ISO INTERNATIONAL STANDARD 6332 Second edition 1988-02-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXKAYHAPOAHAA OPrAHM3ALMH O CTAHAAPTM3ALWM Water quality - Determination of iron Spectrometric method using 1,10-phenanthroline Qualite deI'eau - Dosage dufer-Methode spectrometrique a laphénanthroline-1,10 Referencenumber ISO 6332: 1988 (E) Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental 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. They are approved in accordance with IsO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 6332 was prepared by Technical Committee ISO/TC 147, Water quality. This second edition cancels and replaces the first edition (IS0 6332 : 1982), of which it constitutes a technical revision. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. International Organization for Standardization, 1988: Printed in Switzerland rking permited withoutlicense from IHS Not for Resale ISO 6332 : 1988 (E) INTERNATIONAL STANDARD Water quality - Determination of iron Spectrometric method using 1,10-phenanthroline 1 Scope and field of application 4 Reagents This International Standard specifies a 1,10-phenanthroline Use only reagents of recognized analytical grade. spectrometric method for the determination of iron in water and waste water. Procedures are described for the determina- The water used shall have as low an iron concentration as tion of possible; a measurable iron concentration in the reagents is permissible provided that the lowest concentration to be deter- a) total iron (sum of dissolved and undissolved iron) : mined is at least three times the standard deviation of the predetermined results of blank tests. Deionized water or water 1) direct determination, distilled from an all-glass apparatus has been found to be suitable. 2) determination after decomposition; b) total dissolved iron [sum of dissolved iron(l) and 4.1 Sulfuric acid, Q = 1,84 g/ml. iron(II)]; 4.2 Sulfuric acid solution, c(1/2 H2SO4) ~ 4,5 mol/l. c) determination of dissolved iron(l). Add slowly and with vigorous stirring 1 volume of concentrated The methods are applicable to the determination of iron con- centrations between 0,01 and 5 mg/l. Iron concentrations sulfuric acid (4.1) to 3 volumes of water while cooling. above 5 mg/l may be determined after suitable dilution of the sample. 4.3 Nitric acid, concentrated, Q = 1,40 g/ml. For interferences see clause 10. 4.4 Hydrochloric acid solution, Q =- 1,12 g/ml, c(HCI) ~ 7,7 mol/l. 2 Reference 4.5 Acetate buffer. iso 5667-1, Water quality -- Sampling - Part 1 : Guidance on the design of sampling programmes. Dissolve 40 g of ammonium acetate (CHgCOONH4) and 50 ml of glacial acetic acid (CHCOOH) (α = 1,06 g/ml) in water and dilute to 100 ml with water. Principle 3 4.6 Hydroxylammonium chloride, 100 g/l solution. Addition of 1,10-phenanthroline solution to a test portion and photometric measurement of the orange-red complex at a Dissolve 10 g of hydroxylammonium chloride (NH2OH.HCI) in wavelength of about 510 nm. water and dilute to 100 ml. If determining total iron or total soluble iron, hydroxyl- This solution is stable for at least 1 week.