1、BSI Standards PublicationBS EN ISO 19071:2016Leather Chemical tests Determination of chromium(VI) and the reductive potential for chromium tanning agents BS EN ISO 19071:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 19071:2016. The UK participation in
2、 its preparation was entrusted to Technical Committee TCI/69, Footwear, leather and coated fabrics.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are resp
3、onsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 83035 8 ICS 59.140.30 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Stan
4、dards Policy and Strategy Committee on 30 April 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 19071 April 2016 ICS 59.140.30 English Version Leather - Chemical tests - Determination of chromium (VI) and the red
5、uctive potential for chromium tanning agents (ISO 19071:2016) Cuir - Essais chimiques - Dtermination de la teneur en chrome (VI) et du potentiel de rduction des agents de tannage au chrome (ISO 19071:2016) Leder - Chemische Prfungen - Bestimmung von Chrom (VI) und deren Reduktionspotential fr Chrom-
6、Gerbstoffe (ISO 19071:2016) This European Standard was approved by CEN on 13 February 2016. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date
7、lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation un
8、der the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former
9、 Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUR
10、OPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 19071:2016 EBS EN ISO 19071:2016EN ISO 19071:2016 (E) 3
11、European foreword This document (EN ISO 19071:2016) has been prepared by Technical Committee IULTCS “International Union of Leather Technologists and Chemists Societies“ in collaboration with Technical Committee CEN/TC 289 “Leather” the secretariat of which is held by UNI. This European Standard sha
12、ll be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 2016, and conflicting national standards shall be withdrawn at the latest by October 2016. Attention is drawn to the possibility that some of the elements of this doc
13、ument may 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:
14、 Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
15、Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 19071:2016 has been approved by CEN as EN ISO 19071:2016 without any modification. BS EN ISO 19071:2016ISO 19071:2016(E)IULTCS/IUC 35:2016(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Principle
16、14 Reagents 15 Apparatus . 26 Sampling and sample preparation 27 Determination of chromium (VI) content using the standard addition procedure 27.1 General . 27.2 Procedure 28 Quality control 39 Calculation and expression of the results 310 Test report . 5Bibliography 6 ISO 2016 All rights reserved i
17、iiContents PageBS EN ISO 19071:2016ISO 19071:2016(E)ForewordISO (the International 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. Eac
18、h member body interested in a subject for which a technical committee has been 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 Internation
19、al Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different
20、types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not
21、be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is infor
22、mation given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see th
23、e following URL: Foreword - Supplementary informationISO 19071 was prepared by the Chemical Testing Commission of the International Union of Leather Technologists and Chemists Societies (IUC Commission, IULTCS) in collaboration with the European Committee for Standardization (CEN) Technical Committe
24、e CEN/TC 289, Leather, the secretariat of which is held by UNI, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).IULTCS, originally formed in 1897, is a world-wide organization of professional leather societies to further the advancement of leather sci
25、ence 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.IULTCS/IUC 35:2016(E)iv ISO 2016 All r
26、ights reservedBS EN ISO 19071:2016ISO 19071:2016(E)IntroductionUnder REACH regulations, manufacturers of chemicals are required to register their products before placing them on the market. Accordingly, a new method is given for the determination of chromium (VI) in chromium tanning agents.Chromium
27、tanning agents consist of chromium sulfate, containing additional hydroxyl groups in different amounts. These tanning agents exhibit a reductive potential. In the presence of reducing agents the recovery rate of chromium (VI) can be significantly lower than 90 %.Consequently another procedure has to
28、 be selected to determine the exact chromium (VI) content. This is based on the standard addition procedure, and was developed in consultation with TEGEWA working group “Leather Auxiliaries” (TEGEWA is the Association of German Manufacturers of Textile, Leather and Washing Agent chemical products).I
29、ULTCS/IUC 35:2016(E) ISO 2016 All rights reserved vBS EN ISO 19071:2016BS EN ISO 19071:2016Leather Chemical tests Determination of chromium (VI) and the reductive potential for chromium tanning agents1 ScopeThis International Standard specifies a test method for the determination of chromium (VI) co
30、ntent in chromium tanning agents. The results give information about the reductive potential of the chromium tanning agent.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references,
31、only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 3696, Water for analytical laboratory use Specification and test methods3 PrincipleThe chromium tanning agent is dissolved in water. After reaction of chromium
32、 (VI) with 1,5-diphenylcarbazide the resulting complex is extracted using n-hexanol. The concentration of the complex in the extract is determined by photometry at 540 nm.Due to the presence of reducing agents in commercial chromium tanning agents, it is necessary to use the method of standard addit
33、ion to determine the reductive potential. The procedure is repeated by adding different amounts of chromium (VI) to the original solution of the chromium tanning agent.4 ReagentsAll reagents used shall have at least analytical grade purity.4.1 Deionised water, freshly prepared according to ISO 3696,
34、 grade 3.4.2 Phosphoric acid solution, 700 ml o-phosphoric acid ( = 1,71 g/ml1) made up to 1 000 ml with water (4.1).4.3 Chromium (VI) stock solution 1 mg Cr(VI)/ml. Potassium dichromate, (K2Cr2O7), is dried (16 2) h at (102 2) C. Dissolve 2,829 g of the dried potassium dichromate in water into a 1
35、000 ml volumetric flask and make up to the mark with water (4.1).4.4 Chromium (VI) standard solution I 10 g Cr(VI)/ml. Pipette 10 ml of the chromium (VI) stock solution into a 1 000 ml volumetric flask and make up to the mark with water (4.1).4.5 Glacial acetic acid.1) = mass concentrationINTERNATIO
36、NAL STANDARDISO 19071:2016(E)IULTCS/IUC 35:2016(E) ISO 2016 All rights reserved 1BS EN ISO 19071:2016ISO 19071:2016(E)4.6 Diphenylcarbazide solution. Dissolve 1,0 g of 1,5-diphenylcarbazide, CO(NHNHC6H5)2, in 100 ml acetone and make acidic with one drop of glacial acid. The solution may be stored in
37、 a brown flask with stopper (5.3) in a refrigerator at approximately 4 C for one week.4.7 n-Hexanol.4.8 Sodium chloride.4.9 Acetone.5 ApparatusUsual laboratory equipment and, in particular, the following.5.1 Volumetric flasks.5.2 Pipettes.5.3 Brown coloured flask with stopper, 100 ml.5.4 Separation
38、funnel, 100 ml.5.5 Horizontal mechanical shaker, capable of 250 r/min shaking speed.5.6 Analytical balance.5.7 Spectrophotometer, capable of measuring the absorbance at wavelength 540 nm.5.8 Photometric cell, 20 mm path length or any other suitable cell length.6 Sampling and sample preparationThe ch
39、romium tanning agent shall be homogenized carefully prior to the collection of a representative sample.NOTE Solid samples are used in the powdered state, if possible. Otherwise they are to be ground.The analytical solution of the chromium tanning agent shall be used immediately after preparation.7 D
40、etermination of chromium (VI) content using the standard addition procedure7.1 GeneralTanning agents usually have an unknown reductive potential. Therefore, the first added amounts of chromium (VI) have to be sufficiently high. Typical starting amounts for the first steps of standard additions are 6
41、0 g chromium (VI) and 40 g chromium (VI) (4.4).7.2 ProcedureEach concentration level may be prepared separately and without any delay.IULTCS/IUC 35:2016(E)2 ISO 2016 All rights reservedBS EN ISO 19071:2016ISO 19071:2016(E)Weigh 1,000 g 0,001 g of chromium tanning agent for each concentration level (
42、in total at least 4 levels) in separate 50 ml volumetric flasks. Dissolve the tanning agent in a small amount of water (4.1) before adding 60 g, 40 g, 30 g and 20 g chromium (VI) (4.4) and fill up with water to 50 ml.Pipette 25 ml of the obtained solution in a 100 ml separation funnel. Add 0,5 ml of
43、 phosphoric acid solution (4.2) and 0,5 ml of diphenylcarbazide solution (4.6) and shake the funnel several times by hand. After at least 5 min, add approximately 3 g of sodium chloride (to improve the phase separation) and approximately 5 ml of n-hexanol to the separation funnel.Shake the separatio
44、n funnel for an additional 5 min (approximately) at 250 r/min in a horizontal shaker (5.5). Allow the separation funnel to stand for 2 min to 3 min to allow phase separation. Transfer the organic phase into a 25 ml volumetric flask (first extraction).Using the aqueous phase, repeat the extraction wi
45、th approximately 5 ml of fresh n-hexanol as described above after addition of 0,5 ml of the solution of diphenylcarbazide (second extraction).If the extract after a third extraction is not coloured red-purple, the extraction may be terminated. If not, the extraction shall be continued.Make up the or
46、ganic phases collected in the volumetric flask to 25 ml with n-hexanol. Measure the absorbance at 540 nm, 10 min after the end of extraction procedure, using the spectrophotometer (5.7) and the photometric cell (5.8). Use n-hexanol for the photometric cell of the reference beam.The procedure as desc
47、ribed shall be repeated with each concentration level of the added chromium (VI).In the case of chromium tanning agents with an enhanced amount of reducing substances the standard addition has to be carried out with an increased amount of chromium (VI). To avoid dilution effects caused by adding hig
48、h amounts of chromium (VI) stock solution, stock solutions with higher chromium (VI) concentrations shall be used in this case.8 Quality controlThe recovery rate of the control sample 15 g chromium (VI) has to be determined daily. The control sample is prepared according to Clause 7, using water as
49、the matrix.The chromium (VI) content of the calibration control samples is determined using a calibration curve of 5 g, 10 g, 20 g, 25 g and 35 g chromium (VI). The calibration levels are prepared according to Clause 7, using water as the matrix.9 Calculation and expression of the resultsThe absorption values obtained are used to calculate the chromium (VI) content of the chromium tanning agent according to the standard addition procedure.The determined extinction is plotted against the ratio of the added amount of chrom
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