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Ref. No. : ISO/R 714-1968 (E)
IS0
I NT ERN AT1 ON A L ORGAN IZATl O N FOR STAN DARD IZATl O N
IS0 RECOMMENDATION
R 714
CHEMICAL ANALYSIS OF ZINC
PHOTOMETRIC DETERMINATION OF IRON
1st EDITION
May 1968
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The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
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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 714, Chemical analysis of zinc - Photometric determination of
iron, was drawn up by Technical Committee ISO/TC 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
adoption of a Draft IS0 Recommendation.
In September 1966, this Draft IS0 Recommendation (No. 993) 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 :
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One Member Body opposed the approval of the Draft :
Japan
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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ISO/R 714-1968 (E)
IS0 Recommendation R 714 May 1968
CHEMICAL ANALYSIS OF ZINC
PHOTOMETRIC DETERMINATION OF IRON
1. SCOPE
This IS0 Recommendation describes a photometric method for the determination of iron in zinc.
The method applies to the types of zinc defined in IS0 Recommendation R 752, Zinc ingots,
provided that the copper content does not exceed 0.01
It is suitable for the determination of iron content between 0.001 and 0.1 O/,,.
2. PRINCIPLE OF THE METHOD
Photometric determination of the yellow colour of the sulphosalicylic acid ferric complex formed in
an ammoniacal solution.
3. REAGENTS
All the reagents should be of analytical reagent grade.
Distilled or demineralized water should be used for preparing the solutions and during the actual
determination.
3.1 Ammonia solution (d = 0.91).
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Hydrochloric acid (d = 1.19).
3.2
3.3 Hydrogen peroxide, 30 H,O, (rnlm).
3.4 Sulphosalicylic acid solution containing 400 g per litre.
3.5 Nickel chloride solution containing 2 g of NiCl, .6H,O per litre.
3.6 Standard iron solution
Weigh 0.250 g of pure iron with an accuracy of -+ 0.001 g and attack with a few millilitres of
hydrochloric acid (3.2). Oxidize with a few drops of hydrogen peroxide (3.3). Decompose the
excess hydrogen peroxide by boiling. Cool. Transfer quantitatively to a 1 litre volumetric flask.
Make up the volume to 1 litre with water. Mix. Transfer 100 ml of this solution to a 500 ml
volumetric flask. Make up the volume to 500 ml with water. Mix.
1 ml of this solution contains 0.050 mg of iron.
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ISO/R 714-1968 (E)
4. APPARATUS
4.1 Ordinary laboratory equipment.
4.2 Photometer, wavelength 425 nm, and 1 cm celis.*
5. SAMPLING
The requirements of IS0 Recommendation R .,** Selection and preparation of samples for analysis,
should apply.
6. PROCEDURE
6.1 Test portion
...