EN ISO 14673-3-2004 en Milk and milk products - Determination of nitrate and nitrite contents - Part 3 Method using cadmium reduction and flow injection analysis with in-line dialy.pdf

1、BRITISH STANDARD BS EN ISO 14673-3:2004 Incorporating Corrigendum No. 1 Milk and milk products Determination of nitrate and nitrite contents Part 3: Method using cadmium reduction and flow injection analysis with in-line dialysis (Routine method) The European Standard EN ISO 14673-3:2004 has the sta

2、tus of a British Standard ICS 67.100.10 BS EN ISO 14673-3:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 25 February 2004 BSI 19 March 2004 ISBN 0 580 43491 5 National foreword This British Standard is the official English language vers

3、ion of EN ISO 14673-3:2004. It is identical with ISO 14673-3:2004. It supersedes BS EN ISO 14673-3:2001 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/5, Milk and milk products, which has the responsibility to: A list of organizations represented

4、on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by

5、 using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immuni

6、ty from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them i

7、n the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN ISO title page, the EN ISO foreword page, the ISO title page, pages ii to v, a blank page, pages 1 to 10, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicat

8、es when the document was last issued. Amendments issued since publication Amd. No. Date Comments 15081 Corrigendum No. 1 19 March 2004 Corrected EN ISO foreword pageEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM ENISO146733 February2004 ICS67.100.10 SupersedesENISO146733:2001 Englishversion Milkandm

9、ilkproductsDeterminationofnitrateandnitrite contentsPart3:Methodusingcadmiumreductionandflow injectionanalysiswithinlinedialysis(Routinemethod)(ISO 146733:2004) LaitetproduitslaitiersDterminationdesteneursen nitratesetennitritesPartie3:Mthodeparrductionau cadmiumetdanalyseparinjectiondefluxavecdialy

10、seen ligne(Mthodederoutine)(ISO146733:2004) MilchundMilchprodukteBestimmungdesNitratund NitritgehaltesTeil3:VerfahrenmitCadmiumreduktion undFlieinjektionsanalysemitInlineDialyse (Routineverfahren)(ISO146733:2004) ThisEuropeanStandardwasapprovedbyCENon2February2004. CENmembersareboundtocomplywiththeC

11、EN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheCentralSecretariatortoanyCENmember. ThisEuropeanStandardexi

12、stsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,

13、Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG

14、ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMembers. Ref.No.ENISO146733:2004:ECORRECTED20040303 Foreword Thisdocument(ENISO146733:2004)hasbeenpreparedbyTechnicalCommitteeISO/TC34 “Agriculturalfoodproducts“incolla

15、borationwithTechnicalCommitteeCEN/TC302“Milkand milkproductsMethodsofsamplingandanalysis“,thesecretariatofwhichisheldbyNEN. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationof anidenticaltextorbyendorsement,atthelatestbyAugust2004,andconflictingnational standardsshallb

16、ewithdrawnatthelatestbyAugust2004. ThisdocumentsupersedesENISO146733:2001. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsof thefollowingcountriesareboundtoimplementthisEuropeanStandard:Austria,Belgium, Cyprus,CzechRepublic,Denmark,Estonia,Finland,France,Germany,Greece

17、,Hungary, Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland, Portugal,Slovakia,Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. Endorsementnotice ThetextofISO146733:2004hasbeenapprovedbyCENasENISO146733:2004withoutany modifications. ENISO146733:2004 Reference number

18、s ISO 14673-3:2004(E) IDF 189-3:2004(E)INTERNATIONAL STANDARD ISO 14673-3 IDF 189-3 Second edition 2004-02-01 Milk and milk products Determination of nitrate and nitrite contents Part 3: Method using cadmium reduction and flow injection analysis with in-line dialysis (Routine method) Lait et produit

19、s laitiers Dtermination des teneurs en nitrates et en nitrites Partie 3: Mthode par rduction au cadmium et danalyse par injection de flux avec dialyse en ligne (Mthode de routine) ENISO146733:2004ENISO146733:2004ii Contents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Terms and definition

20、s. 1 4 Principle . 2 5 Reagents 2 6 Apparatus. 3 7 Sampling 5 8 Preparation of test sample. 5 8.1 Cheese 5 9 Procedure. 6 9.1 Checking the reducing capacity of the cadmium column 6 9.2 Regeneration of the cadmium column 6 9.3 Test portion . 6 9.4 Extraction. 6 9.5 Determination of nitrite content 7

21、9.6 Determination of nitrate content . 7 10 Calculation and expression of results 7 10.1 Nitrite content 7 10.2 Nitrate content. 8 11 Precision 8 11.1 General. 8 11.2 Nitrite content 8 11.3 Nitrate content. 9 12 Test report 9 Bibliography . 10 ENISO146733:2004iii Foreword ISO (the International Orga

22、nization 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 establis

23、hed 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 matters of electrotechnical standardization

24、. 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 circulated to the member bodies for voting. P

25、ublication 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 for identifying any or all such pate

26、nt rights. ISO 14673-3IDF 189-3 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC Interna

27、tional. This second edition cancels and replaces the first edition (ISO 14673-3IDF 189-3:2001), of which it constitutes a minor revision. ISO 14673IDF 189 consists of the following parts, under the general title Milk and milk products Determination of nitrate and nitrite contents: Part 1: Method usi

28、ng cadmium reduction and spectrometry Part 2: Method using segmented flow analysis (Routine method) Part 3: Method using cadmium reduction and flow injection analysis with in-line dialysis (Routine method) ENISO146733:2004iv Foreword IDF (the International Dairy Federation) is a worldwide federation

29、 of the dairy 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 and AOAC International in the development of standard methods of analysis and sam

30、pling for milk and milk products. 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 National Committees casting a vote. ISO 14673-3

31、IDF 189-3 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products, and the International Dairy Federation (IDF), in collaboration with AOAC International. It is being published jointly by ISO and IDF and separately by AOAC International. All work was c

32、arried out by the Joint ISO/IDF/AOAC Action Team, Minerals and minor compounds, of the Standing Committee on Minor components characterization of physical properties, under the aegis of its project leader, Mr G. Brthen (NO). This second edition, together with ISO 14673-1IDF 189-1 and ISO 14673-2IDF

33、189-2, cancels and replaces IDF 84A:1984, IDF 95A:1982, IDF 96A:1987, IDF 97A:1985 and IDF 120:1984, which have been technically revised. ENISO146733:2004vblank Milk and milk products Determination of nitrate and nitrite contents Part 3: Method using cadmium reduction and flow injection analysis wit

34、h in-line dialysis (Routine method) 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

35、safety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope This part of ISO 14673IDF 189 specifies a routine method for the determination of the nitrate and nitrite contents of milk and milk products by cadmium reduction and flow injection analysis (F

36、IA). The method is applicable to hard, semi-hard and soft cheeses of various ages, and processed cheese. The detection limits of the method are 0,5 mg of nitrate ions per kilogram and 1,0 mg of nitrite ions per kilogram. The method is also applicable to whey powder, milk powder and milk-based infant

37、 food. NOTE 1 The method closely resembles the FIA method described in reference 2 for the determination of nitrate and nitrite in milk and fluid dairy products. Adaptations were made to allow for the analysis of cheese and to obtain sufficient sensitivity for the determination of low levels of nitr

38、ite in cheese and milk-based infant foods. NOTE 2 For determination of nitrite and nitrate following cadmium reduction, use is made of the same colour reaction as described in ISO 14673-1IDF 189-1. 2 Normative references The following referenced documents are indispensable for the application of thi

39、s document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 14673-1IDF 189-1, Milk and milk products Determination of nitrate

40、and nitrite contents Part 1: Method using cadmium reduction and spectrometry 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 nitrate content mass fraction of nitrate determined by the procedure specified in this part of ISO 14673IDF 189 NOTE

41、The nitrate content is expressed as the mass in milligrams of nitrate ions (NO 3 ) per kilogram of product. ENISO146733:20041 3.2 nitrite content mass fraction of nitrite determined by the procedure specified in this part of ISO 14673IDF 189 NOTE The nitrite content is expressed as the mass in milli

42、grams of nitrite ions (NO 2 ) per kilogram of product. 4 Principle 4.1 A test portion is suspended in a warm extraction buffer solution. Fat is separated by centrifuging and rapid cooling. Analyses are made of small portions of the de-fatted solution by flow injection analysis (FIA). In- line dialys

43、is is used to remove protein and remaining fat. The nitrate ions are reduced to nitrite ions by cadmium. The nitrite ions are reacted with sulfanilamide and N-1-naphthyl ethylenediamine dihydrochloride to give a red-coloured azo dye. The colour is measured in a flow cell at maximum absorption of the

44、 dye at 540 nm with reference to the absorption measured at 620 nm. 4.2 The nitrite and nitrate contents of the test sample are calculated with reference to the measured absorbances for a series of standard solutions of nitrite and nitrate, respectively. If the nitrite content exceeds 0,5 mg/kg, or

45、exceeds 10 % of the nitrate content, correction of the nitrate content is made by subtracting the nitrite content from the obtained nitrate results. 5 Reagents Use only reagents of recognized analytical grade unless otherwise specified. 5.1 Water, distilled or deionized, or water of equivalent purit

46、y, free from nitrate and nitrite ions. 5.2 Cadmium reduction column, for example Aquatec-Tecator 1) . 5.3 Extraction buffer solution or carrier solution (C2). Dissolve 26,6 g of ammonium chloride (NH 4 Cl) in 800 ml water in a 1 000 ml conical flask. By adding concentrated ammonia, adjust the pH to

47、8,5. Dilute to 1 000 ml with water and mix. 5.4 Hydrochloric acid (HCl), ( 20= 1,19 g/ml). 5.5 Reagent solution (R1). Dissolve 5,0 g sulfanilamide (NH 2 C 6 H 4 SO 2 NH 2 ) in a mixture of 300 ml water and 26 ml of hydrochloric acid (5.4) in a 500 ml volumetric flask (6.3). Dilute to the mark with water and mix. 5.6 Reagent solution (R2). Dissolve 0,5 g of N-1-naphthyl ethylenediamine dihydrochloride (C 10 H 7 NHCH 2 CH 2 NH 2 2HCl) in water in a 500 ml volumetric flask (6.3). Dilute to the mark with water and mix. The solution may be stored for up to 1 week in a well-stoppered brown bott