous phase, collecting it in a second separating funnel. Two further extractions are performed in the

45、 same manner on the aqueous phase, using 60 ml to 70 ml diethyl ether each time. 9.1.4 The diethyl ether extracts are combined in a separating funnel and washed with water (50 ml at a time) until the washing water gives a neutral reaction against phenolphthalein. Discard the washing water, dry with

46、anhydrous sodium sulfate (5.4) and filter into a 250 ml round-bottomed flask (6.3) that has previously been weighed, and wash the funnel and filter with small quantities of diethyl ether which are added to the total. 9.1.5 Distil the ether down to a few millilitres, then bring to dryness under a sli

47、ght vacuum or under a stream of nitrogen, completing the drying process in an oven (6.15) maintained at 103 C for approximately 10 min; weigh (6.13) after cooling in a desiccator (6.14). 9.2 Separation of alcoholic fractions 9.2.1 Prepare basic TLC plates by immersing the silica gel plates (5.5) com

48、pletely in an 0,2 mol/l potassium hydroxide solution (5.2) for 10 s, leaving them to dry for 2 h under an extractor hood and finally placing them in an oven (6.15) at 100 C for 1 h. NOTE When basic silica gel plates are used to separate the alcoholic fraction, there is no need to treat the unsaponif

49、iable matter with alumina. It follows that all acid compounds (fatty acids and others) are retained at the origin, thereby producing both aliphatic alcohol and terpenic alcohol bands, which are both separated distinctly from the sterol band. Remove the plate from the oven and keep in a desiccator (6.14) until required for use (plates treated in this way shall be used within 15 days). 9.2.2 Place a hexane-diethyl ether mixture (volume fraction of hexane 65 ml/100 ml and of diethyl ether 35 ml/100 ml) in