EN ISO 5536-2013 en Milk fat products - Determination of water content - Karl Fischer method《乳脂品 水含量的测定 卡尔费休法》.pdf

1、BS ISO 5536:2009ICS 67.100.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDMilk fat products Determination of watercontent Karl FischermethodBS EN ISO 5536:2013BS EN ISO 5536:2013ISBN 978 0 580 79332 5Amendments/corrigenda issued since publicationDate Comments

2、30 November 2013 This corrigendum renumbers BS ISO 5536:2009 as BS EN ISO 5536:2013This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2010. The British Standards Institution 2013. Published by BSI Standards Limited 2013National foreword

3、This British Standard is the UK implementation of EN ISO 5536:2013. It is identical to ISO 5536:2009. It supersedes BS ISO 5536:2009 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee AW/5, Chemical analysis of milk and milk products.A list of organizatio

4、ns represented on this committee can be obtained on request to its secretary.The 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 cannot confer immunity from legal obligations.EURO

5、PEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 5536 May 2013 ICS 67.100.10 English Version Milk fat products - Determination of water content - Karl Fischer method (ISO 5536:2009) Produits base de matire grasse laitire - Dtermination de la teneur en eau - Mthode de Karl Fischer (ISO 5536:2009)

6、 Milchfett-Erzeugnisse - Bestimmung des Wassergehaltes -Karl-Fischer-Verfahren (ISO 5536:2009) This European Standard was approved by CEN on 16 May 2013. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the sta

7、tus of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, G

8、erman). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croa

9、tia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and U

10、nited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 5536:

11、2013: EEN ISO 5536:2013 (E) 3 Foreword The text of ISO 5536:2009 has been prepared by Technical Committee ISO/TC 34 “Food products” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 5536:2013 by Technical Committee CEN/TC 302 “Milk and milk products - Meth

12、ods 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 publication of an identical text or by endorsement, at the latest by November 2013, and conflicting national standards shall be withdrawn at the l

13、atest by November 2013. Attention is drawn to the possibility that some of the elements of 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 nationa

14、l standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithua

15、nia, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 5536:2009 has been approved by CEN as EN ISO 5536:2013 without any modification. iiBS EN ISO 5536:2013EN ISO 5536:

16、2013 (E)BS ISO 5536:2009INTERNATIONAL STANDARD ISO 5536:2009(E)IDF 23:2009(E) ISO and IDF 2009 All rights reserved 1Milk fat products Determination of water content Karl Fischer method 1 Scope This International Standard specifies a method for the determination of the water content of milk fat produ

17、cts by the Karl Fischer (KF) method. The method is applicable to butteroil (anhydrous butteroil, anhydrous butterfat, anhydrous milk fat) with a water content not exceeding 1,0 % mass fraction. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1

18、water content of milk fat products 2HOwmass fraction of water determined by the procedure specified in this International Standard NOTE The water content is expressed as a percentage mass fraction. 3 Principle The test sample is directly titrated with a commercially available two-component Karl Fisc

19、her reagent at a temperature of approximately 40 C. The water content is calculated from the amount of reagent used. 4 Reagents Use only reagents of recognized analytical grade, unless otherwise specified, and distilled or demineralized water or water of equivalent purity. Avoid absorption of moistu

20、re from the environment. 4.1 Karl Fischer (KF) reagent, a commercially available pyridine-free two-component reagent consisting of a titration component (4.2) and a solvent component. Alternatively, a pyridine-free one-component KF reagent consisting solely of a titration component (4.2) can also be

21、 used, in which case, methanol (4.6) is used as the solvent component. 4.2 Titration component. The titration component of the KF reagent (4.1) shall have a water equivalent of approximately 2 mg/ml. 4.3 1-Octanol (C8H17OH) BS EN ISO 5536:2013BS ISO 5536:2009ISO 5536:2009(E) IDF 23:2009(E) 2 ISO and

22、 IDF 2009 All rights reserved4.4 Working medium. Prepare the working medium by mixing equal volumes of the solvent component of the KF reagent (4.1) and 1-octanol (4.3) (1+1) directly in the titration vessel of the KF apparatus (5.1). 4.5 Water standard, wH2O= 10 mg/g. For the determination of the w

23、ater equivalent of the titration component, use a commercially available liquid water standard. 4.6 Methanol (CH3OH), with a water content of not more than 0,05 % mass fraction. 5 Apparatus Usual laboratory apparatus and in particular the following. Ensure that all equipment is completely dry before

24、 use. 5.1 Karl Fischer (KF) apparatus. Use an automatic volumetric KF apparatus, with a burette of capacity 5 ml (preferably) or 10 ml and a double-jacketed titration vessel with a water inlet and outlet to carry out the titration at approximately 40 C. 5.2 Water bath, capable of maintaining a tempe

25、rature of 40 C 5 C; equipped with a thermostat and a pump for heating the double-jacketed titration vessel of the KF apparatus (5.1). 5.3 Analytical balance, capable of weighing to the nearest 1 mg, with a readability of 0,1 mg. 5.4 Disposable syringes, of capacity 5 ml or 10 ml; for dosing the wate

26、r standard (4.5) and the test portion (7.5). 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

27、is given in ISO 707IDF 501. 7 Procedure 7.1 KF apparatus drift 7.1.1 Determine the drift of the KF apparatus (5.1) every day and/or when the working conditions change as follows. Mix approximately 30 ml of working medium (4.4) in the titration vessel of the KF apparatus (5.1). Heat the vessel and it

28、s contents to 40 C using the water bath (5.2). Pre-titrate the working medium. Then carry out a titration over 5 min (without addition of a test sample). IMPORTANT During each titration the amount of working medium used shall completely cover the electrodes of the KF apparatus. BS EN ISO 5536:2013IS

29、O 5536:2009(E)IDF 23:2009(E)BS ISO 5536:2009ISO 5536:2009(E) IDF 23:2009(E) ISO and IDF 2009 All rights reserved 37.1.2 Calculate the KF apparatus drift, qV, expressed in millilitres per minute, by using Equation (1): dVVqt= (1) where Vdis the volume, in millilitres, of the amount of titration compo

30、nent (4.2) used in the titration (7.1.1); t is the time, in minutes. Or calculate the KF apparatus drift, qm, expressed in milligrams per minute, by using Equation (2): demVqt= (2) where eis the water equivalent (7.2) of the titration component (4.2), in milligrams per millilitre, used in the titrat

31、ion (7.1.1). 7.2 Water equivalent of the titration component of the KF reagent 7.2.1 Titration To calculate for each determination the water equivalent of a titration component accurately, carry out the titration in this subclause and the calculation step (7.2.2) five times. Mix approximately 30 ml

32、of working medium (4.4) in the titration vessel of the KF apparatus (5.1) (see also 7.1.1, “important” notice). Heat the vessel and its contents using the water bath (5.2) to 40 C. Pre-titrate the working medium. Take up between 0,6 g and 0,9 g of water standard (4.5) (corresponding to about 6 mg to

33、 9 mg of water) in a disposable syringe (5.4). Weigh the syringe and its contents, and record its mass to the nearest 0,1 mg. It is also possible to take up more than 0,6 g to 0,9 g of water standard and to use the same filling of the syringe for several titrations (one immediately after the other).

34、 In that case, approximately 0,6 g to 0,9 g of water standard should also be used for each titration, the exact amount being calculated each time by weighing the syringe and its remaining contents after each injection. Add the water standard to the titration vessel. Weigh the empty syringe again and

35、 record its mass to the nearest 0,1 mg. Subtract the mass of the empty syringe from that of the syringe with water standard before addition of the water standard to the vessel to obtain the net mass of the water standard added to the titration vessel, mw, i(for i = 1 5). Record the net mass of the a

36、dded water standard to the nearest 0,1 mg. Carry out a titration while using as shut-off criterion the 10 s stop delay time mentioned in 7.3. Record, for i = 1 5, the volume, Ve, i, in millilitres, of titration component. Do not perform more than three titrations on one portion of working medium. Af

37、ter three titrations on one portion, carry out further titrations by again mixing 30 ml working medium (4.4) in the titration vessel of the apparatus. 7.2.2 Calculation Calculate the water equivalent of the titration component, e, i, expressed in milligrams of water per millilitre, as the mean value

38、 of the five (for i = 1 5) single titrations (7.2.1), by using Equation (3). BS EN ISO 5536:2013ISO 5536:2009(E)IDF 23:2009(E)BS ISO 5536:2009ISO 5536:2009(E) IDF 23:2009(E) 4 ISO and IDF 2009 All rights reserved2e,w, H O, se,iiimwV = (3) where w,im is the mass, in grams, of water standard used for

39、titration i (7.2.1); 2H O, sw is the water mass fraction, in milligrams per gram, of the water standard; e,iVis the volume, in millilitres, of titration component (4.2) in titration i (7.2.1). 7.2.3 Mean value Calculate the water equivalent of the titration component, e, expressed in milligrams of w

40、ater per millilitre, as the mean value of the five (i = 1 5) single titrations (7.2.1) by using Equation (4): 5e,1e5ii=(4) 7.2.4 Expression of water equivalent Express the (mean) value of water equivalent to three decimal places. 7.3 Shut-off criterion According to the features of the apparatus used

41、, the stop criterion shall either be a stop delay time of 10 s or a stop drift slightly above the measured drift (7.1). 7.4 Preparation of the test sample Mix the test sample by blending thoroughly at 35 C to 40 C to completely disperse the water. 7.5 Determination Mix approximately 30 ml of working

42、 medium (4.4) in the titration vessel of the KF apparatus (5.1) (see also 7.1.1, “important” notice). Heat the vessel and its contents using the water bath (5.2) at 40 C. Pre-titrate the working medium. Take up approximately 5 g of test sample (7.4) in a disposable syringe (5.4). Weigh the syringe w

43、ith the test portion and record the total mass to the nearest 0,1 mg. Add the test portion to the titration vessel. Weigh the empty syringe again and record its mass to the nearest 0,1 mg. Subtract the mass of the syringe from that of the test portion and the syringe to obtain the net test portion m

44、ass, m. Record the net mass to the nearest 0,1 mg. Carry out a titration and record the volume, V, in millilitres, of titration component. Do not perform more than three titrations on one portion of the working medium. If the titrator does not automatically calculate the results (see 8.1), record th

45、e titration time, t. BS EN ISO 5536:2013ISO 5536:2009(E)IDF 23:2009(E)BS ISO 5536:2009ISO 5536:2009(E) IDF 23:2009(E) ISO and IDF 2009 All rights reserved 5It is recommended to carry out several replicates for each sample to obtain more accurate results. In that case, record for each replicate, i, t

46、he individual test portion mass, mi, the amount of titration component, Vi, and the titration time, ti. 8 Calculation and expression of results 8.1 Calculation Appropriate automatic calculation by the titrator may also be used, if available. 8.1.1 Calculate the water content of the test sample, 2HOw

47、 , expressed as a percentage mass fraction, by using either Equation (5) or (6): ()2eHO100VV qtwm= (5) or 2eHO100mV qtwm = (6) where V is the volume, in millilitres, of titration reagent (7.5); qVis the numerical value of the drift (7.1.2), in millilitres per minute; qmis the numerical value of the

48、drift, in milligrams per minute (7.1.2); t is the titration time, in minutes (7.5); eis the water equivalent of the titration component, in milligrams per millilitre (7.2.3); m is the mass, in milligrams, of the test portion (7.5). 8.1.2 If n replicates for a sample have been carried out, calculate

49、for each of the replicates, i, the individual water content of the test sample, 2H O,iw expressed as percentage mass fraction, by using either Equation (7) or (8): ()2eH O,100i ViiiV qtwm= (7) or e2H O,100i miiiV qtwm = (8) where Viis the volume, in millilitres, of titration reagent for replicate i (7.5); tiis the titration time, in minutes, for replicate i (7.5); miis the mass, in milligrams, of the test portion for replicate i (7.5); i is the number of replicates for i = 1 to n. BS EN ISO 5536:2013IS