SANS 5398-1-2010 Leather - Chemical determination of chromic oxide content Part 1 Quantification by titration《皮革 氧化铬含量的化学测定 第1部分：用滴定量化》.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-23177-4 SANS 5398-1:2010Edition 1ISO 5398-1:2007Edition 1SOUTH AFRICAN NATIONAL STANDARD Leather Chemical determination of chromic oxide c

4、ontent Part 1: Quantification by titration This national standard is the identical implementation of ISO 5398-1:2007 and is adopted with the permission of the International Organization for Standardization. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0

5、001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 5398-1:2010 Edition 1 ISO 5398-1:2007 Edition 1 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee SABS SC 120B, Leather Leather test methods, in accordance with

6、 procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in January 2010. Reference numberISO 5398-1:2007(E)IULTCS/IUC 8:1:2007(E)ISO 2007INTERNATIONAL STANDARD ISO5398-1IULTCS/IUC8:1First edition2007-08-01Leather Chemical dete

7、rmination of chromic oxide content Part 1: Quantification by titration Cuir Dosage chimique de loxyde de chrome Partie 1: Quantification par titrage SANS 5398-1:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 5398-1:2007(E) IULTCS/IUC

8、 8:1:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloadin

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11、below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the ad

12、dress below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedSANS 5398-1:2010This s tandard may only

13、 be used and printed by approved subscription and freemailing clients of the SABS .ISO 5398-1:2007(E) IULTCS/IUC 8:1:2007(E) ISO 2007 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references 1 3 Terms and definitions .1 4 Principle1 5 Sampling and sample prepa

14、ration.2 6 Reagents.2 6.1 Wet oxidation method .2 6.2 Alkaline fusion method .2 6.3 Iodometric titration 2 7 Apparatus .2 8 Methods 3 8.1 Preparation of analytical solution3 8.2 Measurement of the aqueous solution3 9 Calculation and expression of results.4 9.1 General4 9.2 Repeatability.4 10 Test re

15、port 4 Annex A (informative) Determination of water and other volatile matter5 SANS 5398-1:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 5398-1:2007(E) IULTCS/IUC 8:1:2007(E) iv ISO 2007 All rights reservedForeword ISO (the Internat

16、ional 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 bee

17、n established 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. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical stand

18、ardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for

19、 voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all

20、 such patent rights. This part of ISO 5398 was prepared by the Chemical Tests Commission of the International Union of Leather Technologists and Chemists Societies (IUC Commission, IULTCS) in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 289, Leather,

21、 the secretariat of which is held by UNI, in accordance with the agreement on technical co-operation between ISO and CEN (Vienna Agreement). It is based on IUC 8 originally published in J. Soc. Leather Trades Chemists 49, p. 17, (1965) and declared an official method of the IULTCS in 1965. IULTCS, o

22、riginally formed in 1897, is a world-wide organization of professional leather societies to further the advancement of leather science and technology. IULTCS has three Commissions, which are responsible for establishing international methods for the sampling and testing of leather. ISO recognizes IU

23、LTCS as an international standardizing body for the preparation of test methods for leather. ISO 5398 consists of the following parts, under the general title Leather Chemical determination of chromic oxide content: Part 1: Quantification by titration Part 2: Quantification by colorimetric determina

24、tion Part 3: Quantification by atomic absorption spectrometry Part 4: Quantification by inductively coupled plasma optical emission spectrometer (ICP-OES) SANS 5398-1:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 5398-1:2007(E) IULT

25、CS/IUC 8:1:2007(E) ISO 2007 All rights reserved vIntroduction ISO 5398 has been split into four parts, each describing methods suitable for the determination of the chromic oxide content in leather. The different techniques have been described to reflect the variations in industrial practice compare

26、d with the more sensitive analytical equipment available for test laboratories. Variations also exist in the range of chromic oxide that the methods are deemed suitable to quantify. ISO 5398-1 describes a traditional technique applied in industry that does not require the use of advanced analytical

27、equipment. SANS 5398-1:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .SANS 5398-1:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .INTERNATIONAL STANDARD ISO 5398-1:2007(E)IULT

28、CS/IUC 8:1:2007(E) ISO 2007 All rights reserved 1Leather Chemical determination of chromic oxide content Part 1: Quantification by titration 1 Scope This part of ISO 5398 describes a method for the determination of chromium in aqueous solution obtained from leather. This is an analysis for total chr

29、omium in leather; it is not compound specific or specific to its oxidation state. This method describes the determination of chrome by iodometric titration and is to be applicable to chromium-tanned leathers which are expected to have chromic oxide contents in excess of 0,3 %. Two different methods

30、are described as alternatives for obtaining chromium in a suitable solution. It is appropriate to use either method. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated ref

31、erences, the latest edition of the referenced document (including any amendments) applies. ISO 2418, Leather Chemical, physical and mechanical and fastness tests Sampling location ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 4044, Leather Chemical tests Prepa

32、ration of chemical test samples ISO 4047, Leather Determination of sulphated total ash and sulphated water-insoluble ash ISO 4684, Leather Chemical tests Determination of volatile matter 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 chromic

33、 oxide content amount of chromium in leather, determined by this method and reported as chromic oxide NOTE The chromic oxide content is expressed in percentage by mass, based on dry matter. 4 Principle The chromium present in the leather is solubilized in the hexavalent state followed by analysis of

34、 the solution by iodometric titration. SANS 5398-1:2010This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 5398-1:2007(E) IULTCS/IUC 8:1:2007(E) 2 ISO 2007 All rights reserved5 Sampling and sample preparation If possible, sample in accordance

35、 with ISO 2418 and grind leather in accordance with ISO 4044. If sampling in accordance with ISO 2418 is not possible (as in the case of leathers from finished products like shoes, garments), details about sampling shall be given together with the test report. Weigh accurately the ground leather to

36、the nearest 0,001 g. (Suggested masses are full chrome leather 1 g, semi-chrome leather 2 g, leather with low chrome content 2 g to 5 g.) From every leather, a minimum of two determinations shall be made. 6 Reagents Unless otherwise stated, only analytical grade chemicals are to be used. The water s

37、hall be grade 3 in accordance with ISO 3696:1987. All solutions are aqueous solutions. 6.1 Wet oxidation method 6.1.1 Nitric acid, 70 %. 6.1.2 Sulfuric acid, concentrated (98 %), and perchloric acid (60 % to 70 %), mixed together in the ratio of 1:3 by volume. 6.1.3 Orthophosphoric acid, 90 %. 6.2 A

38、lkaline fusion method 6.2.1 Fusion mixture, consisting of equal masses of sodium carbonate (Na2CO3), potassium carbonate (K2CO3) and sodium tetraborate (Na2B4O7). 6.2.2 Hydrochloric acid, concentrated (37 %). 6.3 Iodometric titration 6.3.1 Potassium iodide solution, freshly prepared, 100 g/l. 6.3.2

39、Sodium thiosulfate, 0,1 mol/l standardized solution in water. 6.3.3 Starch indicator solution, 10 g/l (or soluble starch powder). 7 Apparatus Usual laboratory apparatus is required and, in particular, the following. 7.1 Conical flask, 500 ml, with ground glass stopper. 7.2 Crucible, glazed porcelain

40、 or platinum (required for alkaline fusion method only). 7.3 Burette, 50 ml. 7.4 Filtration device, using simple paper, glass fibre (GFC) or membrane type filters. 7.5 Antibumping granules (or similar) (wet oxidation method). SANS 5398-1:2010This s tandard may only be used and printed by approved su

41、bscription and freemailing clients of the SABS .ISO 5398-1:2007(E) IULTCS/IUC 8:1:2007(E) ISO 2007 All rights reserved 38 Methods 8.1 Preparation of analytical solution 8.1.1 Wet oxidation method WARNING It is imperative that nitric acid is added first because of the possible explosive reaction of p

42、erchloric acid with leather. Accurately weigh a mass of leather (see Clause 5) into the conical flask (7.1). Add 10 ml of nitric acid (6.1.1) and allow to stand for 2 min. Add 15 ml of mixed sulfuric/perchloric acids (6.1.2) and a few antibumping granules (7.5). Place a funnel or splash bulb in the

43、neck of the flask and heat to boiling on a wire gauze over a moderate flame. As soon as the reaction mixture begins to turn orange, lower the flame. After a complete change of colour, heat gently for at least 2 min. Allow to cool in air for 5 min and dilute to approximately 200 ml. Boil for 10 min t

44、o eliminate any chlorine. Allow to cool and add 5 ml of orthophosphoric acid (6.1.3) to mask any iron. The use of a sulfuric/perchloric acid mixture is preferred to the use of the individual acids as it prevents the accidental use of perchloric acid alone. In the case of incomplete oxidation (i.e. t

45、he solution does not change to an orange colour), it is permissible to add further mixed sulfuric/perchloric acid to the sample. 8.1.2 Alkaline fusion method Ash the accurately weighed sample of leather (see Clause 5) in accordance with ISO 4047. In the crucible (7.2) containing the leather ash, car

46、efully add 5 g of fusion mixture (6.2.1) and mix well using a platinum wire or thin glass rod. Start by heating the crucible gently on an open flame, then heat more fiercely for approximately 30 min. (A muffle furnace operating at 750 C 50 C for at least 30 min may be used to heart the melt). After

47、cooling, place the crucible in a beaker containing 100 ml to 150 ml of boiling water and continue to heat the water until the fusion mixture has completely dissolved. Filter (7.4) the solution obtained into the conical flask (7.1). Thoroughly wash the beaker, crucible and filter with hot water colle

48、cting the washings in the flask. Carefully add at least 10 ml hydrochloric acid to the flask and allow to cool down to room temperature. 8.2 Measurement of the aqueous solution Add to the solution obtained from 8.1.1 or 8.1.2 20 ml of potassium iodide solution (6.3.1), stopper the flask and leave to

49、 stand for 10 min in the dark. Titrate with 0,1 mol/l sodium thiosulfate solution (6.3.2) until the solution in the flask is either light green or blue using 5 ml of starch indicator solution (6.3.3) (or a small quantity of starch powder), added towards the end of titration. Note the millilitres of thiosulfate solution used. If starch solution is used, it should either be freshly prepared or should have been prepared with the addition of a little mercuric iodide to preserve the solution for several month