(ISo International Standard 4193 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKAYHAPOAHAA OPTAHM3AUWA HO CTAHAAPTM3AUWMORGANISATION INTERNATIONALE DE NORMALISATION Aluminium and aluminium alloys - Determination of chromium content - Flame atomic absorption spectrometric method Aluminium et alliages d'aluminium - Dosage du chrome - Methode par spectrométrie dabsorption atomique dans la flamme First edition -- 1981-12-01 ISO 4193-1981 (E) UDC 669.71 : 543.422 : 546.76 Ref.No.ISO4193-1981 (E) Descriptors : aluminium, aluminium alloys, chemical analysis, determination of content, chromium, atomic absorption spectroscopic method. Pricebased on 3pages ational Organization for Standardizatio No reproduction or networking permited without license from IHS Not for Resale Foreword Iso (the International Organization for Standardization) is a woridwide federation of national standards institutes (Iso member bodies). The work of developing Inter- national Standards is carried out through Iso technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. International Standard ISO 4193 was developed by Technical Committee ISO/TC 79, Light metals and their alloys, and was circulated to the member bodies in December 1980. It has been approved by the member bodies of the following countries : Australia Germany, F.R. Romania Austria Hungary South Africa, Rep. of Brazil India Spain Canada Italy Sweden China Japan Switzerland Czechoslovakia Korea, Rep. of United Kingdom Egypt, Arab Rep. of Norway USA France Poland USSR The member body of the following country expressed disapproval of the document on technical grounds : Netherlands InternationalOrganizationforStandardization,1981 Printed in Switzeriand No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONALSTANDARD ISO4193-1981 (E) Aluminium and aluminium alloys - Determination of chromium content -- Flame atomic absorption spectrometric method Scope and field of application 3.5 Hydrofluoric acid, Q approximately 1,13 g/ml, about 40 % (m/m) solution. This International Standard specifies a flame atomic absorption spectrometric method for the determination of the chromium content of aluminium and its alloys. 3.6 Nitric acid, @ approximately 1,4 g/ml, about 68 % (m/m) or approximately 15 mol/l solution. The method is applicable to products having chromium (Cr) contents between 0,003 and 0,6 % (m/m).1) 3.7 Aluminium, 20 g/l solution. 2 Principle Weigh,tothenearest0,01g,20gof previouslypickled,extra pure aluminium (3.1), place it in a 1 000 ml beaker and cover Dissolution of a test portion in hydrochloric acid and hydrogen witha watchglass.Add,in small portions,600ml of the hydrochloric acid solution (3.2) and, if necessary, a drop of peroxide. Aspiration of the solution into an air-acetylene or, metallic mercuryto assisttheattack.If necessary,warmgently preferably,dinitrogen oxide acetylene flame,and comparison to aid the dissolution, and then add a few drops -of the of theabsorbanceofresonanceenergyof chromiumbythetest hydrogen peroxide solution (3.3).After cooling,quantitatively solution (wavelength of 357,9 nm normally) with that of stan- transfer the solution thus obtained to a 1000 ml volumetric dard solutions. flask, dilute to the mark and mix. 3Reagents 3.8 Chromium, standard solution corresponding to 0,5 g of Cr per litre. During the analysis, use only reagents of recognized analytical grade and distilied or deionized water. Weigh, to the nearest 0,001 g, 1,414 g of extra pure potassium dichromate (≥99,9 % K2Cr207), previously dried at 140 °C, 3.1 Aluminium