1、BRITISH STANDARD BS EN ISO 14673-1:2004 Incorporating Corrigendum No. 1 Milk and milk products Determination of nitrate and nitrite contents Part 1: Method using cadmium reduction and spectrometry The European Standard EN ISO 14673-1:2004 has the status of a British Standard ICS 67.100.10 BS EN ISO
2、14673-1:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 25 February 2004 BSI 18 March 2004 ISBN 0 580 43489 3 National foreword This British Standard is the official English language version of EN ISO 14673-1:2004. It is identical with I
3、SO 14673-1:2004. It supersedes BS EN ISO 14673-1:2001 which is withdrawn.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 on this committee can be obtained on request to it
4、s 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 using the “Search” facility of the BSI Electronic
5、 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 immunity from legal obligations. aid enquirers to unders
6、tand 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 in the UK. Summary of pages This document comprises
7、 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 13, the Annex ZA page, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last i
8、ssued. Amendments issued since publication Amd. No. Date Comments 15079 Corrigendum No. 1 18 March 2004 Corrected EN ISO foreword page and incorporating the Annex ZA EUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM ENISO146731 February2004 ICS67.100.10 SupersedesENISO146731:2001 Englishversion Milkand
9、milkproductsDeterminationofnitrateandnitrite contentsPart1:Methodusingcadmiumreductionand spectrometry(ISO146731:2004) LaitetproduitslaitiersDterminationdesteneursen nitratesetennitritesPartie1:Mthodeparrductionau cadmiumetspectromtrie(ISO146731:2004) MilchundMilchprodukteBestimmungdesNitratund Nitr
10、itgehaltesTeil1:VerfahrenmitCadmiumreduktion undSpektrometrie(ISO146731:2004) ThisEuropeanStandardwasapprovedbyCENon2February2004. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration
11、.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheCentralSecretariatortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoit
12、sownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Polan
13、d,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnationalMem
14、bers. Ref.No.ENISO146731:2004:ECORRECTED20040225 Foreword Thisdocument(ENISO146731:2004)hasbeenpreparedbyTechnicalCommitteeISO/TC34 “Agriculturalfoodproducts“incollaborationwithTechnicalCommitteeCEN/TC302“Milkand milkproductsMethodsofsamplingandanalysis“,thesecretariatofwhichisheldbyNEN. ThisEuropea
15、nStandardshallbegiventhestatusofanationalstandard,eitherbypublicationof anidenticaltextorbyendorsement,atthelatestbyAugust2004,andconflictingnational standardsshallbewithdrawnatthelatestbyAugust2004. ThisdocumentsupersedesENISO146731:2001. AccordingtotheCEN/CENELECInternalRegulations,thenationalstan
16、dardsorganizationsof thefollowingcountriesareboundtoimplementthisEuropeanStandard:Austria,Belgium, Cyprus,CzechRepublic,Denmark,Estonia,Finland,France,Germany,Greece,Hungary, Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norway,Poland, Portugal,Slovakia,Slovenia,Spain,Sweden,Sw
17、itzerlandandUnitedKingdom. Endorsementnotice ThetextofISO146731:2004hasbeenapprovedbyCENasENISO146731:2004withoutany modifications. NOTENormativereferencestoInternationalStandardsarelistedinAnnexZA(normative). ENISO146731:2004 Reference numbers ISO 14673-1:2004(E) IDF 189-1:2004(E)INTERNATIONAL STAN
18、DARD ISO 14673-1 IDF 189-1 Second edition 2004-02-01 Milk and milk products Determination of nitrate and nitrite contents Part 1: Method using cadmium reduction and spectrometry Lait et produits laitiers Dtermination des teneurs en nitrates et en nitrites Partie 1: Mthode par rduction au cadmium et
19、spectromtrie ENISO146731:2004 ii ENISO146731:2004 iiiContents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 2 4 Principle . 2 5 Reagents 2 6 Apparatus. 4 7 Sampling 5 8 Preparation of test sample. 5 8.1 Dried milk and dried whey 5 8.2 Caseins and caseinates 5 8.3 Che
20、ese 6 8.4 Whey cheese . 6 9 Procedure. 6 9.1 Preparation of the copperized cadmium column 6 9.2 Checking the reducing capacity of the column . 6 9.3 Regeneration of the column. 7 9.4 Preparation of test portion. 7 9.5 Extraction and deproteination . 8 9.6 Reduction of nitrate to nitrite. 8 9.7 Blank
21、 test . 9 9.8 Determination 9 9.9 Preparation of calibration graph . 9 10 Calculation and expression of results 9 10.1 Nitrite content 9 10.2 Nitrate content. 10 11 Precision 10 11.1 General. 10 11.2 Repeatability 10 12 Test report 11 Bibliography . 13 ENISO146731:2004iv Foreword ISO (the Internatio
22、nal 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 for which a technical committee has been
23、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 all matters of electrotechnical standar
24、dization. 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 v
25、oting. 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 responsible for identifying any or all s
26、uch patent rights. ISO 14673-1IDF 189-1 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
27、 International. This second edition cancels and replaces the first edition (ISO 14673-1IDF 189-1:2001), 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: Me
28、thod using 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) ENISO146731:2004 vForeword IDF (the International Dairy Federation) is a worldwide fed
29、eration 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
30、and sampling 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
31、14673-1IDF 189-1 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 wor
32、k was carried 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 14673-2IDF 189-2 and ISO 14673
33、-3IDF 189-3, cancels and replaces IDF 84A:1984, IDF 95A:1982, IDF 96A:1987, IDF 97A:1985 and IDF 120:1984, which have been technically revised. ENISO146731:2004 1Milk and milk products Determination of nitrate and nitrite contents Part 1: Method using cadmium reduction and spectrometry WARNING The u
34、se 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 determine the app
35、licability of regulatory limitations prior to use. 1 Scope This part of ISO 14673IDF 189 specifies a method for the determination of the nitrate and nitrite contents of milk and milk products by cadmium reduction and spectrometry. The method is applicable to whole and partly skimmed and skimmed drie
36、d milk; hard, semi-hard and soft cheeses; processed cheese; whey cheese, caseins and caseinates, and dried whey. The method may be performed using automatic equipment, in particular by segmented flow analysis (SFA) or flow injection analysis (FIA), thus reducing cadmium contamination in laboratory w
37、ork places and waste water. NOTE These methods are described in ISO 14673-2IDF 189-2 and ISO 14673-3IDF 189-3, respectively. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For und
38、ated references, the latest edition of the referenced document (including any amendments) applies. ISO 565, Test sieves Metal wire cloth, perforated metal plate and electroformed sheet Nominal sizes of openings ISO 648, Laboratory glassware One-mark pipettes ISO 835-1, Laboratory glassware Graduated
39、 pipettes Part 1: General requirements ISO 1042, Laboratory glassware One-mark volumetric flasks ENISO146731:20042 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
40、in this part of ISO 14673IDF 189 NOTE The nitrate content is expressed as the mass in milligrams of nitrate ions (NO 3 ) per kilogram of product. 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
41、as the mass in milligrams of nitrite ions (NO 2 ) per kilogram of product. 4 Principle A test portion is dispersed in warm water, with precipitation of the fat and proteins, then filtration. The nitrate ions are reduced to nitrite ions in a portion of the filtrate by means of copperized cadmium. A r
42、ed colour is developed in portions of both unreduced filtrate and the reduced solution, by addition of sulfanilamide and N-1-naphthyl ethylenediamine dihydrochloride. Spectrometric measurements are carried out at a wavelength of 538 nm. The nitrite content of the sample and the total nitrite content
43、 after reduction of nitrate ions are calculated by comparing the measured absorbances with those of a set of sodium nitrite calibration solutions. The nitrate content is calculated from the difference between these two contents. 5 Reagents Use only reagents of recognized analytical grade unless othe
44、rwise specified. 5.1 Water, distilled or deionized, or water of equivalent purity, free from nitrate and nitrite ions. To avoid the possible inclusion of small gas bubbles in the copperized cadmium column (9.1.6), freshly boil the distilled or deionized water and cool to room temperature. Use the th
45、us-prepared water for the preparation of the column (9.1), to check the reducing capacity of the column (9.2), and to regenerate the column (9.3). 5.2 Cadmium granules, of diameter 0,3 mm to 0,8 mm. Prepare cadmium granules, if not available commercially, as follows. Place a suitable number of zinc
46、rods in a beaker. Cover the rods with cadmium sulfate solution (5.3). Scrape the cadmium sponge from the rods from time to time over a period of 24 h. Remove the zinc rods and decant the liquid until only sufficient remains to cover the cadmium sponge. Wash the sponge two or three times with water.
47、Transfer the cadmium sponge to a laboratory blender together with 400 ml of the hydrochloric acid working solution (5.7) and blend for a few seconds to obtain granules of the required size. Return the contents of the blender to the beaker and leave to stand for several hours, while stirring occasionally to remove bubbles. Decant most of the liquid and immediately copperize the granules as described in 9.1. WARNING Because of its toxicity, the used cadmium should be delivered as chemical waste to the relevant authorities. ENISO146731:2004 35.3 Cadmium sulfate solution, c(CdSO 4 8H 2
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