欢迎来到麦多课文档分享! | 帮助中心 海量文档,免费浏览,给你所需,享你所想!
麦多课文档分享
全部分类
  • 标准规范>
  • 教学课件>
  • 考试资料>
  • 办公文档>
  • 学术论文>
  • 行业资料>
  • 易语言源码>
  • ImageVerifierCode 换一换
    首页 麦多课文档分享 > 资源分类 > PDF文档下载
    分享到微信 分享到微博 分享到QQ空间

    EN ISO 20541-2008 en Milk and milk products - Determination of nitrate content - Method by enzymatic reduction and molecular-absorption spectrometry after Griess reaction《奶和奶制品 硝酸盐.pdf

    • 资源ID:726512       资源大小:780.53KB        全文页数:24页
    • 资源格式: PDF        下载积分:10000积分
    快捷下载 游客一键下载
    账号登录下载
    微信登录下载
    二维码
    微信扫一扫登录
    下载资源需要10000积分(如需开发票,请勿充值!)
    邮箱/手机:
    温馨提示:
    如需开发票,请勿充值!快捷下载时,用户名和密码都是您填写的邮箱或者手机号,方便查询和重复下载(系统自动生成)。
    如需开发票,请勿充值!如填写123,账号就是123,密码也是123。
    支付方式: 支付宝扫码支付    微信扫码支付   
    验证码:   换一换

    加入VIP,交流精品资源
     
    账号:
    密码:
    验证码:   换一换
      忘记密码?
        
    友情提示
    2、PDF文件下载后,可能会被浏览器默认打开,此种情况可以点击浏览器菜单,保存网页到桌面,就可以正常下载了。
    3、本站不支持迅雷下载,请使用电脑自带的IE浏览器,或者360浏览器、谷歌浏览器下载即可。
    4、本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰。
    5、试题试卷类文档,如果标题没有明确说明有答案则都视为没有答案,请知晓。

    EN ISO 20541-2008 en Milk and milk products - Determination of nitrate content - Method by enzymatic reduction and molecular-absorption spectrometry after Griess reaction《奶和奶制品 硝酸盐.pdf

    1、BS EN ISO20541:2008ICS 67.100.01NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDMilk and milk products Determination ofnitrate content Method by enzymaticreduction andmolecular-absorptionspectrometry afterGriess reaction (ISO20541:2008)This British Standardwas p

    2、ublished underthe authority of theStandards Policy andStrategy Committee on 30September 2008 BSI 2008ISBN 978 0 580 56968 5Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 20541:2008National forewordThis British Standard is the UK implementation of EN ISO 20541:2008.The UK partic

    3、ipation in its preparation was entrusted to TechnicalCommittee AW/5, Chemical analysis of milk and milk products.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Us

    4、ers are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 20541September 2008ICS 67.100.01English VersionMilk and milk products - Determination of nitrate content -Method by en

    5、zymatic reduction and molecular-absorptionspectrometry after Griess reaction (ISO 20541:2008)Lait et produits laitiers - Dtermination de la teneur ennitrates - Mthode par rduction enzymatique etspectromtrie dabsorption molculaire aprs raction deGriess (ISO 20541:2008)Milch und Milcherzeugnisse - Bes

    6、timmung desNitratgehaltes - Verfahren mit enzymatischer Reduktionund Moleklabsorptionsspektrometrie nach Griess-Reaktion (ISO 20541:2008)This European Standard was approved by CEN on 6 August 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the condition

    7、s for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three offic

    8、ial versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Be

    9、lgium, Bulgaria, 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.EUROPEAN COMMITTEE FOR

    10、STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 20541:2008: EBS EN ISO 20541:2008EN ISO 20541:

    11、2008 (E) 3 Foreword This document (EN ISO 20541:2008) has been prepared by Technical 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 Europea

    12、n Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2009, and conflicting national standards shall be withdrawn at the latest by March 2009. Attention is drawn to the possibility that some of the elements o

    13、f this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European

    14、 Standard: Austria, Belgium, Bulgaria, 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 the United Kin

    15、gdom. Endorsement notice The text of ISO 20541:2008 has been approved by CEN as a EN ISO 20541:2008 without any modification. BS EN ISO 20541:2008ISO 20541:2008(E) IDF 197:2008(E) ISO and IDF 2008 All rights reserved iiiContents Page Foreword iv Foreword. v 1 Scope . 1 2 Normative references . 1 3 T

    16、erms and definitions. 1 4 Principle. 2 5 Reagents 2 6 Apparatus 4 7 Sampling 5 8 Preparation of test sample. 5 8.1 Dried milk, dried whey and milk protein concentrates . 5 8.2 Caseins and caseinates . 5 8.3 Cheese . 6 8.4 Whey cheese . 6 9 Procedure 6 9.1 Preparation of the test portion 6 9.2 Remova

    17、l of fat and protein 6 9.3 Reagent blank test 7 9.4 Determination 7 9.5 Calibration . 9 10 Calculation and expression of results 9 10.1 Nitrite (matrix blank) content (see Clause 4, Note 3) 9 10.2 Total nitrite/nitrate content 9 10.3 Nitrate content. 10 11 Precision 10 11.1 Interlaboratory testing 1

    18、0 11.2 Repeatability 10 11.3 Reproducibility 11 12 Test report . 11 Annex A (informative) Interlaboratory trials 12 Bibliography . 15 BS EN ISO 20541:2008ISO 20541:2008(E) IDF 197:2008(E) iv ISO and IDF 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a wo

    19、rldwide 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 established has the right to be represented o

    20、n 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. International Standards are drafted

    21、 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. Publication as an International Standa

    22、rd 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 patent rights. ISO 20541IDF 197 was prepa

    23、red 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. BS EN ISO 20541:2008ISO 20541:2008(E) IDF 197:2008(E) ISO and IDF 2008 All rights reserved vForeword IDF (the In

    24、ternational Dairy Federation) is a non-profit organization representing the dairy sector worldwide. IDF membership comprises National Committees in every member country as well as regional dairy associations having signed a formal agreement on cooperation with IDF. All members of IDF have the right

    25、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. Draft International Standards adopted by the Action Teams and Standing Committees are circulated to

    26、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 that some of the elements of this document may be the subject of patent rights. IDF shall not be held r

    27、esponsible for identifying any or all such patent rights. ISO 20541IDF 197 was prepared by the International Dairy Federation (IDF) and Technical Committee ISO/TC 34, Food products, Subcommittee SC 5, Milk and milk products. It is being published jointly by IDF and ISO. All work was carried out by t

    28、he Joint ISO-IDF Action Team Minor compounds of the Standing Committee on Minor components and characterization of physical properties under the aegis of its project leaders, Mr. M. Carl (DE) and Mrs. C. Bckman (FL). BS EN ISO 20541:2008BS EN ISO 20541:2008INTERNATIONAL STANDARD ISO 20541:2008(E)IDF

    29、 197:2008(E) ISO and IDF 2008 All rights reserved 1Milk and milk products Determination of nitrate content Method by enzymatic reduction and molecular-absorption spectrometry after Griess reaction WARNING The use of this International Standard may involve hazardous materials, operations and equipmen

    30、t. 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 applicability of regulatory limitations prior to use. 1 Scope This International Standard spe

    31、cifies a method for the determination of the nitrate content of milk and milk products by molecular-absorption spectrometry after Griess reaction (preceded by enzymatic reduction). The method is, in particular, applicable to whole, partly skimmed, skimmed and dried milk, hard, semi-hard and soft che

    32、eses, processed cheese, whey cheese, caseins, caseinates, dried whey and milk protein concentrates. The method can be used at contents corresponding to a measured concentration in the sample solution (with blank subtracted) of more than 0,2 mg/l. 2 Normative references The following referenced docum

    33、ents are indispensable for the application of this document. For dated references only the edition cited applies. For undated references the last edition of the referenced document (including any amendments) applies. ISO 565, Test sieves Metal wire cloth, perforated metal plate and electroformed she

    34、et Nominal sizes of openings ISO 648, Laboratory glassware Single-volume pipettes ISO 835, Laboratory glassware Graduated pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 3696, Water for analytical laboratory use Specification and test methods 3 Terms and definitions For the pu

    35、rposes of this document, the following terms and definitions apply. 3.1 nitrite content mass fraction of nitrite compounds determined by the procedure specified in this International Standard BS EN ISO 20541:2008ISO 20541:2008(E) IDF 197:2008(E) 2 ISO and IDF 2008 All rights reserved3.2 nitrate cont

    36、ent mass fraction of nitrate compounds determined by the procedure specified in this International Standard NOTE The nitrate content is expressed as the mass fraction in milligrams of nitrate ion (NO3) per kilogram of product. 4 Principle A test portion is dispersed in warm water. The fat and protei

    37、ns are removed either by precipitation using Carrez reagents and filtering or by centrifugal ultra-filtration using membrane cones (see Notes 1 and 2). The nitrate is reduced to nitrite in a portion of the filtrate by means of nitrate reductase. A red-violet azo dye is developed, in portions of both

    38、 the unreduced filtrate (for nitrite) and the reduced solution (for nitrate), by addition of sulfanilamide and N-(1-naphthyl)ethylenediamine dihydrochloride, and the absorbance measured at a wavelength of 540 nm (or Hg 546 nm). The nitrite content of the sample and the total nitrite content after re

    39、duction of nitrate 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. NOTE 1 The two alternative procedures for removal of fat and protein are described in

    40、 9.2.1 and 9.2.2. NOTE 2 For whey powder, whey protein concentrate and similar products, ultra-filtration is used in preference to Carrez precipitation as the latter often leads to turbidity problems and, as a consequence, to poor precision. NOTE 3 The low endogenous nitrite level is not reported bu

    41、t taken into account in the matrix blank solution. 5 Reagents Unless otherwise specified, use only reagents of recognized analytical grade, free of nitrate and nitrite, and water complying with ISO 3696 grade 3 at least, free from nitrate and nitrite. Water used for preparation of enzyme or coenzyme

    42、 solutions shall be freshly double-distilled or of equivalent purity. 5.1 Sodium hydroxide solution, c(NaOH) = 1 mol/l. 5.2 Sodium chloride solution, c(NaCI) = 0,9 g/100 ml. 5.3 Hydrochloric acid, 20(HCI) = 1,19 g/ml. 5.4 Hydrochloric acid solution, c(HCI) = 2 mol/l. Carefully add 160 ml of hydrochl

    43、oric acid (5.3) to about 700 ml of water in a 1 000 ml one-mark volumetric flask (6.4) while regularly swirling the contents. Cool the contents to room temperature. Dilute to the mark with water and mix carefully. 5.5 Carrez reagents, as follows: 5.5.1 Carrez reagent I: Potassium hexacyanoferrate(II

    44、) solution, c(K4Fe(CN)6.3H2O) = 150 g/l. Dissolve 15,0 g of potassium hexacyanoferrate(II) trihydrate in water in a 100 ml one-mark volumetric flask (6.4). Dilute to the mark with water and mix. 5.5.2 Carrez reagent II: Zinc sulfate solution, c(ZnSO4.7H2O) = 300 g/l. Dissolve 30,0 g of zinc sulfate

    45、heptahydrate in water in a 100 ml one-mark volumetric flask (6.4). Dilute to the mark with water and mix. BS EN ISO 20541:2008ISO 20541:2008(E) IDF 197:2008(E) ISO and IDF 2008 All rights reserved 35.6 Standard solutions, as follows: 5.6.1 Sodium nitrite (NaNO2) stock solution. Accurately weigh (75,

    46、0 0,1) mg of pre-dried (at 102 C for 2 h) sodium nitrite into a 100 ml one-mark volumetric flask. Dissolve it in a suitable amount of water. Dilute to the mark with water and mix. The nitrite stock solution obtained contains 500 mg of nitrite per litre. Prepare calibration solutions by diluting the

    47、stock solution with water to give several solutions with different nitrite concentrations in the range from 0,05 mg/I to 5,0 mg/I. When stored at room temperature, the sodium nitrite stock solution remains stable for 1 day. 5.6.2 Potassium nitrate (KNO3) stock solution. Accurately weigh (81,5 0,1) m

    48、g of pre-dried (at 102 C for 2 h) potassium nitrate into a 100 ml one-mark volumetric flask. Dissolve it in a suitable amount of water. Dilute to the 100 ml mark with water and mix. The obtained nitrate stock solution contains 500 mg of nitrate per litre. Prepare calibration solutions by diluting th

    49、e stock solution with water to give several solutions with different nitrate concentrations in the range from 0,05 mg/I to 5,0 mg/I. When stored at 4 C, the potassium nitrate stock solution remains stable for 1 week. 5.7 Potassium phosphate buffer solution, pH = 7,5. Accurately weigh (57,6 0,1) mg of dipotassium hydrogen phosphate (K2HPO4.3H2O) into a 100 ml one-mark volumetric flask. Dissolve it in a suitable amount of water. Dilute to the mark with water and mix. Accurately weigh (17,0 0,1) mg of potassium dihyd


    注意事项

    本文(EN ISO 20541-2008 en Milk and milk products - Determination of nitrate content - Method by enzymatic reduction and molecular-absorption spectrometry after Griess reaction《奶和奶制品 硝酸盐.pdf)为本站会员(花仙子)主动上传,麦多课文档分享仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知麦多课文档分享(点击联系客服),我们立即给予删除!




    关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

    copyright@ 2008-2019 麦多课文库(www.mydoc123.com)网站版权所有
    备案/许可证编号:苏ICP备17064731号-1 

    收起
    展开