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Ref. No. : ISO/R 715-1968 (E)
IS0
I N T ER N AT I O N A L ORGAN 1 Z AT 1 ON FOR STAND AR D IZATl ON
IS0 RECO M M EN DATI O N
R 715
CHEMICAL ANALYSIS OF ZINC
POLAROGRAPHIC DETERMINATION OF LEAD
1st EDITION
May 1968
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belongs to IS0 Member Bodies. Reproduction of these
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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 71 5, Chemical analysis of zinc - Polarographic determination of
lead, was drawn up by Technical Committee ISOlTC 18, Zinc and zinc alloys, the Secretariat of which
is held by the Institut Belge de Normalisation (IBN).
Work on this question by the Technical Committee began in 1963 and led, in 1965, to the
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adoption of a Draft IS0 Recommendation.
In September 1966, this Draft IS0 Recommendation (No. 994) 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 Israel
Spain
Australia Ireland Switzerland
Belgium Italy Thailand
Canada Korea, Rep. of Turkey
Chile Korea, D.P. Rep. of U.A.R.
Czechoslovakia New Zealand United Kingdom
France Norway U.S.A.
Hungary South Africa, U.S.S.R.
India Rep. of Yugoslavia
One Member Body opposed the approval of the Draft :
Germany
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The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in May 1968, to accept it as an IS0 RECOMMENDATION.
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M/R 715-1968 (E
IS0 Recommendation R 715 May 1968
CHEMICAL ANALYSIS OF ZINC
POLAROGRAPHIC DETERMINATION OF LEAD
1. SCOPE
This IS0 Recommendation describes a polarographic method for the determination of lead in zinc.
The method applies to the following types of zinc : Zn 99.5, Zn 98.5 and Zn 98, defined in IS0
Recommendation R 752, Zinc ingots.
It is suitable for the determination of lead content between 0.1 and 3 O/'.
2. PFUNCIPLE OF THE METHOD
Polarographic determination of lead in an ammoniacal tartrate cyanide solution.
3. REAGENTS
All the reagents should be of analytical reagent grade.
Distilled or demineralized water should be used for preparing solutions and during the actual deter-
mination.
Zinc 99.99 'lo pure.
3.1
3.2 Nitric acid (d = 1.3 to 1.4).
3.3 Hydrochloric acid (d = 1.19).
3.4 Ammonia solution (d = 0.91).
Tartaric acid solution, 300 g per litre.
3.5
3.6 Potassium cyanide solution, 100 g per litre.
Pure gelatine (sulphate free) solution, 5 g per litre. To preserve the solution, add salicylic acid
3.7
in the proportion of 1 g per litre.
Standard lead solution No. 1
3.8
Dissolve 1 g of pure lead in 10 ml of nitric acid (3.2) and 50 mi of water. Mow to cool.
Transfer quantitatively to a 500 ml volumetric flask. Make up to volume with water.
1 ml of this solution contains 2 mg of lead.
Standard lead solution No. 2
3.9
Transfer 10 mi of standard lead
...