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IS0
I N T E RN AT1 ON A L O RG A N IZATl O N FOR STAN DA RDl ZATl ON
IS0 RECOMMENDATION
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R 809
CHEMICAL ANALYSIS OF MAGNESIUM AND MAGNESIUM ALLOYS
PHOTOMETRIC DETERMINATION OF MANGANESE
PERIODATE METHOD
(Manganese content between 0.01 and 0.8 'L)
1st EDITION
August 1968
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The copyright of IS0 Recommendations and IS0 Standards
belongs 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 809, Chemical analysis of magnesium and magnesium alloys -
Photomem'c determination of manganese - Periodate method (Manganese content between O. O1 and
O.ûo/J, was drawn up by Technical Committee ISOlTC 79, Light metals and their alloys, the
Secretariat of which is held by the Association Française de Normalisation (AFNOR).
U
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. 1130) 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 :
South Africa,
Argentina India
Rep. of
Austria Ireland
Israel Spain
Belgium
Italy Sweden
Bulgaria
Canada Japan Switzerland
Chile Korea, Rep. of Turkey
United Kingdom
Czechoslovakia Netherlands
New Zealand U.S.A.
France
Norway U.S.S.R.
Germany
Hungary Poland Yugoslavia
No Member Body opposed the approval of the Draft.
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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 809-1968 (E)
IS0 Recommendation R 809 August 1968
CHEMICAL ANALYSIS OF MAGNESIUM AND MAGNESIUM ALLOYS
PHOTOMETRIC DETERMINATION OF MANGANESE
PERIODATE METHOD
(Manganese content between 0.01 and 0.8 ‘l,)
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 between 0.01 and 0.8
2. PRINCIPLE
2.1 Attack of the sample with sulphuric acid, followed by oxidation with nitric acid.
2.2 Oxidation of manganese (II) to manganese (VII) by means of potassium periodate (acidity
approximately SN), 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 (KI04).
3.2 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 mi.
Nitric acid, d = 1.40 (approximately 15 N).
3.3
The acid should be free from nitric fumes. To eliminate these fumes, boil for a short while or
pass through it a current of carbon dioxide.
3.4 Phosphoric acid, d = 1.7 1 (approximately 45 N).
Hydrofluoric acid, 40 (d = approximately 1.15).
3.5
3.6 Water free from reducing agents
Bring to the boil water acidified with 1 O mi per litre of sulphuric acid (3.2); 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.)
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ISO/R 809-1968 (E)
3.1 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.
3.8 Standard manganese solution, 1 g per litre (1 ml contains 1 mg of manganese).
Either :
3.8.1 In a tall-form beaker of suitable capacity (e.g. 400 mi), dissolve 2.877 g of very pure potas-
sium permanganate (KMn04) in about ,200 ml of water and add 40 ml of sulphuric acid
(3.2). 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 mi volumetric flask and make
up to volume with water.
Or :
3.8.2 In a tall-form beaker of suitable capacity (e.g. 600 mi), dissolve 1 f 0.001 g of electrolytic
manganese (purity > 99.9 with 40 ml of sulphuric acid (3.2) 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 mi of sulphuric
acid (3.2) and approximately 100 ml of water. Stir and after a few minutes decant the acid solution and
introduce some doubly distilled water into the beaker. Decant and wash with doubly distilled water several
times; finally, place the manganese in acetone and shake. Decant the acetone, dry the metal in a hot air
oven at 100 OC for approximately 2 minutes, then allow to cool in a desiccator.
3.9 Standard manganese solution, 0.1 g per litre (1 ml contains 0.1 mg of manganese).
Take 100.0 ml of standard manganese solution (3.8), place in a 1000 ml volumetric flask and
make up to volume with water.
4. APPARATUS
4.1 Ordinary laboratory apparatus
All volumetric apparatus should comply with national standards.
4.2 Electrophotometer or spectrophotometer (wavelength about 525 nm).
5. SAMPLING
5.1 Laboratory sample
See the appropriate national standard on sampling.
5.2 Test sample
Chips not more than 1 mm thick should be obtained from the laboratory sample by milling or
drilling.
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ISO/R 809-1968 (E)
6. PROCEDURE
6.1 Calibration graph
6.1.1 Preparation of the compensating solution (Term O). Place 20 ml of nitric acid (3.3) in a
platinum dish and evaporate to dryness. Take up the residue in a little warm water and
transfer the solution to a vessel of suitable capacity (e.g. 250 ml). Dilute to approximately
40 ml with water and add 15 ml of sulphuric acid (3.2), 5 ml of nitric acid (3.3) and 5 ml of
phosphoric acid (3.4). Continue as described under clause 6.1.3.
6.1.2 Preparation of the manganese s
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