1、October 2007DEUTSCHE NORM English price group 8No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 59.140.30!$IH“1389137ww
2、w.din.deDDIN EN ISO 5398-1Leather Chemical determination of chromic oxide content Part 1: Quantification by titration (ISO 5398-1:2007)English version of DIN EN ISO 5398-1:2007-10Leder Chemische Bestimmung des Chromoxidgehalts Teil 1: Bestimmung durch Titration (ISO 5398-1:2007)Englische Fassung DIN
3、 EN ISO 5398-1:2007-10www.beuth.deDocument comprises 11 pagesDIN EN ISO 5398-1:2007-10 2 National foreword This standard has been prepared by Technical Committee CEN/TC 289 “Leather” (Secretariat: UNI, Italy), in collaboration with the International Union of Leather Technologists and Chemists Societ
4、ies (IULTCS). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee NA 062-05-52 Chemische Prfverfahren fr Leder. This part of ISO 5398 was prepared by the Chemical Tests Commission of the Internati
5、onal 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, the secretariat of which is held by UNI, in accordance with the agreement on technical co-operation betw
6、een 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, originally formed in 1897, is a world-wide organization of professional leather societies to further the a
7、dvancement 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 IULTCS as an international standardizing body for the preparation of test methods for leather. EN ISO 5398
8、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 determination Part 3: Quantification by atomic absorption spectrometry Part 4: Quantification by inductively co
9、upled plasma optical emission spectrometer (ICP-OES) The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 2418 DIN EN ISO 2418 ISO 3696 DIN ISO 3696 ISO 4044 DIN EN ISO 4044 ISO 4047 DIN EN ISO 4047 ISO 4684 DIN EN ISO 4684 National Annex NA
10、 (informative) Bibliography DIN EN ISO 2418, Leather Chemical, physical and mechanical and fastness tests Sampling location DIN EN ISO 4044, Leather Chemical tests Preparation of chemical test samples DIN EN ISO 4047, Leather Determination of sulphated total ash and sulphated water-insoluble ash DIN
11、 EN ISO 4684, Leather Chemical tests Determination of volatile matter DIN ISO 3696, Water for analytical laboratory use Specification and test methods EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 5398-1August 2007ICS 59.140.30English VersionCuir - Dosage chimique de loxyde de chrome - Parti
12、e 1:Quantification par titrage (ISO 5398-1:2007)Leder - Chemische Bestimmung des Chromoxidgehalts -Teil 1: Bestimmung durch Titration (ISO 5398-1:2007)This European Standard was approved by CEN on 28 July 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate
13、the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists i
14、n three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies o
15、f Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN C
16、OMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 5398-1:2007: ELeather - Chemical
17、determination of chromic oxide content -Part 1: Quantification by titration (ISO 5398-1:2007)Contents Page 1 2 3 4 5 6 6.1 6.2 6.3 7 8 8.1 8.2 9 9.1 9.2 10 2Scope 5 Normative references 5 Terms and definitions .5 Principle5 Sampling and sample preparation.6 Reagents.6 Alkaline fusion method .6 Appar
18、atus .6 Iodometric titration 6 Methods 7 Measurement of the aqueous solution7 Calculation and expression of results.8 Preparation of analytical solution7 General8 Test report 8 Annex A (informative) Determination of water and other volatile matter9 Repeatability.8 Wet oxidation method .6 Introductio
19、n .4Foreword3EN ISO 5398-1:2007 (E)3 Foreword This document (EN ISO 5398-1:2007) has been prepared by Technical Committee CEN/TC 289 “Leather”, the secretariat of which is held by UNI, in collaboration with the International Union of Leather Technologists and Chemists Societies (IULTCS). This Europe
20、an Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2008, and conflicting national standards shall be withdrawn at the latest by February 2008. According to the CEN/CENELEC Internal Regulations, the nat
21、ional standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
22、 Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN ISO 5398-1:2007 (E)Introduction 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
23、 been described to reflect the variations in industrial practice compared 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 a
24、pplied in industry that does not require the use of advanced analytical equipment. 4EN ISO 5398-1:2007 (E)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 chromium in leather; it is not compoun
25、d 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 are described as alternatives for o
26、btaining 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 references, the latest edition of the
27、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 Preparation of chemical test samples ISO
28、 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 oxide content amount of chromium i
29、n 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 the solution by iodometric titrati
30、on. 5EN ISO 5398-1:2007 (E)5 Sampling and sample preparation If possible, sample in accordance 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
31、sampling shall be given together with the test report. Weigh accurately the ground leather to 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
32、 Reagents Unless otherwise stated, only analytical grade chemicals are to be used. The water shall 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 % t
33、o 70 %), mixed together in the ratio of 1:3 by volume. 6.1.3 Orthophosphoric acid, 90 %. 6.2 Alkaline 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 %
34、). 6.3 Iodometric titration 6.3.1 Potassium iodide solution, freshly prepared, 100 g/l. 6.3.2 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 f
35、ollowing. 7.1 Conical flask, 500 ml, with ground glass stopper. 7.2 Crucible, glazed porcelain 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
36、 oxidation method). 6EN ISO 5398-1:2007 (E)8 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 perchloric acid with leather. Accurately weigh a mass of leather (see Clause 5
37、) 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 neck of the flask and heat to boiling on a wire gauze over a moderate flame.
38、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 to eliminate any chlorine. Allow to cool and add 5 ml of orthophosphoric acid
39、(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. the solution does not change to an orange colour), it is permissible to add fu
40、rther 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, carefully add 5 g of fusion mixture (6.2.1) and mix well using a platinum wire o
41、r 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 cooling, place the crucible in a beaker containing 100 ml to 150 ml of boilin
42、g 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 collecting the washings in the flask. Carefully add at least 10 ml hydrochloric ac
43、id 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 stand for 10 min in the dark. Titrate with 0,1 mol/l sodium thiosulfate solu
44、tion (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 fr
45、eshly prepared or should have been prepared with the addition of a little mercuric iodide to preserve the solution for several months. If the titre is in excess of 50 ml, the analysis should be repeated using either smaller sample size or with appropriate dilution of the solution obtained from 8.1.1
46、 or 8.1.2. 7EN ISO 5398-1:2007 (E)9 Calculation and expression of results 9.1 General Calculate the following percentage. The percentage by mass on dry matter, wCr, of chromic oxide, Cr2O3, in the leather is given by the equation 1Cr00,002 53 100VFwm= where V1is the volume, in millilitres (ml), of 0
47、,1 mol/l thiosulfate solution used for the titration; m0is the mass of the original leather sample, in grams (g); F is the factor to correct to 0 % volatile matter; it is calculated as follows: W100100Fw=where wWis the volatile matter content, based on ISO 4684, in percentage by mass. NOTE 1 ml of e
48、xactly 0,1 mol/l thiosulfate solution is equivalent to 0,002 53 g Cr2O3.It is also permissible, if required, to quote the results based on the dry, degreased mass of the sample. 9.2 Repeatability The results of the duplicate determination should not differ by more than 0,1 % calculated on the origin
49、al mass of the leather. 10 Test report The test report shall include the following: a) a reference to this part of ISO 5398 (ISO 5398-1:2007); b) a description of the leather; c) a reference to the method used for sample preparation, type of digestion and measurement; d) the volatile matter content of the leather, in percentage; e) the results obtained based on dry sample mass to one decimal place in percentage; f) details of any deviations from the described procedures. 8EN ISO 5398-1:2007 (E)Annex A (informative) Deter
