ISO-5509-2000.pdf
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1、Reference number ISO 5509:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 5509 Second edition 2000-04-01 Animal and vegetable fats and oils Preparation of methyl esters of fatty acids Corps gras dorigines animale et vgtale Prparation des esters mthyliques dacides gras ISO 5509:2000(E) PDF disclaimer Thi
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6、ter. ISO copyright office Case postale 56 ? CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 734 10 79 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reserved -,-,- ISO 5509:2000(E) ISO 2000 All rights reservediii Foreword ISO (the International Organization
7、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 technical committee has been established has t
8、he 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 matters of electrotechnical standardization. Interna
9、tional 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 voting. Publication as an International Standard requires approval by at least 75 % of the memb
10、er 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 identifying any or all such patent rights. International Standard ISO 5509 was prepared by Technical Com
11、mittee ISO/TC 34,Agricultural food products, Subcommittee SC 11,Animal and vegetable fats and oils. This second edition cancels and replaces the first edition (ISO 5509:1978), which has been technically revised. Annex A forms a normative part of this International Standard. Annex B is for informatio
12、n only. -,-,- ISO 5509:2000(E) iv ISO 2000 All rights reserved Introduction ISO 5509 contains three different procedures to prepare methyl esters. The general method is the BF3method which is applicable to oils and fats and free fatty acids but which is less applicable to caproic acid (C6) and not a
13、pplicable to butyric acid (C4). The application field is GLC, TLC and IR. Two alternative methods not involving BF3are given using trimethylsulfonium hydroxide and potassium hydroxide in methanol. Both methods are rapid methods for GLC analysis only. The second method (trimethylsulfonium hydroxide m
14、ethod), which is for GLC analyses only, can be used for all fats and oils including milk fat and milk fat containing blends. In the case of short fatty acids (C4 to C8) the use of an internal standard is recommended. The third method (trans-esterification method) can be used for neutral oils and fat
15、s, and can also be used for the quantitative analysis of oils and fats with short-chain fatty acids down to butyric acid (C4). For the determination of C4 and/or C6, only the internal standard method is maintained. The principal new approach in this revision is the use of isooctane as solvent instea
16、d of hexane or pentane. This is based on references 1 and 2, which showed better results especially for the BF3method when using isooctane. -,-,- INTERNATIONAL STANDARDISO 5509:2000(E) ISO 2000 All rights reserved1 Animal and vegetable fats and oils Preparation of methyl esters of fatty acids 1Scope
17、 This International Standard specifies methods of preparing the methyl esters of fatty acids. It includes methods for preparing fatty acid methyl esters from animal and vegetable fats and oils, fatty acids and soaps. To cover different requirements, three methylation methods are specified, as follow
18、s: a)boron trifluoride (BF3) method (see clause 3); b)trimethylsulfonium hydroxide (TMSH) method (see clause 4); c)trans-esterification method (see clause 5). Methyl esters so produced are used in various analytical procedures requiring such derivatives, for example gas- liquid chromatography (GLC),
19、 thin-layer chromatography (TLC) and infrared spectrometry (IR). 2Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, an
20、y of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative documen
21、t referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 661,Animal and vegetable fats and oils Preparation of test sample. ISO 3696,Water for analytical laboratory use Specification and test methods. 3General method using boron trifluoride WAR
22、NING The method described involves the use of potentially hazardous reagents. Normal precautions shall be taken for eye protection and for protection from the dangers of corrosive chemical burns. Boron trifluoride is poisonous. For this reason, it is not recommended that the analyst prepare the meth
23、anolic solution of boron trifluoride from methanol and boron trifluoride. (See A.1 in annex A.) 3.1Principle The glycerides are saponified with methanolic sodium hydroxide. The soaps are converted into methyl esters by reaction with a boron trifluoride/methanol complex. For analysis of pure fatty ac
24、ids and soaps, saponification with sodium hydroxide is not necessary and esters can be prepared directly by reaction with boron trifluoride. ISO 5509:2000(E) 2 ISO 2000 All rights reserved 3.2Applicability This method is to be preferred for most oils, fats and derivatives (fatty acids, soaps) with t
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