5196/2 nternational Standard (ISO INTERNATIONALORGANIZATION FOR STANDARDIZATION·MEKAYHAPOAHAR OPrAHM3AMR NO CTAHAAPTW3AUWM-ORGANISATION INTERNATIONALE DE NORMALISATION Magnesium alloys - Determination of thorium Part 2 : Titrimetric method Alliages de magnesium - Dosage du thorium -- Partie 2: Methode titrimetrique First edition - 1980-12-01 ISO 5196/2-1980 (E) UDC 669.721 : 543.24 : 546.841 Ref.No.ISO5196/2-1980 (E) Descriptors : magnesium alloys, chemical analysis, determination of content, thorium, titration. Price based on 3 pages Coovriaht International Oraanization for Standardizatior Foreword Iso (the International Organization for Standardization) is a worldwide 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 So 5196/2 was developed by Technical Committee ISO/TC 79, Light metals and their alloys, and was circulated to the member bodies in August1979. It has been approved by the member bodies of the following countries : Australia Hungary Romania Austria India South Africa, Rep. of Chile Italy Spain China Japan Sweden Czechoslovakia Norway Switzerland France Philippines USSR Germany, F. R. Portugal Yugoslavia The member body of the following country expressed disapproval of the document on technical grounds : United Kingdom @international Organization for Standardization, 1980 ISO5196/2-1980(E) INTERNATIONALSTANDARD Magnesium alloys - Determination of thorium - Part 2 : Titrimetric method Scope and field of application 3.3 Hydroxylammonium chloride, 100 g/l solution. This International Standard specifies a titrimetric method for Dissolve 10 g of hydroxylammonium chloride (NH2OH.HCI) in the determination of thorium in magnesium alloys which do not water,makeupthevolumeto100miandmix. contain silver. 3.4Ammonium hydroxide solution (o approximately The method is applicable to products having thorium contents 0,91 g/ml). between 0,2 and 5,0 % (m/m). 3.5 Ammonium hydroxide solution (o approximately 0,98 g/ml). 2Principle Dilute 200 ml of the ammonium hydroxide solution (3.4) with Dissolution of a test portion in hydrochloric acid. Formation of water,makeupthevolumeto1000ml andmix. complexes of iron and cerium by the addition of hydroxyl- ammonium chloride. Formation of a zirconium complex by 3.6 Buffer solution addition, at approximately 90 °C, of EDTA solution, using xylenot orange as indicator Add 80 ml of approximately 0,25 mol/I [2 % (V/V)) hydro- chloric acid solution to 500 mi of 15 g/l potassium chloride Titration of the thorium, at approximately 90 oc in buffered solution. medium, against EDTA solution using xylenol orange as in- dicator. 3.7 Zirconium, 0,5 g/l standard solution. 3.7.1 Preparation of the solution 3 Reagents Prepare the solution using one of the following methods. During the analysis, use only reagents of recognized analytical quality and only distilled water orwater of equivalent purity. 3.7.1.1 Weigh, to the nearest 0,001 g, 0,500 g of pure zir conium [content > 99,9 % (m/m)] and placeit in a dry beaker, 3.1Hydrochloric acid(g approximately 1,1g/ml),20 % Add 30ml of methanol and,while cooling,5ml of bromine. (m/m)orapproximately6mol/lsolution. Whenthereactionhasstopped,heatmoderatelytocomplete the attack. Add 40 ml of the hydrochloric acid solution (3.1), Dilute500mlofhydrochloricacid(gapproximately1,19g/ml), bring to the boil and boil until a colourless solution is obtained, approximately 12 mol/l solution, with water, make up the mai