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IS0
I N T ERN AT1 O N A L O RG A N lZ AT1 O N FO R STA N DARD l ZATl ON
IS0 RECOMMENDATION
R 791
CHEMICAL ANALYSIS OF MAGNESIUM AND ITS ALLOYS
GRAVIMETRIC DETERMINATION OF ALUM1 N IUM
IN MAGNESIUM ALLOYS
(Aluminium content between 1.5 and 12.0
1 st EDIT I ON
July 1968
COPYRIGHT RESERVED
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 79 1, Chemical analysis of magnesium and its alloys - Gravimetnc
determination of aluminium in magnesium alloys (Aluminium content between 1.5 and 12.0 '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 1956 and led, in 1963, to the adop
tion of a Draft IS0 Recommendation.
In June 1966, this Draft IS0 Recommendation (No. 964) was circulated to ali the IS0 Member
Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature, by the
following Member Bodies :
Argentina Korea, Rep. of Spain
Austria India Sweden
Belgium
Ireland Switzerland
Brazil
Israel Turkey
Bulgaria Italy U.A.R.
Canada Japan United Kingdom
Chile Netherlands U.S.A.
Czechoslovakia Norway U.S.S.R.
France Poland Y ugnslavia
Germany South Africa,
Rep. of
Hungasr
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 July 1968, to accept it as an IS0 RECOMMENDATION.
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e
ISOlR 791-1968 (1
IS0 Recommendation R 791 July 1968
CHEM CAL ANALYSIS OF MAGNESIUM AND ITS ALLOYS
GRAVIMETRIC DETERMINATION OF ALUMINIUM
IN MAGNESIUM ALLOYS
(Aluminium content between 1.5 and 12.0
1. SCOPE
1.1 This IS0 Recommendation describes a gravimetric method for the determination of aluminium
in magnesium alloys other than those containing zirconium, thorium or rare earths.
1.2 The method is applicable to the determination of aluminium content between 1.5 and 12.0 O/,.
2. PRINCIPLE
2.1 Attack with hydrochloric acid.
2.2 Precipitation of the aluminium by ammonium benzoate in a reducing acetic medium.
2.3 Dissolution of the precipitate and reprecipitation of the aluminium as oxyquinolate in a buffered
acetate medium, or in the presence of potassium cyanide.
2.4 Filtration, washing, drying and weighing of the precipitate.
3. REAGENTS
Sodium sulphite (Na, SO,. 7H, O).
3.1
3.2 Hydrochloric acid, d = 1.19 (approximately 12 N).
3.3 Hydrochloric acid, d = 1 .O5 (approximately 3 N).
Take 25 mi of hydrochloric acid, d = 1.19 (approximately 12 N), and make up the volume to
100 ml with water.
3.4 Nitric acid, d = 1.33 (approximately 1 1 N).
Take 75 ml of nitric acid, d = 1.40 (approximately 15 N), and make up the volume to 1 O0 ml
with water.
3.5 Ammonia solution, d = 0.90 (approximately 14.4 N).
3.6 Ammonia solution, d = 0.97 (approximately 3.6 N).
Take 25 ml of ammonia solution, d = 0.90 (approximately 14.4 N), and make up the volume to
1 O0 ml with water.
3.7 Complexing solution.
Dissolve in a little water 50 g of hydroxylammonium chioride (NH,OH.HCl), 50 g of ammo-
nium chloride(NH,Cl), 50 ml of glacial acetic acid, d = 1.05 (approximately 17.4 N), and make
up the volume to 1000 ml with water.
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ISO/R 791 -1968 (I
3.8 Ammonium benzoate solution, 100 g per litre.
Dissolve 100 g of ammonium benzoate (C6H5COONH4) in warm water, add 0.001 g of thymol
and, after cooling, make up the volume to loo0 ml with water.
3.9 Ammonium benzoate wash solution.
Dilute 100 ml of ammonium benzoate solution (3.8) with 900 ml of water and add 20 ml of
glacial acetic acid, d = 1 .O5 (approximately 17.4 N).
3.10 Tartaric acid solution, 500 g per litre.
Dissolve 500 g of tartaric acid [HOOC(CHOH), COOH] in water and make up the volume to
1000 ml.
3.11 Acetic acid, d = 1 .O1 (approximately 1.7 N).
Take 1 O0 ml of glacial acetic acid, d = 1 .O5 (approximately 17.4 N), and make up the volume to
1000 ml with water.
3.12 Acetic acid solution of 8-hydroxyquinoline, 20 g per litre.
Dissolve 20 g of 8-hydroxyquinoline (HO.C,H,N : CH.CH : CH) in 80 ml of glacial acetic acid,
d = 1.05 (approximately 17.4 N), and make up the volume to 1 O00 ml with water.
(Store in a dark glass bottle).
3.13 Ammonium acetate solution, 600 g per litre.
Dissolve 600 g of ammonium acetate (CH,COONH,) in water and make up the volume to
1000 ml.
3.1
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