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UDC 676.1.06 : 620.1
IS0
INTERN AT I ON A L ORGANIZATION FOR STAND AR0 IZATl ON
IS0 RECO M MEN DATIO N
R 777
PU LPS
DETERMINATION OF CALCIUM CONTENT
1st EDITION
July 1968
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The copyright of IS0 Recommendations and IS0 Standards
belong to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 777, Pulps - Determination of calcium content, was drawn up
by Technical Committee ISO/TC 6, Paper, board and pulps, the Secretariat of which is held by the
Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1965 and led, the same year, to
the adoption of a Draft IS0 Recommendation.
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In November 1966, this Draft IS0 Recommendation (No. 1068) was circulated to all the IS0
Member Bodies for enquiry. It was approved,subject to a few modifications of an editorial nature, by
the following Member Bodies :
Argentina India Portugal
Australia Iran Romania
Belgium Israel Spain
Brazil Italy Sweden
Bulgaria Japan Switzerland
Canada Korea, Rep. of Turkey
Czechoslovakia Korea, D.P.R. of U.A.R.
Denmark Mexico United Kingdom
Finland Netherlands U.S.A.
France New Zealand U.S.S.R.
Germany Norway Yugoslavia
One Member Body opposed the approval of the Draft
Cuba
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in July 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 777-1968 (E
IS0 Recommendation R 777 July 1968
PU LPS
DETERMINATION OF CALCIUM CONTENT
I. SCOPE
This IS0 Recommendation describes a method for the determination of the calcium content of pulp.
2. FIELD OF APPLICATION
This method applies to all kinds of pulp.
3. PRINCIPLE OF THE METHOD
The pulp is ashed and the ash is dissolved in nitric acid. Calcium is determined volunietrically with
solution of the disodium salt of ethylenediaminetetraacetic acid at a pH above 12. Other metal ions
are masked with triethanolamine.
4. REAGENTS
All reagents should be of analytical grade and the distilled water used should not contain copper.
4.1 ,Vitric acid, about 5 M. Dilute 325 ml of nitric acid (d = 1.4) to 1 litre with distilled water.
4.2 Hydrochloric acid, about 6 M. Dilute 500 ml of hydrochloric acid (d = 1.19) to 1 litre with
distilled water.
4.3 Hydrochloric acid. 1 M. Dilute 82.5 ml of hydrochloric acid (d = 1.19) to 1 litre with
distilled water.
4.4 Potassium hydroxide solution, about 8 M, 449 g of potassium hydroxide per litre.
Triethanolamine solution. Dissolve 100 g of triethanolamine [(Cz H5 O), NI in distilled water
4.5
and dilute to 1 litre.
4.6 Hydroxylamine hydrochloric solution. Dissolve 2 g of hydroxylamine hydrochloride
(NH, OH.HC1) in 100 ml of distilled water.
4.7 Standard calcium solution, 0.01 M. Weigh 1 g of chemically pure calcium carbonate, dried at a
temperature not exceeding 200 OC, to the nearest 0.001 g into a 500 ml beaker. Add 100 ml of
distilled water and add drop by drop from a burette the smallest amount (about 20 mi) of 1 M
hydrochloric acid, necessary to dissolve the carbonate. Boil out the carbon dioxide, cool, and
transfer quantitatively by rinsing with distilled water into a 1 litre volumetric flask and dilute to
the mark. Calculate M,, = g CaCO3/100.1 as the molarity of the standard solution.
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ISO/R 777-1968 (1
4.8 Solution of disodium salt of ethylenediaminetetraacetic acid (EDTA), 0.01 M. Dissolve 3.80 g
of the disodium salt of ethylenediaminetetraacetic acid, (Cl oH1408NzNaz. 2Hz0), in
distilled water in a 1 litre volumetric flask and dilute to the mark.
Keep the solution in a polyethylene bottle, standardize the solution by adding to a conical
flask 20.00 mi of 0.01 M standard calcium solution, 40 ml of distilled water, 5 ml of potassium
hydroxide solution, 2 ml of hydroxylamine hydrochloride solution and about 100 mg of cal-red
indicator. Titrate with the EDTA solution to a colour change from wine-red to pure blue.
Titrate also a blank solution containing all the reagents except the standard calcium solution,
which is replaced by an equal volume of distilled water.
Calculate the molarity of the EDTA solution from the foll
...