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IS0
I N T ERN AT1 O N A L O RG A N IZ AT1 O N FOR STA N DAR DI Z AT1 ON
IS0 RECOMMENDATION
R 810
CHEMICAL ANALYSIS OF MAGNESIUM AND MAGNESIUM ALLOYS
PHOTOMETRIC DETERMINATION OF MANGANESE
PERIODATE METHOD
(Manganese content less than 0.01
1st EDITION
August 1968
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BRIEF HISTORY
The IS0 Recommendation R 810, Chemical analysis of magnesium and magnesium alloys -
Photometric determination of manganese - Periodate method (Manganese content less than O. O1 'Io),
was drawn up by Technical Committee ISO/TC 79, Light metals and their alloys, the Secretariat of
which is held by the Association Française de Normalisation (AFNOR).
Work on this question by the Technical Committee began in 1957 and led, in 1965, to the
adoption of a Draft IS0 Recommendation.
In December 1966, this Draft IS0 Recommendation (No. 1131) 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 South Africa,
Austria Rep. of
Ireland
Belgium Israel Spain
Bulgaria Switzerland
Italy
Canada Japan Sweden
Chile Korea, Rep. of Turkey
Czechoslovakia Netherlands United Kingdom
France New Zealand U.S.A.
Germany Norway U.S.S.R.
Hungary Poland Yugoslavia
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in August 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 810-1968 (E)
IS0 Recommendation R 810 August 1968
CHEMICAL ANALYSIS OF MAGNESIUM AND MAGNESIUM ALLOYS
PHOTOMETRIC DETERMINATION OF MANGANESE
PERIODATE METHOD
(Manganese content less than 0.01
1. SCOPE
This IS0 Recommendation describes a photometric method for the determination of manganese in
magnesium and magnesium alloys which do not contain zirconium, rare earths, or thorium.
The method is applicable to the determination of manganese content less than 0.01 O/’.
2. PRINCIPLE
2.1 Attack of the sample with sulphuric acid, followed by oxidation with ammonium persulphate.
2.2 Oxidation of manganese (II) to manganese (VII) by means of potassium periodate (acidity
approximately 2 N), in the presence of phosphoric acid.
2.3 Photometric measurement at a wavelength of about 525 nm.
3. REAGENTS
For the preparation of solutions and during the analysis use doubly distilled water.
3.1 Potassium periodate (KIO,).
3.2 Ammonium persulphate [(NH,),S,O,].
3.3 Sulphuric acid, d = 1.26 (approximately 9 N).
Carefully add 25 ml of sulphuric acid, d = 1.84 (approximately 35.6 N), to water, cool and
make up the volume to 100 ml.
3.4 Phosphoric acid, d = 1.71 (approximately 45 N).
3.5 Water free from reducing agents
Bring to the boil water acidified with 10 ml per litre of sulphuric acid (3.3); add a few crystals
of potassium periodate (3.1) and maintain at boiling point for approximately 10 minutes.
(The term “water” without qualification indicates doubly distilled water).
3.6 Sodium nitrite solution, 20 g per litre.
Dissolve 2 g of sodium nitrite (NaNO,) in a little water and make up the volume to 100 ml.
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ISO/R 810-1968 (E)
3.7 Standard manganese solution, 1 g per litre (1 ml contains 1 mg of manganese).
Either :
3.7.1 In a tall-form beaker of suitable capacity (e.g. 400 mi), dissolve 2.877 g of very pure
potassium permanganate (KMnO,) in about 200 ml of water and add 40 rnl of sulphuric
acid (3.3). Reduce the permanganate solution by adding a few crystals of sodium sulphite
or by adding hydrogen peroxide (100 to 110 volumes). Boil the solution to eliminate
excess of sulphur dioxide or hydrogen peroxide, cool, transfer to a 1000 ml volumetric
flask and make up to voiume with water.
Or :
3.7.2 In a tall-form beaker of suitable capacity (e.g. 600 mi), dissolve 1 f 0.001 g of electrolytic
manganese (purity 299.9 O/') with 40 ml of sulphuric acid (3.3) and approximately 80 ml
of water. Boil the solution for several minutes. Cool, transfer to a 1000 ml volumetric
flask and make up to volume.
NOTE. - Free the electrolytic manganese of any surface oxidation present by placing several grammes
of the metal in a glass beaker of approximately 250 to 300 ml capacity, containing 60 to 80 ml of
sulphuric acid (3.3), and approximately 100 ml of water. Stir and after a few minutes decant the acid
solution and introduce some doubly distilled water into the beakcr. Decant and wash with doubly
distilled water several times; finally,$lace the manganese in acetone and shake. Decant the acetone, dry
the metal in a hot air oven at 100 C for approximately 2 minutes, then allow to cool in a desiccator.
3.8 Standard manganese solution, 0.02 g per litre (1 mi contains 0.02 mg of manganese).
Take 20.0 ml of standard manganese so
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