1、BSI Standards Publication BS ISO 6495-1:2015 Animal feeding stuffs Determination of water-soluble chlorides content Part 1: Titrimetric methodBS ISO 6495-1:2015 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO 6495-1:2015. It supersedes BS 5766-5:1999 which is
2、 withdrawn. The UK participation in its preparation was entrusted to Technical Committee AW/10, Animal feeding stuffs. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a con
3、tract. Users are responsible for its correct application. The British Standards Institution 2015. Published by BSI Standards Limited 2015 ISBN 978 0 580 58083 3 ICS 65.120 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the
4、authority of the Standards Policy and Strategy Committee on 31 July 2015. Amendments issued since publication Date Text affectedBS ISO 6495-1:2015 ISO 2015 Animal feeding stuffs Determination of water-soluble chlorides content Part 1: Titrimetric method Aliments des animaux Dtermination de la teneur
5、 en chlorures solubles dans leau Partie 1: Mthode titrimtrique INTERNATIONAL STANDARD ISO 6495-1 First edition 2015-06-15 Reference number ISO 6495-1:2015(E)BS ISO 6495-1:2015ISO 6495-1:2015(E)ii ISO 2015 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2015 All rights reserved. Unless otherwise
6、 specified, no part of this publication 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
7、 or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in SwitzerlandBS ISO 6495-1:2015ISO 6495-1:2015(E)Foreword iv 1 Scope . 1 2 Normative references
8、 1 3 Principle 1 4 Reagents 1 5 Apparatus . 3 6 Sampling 4 7 Preparation of test sample . 4 8 Procedure. 4 8.1 Preparation of test solution . 4 8.1.1 General 4 8.1.2 Preparation of test solution of sample free from organic matter 4 8.1.3 Preparation of test solution of sample containing organic matt
9、er, excluding the products listed in 8.1.4 4 8.1.4 Cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidal substances 4 8.2 Titration 5 8.3 Blank test . 5 9 Expression of results 6 10 Precision . 6 10.1 Interlaboratory test. 6 10.
10、2 Repeatability . 7 10.3 Reproducibility . 7 11 Test report . 7 Annex A (informative) Results of interlaboratory test 8 Bibliography 9 ISO 2015 All rights reserved iii Contents PageBS ISO 6495-1:2015ISO 6495-1:2015(E) Foreword ISO (the International Organization for Standardization) is a worldwide f
11、ederation 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 on that co
12、mmittee. 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. The procedures used to develop this document
13、 and those intended for its further maintenance are described in the 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,
14、Part 2 (see www.iso.org/directives). 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. Details of any patent rights identified during the development o
15、f the document will be in the Introduction and/or on the ISO list of 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 specifi
16、c terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 34, Food Products, Su
17、bcommittee SC 10, Animal feeding stuffs. This first edition of ISO 6495-1 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: Titrimetr
18、ic methodiv ISO 2015 All rights reservedBS ISO 6495-1:2015INTERNATIONAL ST ANDARD ISO 6495-1:2015(E) Animal feeding stuffs Determination of water-soluble chlorides content Part 1: Titrimetric method 1 Scope This part of ISO 6495 specifies a method for the determination of water-soluble chloride cont
19、ent, expressed as sodium chloride, of animal feeding stuffs. This method is applicable to animal feeding stuffs containing water-soluble chloride content, expressed as sodium chloride, 0,05 %. 2 Normative references The following documents, in whole or in part, are normatively referenced in this doc
20、ument and are indispensable to its application. For dated references, only the edition 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 methods ISO 6497, Anima
21、l feeding stuffs Sampling ISO 6498, Animal feeding stuffs Guidelines for sample preparation 3 Principle The 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 ar
22、e precipitated as silver chloride by means of standard volumetric solution of silver nitrate. The excess silver nitrate is titrated with a standard volumetric solution of ammonium thiocyanate or potassium thiocyanate, by Volhards method. 4 Reagents Use only reagents of recognized analytical grade. 4
23、.1 Water, complying with at least grade 3 in accordance with ISO 3696. 4.2 Acetone. 4.3 n-Hexane. 4.4 Nitric acid, mass concentration 20 (HNO 3 ) = 1,38 g/ml. 4.5 Dilute nitric acid, volume fraction (HNO 3 ) = 2 %. Dilute 20 ml nitric acid (4.4) to 1000 ml with water (4.1). ISO 2015 All rights reser
24、ved 1BS ISO 6495-1:2015ISO 6495-1:2015(E) 4.6 Potassium chromate solution, mass concentration (K 2 CrO 4 ) = 5 % in water (4.1). 4.7 Ammonium iron(III) sulfate, saturated solution. Prepare from NH 4 Fe(SO 4 ) 2 12H 2 O dissolved in water (4.1) until saturation. Approximately 125 g ammonium iron(III)
25、 sulfate per 100 ml water is required. 4.8 Activated carbon, free from chloride and not capable of adsorbing chloride. 4.9 Carrez I solution. Dissolve 10,6 g of potassium hexacyanoferrate(II) trihydrate K 4 Fe(CN) 6 3H 2 O in water (4.1). Dilute to 100 ml with water (4.1). 4.10 Carrez II solution. D
26、issolve 21,9 g of zinc acetate dihydrate Zn(CH 3 COO) 2 2H 2 O in water (4.1), and add 3 ml of glacial acetic acid. Dilute to 100 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 m
27、ol/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 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)
28、 and mix well. The concentration of standard sodium chloride solution can be calculated using Formula (1): = (1) where c NaCl is 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, c s= 0,1 m
29、ol/l. The molarity of the standard volumetric solution should be known to 0,000 1 mol/l, and duplicate titrations shall agree within 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 1
30、7,0 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 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
31、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 6495-1:2015(E) The concentration of standard silver nitrate solution can be calculated using Formula (2): (2) where c s is the concentration of standard silver nitrate so
32、lution (4.12), in mol/l; c NaCl is the concentration of standard sodium chloride solution (4.11), in mol/l; V s is the volume of standard silver nitrate solution (4.12) used for titration, in ml. 4.13 Ammonium thiocyanate or potassium thiocyanate, standard volumetric solution, c t= 0,1 mol/l. The mo
33、larity 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 of 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
34、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) sulfate solution (4.7). Titrate while shaking vigorously with standard ammonium, or potassium thiocyanate solution until a reddish brown colour persists for at l
35、east 30 s. The concentration of standard ammonium or potassium thiocyanate solution can be calculated using Formula (3): (3) where c t is the concentration of standard ammonium or potassium thiocyanate solution (4.13), in mol/l; c s is the concentration of standard silver nitrate; V t is the volume
36、of standard ammonium or potassium thiocyanate solution (4.13) used for titra- tion, in ml. 5 Apparatus Usual laboratory apparatus and, in particular, the following. 5.1 Rotary shaker, operating at a rotation frequency of approximately 35 min1 to 40 min1. 5.2 V olumetric flasks, class A of capacities
37、 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 balance, 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 S
38、ampling Sampling 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 the laboratory received a sample which is truly representative and has not been damaged or changed during transport or storage. 7 Preparation of tes
39、t sample Prepare 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) so that it passes completely through a sieve with 1 mm apertures. Mix thoroughly. 8 Procedure 8.1 Preparation of test solution 8.1.1 General If
40、 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, unless the test sample concerns cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage
41、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 matter Accurately 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. Transf
42、er 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 to the mark with water (4.1), then mix, and filter through the filter paper (5.6). Proceed in accordance with 8.2. 8.1.3 Preparation of
43、test solution of sample containing organic matter, excluding the products listed in 8.1.4 Accurately weigh, 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 40
44、0 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 the rotary shaker (5.1). Dilute to the mark with water (4.1), then mix and filter through the filter paper (5.6). Proceed in accordan
45、ce with 8.2. 8.1.4 C ook ed feeding stuffs, flax cak es and flour , pr oducts rich in flax flour , and other pr oducts rich in mucilage or in colloidal substances Accurately weigh, 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 5
46、00 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).4 ISO 2015 All rights reservedBS ISO 6495-1:2015ISO 6495-1:2015(E) Mix for 30 m
47、in 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 200 ml volumetric flask (5.2). Dilute to the mark with acetone (4.2), then mix, bring the volume to the mark with acet
48、one or water, remix and filter through the filter paper(5.6). Proceed in accordance with 8.2. 8.2 Titration By means of a pipette (5.3), transfer to a conical flask an aliquot portion of between 25 ml and 100 ml (V a ) of the filtrate. The aliquot portion shall not contain more than 150 mg of chlori
49、de. 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 standard 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 si
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