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1、INTERNATIONAL STANDARD 714 ,NTERNAT,ONAL ORGAN,ZAT,ON FOR STANDARDlZATlON .MEXAYHAPOnHAX OPrAHM3ALWX IlO CTAHAPTM3ALWiA.ORGANlSATlON INTERNATIONALE DE NORMALISATION Zinc - Determination of iron content - Photometric method Zinc - Dosage du fer - Mthode photomktrique First edition - 1975-07-15 UDC 66
2、9.5 : 543.4 : 669.12 Descriptors : zinc, chemical analysis, determination of content, iron, photometric analysis. Ref. No. IS0 714-1975 (E) Price based on 2 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/99725
3、45001 Not for Resale, 04/25/2007 22:29:52 MDTNo reproduction or networking permitted without license from IHS -,-,- FOREWORD IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 Member Bodies). The work of developing International S
4、tandards is carried out through IS0 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 i
5、n 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 IS0 Council. Prior to 1972, the results of the work of the Technical Committees were published as IS0 Recommendatio
6、ns; these documents are now in the process of being transformed into International Standards. As part of this process, Technical Committee lSO/TC 18 has reviewed IS0 Recommendation R 714 and found it technically suitable for transformation. International Standard IS0 714 therefore replaces IS0 Recom
7、mendation R 714-I 968 to which it is technically identical. IS0 Recommendation R 714 was approved by the Member Bodies of the following countries : Australia Belgium Brazil Canada Chile Czechoslovakia Egypt, Arab Rep. of France Germany Hungary India Ireland Israel Italy Korea, Rep. of Korea, D.P. Re
8、p. of New Zealand Norway South Africa, Rep. of Spain Switzerland Thailand Turkey United Kingdom U.S.A. U.S.S.R. Yugoslavia The Member Body of the following country expressed disapproval of the Recommendation on technical grounds : Japan No Member Body disapproved the transformation of ISO/R 714 into
9、 an International Standard. 0 International Organization for Standardization, 1975 l Printed in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 22:29:52 MDTNo reprodu
10、ction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 714-1975 (El Zinc - Determination of iron content - Photometric method 1 SCOPE AND FIELD OF APPLICATION This International Standard specifies a photometric method for the determination of the iron content of zinc
11、. The method is applicable to the types of zinc defined in ISO/R 752, provided that the copper content does not exceed 0,Ol %. It is suitable for the determination of iron contents between 0,001 and 0.1 %. 2 REFERENCES ISO/R 752, Zinc ingots. IS0 3751, Zinc ingots - Selection and preparation of samp
12、les for chemical analysis. 1) 3 PRINCIPLE Photometric determination of the yellow colour of the sulphosalicylic acid ferric complex formed in an ammoniacal solution. 4 REAGENTS During the analysis, use only reagents of analytical reagent grade and distilled or demineralized water. 4.1 Ammonia soluti
13、on, p 0,91 g/ml. 4.2 Hydrochloric acid, p 1 ,I9 g/ml. 4.3 Hydrogen peroxide, 30 % (m/m) H202. 4.4 Sulphosalicylic acid, 400 g/l solution. 4.5 Nickel chloride solution containing 2 g of NiC12.6H20 per litre. 4.6 Iron, standard solution. Weigh 0,250 g of pure iron to the nearest 0,001 g and attack wit
14、h a few millilitres of hydrochloric acid (4.2). Oxidize with a few drops of hydrogen peroxide (4.3). Decompose the excess hydrogen peroxide by boiling. Cool. Transfer quantitatively to a 1 I volumetric flask. Dilute to the mark and mix. Transfer 100 ml of this solution to a 500 ml volumetric flask.
15、Dilute to the mark and mix. 1 ml of this solution contains 0,050 mg of iron. 5 APPARATUS Ordinary laboratory apparatus and 5.1 Photometer, wavelength 425 nm, and 1 cm cells.*) 6 SAMPLING Sampling shall be carried out in accordance with the requirements of IS0 3751. 7 PROCEDURE 7.1 Test portion Weigh
16、 10 g of the test sample to the nearest 0,Ol g. 7.2 Blank test Simultaneously with the actual determination, carry out a blank test using the same quantities of each reagent and following the same procedure. 7.3 Plotting of the calibration curve3) 7.3.1 Introduce into a series of 100 ml volumetric f
17、lasks, 0, 2, 5, 10 and 20 ml respectively of the standard iron solution (4.6). 1) At present at the staga of draft. 2) The dilutions and aliquot parts defined in this International Standard only apply if 1 cm cells are used. It is necessary to apply the appropriate modifications in the case of cells
18、 with other dimensions. 3) Valid for 1 cm cells and a range of contents of 0 - 0.1 - 0.25 - 0.5 and 1 mg of iron corresponding to 0 - 0,Ol - 0,025 - 0.05 and 0,l % in the case of the procedure specified in 7.4.2, and to 0 - 0,001 - 0,002 5 - 0,005 and 0.01 % in the case of the procedure specified in
19、 7.4.3. It is necessary to apply the appropriate modifications in the case of cells with other dimensions. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 22:29:52 MDTNo reprod
20、uction or networking permitted without license from IHS -,-,- ISO714-1975(E) 7.3.2 Add successively - 5 ml of sulphosalicylic acid solution (4.4), - ammonia solution (4.1) until the solution has a yellow colour, then 20 ml in excess. 7.3.3 Cool. Dilute to the mark and mix. 7.3.4 Measure the absorban
21、ce of these solutions against the solution to which no iron has been added, with the photometer (5.1) at a wavelength of 425 nm. 7.4 Determination 7.4.1 Transfer the test portion to a 500 ml conical flask and attack with 50 ml of hydrochloric acid (4.2). Oxidize and complete the solution by adding a
22、 few drops of hydrogen peroxide (4.3). Decompose the excess hydrogen peroxide by boiling. NOTE - If dissolution is very difficult, 2 ml of nickel chloride solution (4.5) may be added to expedite the attack. 7.4.2 For iron contents equal to or greater than 0,Ol %, proceed as follows : 7.4.2.1 Allow t
23、o cool. Transfer quantitatively to a 250 ml volumetric flask. Dilute to the mark and mix. 7.4.3 For iron contents less than 0,Ol %, proceed as follows : 7.4.3.1 Evaporate just to a syrupy consistency. 7.4.3.2 Cool. 7.4.3.3 Take up with a minimum of water and transfer quantitatively to a 100 ml volum
24、etric flask so as not to exceed 30 ml. 7.4.3.4 Add successively - 5 ml of sulphosalicylic acid solution (4.4), - ammonia solution (4.1) until the solution has a yellow colour, then 50 ml in excess. 7.4.3.5 Cool. Dilute to the mark and mix. 7.5 Photometric measurement Measure the absorbance of the so
25、lution against the blank solution at a wavelength of 425 nm. 8 EXPRESSION OF RESULTS Determine the iron content by means of the appropriate calibration curve (7.3). 7.4.2.2 Transfer a 25 ml aliquot to a 100 ml volumetric flask. 9 TEST REPORT 7.4.2.3 Add successively - 25 ml of water, - 5 ml of sulph
26、osalicylic acid solution (4.4), - ammonia solution (4.1) until the solution has a yellow colour, then 20 ml in excess. 7.4.2.4 Cool. Dilute to the mark and mix. The test report shall mention the method used and the results obtained. It shall also mention all operational details not provided for in t
27、his International Standard, or any optional details, as well as any circumstances which could have influenced the results. The test report shall include all details required for complete identification of the sample. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 22:29:52 MDTNo reproduction or networking permitted without license from IHS -,-,-