1、January 2007DEUTSCHE NORM English price group 8No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 67.100.30!,v_“9836092ww
2、w.din.deDDIN EN ISO 5943Cheese and processed cheese products Determination of chloride content Potentiometric titration method (ISO 5943:2006)English version of DIN EN ISO 5943:2007-01Kse und Schmelzkse Bestimmung des Chloridgehaltes Potentiometrisches Titrationsverfahren (ISO 5943:2006)Englische Fa
3、ssung DIN EN ISO 5943:2007-01SupersedesDIN EN ISO 5943:2006-04www.beuth.deDocument comprises 10 pages04.07DIN EN ISO 5943:2007-01 2 National foreword This standard falls within the responsibility of Technical Committee CEN/TC 302 “Milk and milk products Methods of sampling and analysis” (Secretariat
4、: the Netherlands). It is identical with International Standard ISO 5943:2006 which was prepared by Technical Committee ISO/TC 34 “Agricultural food products” (Secretariat: Hungary), Subcommittee SC 5 “Milk and milk products” (Secretariat: the Netherlands). Based on the results of the unique accepta
5、nce procedure (UAP), ISO 5943:2006 has been adopted as European Standard EN ISO 5943. The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und land-wirtschaftliche Produkte (Foodstuffs and Agricultural Products Standards Committee), Technical Committee Chemisc
6、he und physikalische Untersuchung von Milch und Milchprodukten. The DIN Standards corresponding to the International Standards referred to in the bibliography of the EN are as follows: ISO 707 DIN EN ISO 707 ISO 5725-1 DIN ISO 5725-1 ISO 5725-2 DIN ISO 5725-2 Amendments This standard differs from DI
7、N EN ISO 5943:2006-04 as follows: a) In the calculation given in 9.1, an error has been corrected. A factor of 1 000 has been added and the molar mass is now used. Previous editions DIN 10328: 1970-11, 1982-08, 1986-10 DIN EN ISO 5943: 2006-04 National Annex NA (informative) Bibliography DIN EN ISO
8、707, Milk and milk products Guidance on sampling DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions DIN ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determina
9、tion of repeatability and reproducibility of a standard measurement method EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 5943 January 2006 ICS 67.100.30 English Version Cheese and processed cheese products - Determination of chloride content - Potentiometric titration method (ISO 5943:200
10、6) Fromages et fromages fondus - Dtermination de la teneur en chlorures - Mthode par titrage potentiomtrique (ISO 5943:2006) Kse und Schmelzkse - Bestimmung des Chlorid-gehaltes - Potentiometrisches Titrationsverfahren (ISO 5943:2006) This European Standard was approved by CEN on 28 December 2005. C
11、EN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on ap
12、plication 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 translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat ha
13、s the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Ro
14、mania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reser
15、ved worldwide for CEN national Members. Ref. No. EN ISO 5943:2006: EEN ISO 5943:2006 (E) Contents Page Foreword3 1 Scope 4 2 Terms and definitions .4 3 Principle4 4 Reagents.4 5 Apparatus .5 6 Sampling.5 2 7 Preparation of test sample .5 8 Procedure.5 8.1 Test portion5 8.2 Determination 6 8.3 Blank
16、test .6 9 Calculation and expression of results 6 9.1 Calculation .6 9.2 Expression of results6 10 Precision 7 10.1 Interlaboratory test7 10.2 Repeatability 7 10.3 Reproducibility 7 11 Test report7 Bibliography8 EN ISO 5943:2006 (E) Foreword 3 This document (EN ISO 5943:2006) has been prepared by Te
17、chnical Committee ISO/TC 34 “Agricultural food products“ in collaboration 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 publi
18、cation of an identical text or by endorsement, at the latest by April 2007, 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 fol
19、lowing countries are bound to implement this European Standard: Austria, 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, Sp
20、ain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 5943:2006 has been approved by CEN as EN ISO 5943:2006 without any modifications. EN ISO 5943:2006 (E) 1 Scope This International Standard specifies a potentiometric titration method for the determination of the chloride
21、 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 and definitions For the purposes of this document, the following terms and definitions apply. 2.1 chloride conte
22、nt 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 percent, of chloride ion or sodium chloride or any other chloride. 3 Principle A test portion is suspended in water.
23、 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 analytical grade, unless otherwise specified, and distilled or demineralized water or water of at least equivalent p
24、urity. 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 dilute to 1 000 ml. Standardize the solution against sodium chloride (NaCl), which has previously been dried at 300
25、 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. 4 EN ISO 5943:2006 (E) 5 Apparatus 5.1 Device for grinding or grating cheese, capable of being cleaned easily. 5.2 Analytical
26、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.g. a silver electrode) and a reference electrode e.g. a mercury(l) sulfate electrode. 5.5 Vessel, suitable
27、 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 the nearest 0,01 ml. The burette, or automatic plunger burette, should preferably be made of brown glass.
28、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 method specified in this International Standard. A recommended sampling method is given in ISO 707IDF 501. 7 Pr
29、eparation 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 consumed. Grind or grate the sample by means of an appropriate device (5.1). Mix the ground or grated mass qu
30、ickly, 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 sample to an airtight container to await analysis, which should be carried out as soon as possible after gri
31、nding. 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 temperature should be 10 C to 12 C. Clean the device after grinding or grating each sample. 8 Procedure 8.1 Tes
32、t portion Weigh, to the nearest 0,001 g, 2 g to 5 g of the test sample (Clause 7) into the vessel (5.5). 5 EN ISO 5943:2006 (E) 8.2 Determination 8.2.1 Add 30 ml of water at about 55 C. Suspend the test portion using the blender (5.3). Rinse the blender with approximately 10 ml of water, collecting
33、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 silver nitrate standard solution (4.1) using the burette (5.7), stirring continuously, until the endpo
34、int 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 ml) of the silver nitrate standard solution. 8.3 Blank test Carry out a blank test using the reagents
35、 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 %cVV Mwm = where V0is the volume, in millilitres, of the silver nitrate standard solution used in the bl
36、ank 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 the silver nitrate standard solution (4.1); m is the mass, in grams, of the test portion (8.1); M is
37、 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 expression as % KCl. 9.2 Expression of results Report the result to the second decimal place. 6 EN ISO
38、 5943:2006 (E) 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 5725:19861). 10.2 Repeatability The absolute difference between two independent single test resul
39、ts, 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 greater than 0,02 g of Clion (for the equivalent quantity of any chloride) per 100 g of product. 1
40、0.3 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 equipment, will in not more than 5 % of cases be greater than 0,06 g of Clion (or the equivalent q
41、uantity 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 det
42、ails not specified in this International Standard, or regarded as optional, together with details of any incidents which may have influenced the test results; e) the test results obtained, mentioning clearly the way in which they are expressed. 7 1) ISO 5725:1986, Precision of test methods Determina
43、tion of repeatability and reproducibility for a standard test method by inter-laboratory tests (now withdrawn), was used to calculate the precision data. EN ISO 5943:2006 (E) Bibliography 1 ISO 707IDF 50, Milk and milk products Guidance on sampling 2 ISO 5725-1:1994, Accuracy (trueness and precision
44、) of measurement methods and results Part 1: General principles and definitions 3 ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method 4 POORTVLIET, L.J. and HORWITZ, W. J. Assoc. Off. Anal. Chem., 65, 1982, p. 1350 8
