EN ISO 4048:2018

• Abstract:

  This document specifies a method for the determination of the substances in leather which are soluble in dichloromethane. This method is applicable to all types of leather.; Not all fatty and similar substances can be extracted from leather with organic solvents; they may be in part soluble and partly bound to the leather. On the other hand, the solvent can dissolve non-fatty substances, for example sulfur and impregnants, both of which cause difficulty in the determination of the acid value and saponification value of the fat.; This document includes two techniques for extraction of the fatty substances: 1) extraction using the Soxhlet apparatus; and 2) extraction using a pressurized extraction system.; As the extraction is frequently done in conjunction with determination of the free fatty acid content of the leather, a suitable procedure for determination of the free fatty acids extracted by this method is included.; The apparatus and technique described in this method are also suitable for the extraction by solvents other than dichloromethane (although the temperature conditions may need to be varied for high pressure extraction).

• Status: Published
• Publication Date: 17-Jul-2018
• Withdrawal Date: 30-Jan-2019
• ICS: 59.140.30 - Leather and furs
• Technical Committee: CEN/TC 289 - Leather
• Drafting Committee: CEN/TC 289 - Leather
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 18-Jul-2018
• Completion Date: 18-Jul-2018
• Ref Project: SIST EN ISO 4048:2018 - Leather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid content (ISO 4048:2018)

• Replaces: EN ISO 4048:2008 - Leather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid content (ISO 4048:2008)
• Effective Date: 01-Aug-2018
• Refers: ISO 4684:2005 - Leather — Chemical tests — Determination of volatile matter
• Effective Date: 25-Aug-2026
• Refers: ISO 2418:2017 - Leather — Chemical, physical and mechanical and fastness tests — Sampling location
• Effective Date: 09-Feb-2026
• Refers: ISO 4044:2017 - Leather — Chemical tests — Preparation of chemical test samples
• Effective Date: 09-Feb-2026
• Refers: EN 1457-1:2012 - Chimneys - Clay/ceramic flue liners - Part 1: Flue liners operating under dry conditions - Requirements and test methods
• Effective Date: 28-Jan-2026
• Referred By: CEN/TR 15990:2010 - Data Sheets - Footwear Tests Materials and Test Adhesives
• Effective Date: 28-Jan-2026
• Referred By: CEN/TR 15990:2021 - Data sheets - Footwear tests materials and test adhesives
• Effective Date: 28-Jan-2026
• Referred By: EN 420:2003+A1:2009 - Protective gloves - General requirements and test methods
• Effective Date: 28-Jan-2026
• Referred By: EN 16419:2014 - Leather - Chamois leather for cleaning purposes - Classification and requirements
• Effective Date: 28-Jan-2026
• Referred By: EN 17673:2022 - Protective clothing - Protection against heat and flame - Requirements and test methods for garments with integrated smart textiles and non textile elements
• Effective Date: 28-Jan-2026
• Referred By: EN ISO 20863:2004 - Footwear - Test method for stiffeners and toepuffs - Bondability (ISO 20863:2004)
• Effective Date: 28-Jan-2026
• Consolidated By: ISO 4048:2018 - Leather — Chemical tests — Determination of matter soluble in dichloromethane and free fatty acid content
• Effective Date: 12-Feb-2026

Overview

EN ISO 4048:2018 - "Leather - Chemical tests - Determination of matter soluble in dichloromethane and free fatty acid content" is a CEN-adopted ISO method for quantifying substances in leather that are extractable with dichloromethane and for determining the free fatty acid content of those extracts (expressed as oleic acid). The procedure applies to all types of leather and standardizes sample preparation, extraction, solvent handling and calculation of results.

Key topics and technical requirements

• Scope and applicability: Method for determining extractable matter soluble in dichloromethane and the free fatty acid content; applicable to all leather types.
• Sampling and sample prep: Refers to ISO 2418 for sampling location and ISO 4044 for grinding/preparation; samples normally analysed in duplicate.
• Extraction techniques: Two validated options
  • Soxhlet extraction (conventional solvent reflux)
  • Pressurized extraction system (accelerated/pressurized solvent extraction)
    Equipment providing equivalent results is permitted; temperature adjustments may be needed for high‑pressure extraction.
• Reagents and titration: Uses dichloromethane for extraction. Free fatty acids are determined after extraction using a mixed solvent (diethyl ether + 95% ethanol, neutralized) and titration with 0.1 mol/L sodium hydroxide using phenolphthalein (alternatives noted for dark solutions).
• Apparatus and conditions: Analytical balance (0.1 mg), oven at (102 ± 2) °C for drying extracts, desiccator, Soxhlet or pressurized extractor, filter thimbles, pre‑extracted cotton/wool when used.
• Results expression: Calculates mass of matter extractable in dichloromethane and free fatty acid content (as oleic acid). Annexes include comparative sample data and informative repeatability and reproducibility guidance.
• Safety note: Dichloromethane is toxic; handling and disposal instructions must be followed.

Practical applications and users

This standard is used by:

• Leather technologists and analytical chemistry laboratories for quality control and specification testing
• Tanneries and leather product manufacturers to monitor fat-liquor, waxes and non‑fat extractables
• R&D teams assessing finishing, impregnation and ageing effects on leather chemistry
• Regulatory or compliance labs assessing chemical residues and reporting free fatty acid content

Practical benefits:

• Consistent, comparable test results across suppliers and labs
• Basis for product specifications, troubleshooting processing issues (e.g., over‑oiling or impregnants) and assessing material stability

Related standards

• ISO 2418 - Leather - Sampling location
• ISO 4044 - Leather - Preparation of chemical test samples
• ISO 4684 - Leather - Determination of volatile matter
• Supersedes EN ISO 4048:2008

Keywords: EN ISO 4048:2018, dichloromethane extraction, free fatty acid, leather testing, Soxhlet, pressurized extraction, extractable substances.

SLOVENSKI STANDARD
01-oktober-2018
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SIST EN ISO 4048:2008
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Leather - Chemical tests - Determination of matter soluble in dichloromethane and free
fatty acid content (ISO 4048:2018)
Leder - Chemische Prüfungen - Bestimmung der in Dichlormethan löslichen Substanzen
und des freien Fettsäuregehalts (ISO 4048:2018)
Cuir - Essais chimiques - Dosage des matières solubles dans le dichlorométhane et des
acides gras libres (ISO 4048:2018)
Ta slovenski standard je istoveten z: EN ISO 4048:2018
ICS:
59.140.30 Usnje in krzno Leather and furs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 4048
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2018
EUROPÄISCHE NORM
ICS 59.140.30 Supersedes EN ISO 4048:2008
English Version
Leather - Chemical tests - Determination of matter soluble
in dichloromethane and free fatty acid content (ISO
4048:2018)
Cuir - Essais chimiques - Dosage des matières solubles Leder - Chemische Prüfungen - Bestimmung der in
dans le dichlorométhane et des acides gras libres (ISO Dichlormethan löslichen Substanzen und des freien
4048:2018) Fettsäuregehalts (ISO 4048:2018)
This European Standard was approved by CEN on 23 May 2018.

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 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 under 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 Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4048:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 4048:2018) 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 shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2019, and conflicting national standards shall
be withdrawn at the latest by January 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4048:2008.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4048:2018 has been approved by CEN as EN ISO 4048:2018 without any modification.

INTERNATIONAL ISO
STANDARD 4048
IULTCS/IUC 4
Third edition
2018-06
Leather — Chemical tests —
Determination of matter soluble in
dichloromethane and free fatty acid
content
Cuir — Essais chimiques — Dosage des matières solubles dans le
dichlorométhane et des acides gras libres
Reference numbers
ISO 4048:2018(E)
IULTCS/IUC 4:2018(E)
©
ISO 2018
ISO 4048:2018(E)
IULTCS/IUC 4:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 4048:2018(E)
IULTCS/IUC 4:2018(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 2
7 Sampling and preparation of the samples . 3
8 Procedure. 3
8.1 General . 3
8.2 Extraction using the Soxhlet apparatus . 3
8.3 Extraction using a pressurized extraction system . 4
8.4 Determination of free fatty acid content . 4
9 Expression of results . 4
9.1 Calculation of the matter extractable in dichloromethane . 4
9.2 Calculation of the free fatty acid content . 5
10 Test report . 5
Annex A (informative) Comparison of five leather samples . 6
Annex B (informative) Repeatability and reproducibility . 7
Bibliography . 8
ISO 4048:2018(E)
IULTCS/IUC 4:2018(E)
Foreword
ISO (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. Each 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 International 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 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 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 information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html
This document 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, 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 4 published in J. Soc. Leather Tech. Chem., 49, p. 10, 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 advancement of leather science and technology. IULTCS has three Commissions, which
are responsible for establishing international methods for the sampling and the testing of leather.
ISO recognizes IULTCS as an international standardizing body for the preparation of test methods for
leather.
This third edition cancels and replaces the second edition (ISO 4048:2008), which has been technically
revised as follows:
— 5.1 text for dichloromethane has been simplified;
— Clause 7 has been revised to allow analysis of a single sample, for example when too little sample is
available;
— 8.1 has been revised to allow a smaller sample for determining only dichloromethane soluble
substances;
— 8.2.1 and 8.3 have been revised to define a drying time of at least 6 h, and the last paragraph of 8
...