1、BRITISH STANDARD BS EN ISO 14673-2:2004 Incorporating Corrigendum No. 1 Milk and milk products Determination of nitrate and nitrite contents Part 2: Method using segmented flow analysis (Routine method) The European Standard EN ISO 14673-2:2004 has the status of a British Standard ICS 67.100.10 BS E
2、N ISO 14673-2:2004 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 43490 7 National foreword This British Standard is the official English language version of EN ISO 14673-2:2004. It is identical
3、with ISO 14673-2:2004. It supersedes BS EN ISO 14673-2:2001 which is withdrawn.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
4、 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 using the “Search” facility of the BSI Elec
5、tronic 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
6、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 in the UK. Summary of pages This document com
7、prises 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 14, the Annex ZA page and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendment
8、s issued since publication Amd. No. Date Comments 15080 Corrigendum No. 1 19 March 2004 Corrected EN ISO foreword page and incorporating the Annex ZAEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM ENISO146732 February2004 ICS67.100.10 SupersedesENISO146732:2001 Englishversion MilkandmilkproductsDeter
9、minationofnitrateandnitrite contentsPart2:Methodusingsegmentedflowanalysis (Routinemethod)(ISO146732:2004) LaitetproduitslaitiersDterminationdesteneursen nitratesetennitritesPartie2:Mthodedanalyseparflux continussegments(Mthodederoutine)(ISO14673 2:2004) MilchundMilchprodukteBestimmungdesNitratund N
10、itritgehaltesTeil2:Verfahrenmitsegmentierter Flieanalyse(Routineverfahren)(ISO146732:2004) ThisEuropeanStandardwasapprovedbyCENon2February2004. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithout
11、anyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheCentralSecretariatortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCE
12、NmemberintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands
13、,Norway,Poland,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforC
14、ENnationalMembers. Ref.No.ENISO146732:2004:ECORRECTED20040225 Foreword Thisdocument(ENISO146732:2004)hasbeenpreparedbyTechnicalCommitteeISO/TC34 “Agriculturalfoodproducts“incollaborationwithTechnicalCommitteeCEN/TC302“Milkand milkproductsMethodsofsamplingandanalysis“,thesecretariatofwhichisheldbyNEN
15、. ThisEuropeanStandardshallbegiventhestatusofanationalstandard,eitherbypublicationof anidenticaltextorbyendorsement,atthelatestbyAugust2004,andconflictingnational standardsshallbewithdrawnatthelatestbyAugust2004. ThisdocumentsupersedesENISO146732:2001. AccordingtotheCEN/CENELECInternalRegulations,th
16、enationalstandardsorganizationsof 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,Sp
17、ain,Sweden,SwitzerlandandUnitedKingdom. Endorsementnotice ThetextofISO146732:2004hasbeenapprovedbyCENasENISO146732:2004withoutany modifications. NOTENormativereferencestoInternationalStandardsarelistedinAnnexZA(normative). ENISO146732:2004 Reference numbers ISO 14673-2:2004(E) IDF 189-2:2004(E)INTER
18、NATIONAL STANDARD ISO 14673-2 IDF 189-2 Second edition 2004-02-01 Milk and milk products Determination of nitrate and nitrite contents Part 2: Method using segmented flow analysis (Routine method) Lait et produits laitiers Dtermination des teneurs en nitrates et en nitrites Partie 2: Mthode danalyse
19、 par flux continus segments (Mthode de routine) ENISO146732:2004 ii ENISO146732:2004 iiiContents Page Foreword iv 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle . 2 4.1 Nitrate determination 2 4.2 Nitrite determination . 2 5 Reagents 2 6 Apparatus. 5 7 Sampling 5 8 Prepa
20、ration of test sample. 6 8.1 Cheese 6 8.2 Dried milk products and infant food . 6 8.3 Milk and liquid milk products. 6 9 Procedure. 6 9.1 Preparation of the reduction column 6 9.2 Checking the reducing capacity of the column . 7 9.3 Determination of nitrate content . 7 9.4 Determination of nitrite c
21、ontent 8 9.5 Calibration curve. 9 9.6 Checking the drift of standard solutions 9 10 Calculation and expression of results 9 10.1 Calculation. 9 10.2 Expression of results 10 11 Precision 10 11.1 General. 10 11.2 Nitrite content 10 11.3 Nitrate content. 10 12 Test report 11 Bibliography . 14 ENISO146
22、732:2004iv 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 fo
23、r 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
24、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 ar
25、e 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 r
26、esponsible for identifying any or all such patent rights. ISO 14673-2IDF 189-2 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 jointl
27、y by ISO and IDF and separately by AOAC International. This second edition cancels and replaces the first (ISO 14673-2IDF 189-2:2001), 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 a
28、nd nitrite contents: Part 1: Method 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) ENISO146732:2004 vForeword IDF (the International Dairy
29、 Federation) is a worldwide federation 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 o
30、f standard methods of analysis 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
31、Committees casting a vote. ISO 14673-2IDF 189-2 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
32、 by AOAC International. All work 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 IS
33、O 14673-1IDF 189-1 and ISO 14673-3IDF 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. ENISO146732:2004 1Milk and milk products Determination of nitrate and nitrite contents Part 2: Method using segmented flow a
34、nalysis (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 safety and
35、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 segmented flow analysis. The method is applicable to milk,
36、cheese, and liquid and dried milk products and infant foods. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (
37、including any amendments) applies. ISO 648, Laboratory glassware One-mark pipettes ISO 835-1, Laboratory glassware Graduated pipettes Part 1: General requirements ISO 1042, Laboratory glassware One-mark volumetric flasks 3 Terms and definitions For the purposes of this document, the following terms
38、and definitions apply. 3.1 nitrate content mass fraction of nitrate determined by the procedure specified 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 det
39、ermined by the procedure specified in this part of ISO 14673IDF 189 NOTE The nitrite content is expressed as the mass in milligrams of nitrite ions (NO 2 ) per kilogram of product. ENISO146732:20042 4 Principle 4.1 Nitrate determination A test portion is suspended in water. Part of the suspension is
40、 transferred to the analyser for dialysis. The nitrate ions are reduced to nitrite. The nitrite content is determined by a spectrometric method. Standard nitrate solutions are determined by the same procedure. The nitrate content is calculated by comparing the reading obtained from the test portion
41、with the readings from the standard solutions. NOTE Any nitrite present is determined as nitrate. The amount of nitrite is generally small compared to the amount of nitrate. Infant food based on soy-proteins can be an exception to the rule. A correction for the nitrite present can be applied after d
42、etermination of the nitrite content. 4.2 Nitrite determination A test portion is suspended in a solution of ammonium and sodium chloride. Part of the suspension is transferred to the analyser for dialysis. The nitrite content is determined by a spectrometric method. Standard nitrite solutions are de
43、termined by the same procedure. The nitrite content is calculated by comparing the reading obtained from the test portion with that from the standard solution. 5 Reagents Use only reagents of recognized analytical grade unless otherwise specified. 5.1 Water, distilled or deionized, or water of equiv
44、alent purity, free from nitrate and nitrite ions. To avoid the possible inclusion of small gas bubbles in the copperized cadmium column (6.9), freshly boil the distilled or deionized water and cool to room temperature. Use the thus-prepared water for the preparation of the column (9.1), to check the
45、 reducing capacity of the column (9.2), and for regeneration of the column. 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 rods in a beaker. Cover the rods with cadmium sulfate solution (5.3). S
46、crape 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. Transfer the cadmium sponge to a laboratory blender together with 400 m
47、l of the dilute hydrochloric acid (5.6) 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 g
48、ranules as described in 9.1.2. WARNING Because of its toxicity, the used cadmium should be delivered as chemical waste to the relevant authorities. 5.3 Cadmium sulfate solution, c(CdSO 4 8H 2 O) = 40 g/l. Dissolve 40 g of cadmium sulfate in water in a 1 000 ml volumetric flask (6.4). Dilute to the ma
