1、BRITISH STANDARDBS EN ISO 5943:2006Cheese and processed cheese products Determination of chloride content Potentiometric titration methodThe European Standard EN ISO 5943:2006 has the status of a British StandardICS 67.100.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g
2、48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN ISO 5943:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2006 BSI 2006ISBN 0 580 49577 9Nationa
3、l forewordThis British Standard was published by BSI. It is the UK implementation of EN ISO 5943:2006 published on 1 October 2006. It is identical with ISO 5943:2006, published on 3 October 2006. It supersedes BS EN ISO 5943:2006, published on 10 February 2006, which is withdrawn.The UK participatio
4、n in its preparation was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on AW/5 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are respo
5、nsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 5943October 2006ICS 67.100.30 Supersedes EN ISO 5943:2006 English Version
6、Cheese and processed cheese products - Determination ofchloride content - Potentiometric titration method (ISO5943:2006)Fromages et fromages fondus - Dtermination de la teneuren chlorures - Mthode par titrage potentiomtrique (ISO5943:2006)Kse und Schmelzkse - Bestimmung des Chloridgehaltes- Potentio
7、metrisches Titrationsverfahren (ISO 5943:2006)This European Standard was approved by CEN on 14 August 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteratio
8、n. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationu
9、nder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Ice
10、land, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Sta
11、ssart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 5943:2006: E2 Foreword This document (EN ISO 5943:2006) has been prepared by Technical Committee ISO/TC 34 “Agricultural food products“ in collaborati
12、on with Technical Committee CEN/TC 302 “Milk and milk products - Methods of sampling and analysis“, the secretariat of which is held by NEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by April 2
13、007, and conflicting national standards shall be withdrawn at the latest by April 2007. This document supersedes EN ISO 5943:2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria
14、, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The tex
15、t of ISO 5943:2006 has been approved by CEN as EN ISO 5943:2006 without any modifications. EN ISO 5943:2006Reference numbersISO 5943:2006(E)IDF 88:2006(E)INTERNATIONAL STANDARD ISO5943IDF88Fourth edition2006-10-01Cheese and processed cheese products Determination of chloride content Potentiometric t
16、itration method Fromages et fromages fondus Dtermination de la teneur en chlorures Mthode par titrage potentiomtrique EN ISO 5943:2006ii iiiContents Page Foreword iv Foreword. v 1 Scope . 1 2 Terms and definitions. 1 3 Principle. 1 4 Reagents 1 5 Apparatus 2 6 Sampling 2 7 Preparation of test sample
17、. 2 8 Procedure 2 8.1 Test portion . 2 8.2 Determination 3 8.3 Blank test. 3 9 Calculation and expression of results 3 9.1 Calculation. 3 9.2 Expression of results . 3 10 Precision 4 10.1 Interlaboratory test . 4 10.2 Repeatability 4 10.3 Reproducibility 4 11 Test report . 4 Bibliography . 5 EN ISO
18、5943:2006iv 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 member body interested in a subject f
19、or 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 International Electrotechnical Commission (IEC) on
20、 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 prepare International Standards. Draft International Standards adopted by the technical committees a
21、re 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 some of the elements of this document may be the subject of patent rights. ISO shall not be held
22、responsible for identifying any or all such patent rights. ISO 5943IDF 88 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO and IDF. This edition of ISO 5943IDF 8
23、8 cancels and replaces ISO 5943IDF 88:2004, of which it constitutes a minor revision. There was an error in the calculation given in 9.1. A factor of 1 000 has been added and molar mass is now used. EN ISO 5943:2006vForeword IDF (the International Dairy Federation) is a worldwide federation of the d
24、airy sector with a 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
25、. Draft International 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 t
26、hat some of the elements 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 5943IDF 88 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5,
27、 Milk and milk products. It is being published jointly by IDF and ISO. All work was carried out by the former Joint ISO/IDF/AOAC Group of Experts, Nitrate, nitrite and phosphorus in cheese, under the aegis of its chairman, Mr G. Brthen (NO). This edition of ISO 5943IDF 88 cancels and replaces ISO 59
28、43IDF 88:2004, of which it constitutes a minor revision. There was an error in the calculation given in 9.1. A factor of 1 000 has been added and molar mass is now used. EN ISO 5943:2006blank1Cheese and processed cheese products Determination of chloride content Potentiometric titration method 1 Sco
29、pe This International Standard specifies a potentiometric titration method for the determination of the chloride content of cheese and processed cheese products. The method is applicable to all cheeses and processed cheese products containing more than 0,2 % (mass fraction) of chloride ion. 2 Terms
30、and definitions For the purposes of this document, the following terms and definitions apply. 2.1 chloride content of cheese and processed cheese products mass fraction of substances determined by the procedure specified in this International Standard NOTE It is expressed as a mass fraction, in perc
31、ent, of chloride ion or sodium chloride or any other chloride. 3 Principle A test portion is suspended in water. The suspension is acidifed with nitric acid then the chloride ions are titrated potentiometrically with a silver nitrate standard solution. 4 Reagents Use only reagents of recognized anal
32、ytical grade, unless otherwise specified, and distilled or demineralized water or water of at least equivalent purity. 4.1 Silver nitrate standard solution, c(AgNO3) = 0,08 mol/l to 0,12 mol/l. Dissolve 13,6 g to 20,4 g of silver nitrate in water which is practically free from carbon dioxide and dil
33、ute to 1 000 ml. Standardize the solution against sodium chloride (NaCl), which has previously been dried at 300 C, expressing the concentration of the silver nitrate standard solution to four decimal places. Store the solution away from direct light. 4.2 Nitric acid, c(HNO3) 4 mol/l. EN ISO 5943:20
34、062 5 Apparatus 5.1 Device for grinding or grating cheese, capable of being cleaned easily. 5.2 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg. 5.3 Blender. 5.4 Potentiometer, provided with a measuring electrode suitable for the determination of chloride (e
35、.g. a silver electrode) and a reference electrode e.g. a mercury(l) sulfate electrode. 5.5 Vessel, suitable for blending and titrating. 5.6 Graduated cylinders, of capacity 10 ml and 50 ml. 5.7 Burette, graduated in divisions of 0,1 ml, of capacity 50 ml, or an automatic plunger burette, readable to
36、 the nearest 0,01 ml. The burette, or automatic plunger burette, should preferably be made of brown glass. 5.8 Stirrer. 6 Sampling A representative sample should have been sent to the laboratory. It should not have been damaged or changed during transport or storage. Sampling is not part of the meth
37、od specified in this International Standard. A recommended sampling method is given in ISO 707IDF 501. 7 Preparation of test sample Prior to analysis, remove the rind or smear or mouldy surface layer of the cheese, in such a way as to provide a sample representative of the cheese as it is usually co
38、nsumed. Grind or grate the sample by means of an appropriate device (5.1). Mix the ground or grated mass quickly, and if possible grind or grate a second time and again mix thoroughly. If the sample cannot be ground or grated, mix it thoroughly by intensive stirring and kneading. Transfer the test s
39、ample to an airtight container to await analysis, which should be carried out as soon as possible after grinding. If delay is unavoidable, take all precautions to ensure proper preservation of the sample and to prevent condensation of moisture on the inside surface of the container. The storage temp
40、erature should be 10 C to 12 C. Clean the device after grinding or grating each sample. 8 Procedure 8.1 Test portion Weigh, to the nearest 0,001 g, 2 g to 5 g of the test sample (Clause 7) into the vessel (5.5). EN ISO 5943:200638.2 Determination 8.2.1 Add 30 ml of water at about 55 C. Suspend the t
41、est portion using the blender (5.3). Rinse the blender with approximately 10 ml of water, collecting the rinsings in the vessel. 8.2.2 Add 2 ml to 3 ml of the nitric acid (4.2). Put the measuring electrode and the reference electrode into the suspension. Titrate the contents of the vessel with the s
42、ilver nitrate standard solution (4.1) using the burette (5.7), stirring continuously, until the endpoint has nearly been reached. Then titrate cautiously until reaching the endpoint, which corresponds to the maximum potential difference observed between two successive equal additions (of about 0,05
43、ml) of the silver nitrate standard solution. 8.3 Blank test Carry out a blank test using the reagents but omitting the test portion. 9 Calculation and expression of results 9.1 Calculation Calculate the chloride content, wCl, as a mass fraction in percent, by means of the equation: 10Cl()1000100 %cV
44、V Mwm = where V0is the volume, in millilitres, of the silver nitrate standard solution used in the blank test (8.3); V1is the volume, in millilitres, of the silver nitrate standard solution used in the determination (8.2.2); c is the actual concentration, expressed in moles per litre ( 1 000 ml), of
45、 the silver nitrate standard solution (4.1); m is the mass, in grams, of the test portion (8.1); M is the molar mass used for expressing the result as a mass fraction in percent of the chloride concerned, for example, M = 35,5 for expression as % Cl, M = 58,4 for expression as % NaCl, M = 74,6 for e
46、xpression as % KCl. 9.2 Expression of results Report the result to the second decimal place. EN ISO 5943:20064 10 Precision 10.1 Interlaboratory test The values for repeatability and reproducibility were derived from the results of an interlaboratory test (see 4) carried out in accordance with ISO 5
47、725:19861). 10.2 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of cases be gr
48、eater than 0,02 g of Clion (for the equivalent quantity of any chloride) per 100 g of product. 10.3 Reproducibility The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories with different operators using different eq
49、uipment, will in not more than 5 % of cases be greater than 0,06 g of Clion (or the equivalent quantity of any chloride) per 100 g of product. 11 Test report The test report shall specify: a) all information necessary for the complete identification of the sample; b) the sampling method used, if known; c) the test method used, with reference to this International Standard; d) all operating details not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced
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