《BS-ISO-18252-2006.pdf》由会员分享,可在线阅读,更多相关《BS-ISO-18252-2006.pdf(22页珍藏版)》请在三一文库上搜索。
1、BRITISH STANDARD BS ISO 18252:2006 Anhydrous milk fat Determination of sterol composition by gas liquid chromatography (Routine method) ICS 67.100.01 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 18252:2006 This British Standard w
2、as published under the authority of the Standards Policy and Strategy Committee on 15 February 2006 BSI 15 February 2006 ISBN 0 580 47836 X National foreword This British Standard reproduces verbatim ISO 18252:2006 and implements it as the UK national standard. The UK participation in its preparatio
3、n was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk products, 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 publicati
4、ons 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 the necessa
5、ry 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 the interpr
6、etation, or proposals for change, and keep 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 ISO title page, pages ii to v, a blank page, pages 1 to 13 and a
7、 back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference numbers ISO 182
8、52:2006(E) IDF 200:2006(E) INTERNATIONAL STANDARD ISO 18252 IDF 200 First edition 2006-02-01 Anhydrous milk fat Determination of sterol composition by gas liquid chromatography (Routine method) Matire grasse anhydre du lait Dtermination de la composition strolique par chromatographie liquide en phas
9、e gazeuse (Mthode de routine) BS ISO 18252:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv 1 Sco
10、pe 1 2 Normative references1 3 Terms and definitions .1 4 Principle2 5 Reagents.2 6 Apparatus .3 7 Sampling.5 8 Preparation of test sample5 9 Procedure .5 9.1 Sterol standard solutions .5 9.2 Test portion6 9.3 Saponification6 9.4 Extraction of the unsaponifiable matter6 9.5 Qualitative analysis .6 9
11、.6 Quantitative analysis.7 10 Precision.8 10.1 Interlaboratory test8 10.2 Repeatability.8 10.3 Reproducibility.8 11 Test report9 Annex A (informative) Example of the gas-liquid chromatographic analysis.10 Annex B (informative) Results of an interlaboratory trial .11 Bibliography13 BS ISO 18252:2006
12、Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv 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
13、 normally carried out through ISO technical committees. Each 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
14、 in the work. ISO collaborates closely with the International 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 2. The main task of technical committees is to pr
15、epare International Standards. 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 member bodies casting a vote. Attention is drawn to the possibility that
16、 some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 18252IDF 200 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International
17、 Dairy Federation (IDF). It is being published jointly by ISO and IDF. BS ISO 18252:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI v Foreword IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a
18、 National Committee in every member country. Every National Committee has the right to be represented on the IDF Standing Committees carrying out the technical work. IDF collaborates with ISO in the development of standard methods of analysis and sampling for milk and milk products. Draft Internatio
19、nal Standards adopted by the Action Teams and Standing Committees are circulated to the National Committees for voting. Publication as an International Standard requires approval by at least 50 % of the IDF National Committees casting a vote. Attention is drawn to the possibility that some of the el
20、ements of this document may be the subject of patent rights. IDF shall not be held responsible for identifying any or all such patent rights. ISO 18252IDF 200 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk p
21、roducts. It is being published jointly by IDF and ISO. All work was carried out by the Joint ISO-IDF Action Team on Fat, of the Standing Committee on Main components in milk, under the aegis of its project leaders, Mrs. M. Juarez (ES) and Mrs. G. Contarini (IT). BS ISO 18252:2006 Licensed Copy: shef
22、fieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Anhydrous milk fat Determination of sterol composition by gas liquid chromatography (Routine meth
23、od) WARNING The use of this International Standard may involve hazardous materials, operations and equipment. This standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish safety and health practices and
24、determine the applicability of regulatory limitations prior to use. 1 Scope This International Standard specifies a routine gas liquid chromatographic method for the determination of the sterol composition in anhydrous milk fat extracted from dairy products directly on the unsaponifiable matter, wit
25、hout purification and derivatization. The first goal of this International Standard is the quantitative evaluation of cholesterol, which represents about 98 % of the sterol fraction of pure milk fat. Moreover, in the case of analysis of milk fat in a mixture of vegetable fats, the specified procedur
26、e allows the evaluation of the most important phytosterols. The procedure has been validated on milk fat samples containing approximately 28 % to 32 % of vegetable fat. Due to the absence of the purification step, which allows the complete removal of interfering compounds from the unsaponifiable mat
27、ter, particular care should be taken when applying this method to the verification of the purity of milk fat of unknown origin. In the case of suspicious results, the reference method described in ISO 12078IDF 159 can be used. 2 Normative references The following referenced documents are indispensab
28、le for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 14156IDF 172,
29、 Milk and milk products Extraction methods for lipids and liposoluble compounds 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 sterol composition mass fraction of substances determined by the procedure specified in this International Standar
30、d NOTE The sterol composition can be expressed either as milligrams per 100 g of fat, or as percent of total sterol content. BS ISO 18252:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 4 Principle 5cholestane is added to the test sam
31、ple as the internal standard. The fat is saponified with methanolic potassium hydroxide. Unsaponifiable matter is extracted by diethyl ether. It is concentrated and determined by capillary gas-liquid chromatography. Individual sterols are identified by comparison with the retention time of the refer
32、ence standard sample. Sterols are quantified by reference to the internal standard. 5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. 5.1 Water, complying with grade 2 in accordance with ISO 3696:1987. 5.2 Ethanol (C2H5OH), absolute. 5.3 Methanol (CH3OH), conta
33、ining a mass fraction of water of u 0,5 %. 5.4 Saponification reagent, potassium hydroxide methanolic solution, c(KOH) = 2 mol/l. Dissolve 11,2 g of KOH in 100 ml of methanol (5.3) and mix well. 5.5 Sodium sulfate (Na2SO4), anhydrous. 5.6 Diethyl ether (C2H5OC2H5), free from peroxides. 5.7 n-Hexane
34、CH3(CH2)4CH3. 5.8 5 -Cholestane, of purity 99 %. 5.9 5 -Cholestane standard solution. Accurately weigh about 60 mg of 5-cholestane (5.8) into a 100 ml one-mark volumetric flask (6.4). Dilute to the 100 ml mark with n-hexane( 5.7)/ethanol (5.2) with a ratio of 1:10 or n-hexane (5.7) and mix. The 5-ch
35、olestane standard solution may be stored in a refrigerator for one month. 5.10 Cholesterol, of purity 99 %. 5.11 Cholesterol standard solution. Accurately weigh about 60 mg of cholesterol (5.10) into a 100 ml one-mark volumetric flask (6.4). Dilute to the 100 ml mark with ethanol (5.2) or n-hexane (
36、5.7) and mix. The cholesterol standard solution may be stored in a refrigerator for one month. 5.12 Campesterol, of purity 65 %. 5.13 Campesterol standard solution. Accurately weigh about 10 mg of campesterol (5.12) into a 100 ml one-mark volumetric flask (6.4). Dilute to the 100 ml mark with n-hexa
37、ne (5.7) and mix. The campesterol standard solution may be stored in a refrigerator for one month. 5.14 Stigmasterol, of purity 95 %. BS ISO 18252:2006 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 5.15 Stigmasterol standard solution. Ac
38、curately weigh about 10 mg of stigmasterol (5.14) into a 100 ml one-mark volumetric flask (6.4). Dilute to the 100 ml mark with n-hexane (5.7) and mix. The stigmasterol standard solution may be stored in a refrigerator for one month. 5.16 -Sitosterol, of purity 95 %. 5.17 -Sitosterol standard soluti
39、on. Accurately weigh about 10 mg of -sitosterol (5.16) into a 100 ml one-mark volumetric flask (6.4). Dilute to the 100 ml mark with n-hexane (5.7) and mix. The -sitosterol standard solution may be stored in a refrigerator for one month. NOTE Since the phytosterol standard solutions (5.13, 5.15 and
40、5.17) are used only for a qualitative evaluation, they may be replaced by sterols prepared from soya oil having campesterol, stigmasterol and -sitosterol as major components. 6 Apparatus WARNING Since the determination involves the use of volatile flammable solvents, electrical apparatus employed sh
41、all comply with the legislation relating to the hazards in using such solvents. Usual laboratory apparatus and, in particular, the following. 6.1 Drying oven, capable of being maintained at a temperature of between 50 C and 70 C. 6.2 Analytical balance, capable of weighing to the nearest 1 mg, with
42、a readability of 0,1 mg. 6.3 Round-bottomed flasks, with ground neck, of capacity 100 ml. 6.4 One-mark volumetric flasks, of capacity 100 ml. 6.5 Graduated pipettes, of capacity 10 ml. 6.5 One-mark pipettes, of capacity 1 ml. 6.7 Water bath, capable of being maintained at 50 C 2 C and of boiling. 6.
43、8 Reflux condenser, to fit the round-bottomed flask (6.3). 6.9 Separating funnels, of capacity 100 ml. 6.10 Solvent dispenser or graduated cylinders, of capacities 10 ml and 20 ml. 6.11 Distillation or evaporation apparatus (e.g. rotary vacuum evaporator), for distilling or evaporating solvents, mai
44、ntaining all temperatures up to boiling. 6.12 Glass funnels, of diameter 100 mm. 6.13 Dry filter paper, folded, fast grade, of diameter 200 mm. 6.14 Vials, cone shaped inside, of capacities 5 ml and 10 ml. 6.15 Nitrogen supply, with gas purity of at least 99 %. BS ISO 18252:2006 Licensed Copy: sheff
45、ieldun sheffieldun, na, Mon Nov 27 03:46:32 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 6.16 Test tube, with PTFE-lined screw cap, of capacity 50 ml. 6.17 Gas liquid chromatography. 6.17.1 Injector. Maintain the vaporizing type injector (split/splitless), which is equipped with a thermo-stable sept
46、um, at a temperature of 30 C above the maximum oven temperature. In the case of a cold on-column injector, maintain the injector at a temperature several degrees below the boiling point of the solvent. 6.17.2 Oven, capable of being run with the temperature programmed between 50 C and 320 C. 6.17.3 C
47、olumn, fused silica capillary column. Different types of stationary phase, film thickness, column length, and diameter may be used to successfully obtain sterol separation. In any case, the selected column shall produce both a complete separation between the solvent peak and 5-cholestane (i.e. 5-cho
48、lestane shall not elute in the broadening of the solvent) and a baseline resolution among the cholesterol, campesterol, stigmasterol and -sitosterol peaks. Moreover, no baseline bleeding shall appear during the whole gas chromatographic (GC) run. An example of a correct GC profile, obtained by using
49、 the operative conditions listed in 6.18.2, is shown in Figure A.1. NOTE Commercial stationary phases containing dimethylpolysiloxane or dimethylpolysiloxane, together with different percentages of phenyl/cyanopropyl-polysiloxane, are suitable. 6.17.4 Flame ionization detector, capable of being heated to a temperature of 30 C above the final temperature of the column oven. 6.17.5 Carrier gas, nitrogen, helium or hydrogen, of purity at least 99,999 % 6.17.6 Other g
链接地址:https://www.31doc.com/p-3747258.html