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Ref. No. : ISO/R 886-1968 (E)
IS0
I NT ERN AT I ON A L O R G A N IZ AT I O N FOR S TA N DARD IZATl O N
IS0 RECOMMENDATION
R 886
CHEMICAL ANALYSIS OF ALUMINIUM AND ALUMINIUM ALLOYS
PHOTOMETRIC DETERMINATION OF MANGANESE
(Manganese content between 0.005 and 1.5
1
1st EDITION
Decem ber 1968
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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 886, Chemical analysis of aluminium and aluminium alloys -
Photometric determination of manganese (Manganese content between O. 005 and 1.5 'Io), was drawn
up by Technical Committee ISOITC 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 1961 and led, in 1966, to the
adoption of a Draft IS0 Recommendation.
In April 1967, this Draft IS0 Recommendation (No. 1192) 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 :
Australia Hungary Spain
Austria Ireland Sweden
Belgium Israel Switzerland
Canada Italy Thailand
Chile Japan Turkey
Czechoslovakia Netherlands U.S.A.
France Norway U.S.S.R.
Germany Poland Yugoslavia
Greece South Africa, Rep. of
One Member Body opposed the approval of the Draft :
United Kingdom
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in December 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 886-1968 (f
IS0 Recommendation R 886 Decem ber 1968
CHEMICAL ANALYSIS OF ALUMINIUM AND ALUMINIUM ALLOYS
PHOTOMETRIC DETERMINATION OF MANGANESE
(Manganese content between 0.005 and 1.5
1. SCOPE
This IS0 Recommendation describes a photometric method for the determination of manganese in
aluminium and aluminium alloys.
The method is applicable to the determination of manganese contents between 0.005 and 1.5
However, this method does not apply completely to the following special cases :
alloys with a silicon content higher than 10 and a manganese content less than 0.1
(a)
(see Annex);
aluminium alloys containing tin, antimony, bismuth, zirconium, etc.
(b)
(In this IS0 Recommendation these special cases are not treated.)
2. PRINCIPLE
2.1 Attack of the sample with sodium hydroxide.
2.2 Acidification by sulphuric and nitric acids.
2.3 Oxidation of manganese (II) to manganese (VII) by means of potassium periodate (acidity of
solution over 3.5 N approximately), in the presence of phosphoric acid.
2.4 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 Solutions of approximate strength
3.1.1
Water free from reducing agents
Bring to the boil water acidified with 10 ml of sulphuric acid (3.1.4) per litre; add a few
crystals of potassium periodate (KIO,) and maintain at boiling point for approximately
10 minutes (see Note 8.1).
3.1.2 Sodium hydroxide solution, 200 g/l.
In a nickel dish dissolve 200 g of sodium hydroxide (NaOH) in water and, after cooling, make
up the volume to 1000 ml. Keep in a plastic container.
3.1.3 Sulphurous acid solution
Pass a current of sulphur dioxide gas (SO,) through water until saturation point is reached.
3.1.4 Sulphuric acid, d = 1.48 ( approximately 17.5 N).
Carefully add 500 ml of sulphuric acid, d = 1.84 (approximately 35.6 N), to water, cool and
make up the volume to 1000 ml.
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ISO/R 886-1968 (
3.1.5 Sulphuric acid, d = 1.84 (approximately 35.6 N).
3.1.6 Nitric acid, d = 1.40 (approximately 15 N).
3.1.7 Hydrofluoric acid. 40 "/" (d = approximately 1.1 5).
3.1.8 Fluoroboric acid solution
In a plastic flask mix 800 ml of saturated boric acid solution at 20°C with 200 ml of
hydrofluoric acid (3.1.7).
3.1.9 Phosphoric acid, d = 1.71 (approximately 45 N).
3.1.10 Potassium periodate solution, 50 g/l.
Dissolve 50 g of potassium periodate (KiO,) in water, add 200 ml of nitric acid (3.1.6)
and make up the volume to 1000 ml with water.
3.1.11 Sodium nitrite solution, 20 g/l.
Dissolve 2 g of sodium nitrite (NaNO,) in water and make up the volume to 100 ml.
3.2 Standard solutions
3.2.1 Standard manganese solution, 1 g/l (1 ml contains 1 mg of manganese).
Either :
In a tall-form beaker of suitable capacity (e.g. 600 mi) dissolve 2.877 g of very
(a)
pure potassium permanganate (KMnO,) in about 200 ml of water. Add 20 ml of
sulphuric acid (3.1.4) and reduce the solution by means of some crystals of
sodium sulphite (Na,SO,) or by a few millilitres of hydrogen peroxide (100 to
110 volumes).
Boil the solution until the excess sulphur dioxide or hydrogen peroxide is
eliminated, cool, transfer to a 1000 ml volumetric flask and make up to volume
with water.
Or :
In a tail-form beaker of suitable capacity (e.g. 600 mi) dissolve 1 g of electrolytic
(b)
manganese (purity 2 99.9 O/") in 20 ml of sulphuric acid (3.1.4) and approxima-
tely 100 ml of water. Boil the solution for a few minutes. Cool, transfer to a
1000 ml volumetric flask and make up to volume with water (see Note 8.2).
3.2.2 Standard manganese solution, 0.1 g/l (1 ml contains 0.1 mg of manganese).
Take 100 ml of standard solution (3.2.1), place in a 1000 ml volumetric flask and make up
to volume with water.
4. APPARATUS
4.1 Ordinaty laboratory apparatus
All volumetric apparatus should comply with national standards.
4.2 Hotplate fitted with a mechanical or magnetic stirrer.
4.3 Electrophotometer or spectrophotometer (wavelength of about 525 nm).
5. SAMPLING
See the appropriate national standard on sampling.
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ISO/R 886-1968 (I
6. PROCEDURE
6.1 Calibration graph
6.1.1 Preparation of the compensating solution (Term O). In a platinum dish place 7 ml of sul-
phuric acid (3.1.4) and 8 ml of nitric acid (3.1.6) and evaporate to dryness (do not calcine).
Take up the residue in a little warm water, add 8 ml of sulphuric acid (3.1.4), 2 ml of nitric
acid (3.1.6) and 5 ml of phosphoric acid (3.1.9). Transfer the solution to a vessel of suitable
capacity (e.g. 250 mi). Dilute to approximately 70 ml with water and continue according to
the procedure described under clause 6.1.3.
6.1.2 Preparation of manganese solutions. Introduce into a series of six vessels of suitable capacity
(e.g. 250 ml to 300 mi), respectively : 1.0, 2.0, 5.0, 10.0, 15.0 and 20.0 ml of the standard
manganese solution (3.2.2), corresponding respectively to O. 1,0.2,0.5, 1 .O, 1.5 and 2 mg of
manganese. To each vessel add 15 ml of sulphuric acid (3.1.4), 10 ml of nitric acid (3.1.6)
and 5 ml of phosphoric acid (3.1.9) and make up the volume to about 70 ml with water.
6.1.3 Development of the colour. Place the vessels specified in clauses 6.1.1 and 6.1.2 on a hot-
plate fitted with a stirrer (see Note 8.3) and bring the solutions to the boil. Then add to each
solution 10 ml of potassium periodate solution (3.1.10) and continue boiling until the
characteristic colour develops.
5 minutes (1 5 to 30 minutes if the concentration of manganese is less than
Boil for another
or equal to 0.2 mg of manganese in 100 ml of solution). Cool to room temperature, transfer
the solutions into as many 100 ml volumetric flasks, previously rinsed with treated water
(3.1.1), and make up to volume with treated water (3.1.1).
6.1.4 Photomedic measurement. Measure the optical densities at a wavelength of about 525 nm,
having set the instrument to zero optical density against water (AEc). Then destroy the
permanganic acid by means of two drops of sodium nitrite solution (3.1.1 1) and repeat the
measurements of the optical density (AEd), To obtain the value of the optical density due to
the manganese taken, calculate for each dilution the differences
[(A Ec - A Ed) - (A Tc - A Td)]
where ATc and ATd are the optical densities corresponding to the term O, coloured and
decolourized.
Draw a graph plotting, for example, as abscissae the amounts of manganese, expressed in
milligrammes, contained in 100 ml of solution and as ordinates the values corresponding to
the optical density.
6.2 Test portion
Chips, not more than 1 mm thick, obtained by milling or drilling.
Mass : 1 +_ 0.001 g.
6.3 Blank test
Parallel to the analy
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