2992 NTERNATIONAL STANDARD (TSO) INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEKIYHAPOIHA OPTAHИ3ALIH IIO CTAHIAPTH3ALIWIH.ORGANISATION INTERNATIONALE DE NORMALISATION Ammonium sulphate for industrial use - Determination of iron content - 2,2'-bipyridyl photometric method Sulfate d'ammonium a usage industriel -- Dosage du fer -- Méthode photométrique au 2,2'-bipyridyle First edition - 1974-04-01 APR 3 -1974 ANsl Internat Doc Sect UDC 661.522 : 546.72 : 543.42 Ref. No. 1SO 2992-1974 (E) 2992-1974 (E) Descriptors : ammonium compounds, ammonium sulphate, chemical analysis, determination'of content, iron, photometric analysis. Price based on 3 pages from IHS Not for Resale FOREWORD IsO (the Internationat Organization for Standardization) is a worldwide federation of national standards institutes (IsO Member Bodies). The work of developing International Standards is carried out through IsO Technica! 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, to the Member Bodies for approval before their acceptance as International Standards by the IsO Council. International Standard 'isO 2992 was drawn up by Technical Committee 1SO/TC 47, Chemistry, and circulated to the Member Bodies in November 1972. It has been approved by the Member Bodies of the following countries : Hungary South Africa, Rep. of Australia India Austria Spain Sweden Belgium Israel Bulgaria Italy Switzeriand Thailand Czechoslovakia Netherlands Turkey Egypt, Arab Rep. of New Zealand France Poiand United Kingdom Germany Romania U.S.S.R. Pure and Applied Chemistry (IUPAC). No Member Body expressed disapproval of the document. @ international Organization for Standardization, 1974 : Printed in Switzerland Copyright International Organization for Standardization Not for Resale INTERNATIONAL STANDARD ISO 2992-1974 (E) Ammonium sulphate for industrial use -- Determination of iron content - 2,2'-bipyridyl photometric method 1 SCOPE AND FIELD OF APPLICATION solution and transfer quantitatively to a 500 ml one-mark volumetric flask. Dilute to the mark and mix. This International Standard specifies a 2,2'-bipyridyl 1 m! of this standard solution contains 2 mg of Fe. photometric method for the determination of the iron con- tent of ammonium sulphate for industrial use. The method is applicable to iron (Fe) contents equal to or greater than 3.6 Standard iron solution corresponding to 0,2 g of Fe 0,000 1 % (m/m). per litre. Introduce 50,0 ml of the standard iron sotution (3.5) into 2 PRINCIPLE a 500 ml one-mark voiumetric flask, add 5 mi of a 100 g/l sulphuric acid solution, dilute to the mark and mix. Reduction of trivalent iron by hydroxylammonium chloride. Formation of the complex between divalent iron 1 ml of this standard solution contains 0,2 mg of Fe. and 2,2'-bipyridyl in a buffered medium (pH vaiue between 4,5 and 6). 3.7 Standard iron solution corresponding to 0,01 g of Fe per litre. Photometric measurement of the coloured complex at a wavelength of about 522 nm. Introduce 50,0 ml of the standard iron solution (3.6) into a 1 000 ml one-mark voiumetric fiask, dilute to the mark and mix. 3 REAGENTS 1 m! of this standard solution contains 10 μg of Fe. Distilled water, or water of equivalent purity, shall be used Prepare this solution immediately before it is required for in the test. use. 3.1 Hydrochloric acid, approximately N solution. 4 APPARATUS 3.2 Hydroxylammonium chloride, 100 g/l solution. Ordinary laboratory apparatus and hydroxylammonium Dissolve 10 gof chioride (NH,OH.HCi) in water, dilute to 100 ml and mix. 4.1 Spectrophotometer, or 3.3 Ammonium acetate, 300 g/1 solution. 4.2 Photoelectric absorptiometer, fitted with appropriate Dissolve 30 g of ammonium acetate (CH,COONH4) in filters. water, dilute to 100 ml and mix. 5 PROCEDURE 3.4 2,2'-bipyridyl, 10 g/l solution in hydrochloric acid. Dissolve 1 g of 2,2'-bipyridyl in 10 ml of the