UGANDA STANDARD  
      US ISO 6495
First Edition
   2009 -09-04
 
Reference numbe r 
   US ISO 6495:1999
 © UNBS 200 9 
  
Animal feeding stuffs — Determination of water-soluble 
chlorides content 
 US ISO 6495:1999  
 
© UNBS  2009 – All rights reserved Compliance with this standard does not, of itself confer immunity from legal obligations 
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2009  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
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    US ISO 6495:1999  
© UNBS  2009 - All rights reserved National foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry  of Tourism, Trade and 
Industry established by the Act of Parliament of 198 3, of the Laws of Uganda.  UNBS is mandated to co-
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex A limentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS Agr eements of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a gi ven field or area and consists of representatives of 
consumers, traders, academician s, manufacturers, governme nt and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committ ee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council. 
This Uganda Standard, US ISO 6495:1999, Animal feeding stuffs — Determination of water-soluble
chlorides content, is identical with and  has been reproduced from an International Standard ISO 6495:1999,
Animal feeding stuffs — Determination of water-soluble chlorides content, and has been adopted as a Uganda
Standard . 
Wherever the words, "International Standard" a ppear, they should be replaced by "Uganda Standard." A Reference numbe r
ISO 6495:1999 (E)INTERNATIONAL
STANDARDISO
6495
Second edition
1999-04-01
Animal feeding stuffs — Determination
of water-soluble chlorides content
Aliments des animaux — Détermination de la teneur en chlorures solubles
dans l'eauISO 6495:1999(E)
©   ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by an y means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
iiForeword
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 technicalcommittees. Each member body interested in a subject for which a technical committee has been established hasthe right to be represented on that committee. International organizations, governmental and non-governmental, inliaison with ISO, also take part in the work. ISO collaborates closely with the International ElectrotechnicalCommission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.Draft International Standards adopted by the technical committees are 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.
International Standard ISO 6495 was prepared by Technical Committee ISO/TC 34, 
Agricultural food products ,
Subcommittee SC 10, Animal feeding stuffs .
This second edition of ISO 6495 cancels and replaces the first edition (ISO 6495:1980), which has been technically
revised.
Annex A of this International Standard is for information only.INTERNATIONAL STANDARD    © ISO ISO 6495:1999(E)
1Animal feeding stuffs — Determination of water-soluble
chlorides content
1 Scope
This International Standard specifies a method for the determination of the water-soluble chlorides content,
expressed as sodium chloride, of animal feeding stuffs.
The method is applicable to animal feeding stuffs.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of thesepublications do not apply. However, parties to agreements based on this International Standard are encouraged toinvestigate the possibility of applying the most recent editions of the normative documents indicated below. Forundated references, the latest edition of the normative document referred to applies. Members of ISO and IECmaintain registers of currently valid International Standards.
ISO 3696, 
Water for analytical laboratory use — Specification and test methods.
ISO 6498, Animal feeding stuffs — Preparation of test samples.
3 Principle
The chlorides 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 ofstandard volumetric silver nitrate solution. The excess silver nitrate is titrated with a standard volumetric solution ofammonium thiocyanate or potassium thiocyanate.
4 Reagents
Use 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-Hexane.
4.4   Nitric acid , r20(HNO3) = 1,38 g/ml.
4.5   Activated carbon , free from chlorides and not capable of adsorbing chlorides.
4.6   Ammonium iron(III) sulfate , saturated solution.
Prepare from NH 4Fe(SO4)2⋅12H2O.ISO 6495:1999(E) © ISO
24.7   Carrez I solution .
Dissolve in water, 10,6 g of potassium hexacyanoferrate(II) trihydrate [K 4Fe(CN)6⋅3H2O]. Dilute to 100 ml with
water.
4.8   Carrez II solution .
Dissolve in water, 21,9 g of zinc acetate dihydrate [Zn(CH 3COO)2⋅2H2O] and add 3 ml of glacial acetic acid. Dilute
to 100 ml with water.
4.9   Ammonium thiocyanate  or potassium thiocyanate , standard volumetric solution, c(NH4SCN) = 0,1 mol/l or
c(KSCN) = 0,1 mol/l.
4.10   Silver nitrate , standard volumetric solution, c(AgNO3) = 0,1 mol/l.
5 Apparatus
Usual laboratory apparatus and, in particular, the following.
5.1   Rotary shaker , operating at a rotation frequency of approximately 35 min –1 to 40 min –1.
5.2   One-mark volumetric flasks , of capacities 200 ml and 500 ml.
5.3   Pipettes, of appropriate capacity.
5.4   Burettes.
5.5   Analytical balance , capable of weighing to the nearest 0,001 g.
6 Sampling
Sampling is not part of the method specified in this International Standard. A recommended sampling method is
given in ISO 6497 [1].
It is important that the laboratory receive a sample which is truly representative and has not been damaged or
changed during transport or storage.
7 Preparation of test sample
Prepare the test sample in accordance with ISO 6498.
If solid, grind the laboratory sample (usually 500 g) so that it passes completely through a sieve with 1 mm
apertures. Mix thoroughly.
8 Procedure
NOTE  If it is required to check whether the repeatability limit is met (see 10.2), carry out two single determinations in
accordance with 8.1 to 8.5.
8.1 Procedure selection
If the test sample is free from organic matter, proceed in accordance with 8.2.© ISO ISO 6495:1999(E)
3If the test sample contains organic matter, proceed in accordance with 8.3, unless the test sample concerns cooked
feeding stuffs, flax cakes and flour, products rich in flax flour, and other products rich in mucilage or in colloidalsubstances (e.g. dextrinated starch). In this case proceed in accordance with 8.4.
8.2 Preparation of test solution of samples free from organic matter
Weigh, to the nearest 0,001 g, a test portion (mass m) of the prepared test sample of not more than 10 g presumed
to contain not more than 3 g of chlorides. Transfer to a 500 ml volumetric flask (5.2) and add 400 ml of water at atemperature of approximately 20 °C.
Mix for 30 min in the rotary shaker (5.1), dilute to the mark with water (resulting volume V
i), then mix and filter.
Proceed in accordance with 8.5.
8.3 Preparation of test solution of samples containing organic matter, excluding the products
listed in 8.4
Weigh approximately 5 g (mass m) of the prepared test sample to the nearest 0,001 g and transfer to a 500 ml
volumetric flask (5.2). Add 1 g of activated carbon (4.5), 400 ml of water at a temperature of approximately 20 °C,and 5 ml of Carrez I solution (4.7). Stir, then add 5 ml of Carrez II solution (4.8).
Mix for 30 min on the rotary shaker (5.1). Dilute to the mark with water (resulting volume V
i), mix and filter.
Proceed in accordance with 8.5.
8.4 Cooked feeding stuffs, flax cakes and flour, products rich in flax flour, and other products
rich in mucilage or in colloidal substances
Weigh approximately 5 g (mass m) of the prepared test sample to the nearest 0,001 g and transfer to a 500 ml
volumetric flask (5.2). Add 1 g of activated carbon (4.5), 400 ml of water at a temperature of approximately 20 °C,and 5 ml of Carrez I solution (4.7). Stir, then add 5 ml of Carrez II solution (4.8).
Mix for 30 min on the rotary shaker (5.1). Dilute to the mark with water (resulting volume V
i) and mix.
Decant (if necessary, centrifuge). By means of a pipette (5.3), transfer 100 ml of the supernatant liquid to a 200 ml
volumetric flask (5.2).
Mix with acetone (4.2), dilute to the mark with the same solvent, mix and filter.
8.5 Titration
By means of a pipette (5.3), transfer to a conical flask an aliquot portion of between 25 ml and 100 ml (volume Va) of
the filtrate. The aliquot portion shall not contain more than 150 mg of chloride.
Dilute, if necessary, to a volume of not less than 50 ml with water. Add 5 ml of nitric acid (4.4), 2 ml of ammonium
iron(III) sulfate solution (4.6) and 2 drops of ammonium thiocyanate solution or potassium thiocyanate solution (4.9)from a burette (5.4) filled to the zero mark.
NOTE  The remainder of the solution is to be used for titration of the excess silver nitrate.
Add from a burette (5.4), silver nitrate solution (4.10) until the reddish-brown tint disappears, then add an excess
of 5 ml (resulting volume 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 silver nitrate with ammonium thiocyanate solution or potassium thiocyanate solution (4.9) until a
reddish brown tint, persisting for at least 30 s, develops (resulting volume Vt1).ISO 6495:1999(E) © ISO
48.6 Blank test
Carry out a blank test in parallel with the determination, using the same procedure and the same reagents, but
omitting the test portion.
9 Expression of results
Calculate the water-soluble chlorides content, expressed as sodium chloride, by the equation:
wcsss t tt i
aw = MV  Vc  V  V
m  V
Vf  [( ) ( ) ]100 %101 0−− −×× ×c
where
wwcis the water-soluble chlorides content, expressed as sodium chloride, as percentage by mass, of the
test sample;
Mis the molar mass, in grams per mole, of sodium chloride ( M = 58,44 g/mol);
Vs1is the volume, in millilitres, of the silver nitrate solution added for the titration of the test solution (8.5);
Vs0is the volume, in millilitres, of the silver nitrate solution added for the titration of the blank solution (8.6);
csis the concentration, in moles per litre, of the silver nitrate solution (4.10);
Vt1is the volume, in millilitres, of the ammonium thiocyanate solution or potassium thiocyanate solution
used in the titration of the test solution (8.5);
Vt0is the volume, in millilitres, of the ammonium thiocyanate solution or potassium thiocyanate solution
used in the titration of the blank solution (8.6);
ctis the concentration, in moles per litre, of the ammonium thiocyanate or potassium thiocyanate solution
(4.9);
mis the mass, in milligrams, of the test portion;
Viis the volume, in millilitres, of the test solution prepared in 8.2, 8.3 and 8.4 ( Vi = 500 ml);
Vais the volume, in millilitres, of the aliquot portion of filtrate taken (see 8.5);
fis a dilution factor:
f = 2 for cooked feeding stuffs, flax cakes and flour, products rich in flax flour and other products in
mucilage or in colloidal substances (see  8.4);
f = 1 for other animal feeding stuffs (see 8.2 and 8.3).
Report the result1) to the nearest:
 0,05 % for water-soluble chlorides contents less than 1,5 %; 0,1 % for water-soluble chlorides contents greater than or equal to 1,5 %.
                              
                       
1)  Expressed as percentage by mass [% ( m/m)].© ISO ISO 6495:1999(E)
510 Precision
10.1 Interlaboratory test
Details of an interlaboratory test on the precision of the method are summarized in annex A. The values derived
from this interlaboratory test may not be applicable to concentrations ranges and matrices other than those given.
10.2 Repeatability
The absolute difference between two independent single test results, obtained using the same method on identicaltest material in the same laboratory by the same operator using the same equipment within a short interval of time,
will in not more than 5 % of cases exceed the repeatability limit ( r) derived from the equation:
() rw=01340521,,
wc
where
ris the repeatability limit, expressed as percentage by mass;
wcwis the mean of the two single test results, expressed as percentage by mass.
10.3 Reproducibility
The absolute difference between two single test results, obtained using the same method on identical test material
in different laboratories by different operators using different equipment, will in not more than 5 % of cases exceed
the reproducibility limit ( R) derived from the equation:
R = 0,552 % + 0,135 wwc
where
Ris the reproducibility limit, expressed as percentage by mass;
wcwis the mean of the two single test results, expressed as percentage by mass.
11 Test report
The test report shall specify:
 all information necessary for the complete identification of the sample;
 the sampling method used, if known;
 the test method used, with reference to this International Standard;
 all operating details not specified in this International Standard, or regarded as optional, together with details of
any incidents which may have influenced the test results;
 the test result(s) obtained; or
 if the repeatability has been checked, the final quoted result obtained.ISO 6495:1999(E) © ISO
6Annex A
(informative)
Results of interlaboratory test
An interlaboratory test was organized by ISO/TC 34/SC 10, Animal feeding stuffs , in 1987 and carried
out in accordance with ISO 5725:1986 [2]. The final statistical analysis was carried out in accordance with
ISO 5725-2:1994 [4]. In the test 24 laboratories participated. Samples of corn gluten feed, finished mixed feed stuff,
fish meal, mixed feed stuff concentrate (2 types), premixed feed stuff and yeast were investigated.
Table A.1 — Statistical results of the interlaboratory test
Parameter Sample a
123 4567
Number of laboratories retained after
eliminating outliers23 23 23 23 23 23 23
Mean water-soluble chlorides content,
dry matter, % b3,22 0,105 1,56 14,1 3,56 2,54 1,07
Repeatability standard deviation(s
r), %b0,11 0,018 0,05 0,20 0,10 0,08 0,03
Repeatability coefficient of variation, % 3,5 17,2 3,5 1,4 2,9 3,0 2,9
Repeatability limit ( r) (r = 2,8 × sr), %b0,308 0,050 0,140 0,560 0,280 0,224 0,084
Reproducibility standard deviation
(sR), %b0,22 0,22 0,37 0,88 0,50 0,30 0,16
Reproducibility coefficient of variation, % 7 210 24 6 14 12 15
Reproducibility limit ( R)
(R = 2,8 × sR), %b0,616 0,616 1,036 2,464 1,400 0,840 0,448
aSample 1: fish meal;
Sample 2: corn gluten feed;Sample 3: yeast;Sample 4: premixed feed stuff;Sample 5: mixed feed stuff concentrate;Sample 6: mixed feed stuff concentrate;Sample 7: finished mixed feed stuff.
bExpressed as a percentage by mass [% ( m/m)].© ISO ISO 6495:1999(E)
7Bibliography
[1] ISO 6497, Animal feeding stuffs — Sampling.
[2] ISO 5725:1986, Precision of test methods — Determination of repeatability and reproducibility for a standard
test method by inter-laboratory tests (now withdrawn).
[3] ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions.
[4] ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic
method for the determination of repeatability and reproducibility of a standard measurement method.ISO 6495:1999(E) © ISO
ICS  65.120
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