EN ISO 25202:2026

• Abstract:

  This document specifies a method for the determination of free and released glutaraldehyde in leathers, using liquid chromatography (LC).

• Status: Published
• Publication Date: 13-Oct-2026
• ICS: 59.140.30 - Leather and furs
• Technical Committee: CEN/TC 289 - Leather
• Drafting Committee: CEN/TC 289/WG 1 - Chemical test methods
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 14-Oct-2026
• Due Date: 11-Nov-2026
• Completion Date: 14-Oct-2026
• Ref Project: SIST EN ISO 25202:2026 - Leather - Chemical analysis - Determination of glutaraldehyde content (ISO 25202:2026)

• Consolidated By: ISO 25202:2026 - Leather — Chemical analysis — Determination of glutaraldehyde content
• Effective Date: 12-Feb-2026

EN ISO 25202:2026 is a CEN standard for leather chemical analysis. It specifies a liquid chromatography (LC) method for determining free and released glutaraldehyde in leather, which is useful for laboratories, leather manufacturers, and buyers that need a consistent way to measure this substance.

What does EN ISO 25202:2026 specify?

EN ISO 25202:2026 specifies a test method for leather that measures glutaraldehyde by LC after derivatization. The method is aimed at chemical analysis of leather samples, including material taken from finished products when normal sampling is not possible.

The document is organized into scope, normative references, terms and definitions, principle, reagents, apparatus, specimen preparation, procedure, expression of results, and test report. Annex A gives LC operating conditions, and the bibliography points to a related formaldehyde method in leather.

What are the key requirements of EN ISO 25202:2026?

Clause 4 sets out the measurement principle. EN ISO 25202:2026 separates glutaraldehyde from other aldehydes and ketones, reacts the extract with 2,4-dinitrophenylhydrazine (DNPH), and measures the derivative by reversed-phase LC with UV detection at 355 nm. In practice, the lab is not measuring the raw compound directly but a tagged form that can be separated and quantified.

Sample and extraction requirements

Clause 7 requires sampling in line with ISO 2418 and cutting the leather as described in ISO 4044. If sampling from a finished product is not possible, the test report has to record the sampling details. This matters because the result must be traceable to a defined piece of leather.

Clause 8.1 specifies extraction with a detergent solution at 40 °C for a fixed time, followed by immediate filtration and cooling. The leather-to-solution ratio is not to be changed, and extraction and analysis should be done on the same working day. This keeps the result comparable between laboratories.

Derivatization and LC measurement

Clause 8.1.2 requires mixing the filtered extract with acetonitrile, DNPH solution, and water, then allowing the reaction to stand before membrane filtration and LC analysis. For higher glutaraldehyde levels, a smaller aliquot is used. This step converts the analyte into a form that the LC system can separate and detect reliably.

Clause 8.2 requires calibration with six standard solutions and analysis of samples under the same LC conditions. The calibration range is set so the laboratory can build a graph of concentration against peak area. In practice, the lab needs a valid calibration before reporting any sample result.

Calculation and reporting

Clause 9 requires results to be reported in mg/kg to the nearest 0.1 mg/kg, based on the mass of leather tested. The calculation uses the concentration read from the calibration graph, the dilution factor, the test portion mass, and the detergent-solution volume. Clause 10 then requires the report to identify the standard used, the sample, the date, the result, any unusual observations, and any deviations from the procedure.

Annex A gives the LC settings needed to run the method, including the column type, mobile phase program, temperature, wavelength, flow rate, and injection volume. It also notes how to treat the two peaks that can appear for glutaraldehyde-DNPH on a C18 stationary phase.

What terms does EN ISO 25202:2026 define?

EN ISO 25202:2026 uses these key terms and abbreviations in the method:

• Glutaraldehyde - the analyte measured in leather, reported as free and released glutaraldehyde.
• Free glutaraldehyde - glutaraldehyde present in the extract in measurable form before hydrolysis.
• Released glutaraldehyde - glutaraldehyde that is hydrolysed during extraction and then measured with the free portion.
• LC - liquid chromatography, the separation technique used for quantification.
• DNPH - 2,4-dinitrophenylhydrazine, the reagent used to form detectable hydrazones.
• CAS RN - Chemical Abstracts Service Registry Number, the chemical identifier used for reagents and standards.
• Detergent solution - the extraction solution made with sodium dodecylsulfonate or sodium dodecylsulfate.

Who uses EN ISO 25202:2026?

EN ISO 25202:2026 is used by leather testing laboratories, tanneries, quality control teams, and compliance staff. It is also relevant to buyers and technical managers who need test data for leather raw materials or finished goods such as shoes and garments.

The document supports routine chemical testing, specification checks, product verification, and reporting of glutaraldehyde content in mg/kg. Because it includes sampling, extraction, LC analysis, and reporting rules, it is practical for laboratories that need repeatable results.

Which standards are used with EN ISO 25202:2026?

EN ISO 25202:2026 refers to three normative standards:

• ISO 2418 - gives the position and preparation of specimens for leather testing.
• ISO 3696 - specifies the grade of water used for analytical laboratory work.
• ISO 4044 - covers preparation of chemical test samples from leather.

The bibliography also cites ISO 17226-1, a related leather method for determining formaldehyde by HPLC, which helps place this test within the wider set of leather chemical methods.

What does the EN ISO 25202:2026 document contain?

EN ISO 25202:2026 contains a full step-by-step method for extraction, DNPH reaction, LC analysis, calibration, calculation, and reporting. It gives the apparatus list, reagent specifications, specimen preparation guidance, and a worked calculation approach based on calibration data.

Annex A provides a practical LC set-up, including the mobile phase program, separation column, temperature, detection wavelength, and injection volume. The note under Annex A also explains how to handle the double-peak response of glutaraldehyde-DNPH on the stated column type.

SLOVENSKI STANDARD
01-december-2026
Usnje - Kemijska analiza - Ugotavljanje vsebnosti glutaraldehida (ISO 25202:2026)
Leather - Chemical analysis - Determination of glutaraldehyde content (ISO 25202:2026)
Leder - Chemische Analyse - Bestimmung des Glutaraldehydgehalts (ISO 25202:2026)
Cuir - Analyse chimique - Détermination de la teneur en glutaraldéhyde (ISO
25202:2026)
Ta slovenski standard je istoveten z: EN ISO 25202:2026
ICS:
59.140.30 Usnje in krzno Leather and furs
71.040.40 Kemijska analiza Chemical analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 25202
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2026
EUROPÄISCHE NORM
ICS 59.140.30
English Version
Leather - Chemical analysis - Determination of
glutaraldehyde content (ISO 25202:2026)
Cuir - Analyse chimique - Détermination de la teneur Leder - Chemische Analyse - Bestimmung des
en glutaraldéhyde (ISO 25202:2026) Glutaraldehydgehalts (ISO 25202:2026)
This European Standard was approved by CEN on 8 October 2026.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye 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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 25202:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 25202:2026) has been prepared by Technical Committee ISO/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 April 2027, and conflicting national standards shall be
withdrawn at the latest by April 2027.
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.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 25202:2026 has been approved by CEN as EN ISO 25202:2026 without any modification.

International
Standard
ISO
IULTCS
IUC 40
First edition
Leather — Chemical analysis —
2026-10
Determination of glutaraldehyde
content
Cuir — Analyse chimique — Détermination de la teneur en
glutaraldéhyde
Reference numbers
ISO 25202:2026(en)
IULTCS/IUC 40:2026(en) © ISO 2026

ISO 25202:2026(en)
IULTCS/IUC 40:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
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ISO copyright office
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Published in Switzerland
ii
ISO 25202:2026(en)
IULTCS/IUC 40:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Preparation of test specimens . 3
8 Procedure . 3
8.1 Sample processing .3
8.1.1 Extraction .3
8.1.2 Reaction with DNPH .3
8.2 Determination by LC .3
9 Expression of results . 4
9.1 General .4
9.2 Calculation of the glutaraldehyde content .4
9.3 Precision of the test method .4
10 Test report . 4
Annex A (informative) Liquid chromatography conditions. 5
Annex B (informative) Precision: reliability of the method . 6

iii
ISO 25202:2026(en)
IULTCS/IUC 40:2026(en)
Foreword
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