1、BSI Standards PublicationBS ISO 6495-1:2015Animal feeding stuffs Determination of water-solublechlorides contentPart 1: Titrimetric methodBS ISO 6495-1:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 6495-1:2015. Itsupersedes BS 5766-5:1999 which is withdr
2、awn.The UK participation in its preparation was entrusted to TechnicalCommittee AW/10, Animal feeding stuffs.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users
3、are responsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 58083 3ICS 65.120Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStan
4、dards Policy and Strategy Committee on 31 July 2015.Amendments issued since publicationDate Text affectedBS ISO 6495-1:2015 ISO 2015Animal feeding stuffs Determination of water-soluble chlorides content Part 1: Titrimetric methodAliments des animaux Dtermination de la teneur en chlorures solubles da
5、ns leau Partie 1: Mthode titrimtriqueINTERNATIONAL STANDARDISO6495-1First edition2015-06-15Reference numberISO 6495-1:2015(E)BS ISO 6495-1:2015ISO 6495-1:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this public
6、ation may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the countr
7、y of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 6495-1:2015ISO 6495-1:2015(E)Foreword iv1 Scope . 12 Normative references 13 Principle 14 Reagents 15 Apparatus . 36
8、 Sampling 47 Preparation of test sample . 48 Procedure. 48.1 Preparation of test solution . 48.1.1 General 48.1.2 Preparation of test solution of sample free from organic matter 48.1.3 Preparation of test solution of sample containing organic matter, excluding the products listed in 8.1.4 48.1.4 Coo
9、ked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidal substances 48.2 Titration 58.3 Blank test . 59 Expression of results 610 Precision . 610.1 Interlaboratory test. 610.2 Repeatability . 710.3 Reproducibility . 711 Test report .
10、7Annex A (informative) Results of interlaboratory test 8Bibliography 9 ISO 2015 All rights reserved iiiContents PageBS ISO 6495-1:2015ISO 6495-1:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The wor
11、k 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 on that committee. International organizations, governmental and non-governme
12、ntal, 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.The procedures used to develop this document and those intended for its further maintenance are described in the
13、 ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possib
14、ility 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. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of
15、patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as in
16、formation about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 34, Food Products, Subcommittee SC 10, Animal feeding stuffs.This first edition of ISO 6495-1
17、 cancels and replaces ISO 6495:1999, which has been technically revised.ISO 6495 consists of the following parts, under the general title Animal feeding stuffs Determination of water-soluble chloride content: Part 1: Titrimetric methodiv ISO 2015 All rights reservedBS ISO 6495-1:2015INTERNATIONAL ST
18、ANDARD ISO 6495-1:2015(E)Animal feeding stuffs Determination of water-soluble chlorides content Part 1: Titrimetric method1 ScopeThis part of ISO 6495 specifies a method for the determination of water-soluble chloride content, expressed as sodium chloride, of animal feeding stuffs.This method is app
19、licable to animal feeding stuffs containing water-soluble chloride content, expressed as sodium chloride, 0,05 %.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable to its application. For dated references, only the ed
20、ition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 3696, Water for analytical laboratory use Specification and test methodsISO 6497, Animal feeding stuffs SamplingISO 6498, Animal feeding stuffs Guidelines for sample prep
21、aration3 PrincipleThe chloride present in a test portion are dissolved in water. The solution is clarified if the product contains organic matter. It is then slightly acidified with nitric acid and the chlorides are precipitated as silver chloride by means of standard volumetric solution of silver n
22、itrate. The excess silver nitrate is titrated with a standard volumetric solution of ammonium thiocyanate or potassium thiocyanate, by Volhards method.4 ReagentsUse only reagents of recognized analytical grade.4.1 Water, complying with at least grade 3 in accordance with ISO 3696.4.2 Acetone.4.3 n-H
23、exane.4.4 Nitric acid, mass concentration 20(HNO3) = 1,38 g/ml.4.5 Dilute nitric acid, volume fraction (HNO3) = 2 %.Dilute 20 ml nitric acid (4.4) to 1000 ml with water (4.1). ISO 2015 All rights reserved 1BS ISO 6495-1:2015ISO 6495-1:2015(E)4.6 Potassium chromate solution, mass concentration (K2CrO
24、4) = 5 % in water (4.1).4.7 Ammonium iron(III) sulfate, saturated solution. Prepare from NH4Fe(SO4)212H2O dissolved in water (4.1) until saturation. Approximately 125 g ammonium iron(III) sulfate per 100 ml water is required.4.8 Activated carbon, free from chloride and not capable of adsorbing chlor
25、ide.4.9 Carrez I solution.Dissolve 10,6 g of potassium hexacyanoferrate(II) trihydrate K4Fe(CN)63H2O in water (4.1). Dilute to 100 ml with water (4.1).4.10 Carrez II solution.Dissolve 21,9 g of zinc acetate dihydrate Zn(CH3COO)22H2O in water (4.1), and add 3 ml of glacial acetic acid. Dilute to 100
26、ml with water (4.1).4.11 Sodium chloride, standard volumetric solution, c(NaCl) = 0,1 mol/l. The molarity of the standard volumetric solution shall be known to 0,000 1 mol/l.Put about 20 g of finely pulverized sodium chloride in a thin layer on watch glass. Dry at about 250 C for 1 h to 2 h. Let it
27、cool in a desiccator, accurately weigh 5,8 g, recorded to 0,000 1 g (m), and dissolve in water (4.1). Dilute to the mark in a 1 000 ml volumetric flask with water (4.1) and mix well.The concentration of standard sodium chloride solution can be calculated using Formula (1):cmNaCl=58 44,(1)wherecNaCli
28、s the concentration of standard sodium chloride solution, in mol/l;m is the mass of sodium chloride, in grams.4.12 Silver nitrate, standard volumetric solution, cs= 0,1 mol/l.The molarity of the standard volumetric solution should be known to 0,000 1 mol/l, and duplicate titrations shall agree withi
29、n 0,1 ml.Put about 20 g of finely pulverized silver nitrate in a thin layer on watch glass. Dry at about 80 C for 2 h to 3 h. Let it cool in a desiccator, weigh about 17,0 g and dissolve in water (4.1). Dilute to the mark in a 1 000 ml volumetric flask with water (4.1) and mix well.Pipette 20 ml of
30、standard sodium chloride solution (4.11) into a 200 ml conical flask. Add 1 ml of potassium chromate solution (4.6) and titrate while shaking vigorously with standard silver nitrate (4.12) until a reddish brown colour persists for at least 30 s.2 ISO 2015 All rights reservedBS ISO 6495-1:2015ISO 649
31、5-1:2015(E)The concentration of standard silver nitrate solution can be calculated using Formula (2):ccVsNaCls=20(2)wherecsis the concentration of standard silver nitrate solution (4.12), in mol/l;cNaClis the concentration of standard sodium chloride solution (4.11), in mol/l;Vsis the volume of stan
32、dard silver nitrate solution (4.12) used for titration, in ml.4.13 Ammonium thiocyanate or potassium thiocyanate, standard volumetric solution, ct= 0,1 mol/l.The molarity of standard volumetric solution shall be known to 0,000 1 mol/l, and duplicate titrations shall agree within 0,1 ml.Weigh 7,6 g o
33、f ammonium thiocyanate, or 9,7 g of potassium thiocyanate and dissolve in water (4.1). Dilute to the mark in 1 000 ml volumetric flask and mix well.Pipette 20 ml standard silver nitrate (4.12) into a 200 ml conical flask. Add 10 ml of dilute nitric acid (4.5) and 2 ml of saturated ammonium iron(III)
34、 sulfate solution (4.7). Titrate while shaking vigorously with standard ammonium, or potassium thiocyanate solution until a reddish brown colour persists for at least 30 s.The concentration of standard ammonium or potassium thiocyanate solution can be calculated using Formula (3):ccVtst=20(3)wherect
35、is the concentration of standard ammonium or potassium thiocyanate solution (4.13), in mol/l;csis the concentration of standard silver nitrate;Vtis the volume of standard ammonium or potassium thiocyanate solution (4.13) used for titra-tion, in ml.5 ApparatusUsual laboratory apparatus and, in partic
36、ular, the following.5.1 Rotary shaker, operating at a rotation frequency of approximately 35 min1 to 40 min1.5.2 Volumetric flasks, class A of capacities 200 ml, 500 ml, and 1 000 ml.5.3 Pipettes, class A of appropriate capacities.5.4 Burettes, class A of appropriate capacities.5.5 Analytical balanc
37、e, capable of weighing to 0,000 1 g.5.6 Filter paper, of appropriate porosity. ISO 2015 All rights reserved 3BS ISO 6495-1:2015ISO 6495-1:2015(E)6 SamplingSampling is not part of the method specified in this part of ISO 6495. A recommended sampling method is given in ISO 6497.It is important that th
38、e laboratory received a sample which is truly representative and has not been damaged or changed during transport or storage.7 Preparation of test samplePrepare the test sample in accordance with ISO 6498.If solid, grind a representative part, 100 g to 150 g of the laboratory sample (usually 500 g)
39、so that it passes completely through a sieve with 1 mm apertures. Mix thoroughly.8 Procedure8.1 Preparation of test solution8.1.1 GeneralIf the test sample is free from organic matter, proceed in accordance with 8.1.2.If the test sample contains organic matter, proceed in accordance with 8.1.3, unle
40、ss the test sample concerns cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidal substances (e.g. dextrinated starch). In this case proceed in accordance with 8.1.4.8.1.2 Preparation of test solution of sample free from organic
41、 matterAccurately weigh, to 0,000 1 g, not more than 10 g of the test sample (Clause 7) containing not more than 3 g of chloride. Transfer to a 500 ml volumetric flask (5.2) and add about 400 ml of water (4.1) at a temperature of approximately 20 C.Mix for 30 min in the rotary shaker (5.1), dilute t
42、o the mark with water (4.1), then mix, and filter through the filter paper (5.6).Proceed in accordance with 8.2.8.1.3 Preparation of test solution of sample containing organic matter, excluding the products listed in 8.1.4Accurately weigh, to 0,000 1 g, approximately 5 g of the test sample (Clause 7
43、) containing not more than 3 g of chloride. Transfer to a 500 ml volumetric flask (5.2). Add 1 g of activated carbon (4.8), about 400 ml of water (4.1) at a temperature of approximately 20 C, and 5 ml of Carrez I solution (4.9). Then mix and add 5 ml of Carrez II solution (4.10).Mix for 30 min on th
44、e rotary shaker (5.1). Dilute to the mark with water (4.1), then mix and filter through the filter paper (5.6).Proceed in accordance with 8.2.8.1.4 Cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidal substancesAccurately weigh
45、, to 0,000 1 g, approximately 5 g of the test sample (Clause 7) containing not more than 3 g of chloride. Transfer to a 500 ml volumetric flask (5.2). Add 1 g of activated carbon (4.8), about 400 ml of water (4.1) at a temperature of approximately 20 C, and 5 ml of Carrez I solution (4.9). Then mix
46、and add 5 ml of Carrez II solution (4.10).4 ISO 2015 All rights reservedBS ISO 6495-1:2015ISO 6495-1:2015(E)Mix for 30 min on the rotary shaker (5.1). Dilute to the mark with water (4.1), then mix.Decant (if necessary, centrifuge). By means of a pipette (5.3), transfer 100 ml of the supernatant to a
47、 200 ml volumetric flask (5.2).Dilute to the mark with acetone (4.2), then mix, bring the volume to the mark with acetone or water, remix and filter through the filter paper(5.6).Proceed in accordance with 8.2.8.2 TitrationBy means of a pipette (5.3), transfer to a conical flask an aliquot portion o
48、f between 25 ml and 100 ml (Va) of the filtrate. The aliquot portion shall not contain more than 150 mg of chloride.Dilute, if necessary, to a volume of not more than 100 ml with water. Add 5 ml of dilute nitric acid (4.5), 2 ml of saturated ammonium iron(III) sulfate solution (4.7) and 2 drops of s
49、tandard ammonium or potassium thiocyanate solution (4.13) from a burette (5.4) filled to the zero mark.Add standard silver nitrate solution (4.12) from another burette (5.4), while shaking until the reddish brown tint disappears, then add an excess of 5 ml standard silver nitrate solution (total volume of AgNO3= Vs1). Shake vigorously to coagulate the precipitate. If necessary, 5 ml of n-hexane (4.3) may be added to assist coagulation.Titrate the excess standard silver nitrate solution (4.12) with standard ammonium
