1、June 2009DEUTSCHE NORM English price group 9No 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!$Wy;“1528624www.
2、din.deDDIN EN ISO 5398-2Leather Chemical determination of chromic oxide content Part 2: Quantification by colorimetric determination (ISO 5398-2:2009)English version of DIN EN ISO 5398-2:2009-06Leder Chemische Bestimmung des Chromoxidgehaltes Teil 2: Gehaltsbestimmung durch kolorimetrische Bestimmun
3、g (ISO 5398-2:2009)Englische Fassung DIN EN ISO 5398-2:2009-06SupersedesDIN 53309:1968-10www.beuth.deDocument comprises 12 pagesDIN EN ISO 5398-2:2009-06 2 National foreword This standard has been prepared by Technical Committee CEN/TC 289 “Leather” (Secretariat: UNI, Italy), in collaboration with t
4、he International Union of Leather Technologists and Chemists Societies (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. IULTCS, originall
5、y 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 IULTCS as
6、an international standardizing body for the preparation of test methods for leather. 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 4684 DIN EN ISO 4684 Amendments
7、 This standard differs from DIN 53309:1968-10 as follows: a) The content of DIN 53309:1968-10 has been incorporated in DIN EN ISO 5398-2. Previous editions DIN 53309: 1968-10 National Annex NA (informative) Bibliography DIN EN ISO 2418, Leather Chemical, physical and mechanical and fastness tests Sa
8、mpling location DIN EN ISO 4044, Leather Preparation of chemical test samples DIN EN ISO 4684, Leather Chemical tests Determination of volatile matter DIN ISO 3696, Water for analytical laboratory use Specification and test methods EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 5398-2 Janu
9、ary 2009 ICS 59.140.30 English Version Leather Chemical determination of chromic oxide content Part 2: Quantification by colorimetric determination (ISO 5398-2:2009) Cuir Dosage chimique de loxyde de chrome Partie 2: Quantification par dosage colorimtrique (ISO 5398-2:2009) Leder Chemische Bestimmun
10、g des Chromoxidgehaltes Teil 2: Gehaltsbestimmung durch kolorimetrische Bestimmung (ISO 5398-2:2009) This European Standard was approved by CEN on 19 December 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStanda
11、rd the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French,
12、 German). A version in any other language made by translation under 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 of Austria, Belgium, Bulgaria, Cyprus, Cze
13、ch 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 COMMITTEE FOR STANDARDIZATION COMIT EUROP
14、EN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 5398-2:2009: EDIN EN ISO 5398-2:2009-06 EN ISO 5398-2:2009 (E) 2 Conte
15、nts Page Foreword3 Introduction .4 1 Scope 5 2 Normative references 5 3 Terms and definitions .5 4 Principle5 5 Sampling and sample preparation.6 6 Reagents.6 6.1 Alkaline fusion method .6 6.2 Photometric determination .6 7 Apparatus .6 8 Methods 7 8.1 Alkaline fusion method .7 8.2 Measurement of th
16、e aqueous solution7 8.3 Preparation of the calibration solution7 9 Check of the analytical system 8 10 Calculation and expression of results.8 10.1 General8 10.2 Repeatability.8 11 Test report 9 Annex A (informative) Determination of water and other volatile matter. 10 DIN EN ISO 5398-2:2009-06 EN I
17、SO 5398-2:2009 (E) 3 Foreword This document (EN ISO 5398-2:2009) 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 European Standard shal
18、l be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2009, and conflicting national standards shall be withdrawn at the latest by July 2009. Attention is drawn to the possibility that some of the elements of this document m
19、ay be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austri
20、a, 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 the United Kingdom. Introductio
21、n 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 compared with the more sensitive analytical equipment available for
22、 test laboratories. Variations also exist in the range of chromic oxide that the methods are deemed suitable to quantify. ISO 5398-2 describes a colorimetric technique that requires the use of a spectrophotometer. 4DIN EN ISO 5398-2:2009-06 EN ISO 5398-2:2009 (E) 1 Scope This part of ISO 5398 descri
23、bes the determination of chrome by colorimetric means. It is applicable to leathers which are expected to have chromic oxide contents in excess of 0,05 %. This is an analysis for total chromium in leather; it is not compound specific or specific to its oxidation state. 2 Normative references The fol
24、lowing 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 referenced document (including any amendments) applies. ISO 2418, Leather Chemical, physical and mechanical and
25、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 4684, Leather Chemical tests Determination of volatile matter 3 Terms and definitions For the purposes of this
26、document, the following terms and definitions apply. 3.1 chromic 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 Ash obtained from leather is fused
27、 by an alkaline mixture. The chromium present in the leather is solubilized in the hexavalent state followed by analysis of the solution after reaction with 1,5-diphenyl carbazide to diphenyl carbazone by photometric means. 5DIN EN ISO 5398-2:2009-06 EN ISO 5398-2:2009 (E) 5 Sampling and sample prep
28、aration 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 (e.g. leathers from finished products like shoes, garments), details about sampling shall be given together with the test report. Weigh accur
29、ately 0,75 g of the ground leather, depending on the expected content of chrome, to the nearest 0,001 g. From each leather, make a minimum of two determinations using separate leather portions. 6 Reagents Unless otherwise stated, only analytical grade chemicals are to be used. The water shall be gra
30、de 3 in accordance with ISO 3696:1987. 6.1 Alkaline fusion method 6.1.1 Fusion mixture, consisting of equal masses of sodium carbonate (Na2CO3), potassium carbonate (K2CO3) and sodium tetraborate (Na2B4O7). 6.2 Photometric determination 6.2.1 Sulfuric acid, 98 %. 6.2.2 Potassium dichromate stock sol
31、ution (0,2 mg Cr2O3/ml), prepared from 0,387 1 g potassium dichromate (6.2.7) in 1 l distilled water. 6.2.3 Potassium dichromate standard solution, prepared from 50 ml of stock solution (6.2.2) pipetted into a 250 ml volumetric flask and made to volume with distilled water. (1 ml of this solution co
32、ntains 0,04 mg Cr2O3.) 6.2.4 Diphenyl carbazide solution, consisting of 1,00 g of 1,5-diphenyl carbazide dissolved in 100 ml acetone with one drop of glacial acetic acid added. This can be stored for up to two weeks at 4 C. 6.2.5 Acetone. 6.2.6 Glacial acetic acid, 100 %. 6.2.7 Potassium dichromate
33、(K2Cr2O7), dried for 16 h 2 h at 102 C 2 C 7 Apparatus Usual laboratory apparatus is required and, in particular, the following. 7.1 Crucible, glazed porcelain or platinum. 7.2 Spectrophotometer, capable of reading absorbance to a minimum of 3 decimal places at a wavelength of 540 nm. 7.3 Cuvettes,
34、of 1 cm optical path length. 7.4 Muffle furnace. 7.5 Filtration device, using ash-free paper. 6DIN EN ISO 5398-2:2009-06 EN ISO 5398-2:2009 (E) 8 Methods 8.1 Alkaline fusion method Pre-ash the accurately weighed sample of leather (see Clause 5) using an open flame prior to ashing and afterwards ash
35、at 750 C 50 C for 4 h. In the crucible (7.1) containing the leather ash, carefully add 5 g of fusion mixture (6.1.1) and mix well using a platinum wire or thin glass rod. Initially heat the crucible gently on an open flame, then heat more fiercely for approximately 30 min. (A muffle furnace operatin
36、g at 750 C 50 C for approximately 30 min may be used for heating the melt.) After cooling, place the crucible in a beaker containing 100 ml to 150 ml of hand-warm water and continue to heat in the water until the fusion mixture has completely dissolved. No losses of the solution due to splashing sha
37、ll occur. Filter (7.5) the solution obtained into a 1 000 ml volumetric flask. Thoroughly wash the beaker, crucible and filter with hot water, collecting the washings in the volumetric flask. If a green residue is observed in the filter, this shall be ashed as described above with the filtrate being
38、 added to the 1 000 ml flask. Carefully add at least enough sulfuric acid to the flask until pH 1 is reached, allow to cool down to room temperature and make up to volume with distilled water. The resulting solution is stable for 4 days if stored in the dark for samples in excess of 0,5 % Cr2O3. For
39、 lower concentrations, analysis shall be done immediately. 8.2 Measurement of the aqueous solution Add 10 ml, up to 50 ml from leather with an expected low chromium content, of the solution (8.1) to a 100 ml volumetric flask. Add 1 ml of diphenyl carbazide solution (6.2.4). Make up to volume with di
40、stilled water and invert several times to mix thoroughly. The colorimetric measurement should be carried out (15 5) min after the addition of the diphenyl carbazide solution. Measure the absorbance of the test solution against a blank solution prepared using 25 ml distilled water rather than the sam
41、ple, 1 ml sulfuric acid and 1 ml diphenyl carbazide solution (6.2.4) at 540 nm using a 1 cm cuvette. If the absorbance is in excess of that observed from the highest calibration standard, the analysis should be repeated using either smaller sample size, or with appropriate dilution of the solution o
42、btained from 8.1. 8.3 Preparation of the calibration solution From the standard solution of potassium dichromate (6.2.3), add the volumes given in the Table 1 to separate 100 ml volumetric flasks. Table 1 Volumes needed Concentration Vstandardmg Cr2O3/100 ml ml 0,02 0,5 0,04 1 0,08 2 0,16 4 0,24 6 0
43、,28 7 7DIN EN ISO 5398-2:2009-06 EN ISO 5398-2:2009 (E) Add 1 ml of sulfuric acid (6.2.1) to each flask followed by 1 ml of diphenyl carbazide solution (6.2.4). Make up each flask to volume with distilled water and inverted several times to mix thoroughly. Prepare a calibration graph by plotting the
44、 absorbance against the Cr2O3content in milligrams per 100 ml (mg/100 ml). 9 Check of the analytical system Upon each set of analysis or on a daily basis (whichever is the least frequent), a solution prepared from 5 ml standard solution (6.2.3) should be evaluated according to the photometric method
45、 (8.2) to ensure the accuracy of the method. 10 Calculation and expression of results 10.1 General Calculate the chromic oxide content, wCr, in the leather, as a percentage by mass on dry matter according to the following equation. sample1Crsample 2VwFDmV= where sample is the concentration of Cr2O3o
46、btained from the calibration graph, in milligrams per 100 ml (mg/100 ml); msampleis the mass of the original leather sample, in grams (g), (use for the fusion; fusion mixture is dissolved in 1 000 ml); D is the dilution factor of the samples from 8.1 (usually = 1); V1is the volume of the volumetric
47、flask (ml) used for the colorimetric determination; V2is the volume, in millilitres (ml), of the solution (8.1) (10 ml to 50 ml depending on the chromium content); F is the factor to correct to 0 % volatile matter; it is calculated as follows: w100100Fw=where wwis the volatile matter content, based
48、on ISO 4684, in percentage by mass. It is permissible, if required, to quote the results based on the dry, degreased mass of the sample. 10.2 Repeatability The results of the duplicate determination should not differ by more than 0,1 % calculated on the original mass of the leather. The results of t
49、he investigation concerning repeatability of the procedure are given in Table 2. 8DIN EN ISO 5398-2:2009-06 EN ISO 5398-2:2009 (E) Table 2 Repeatability results Amount g Extinction Cr2O3 (dry matter) % 0,748 3 0,585 8 3,371 0,746 7 0,591 3 3,410 0,749 6 0,592 5 3,403 0,752 1 0,590 4 3,380 0,750 2 0,595 9 3,420 0,751 1 0,595 1 3,412 number of values: 6 average content % Cr2O3(dry matter): 3,399 standard derivation % Cr2O3(dry matter): 0,019 variation coefficient (%): 0,56 coefficient interval of average (n =
