EN ISO 4045-2018 en Leather - Chemical tests - Determination of pH and difference figure.pdf

1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Leather - Chemical tests - Determination of pH and difference figureBS EN ISO 4045:2018National forewordThis British Standard is the UK implementation of EN ISO 4045:2018. It is identical to ISO 4045:2018. It supersedes

2、 BS EN ISO 4045:2008, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee TCI/69, Footwear 5.1 and 6.1 have been revised; Clause 7 has been revised: two samples are only prepared when there is enough leather; 8.1 has been revised to more clearly explain th

3、e procedure; 8.2 has been added (previously part of the next clause); 8.3 and 8.4 (previously 8.2 and 8.3) have been revised and the previous title of 8.4 deleted; Clause 9 b) and d) have been revised.iv ISO 2018 All rights reservedBS EN ISO 4045:2018Leather - Chemical tests - Determination of pH an

4、d difference figure1 ScopeThis document specifies a method for determining the pH value and the difference figure of an aqueous leather extract. It is applicable to all types of leather.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their

5、content constitutes requirements 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 fastness tests Sampling locationIS

6、O 3696, Water for analytical laboratory use Specification and test methodsISO 4044, Leather Chemical tests Preparation of chemical test samples3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IEC maintain terminological databases for use in

7、standardization at the following addresses: ISO Online browsing platform: available at https:/www.iso.org/obp IEC Electropedia: available at http:/www.electropedia.org/3.1difference figuredifference between the pH value of a solution and that of its tenfold dilutionNote 1 to entry: The difference fi

8、gure is a measure of the strength of acids and bases and can never exceed a value of 1. The difference figure amounts to 0,70 to 1,00 when a solution contains a free strong acid (or a free strong base). The ionization of weak acids and bases increases with greater dilution, and therefore the differe

9、nce figure can only act as a criterion for the presence of free strong acid or base in aqueous extracts with pH values below 4 or above 10.4 PrinciplePreparation of an aqueous extract from a test portion of the leather and measurement of the pH of the extract, using a pH meter. In cases where the pH

10、 value obtained is below 4,00 or above 10,00, the pH value of a tenfold dilution of the aqueous extract is also determined.5 Reagents5.1 Water, minimum grade 3 in accordance with ISO 3696.INTERNATIONAL STANDARDISO 4045:2018(E) ISO 2018 All rights reserved 1BS EN ISO 4045:2018ISO 4045:20185.2 Buffer

11、solution, for calibrating the electrode system.It is preferable to purchase a commercially available standard buffer solution for measurement as recommended by the pH meter manufacturer. The length of time for which buffer solutions will keep depends on their composition and the method of use. Contr

12、ol of the accuracy of the buffer solution is therefore indispensable. Used buffer solution shall be discarded.6 Apparatus6.1 Suitable shaker, rotating shaker with a frequency of (50 10) r/min or other suitable shaker after validation.6.2 pH meter, with glass electrode, with a measuring range of 0 pH

13、 units to 14 pH units, graduated in 0,01 pH units. The electrode system shall be calibrated prior to each series of measurements against the buffer solution (5.2).Aqueous extracts of heavily fat-liquored leather may in time make the electrode membrane dirty. In such cases, the membrane shall be ligh

14、tly rubbed with a piece of cotton wool dipped in acetone or the electrode should be suspended in a 1:1 water:acetone mixture. After cleaning, the membrane should again be thoroughly soaked in water.6.3 Analytical balance, capable of weighing to an accuracy of 0,01 g.6.4 Wide mouthed flask, with leak

15、-proof stopper, capacity 250 ml.6.5 Measuring cylinder, capacity 100 ml, graduated in 1 ml divisions.6.6 Volumetric flask, capacity 100 ml.6.7 Pipette, capacity 10 ml.7 Sampling and preparation of the samplesSample in accordance with ISO 2418. If sampling in accordance with ISO 2418 is not possible,

16、 then details about sampling shall be given in the test report. Prepare the leather sample in accordance with ISO 4044.Samples should be analysed in duplicate, if it is possible.8 Procedure8.1 Preparation of the extractWeigh (5,0 0,1) g of the test sample into the wide-mouthed flask (6.4) and using

17、the measuring cylinder (6.5) add (100 1) ml of water (5.1) at (20 2) C. Shake well by hand for about 30 s so that the test portion is uniformly wet. Shake mechanically in the shaker (6.1) for between 6,0 h and 6,5 h. Allow the extract to settle. Decant and take the liquid phase for pH measurement, e

18、nsuring that there are no suspended solids.If difficulty is experienced in decanting the extract from the slurry, it may be strained through a clean, dry, non-absorbent mesh (for example, nylon cloth or a coarse sintered glass filter) or centrifuged.2 ISO 2018 All rights reservedBS EN ISO 4045:2018I

19、SO 4045:20188.2 Calibration of the pH meterCalibrate the pH meter with a minimum of two buffer solutions: at least one below the expected value and at least one above the expected value. Both these buffer readings shall be within 0,02 pH units of the correct reading when the pH meter is standardized

20、.8.3 Determination of the pH valueEnsure that the extract (8.1) is at (20 2) C. Immediately after stirring, immerse the electrode in the extract solution and determine the pH value with the pH meter (6.2), to the nearest 0,05 pH unit, as soon as a steady reading has been reached. The reading should

21、be taken within 30 s to 60 s.The result of the pH value is either the mean value of the two individual determinations, or the value for a single sample.The figures shall be given to the nearest 0,05 pH unit.8.4 Determination of the difference figureIf the pH value is below 4,00 or over 10,00, the di

22、fference figure shall be determined, except if precluded by the client or specification. For this determination, using the pipette (6.7), transfer 10 ml of the extract solution into the volumetric flask (6.6) and fill up to the mark with water (5.1). Rinse the electrodes with approximately 20 ml of

23、the diluted solution and then measure the pH value, as in 8.3.The result of the difference figure value is either the mean value of the two individual determinations, or the value for a single sample.The figures shall be given to the nearest 0,05 pH unit.The difference figure is calculated by subtra

24、cting the pH value obtained in 8.4 from that obtained in 8.3. The difference figure result is quoted to the nearest 0,05 pH unit.9 Test reportThe test report shall include the following:a) a reference to this document (i.e. ISO 4045);b) a description of the sample;c) a reference to any instability o

25、f the pH reading of the extract which prevents an unequivocal statement of the pH value or difference figure;d) pH and, if requested, difference figures as measured in 8.3 and 8.4;e) details of any deviations from the prescribed test conditions. ISO 2018 All rights reserved 3BS EN ISO 4045:2018This

26、page deliberately left blankBSI is the national body responsible for preparing British Standards and other standards-related publications, information and services.BSI is incorporated by Royal Charter. British Standards and other standardization products are published by BSI Standards Limited.Britis

27、h Standards Institution (BSI)About usWe bring together business, industry, government, consumers, innovators and others to shape their combined experience and expertise into standards -based solutions.The knowledge embodied in our standards has been carefully assembled in a dependable format and ref

28、ined through our open consultation process. Organizations of all sizes and across all sectors choose standards to help them achieve their goals.Information on standardsWe can provide you with the knowledge that your organization needs to succeed. Find out more about British Standards by visiting our

29、 website at or contacting our Customer Services team or Knowledge Centre.Buying standardsYou can buy and download PDF versions of BSI publications, including British and adopted European and international standards, through our website at where hard copies can also be purchased.If you need interna

30、tional and foreign standards from other Standards Development Organizations, hard copies can be ordered from our Customer Services team.Copyright in BSI publicationsAll the content in BSI publications, including British Standards, is the property of and copyrighted by BSI or some person or entity th

31、at owns copyright in the information used (such as the international standardization bodies) and has formally licensed such information to BSI for commercial publication and use.Save for the provisions below, you may not transfer, share or disseminate any portion of the standard to any other person.

32、 You may not adapt, distribute, commercially exploit, or publicly display the standard or any portion thereof in any manner whatsoever without BSIs prior written consent.Storing and using standardsStandards purchased in soft copy format: A British Standard purchased in soft copy format is licensed t

33、o a sole named user for personal or internal company use only. The standard may be stored on more than 1 device provided that it is accessible by the sole named user only and that only 1 copy is accessed at any one time. A single paper copy may be printed for personal or internal company use only. S

34、tandards purchased in hard copy format: A British Standard purchased in hard copy format is for personal or internal company use only. It may not be further reproduced in any format to create an additional copy. This includes scanning of the document.If you need more than 1 copy of the document, or

35、if you wish to share the document on an internal network, you can save money by choosing a subscription product (see Subscriptions).Reproducing extractsFor permission to reproduce content from BSI publications contact the BSI Copyright & Licensing team.SubscriptionsOur range of subscription services

36、 are designed to make using standards easier for you. For further information on our subscription products go to British Standards Online (BSOL) youll have instant access to over 55,000 British and adopted European and international standards from your desktop. Its available 24/7 and is refreshed d

37、aily so youll always be up to date.You can keep in touch with standards developments and receive substantial discounts on the purchase price of standards, both in single copy and subscription format, by becoming a BSI Subscribing Member.PLUS is an updating service exclusive to BSI Subscribing Member

38、s. You will automatically receive the latest hard copy of your standards when theyre revised or replaced.To find out more about becoming a BSI Subscribing Member and the benefits of membership, please visit a Multi-User Network Licence (MUNL) you are able to host standards publications on your intr

39、anet. Licences can cover as few or as many users as you wish. With updates supplied as soon as theyre available, you can be sure your documentation is current. For further information, email .RevisionsOur British Standards and other publications are updated by amendment or revision. We continually i

40、mprove the quality of our products and services to benefit your business. If you find an inaccuracy or ambiguity within a British Standard or other BSI publication please inform the Knowledge Centre.Useful ContactsCustomer ServicesTel: +44 345 086 9001Email (orders): Email (enquiries): SubscriptionsTel: +44 345 086 9001Email: Knowledge CentreTel: +44 20 8996 7004Email: Copyright & LicensingTel: +44 20 8996 7070Email: BSI Group Headquarters389 Chiswick High Road London W4 4AL UKNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW