ISO 21135:2024

International
Standard
ISO
IULTCS
IUC 442
First edition
Chemicals for the leather tanning
2024-05
industry — Determination of the
total content of certain bisphenols
Produits chimiques pour l’industrie du tannage du cuir —
Détermination de la teneur totale en certains bisphénols
Reference numbers
IULTCS/IUC 442:2024(en) © ISO 2024

IULTCS/IUC 442:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
IULTCS/IUC 442:2024(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
6 Reagents . 2
7 Sampling and sample preparation . 3
8 Procedure . 4
8.1 Extraction .4
8.2 Instrumental analysis .4
9 Expression of results . 4
9.1 Calculation without internal standard .4
9.2 Calculation with internal standard .5
9.3 Calculation of the results as a sum .5
10 Precision . 5
11 Test report . 5
Annex A (informative) Chromatographic analysis operating parameters for LC-MS/MS . 7
Annex B (informative) Chromatographic analysis operating parameters for LC-MS . 9
Annex C (informative) Chromatographic analysis operating parameters for LC-UV, LC-DAD or
LC-FLD . 10
Annex D (informative) Precision: reliability of the method .11
Bibliography .13

iii
IULTCS/IUC 442:2024(en)
Foreword
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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 testing of leather. ISO recognizes IULTCS as an
international standardizing body for the preparation of test methods for leather.
This document was prepared by the Chemical Test 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, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

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IULTCS/IUC 442:2024(en)
Introduction
This document includes a procedure for analysing certain bisphenols in leather tanning chemicals using
liquid chromatography (LC) equipment. With this analytical method, bisphenol A, bisphenol AF, bisphenol B,
bisphenol F and bisphenol S can be determined.
In the leather industry, bisphenol F can be an impurity in synthetic tanning agents. Bisphenol S is a monomer
that is used to manufacture synthetic tanning agents, which can lead to residues in the final product.
Bisphenol A is a synthetic organic chemical primarily used as a monomer in the manufacture of high-
performance plastics, other polymers, such as resins, and in the colour developer for thermoprint paper.
Bisphenol AF is a fluorinated organic compound that is an analogue of bisphenol A in which the two methyl
groups are replaced with trifluoromethyl groups. Bisphenol B is similar to bisphenol A and is used in the
manufacture of plastics and resins.
At present, the official European Chemicals Agency (ECHA) classification recognized in the European Union
(EU) is the following:
[1]
— bisphenol A as toxic to reproduction, skin sensitizer and endocrine disruptor;
[2]
— bisphenol B as endocrine disruptor;
[3]
— bisphenol S as toxic to reproduction and endocrine disruptor.

v
International Standard
IULTCS/IUC 442:2024(en)
Chemicals for the leather tanning industry — Determination
of the total content of certain bisphenols
1 Scope
This document specifies a method for determining the total content (solvent extractable) of the following
bisphenols in chemicals for the leather tanning industry:
— bisphenol A;
— bisphenol AF;
— bisphenol B;
— bisphenol F;
— bisphenol S.
This method requires the use of liquid chromatography (LC) with either a single quadrupole mass
spectrometer (MS), a triple quadrupole mass spectrometer (MS/MS), an ultraviolet (UV) detector, a diode
array detector (DAD) or a fluorescence detector (FLD) to identify and quantify the bisphenols.
NOTE 1 This method can also be used for other bisphenols if they are validated by the laboratory.
NOTE 2 Bisphenol S cannot be detected with FLD.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
The sample of the chemical is extracted in methanol using an ultrasonic bath. Subsequently, an aliquot of the
solution can be directly analysed, using LC-MS, LC-MS/MS or LC with a UV detector (LC-UV), DAD (LC-DAD)
or FLD (LC-FLD).
5 Apparatus
The usual laboratory apparatus and, in particular, the following shall be used:
5.1 Ultrasonic bath, with controllable heating capable of maintaining a temperature of (60 ± 5) °C.

IULTCS/IUC 442:2024(en)
5.2 Glass container with a screw cap, for example volume of 20 ml.
5.3 Suitable syringe membrane filters, for example PTFE with pore size 0,2 µm or PTFE-with pore size
0,45 µm.
5.4 Volumetric flasks, for example volume of 10 ml and 100 ml.
5.5 LC vials, with cap, for example volume of 2 ml.
5.6 Analytical balance, with a resolution of 0,1 mg.
5.7 Pipettes, various sizes, for example volume of 1 ml to 20 ml.
5.8 Instrumental equipment, LC-MS/MS.
5.9 Alternative instrumental equipment, LC-MS, LC-UV, LC-DAD or LC-FLD.
NOTE If two detectors are used, they can be arranged in series on the same LC system.
6 Reagents
If not otherwise specified, analytical reagent grade chemicals shall be used.
® 1)
6.1 Methanol, CAS Registry Number (CAS RN) 67-56-1. For LC-MS/MS it is necessary to have LC-MS
quality. HPLC quality methanol is suitable for LC-UV, LC-DAD or LC-FLD.
6.2 Water, deionised or distilled, ultra-pure quality for LC-MS and LC-MS/MS, HPLC grade for LC-DAD, UV
and FLD.
6.3 Bisphenol A, CAS RN 80-05-7, minimum 98,0 %.
6.4 Bisphenol AF, CAS RN 1478-61-1, minimum 98,0 %.
6.5 Bisphenol B, CAS RN 77-40-7, minimum 98,0 %.
6.6 Bisphenol F, CAS RN 620-92-8, minimum 98,0 %.
6.7 Bisphenol S, CAS RN 80-09-1, minimum 98,0 %.
6.8 Stock solutions of a mix of bisphenol A, AF, B, F and S, ρ = 1 mg/l, 10 mg/l and 50 mg/l.
EXAMPLE 100 mg of each of the respective bisphenols, A (6.3), AF (6.4) B (6.5), F (6.6) and S (6.7), is dissolved in
separate 100 ml volumetric flasks (5.4) with methanol (6.1). Mixed stock solutions are prepared to obtain, respectively,
concentrations of 1 mg/l, 10 mg/l and 50 mg/l in methanol.
6.9 Internal standard, ρ = 50 mg/l.
When using LC-MS or LC-MS/MS, the use of internal standards for each type of bisphenol is highly
recommended to avoid matrix effects.
Examples of suitable mass-labelled internal standards: ®
1) Chemical Abstracts Service (CAS) Registry Number is a trademark of the American Chemical Society (ACS). This
information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the
product named. Equivalent products
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