3255 NTERNATIONAL STANDARD Tso INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXC IyHAPOIHAR OPTAHW3AMA HO CTAHIAPTW3ALIWV.ORGANISATION INTERNATIONALE DE NORMALISATION Magnesium and magnesium alloys --- Determination of aluminium --- Chromazurol S photometric method Magnésium et alliages de magnesium -- Dosage de I'aluminium -- Méthode photometrique au. chromazurol s First edition -- 1974-08-15 ISO 3255-1974 (E) UDC 669.721 : 546.621 : 543.42 Ref. No. iSO 3255-1974 (E) um alloys, chemical analysis, determination of content, aluminium, photometric analysis. Price based on 3 pages Not for Resal FOREWORD IsO (the International Organization for Standardization) is a worldwide federation .of national standards institutes (ISO Member Bodies). The work of develioping International Standards is carried out through ISO Technical Committees. Every up has the right to be represented on that Committee. International organizations, governmental and non-governmental, in liaison with 1sO, aiso take part in the work to the Member Bodies for approval before their acceptance as International Standards by the. ISO Council. International Standard 1sO 3255 was drawn up by Technical Committee ISO/TC 79, Light metals and their alloys, and circulated to the Member Bodies in July 1973. It has been approved by the Member Bodies of the following countries : Australia France Romania Belgium Germany South Africa, Rep. of Hungary Bulgaria Spain Canada Treland Sweden Chile Italy Turkey New Zeaiand Egypt, Arab Rep. of United Kingdom Finland Poland U.S.A. No Member Body expressed disapproval of the document. @ International Organization for Standardization, 1974 Printed in Switzerland Copyright International Organization for Standardization ISO 3255-1974 (E) INTERNATIONAL STANDARD Magnesium and magnesium alloys --- Determination of aluminium -- Chromazurol S photometric method 1 SCOPE AND FIELD OF APPLICATION 3.4 Chromazurol S, 0,1 g/1 methanolic solution. This International Standard specifies a photometric method Dissolve 0,1 g of chromazurol S in a 50 % (V/V) solution of using chromazurol S for the determination of aluminium in water and methanol. Make up the volume to 1 000 ml with the same methanol solution and mix. magnesium and certain magnesium alloys. The method is applicable to the determination of 3.5 Acetone. aluminium content between 0,01 and 0,20 %. This method does not apply to alloys containing zirconium 3.6 Aluminium, 0,05 g/l standard solution. and/or rare earths and/or thorium. Dissolve 0,879 2 g of aluminium potassium sulphate [Al2(SO4)3.K2SO4.24H20] in water. Transfer the solution 2 PRINCIPLE quantitatively to a 1 000 m! volumetric flask, make up to volume and mix. Dissolution with sulphuric acid. 1 ml of this standard solution contains 0,05 mg of Al. Complexing of the iron and the copper by the addition of ascorbic acid and sodium thiosulphate. Formation of the 3.7 Aluminium, 0,012 5 g/l standard solution. aluminium-chromazurol S complex in a buffered medium (pH 5,3 to 5,5). Transfer 50,0 mi of standard aluminium solution (3.6) to a 200 m! volumetric flask, make up to volume and mix. Photometric measurement of the coloured complex at a wavelength of about 545 nm. 1 ml of this standard solution contains 0,012 5 mg of Al. Prepare this solution at the moment of use. 3 REAGENTS equivalent purity. 4 APPARATUS 3.1 Sulphuric acid, p 1,26 g/mi, approximately 9 N solu- Ordinary laboratory apparatus, and tion. Carefully add 250 ml of sulphuric acid (p 1,84 g/ml), 4.1 Spectrophotometer, or 35,6 N approximately, to about 500 ml of water. After cooling, make up the volume to 1 000 ml and mix. 4.2 Photoelectric absorptiometer, fitted withfilters guaranteeing maximum absorption between 535 and 3.2 Ascorbic acid, 10 g/l solution. 555 nm. Dissolve 1 g of ascorbic acid (CHgO) in water. Make up the volume to 100 ml and mix. Use a freshly prepared solution. 5 SAMPLING 3.3 Buffer solution. 5.1 Laboratory sample1) Dissolve 150 g of sodium acetate (CH3.CO0Na.3