International Standard (TSO 6058 INTE RNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAH OPrAHW3ALMA HO CTAHAAPTW3AUWWORGANISATION INTE RNATIONALE DE NORMALISATION Water quality -- Determination of calcium content EDTA titrimetric method Qualite de I'eau -- Dosage du calcium -- Méthode titrimétrique a I'EDTA First edition - 1984-06-01 UDC 543.3 : 543.24 : 546.41 Ref. No. 1SO 6058-1984 (E) Descriptors : water, quality, chemicai analysis, determination of content, calcium, volumetric analysis. Price based on 3 pages CopyrightInternational Organization for Standardization Not for Resale d without license from IHS Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of developing International interested in a subject for which a technical committee has been authorized has the 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 6058 was developed by Technical Committee ISO/TC 147, Water quality, and was circulated to the member bodies in January 1983. It has been approved by the member bodies of the following countries: Australia Hungary Poland Austria India Romania Belgium Iran South Africa, Rep. of Brazil Iraq Spain Canada Italy Sweden China ueder Switzerland Czechoslovakia Korea, Dem. P. Rep. of Thailand Denmark Korea, Rep. of United Kingdom Finland Netherlands USSR France New Zealand Germany, F. R. Norway No member body expressed disapproval of the document. International Organization for Standardization, 1984· Printed in Switzerland d without license from IHS Not for Resale 1SO 6058-1984 (E) INTERNATIONAL STANDARD Water quality - Determination of calcium content -- EDTA titrimetric method Scope and field of application Reagents This International Standard specifies a titrimetric method using During the analysis, use only reagents of recognized analytical ethylenediaminetetraacetic acid (EDTA) for the determination grade and only distilled water or water of equivalent purity. of the calcium content of ground waters, surface waters and drinking waters. It can also be used for municipal and industrial raw waters, provided they do not contain interfering amounts Sodium hydroxide, 2 mol/l, solution. 4.1 of heavy metals. Dissolve 8 g of sodium hydroxide in 100 ml of freshly distilled The method is not applicable to sea waters and other similar water. Store in a polyethylene bottle. waters with a high concentration of salts. It is applicable to waters with calcium contents ranging from 2 to 100 mg/I (0,05 NoTE -- Take precautions to avoid contamination by atmospheric to 2,5 mmol/l). carbon dioxide. For waters containing more calcium than 100 mg/l, a diluted EDTA, standard volumetric solution, sample shall be used. 4:2 c(Na2EDTA) ~ 10 mmol/l. 4.2.1 Preparation References 2 Dry a portion of the disodium salt of EDTA dihydrate isO 385/1, Laboratory glassware Burettes -- Part 1: (C1oH14N20gNa2:2H20) at 80 °C for 2 h, dissolve 3,725 g of the General requirements, 1 dry salt in water and dilute to 1 000 ml in a volumetric flask. Iso 5667, Water quality -- Sampling - Store the EDTA solution in a polyethylene bottle and check the Part 1: Guidance on the design of sampling programmes. concentration at regular intervals. Part 2: Guidance on sampling techniques. Part 3: Guidance on the preservation and handling of 4.2.2 Standardization samples.2) Standardize the solution (4.2.1) against the calcium standard reference solution (4.3) by the procedure described in ciause 7. 3 Principle Use 20,0 ml of the calcium standard reference solution (4.3) and dilute to 50 ml. Complexometric titration of calcium ions with an aqueous solu- tion of the disodium salt of EDTA at a pH value of between 12 4.2.3 Calculation of the