UGANDA STANDARD
 
        US ISO 6490-1
First Edition
  2009-09-04
 
Reference numbe r 
     US ISO 6490-1:1985
 © UNBS 2009
  
Animal feeding stuffs — Determination of calcium content — 
Part 1: Titrimetric method 
 US ISO 6490-1:1985 
 
© 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 
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      US ISO 6490-1:1985  
© 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 under Cap 327, of the Laws of U ganda. 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 6490-1, Animal feeding stuffs — Determination of calcium content — 
Part 1 : Titrimetric method , is identical with and has been reproduced from an International Standard,
ISO 6490-1:1985, Animal feeding stuffs — Determination of calcium content — Part 1 : Titrimetric 
method , and adopted as a Uganda Standard.  
This standard was developed by the Food and Agricu lture Standards Technical Committee (UNBS/TC 2).  
Wherever the words, "International Standard" a ppear, they should be replaced by "Uganda Standard." 
 w - International Standard 
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.ME~AYHAPOAHAR OPTAHi43AL&IR I-IO CTAHAAPTM3A~bl~.ORGANISATION INTERNATIONALE DE NORMALISATION 
Animal feeding stuffs - Determination of Calcium 
content - 
Part 1 : Titrimetric method 
Aliments des animaux - Dktermination de Ia teneur en Calcium - Partie 7 : M& thode titrimhtrigue 
First edition - 1985-11-01 
UDC 636.085/.087 : 543.24 : 546.41 Ref. No. ISO 6490/1-1985 (E) 
Descriptors : animal feeding products, Chemical analysis, determination of content, Calcium, volumetric analysis. 
z - Price based on 2 pages Foreword 
ISO (the International Organization for Standardization) is a worldwide federation of 
national Standards bodies (ISO member bedies). The work of preparing International 
Standards is normally carried out through ISO technical committees. Esch 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, govern- 
mental and non-governmental, in liaison with ISO, also take part in the work. 
Draft International Standards adopted by the technical committees are circulated to 
the member bodies for approval before their acceptance as International Standards by 
the ISO Council. They are approved in accordance with ISO procedures requiring at 
least 75 % approval by the member bodies voting. 
International Standard ISO 6490/1 was prepared by Technical Committee ISO/TC 34, 
Agricultural food products. 
Users should note that all International Standards undergo revision from time to time 
and that any reference made herein to any other International Standard implies its 
latest edition, unless othetwise stated. 
0 International Organkation for Standardkation, 1985 
Printed in Switzerland INTERNATIONAL STANDARD ISO 6490/1-1985 (E) 
Animal feeding stuffs - Determination of Calcium 
content - 
Part 1 : Titrimetric method 
1 Scope and field of application 
This part of ISO 6490 specifies a titrimetric method for the 
determination of the Calcium content of animal feeding stuffs. 
The method is applicable to all animal feeding stuffs having 
Calcium contents greater than 1 g/kg. 
2 References 
ISO 649012, Animal feeding stuffs - Determination of Calcium 
content - Part 2: Atomic absorption spectrometric method. 
ISO 6497, Animal feeding stuffs - Sampling. l) 
ISO 6498, Animal feeding stuffs - Reparation of test samples. 
3 Principle 
Ashing of a test Portion, treatment of the ash with hydrochloric 
acid and precipitation of the Calcium as Calcium oxalate. 
Dissolution of the precipitate in sulfuric acid and titration with 
Standard volumetric potassium permanganate Solution of the 
oxalic acid formed. 
4 Reagents 
All reagents shall be of recognized analytical quality and the 
water used shall be distilled water or water of at least equivalent 
purity. 
4.1 Hydrochlorit acid, approximately 30 % (mlm) 
(-20 = 1,15 g/ml). 
4.2 Nitrit acid, concentrated (020 = 140 g/ml). 
4.3 
(Q20 
4.4 
(&) Sulfuric acid, approximately 20 % (mlm) 
= 1,13 g/ml). 
Ammonia solution, approximately 33 % (mlm) 
= 0,89 g/mlL 
45 . 
4.6 Ammonium oxalate, cold saturated Solution. 
Citric acid monohydrate, 300 g/l Solution. 4.7 Ammonium chloride, 50 g/l Solution. 
4.8 Bromocresol green, 0,4 g/l Solution. 
4.9 Potassium permanganate, Standard volumetric sol- 
ution, c (1/5 KMn04) = 0,l mol/l. 
5 Apparatus 
Usual laboratory apparatus, and in particular 
5.1 Electric muffle furnace, with air circulation, capable of 
being maintained at 550 f 20 OC. 
5.2 Incineration dish, made of platinum, silica or porcelain. 
5.3 Sintered glass filter crucible, of porosity grade P 16 
(Pore size 10 to 16 Pm). 
5.4 Boiling water-bath. 
5.5 Beakers, of capacity 250 ml. 
5.6 Volumetric flask, of capacity 250 ml. 
5.7 Analytical balance. 
6 Sampling 
Take the laboratory Sample as specified in ISO 6497. 
7 Procedure 
7.1 Preparation of the test Sample 
Prepare the test Sample in accordance with ISO 6498. 
7.2 Test Portion 
Weigh, to the nearest 1 mg, approximately 5 g of the test 
Sample (or more if necessary), into the incineration dish (5.2). 
1) At present at the Stage of draft. 
1 so 6490/1-1985 (El 
7.3 Determination where 
V is the volume, in millilitres, of the Standard volumetric 
potassium permanganate soluti on used for the titration; 7.3.1 Ash the test Portion in the electric muffle furnace (5.1), 
maintained at 550 + 20 OC, until all organic matter has been 
destroyed (usually 4 h is sufficient). If some organic matter 
remains (black particles), add a few drops of nitric acid (4.2), 
dry on a hotplate and ash again in the muffle furnace at 
550 + 20 OCfor 30 min. Repeat this until all organic matter has 
been destroyed. Transfer the ash to a 250 ml beaker (5.5). c is the exact concentration, in moles per litre ,oft 
dard volumetric potassium pe rmanganate solu tion; he stan- 
m is the mass, in grams, of the test Portion; 
V' is the volume, 
in 7 .3.3. in millilitres, of the aliquot Portion taken 
7.3.2 Add 40 ml of the hydrochloric acid (4.1), 60 ml of water, 
and a few drops of the nitric acid (4.2). Bring to the boil and boil 
for 30 min. Cool and transfer the Solution to a 250 ml one-mark 
volumetric flask (5.6). Rinse, dilute to the mark with water, mix 
and filter to give the test Solution. Take as the result the arithmetic mean of the values obtained in 
the two determinations (see 7.4), provided that the requirement 
for repeatability (see 8.2) is satisfied. 
Report the result to the nearest 1 g/kg. 7.3.3 By means of a pipette, transfer an aliquot Portion of the 
test Solution (7.3.2), containing 10 to 40 mg of Calcium, ac- 
cording to the expected Calcium content, to a 250 ml beaker 
(5.5). Add 1 ml of the citric acid Solution (4.6) and 5 ml of the 
ammonium chloride Solution (4.7). Dilute to approximately 
100 ml with water. Bring to the boil, add 10 drops of the 
bromocresol green Solution (4.8) and 30 ml of a warm Solution 
of the ammonium oxalate (4.5). If a precipitate forms, dissolve 
it by adding a few drops of the hydrochloric acid (4.1). 8.2 Repeatability 
The differente between the values obtained in the two deter- 
minations, carried out simultaneously or in rapid succession by 
the same analyst, shall not exceed 
1 g/kg (absolute) for Calcium contents less than 50 g/kg; 
Neutralize very slowly with the ammonia Solution (4.4), stirring 
continuously, until a pH of 4,4 to 4,6 is reached (i.e. when the 
indicator changes colour). Place the beaker on a boiling water- 
bath (5.4) and leave for 30 min to allow the precipitate which 
has formed to settle. Remove the beaker from the water bath. 
Leave for 1 h and filter through the filter crucible (5.3). 2 % (relative 
or more. ) of the mean for Calcium contents of 50 g/kg 
9 Notes on procedure 
9.1 For the determination of very low Calcium contents use 
the method specified in ISO 6490/2. Wash the beaker and the crucible with water until the excess 
ammonium oxalate is completely removed as shown by the 
absence of chloride in the washing water. 
9 .2 If the Sample consists exclusively of mineral 
d issolve it in hydro chloric acid without ashing. substances, 
Place the crucible in a 250 ml beaker (5.5) or wide-mouth flask. 
Add 80 ml of the sulfuric acid (4.3) and heat to 70 to 80 OC to 
dissolve the precipitate. For products such as aluminocalcium Phosphates, which are 
difficult to dissolve in acids, mix the test Portion in a platinum 
dish with five times its mass of a mixture comprising equal Parts 
of potassium carbonate and sodium carbonate. Heat carefully 
until the mixture is completely molten. After cooling, dissolve 
in the hydrochloric acid. 7.3.4 Titrate the hot Solution with the Standard volumetric 
potassium permanganate Solution (4.9), until a pink colour, 
persisting for 1 min, is obtained. 
7.4 Number of determinations 9.3 If the magnesium content of the Sample is likely to ex- 
ceed the Calcium content, or in cases of doubt, precipitate the 
Calcium oxalate a second time. Carry out two dete 
same test Sample. rminations on test portions taken from the 
10 Test report 8 Expression of results 
The test report shall show the method used and the result ob- 
tained. lt shall also mention any operating conditions not 
specified in this International Standard, or regarded as op- 
tional, as well as any circumstances that may have influenced 
the results. 8.1 Method of calculation and formula 
The Calcium content, 
Sample, is equal to expressed in grams Per kilogram of 
20,04 x V x c 250 X- 
m V' The test report shall include all the 
plete identification of the Sample. required for the com-