SIST EN ISO 7012-1:2025

Paints and varnishes - Determination of preservatives in water-dilutable coating materials - Part 1: Determination of in-can free formaldehyde (ISO 7012-1:2025)

The method describes the quantitative determination of the concentration of in-can free formaldehyde in water-dilutable coating materials.
Note: The standard can also be applied for polymer dispersions.
The determination method for in-can free formaldehyde can be only of limited suitability for pigmented systems, as the inherent coloration of the material may have an influence on the detection method.

Beschichtungsstoffe - Bestimmung von Konservierungsmitteln in wasserverdünnbaren Beschichtungsstoffen - Teil 1: Bestimmung des freien Formaldehyds im Gebinde (ISO 7012-1:2025)

Dieses Dokument legt die Geräte und analytischen Verfahren zur Bestimmung der Konzentration von freiem Formaldehyd im Gebinde (In can-Formaldehyd) in wasserverdünnbaren Beschichtungsstoffen fest.
Dieses Dokument kann auch auf Polymerdispersionen angewendet werden.
Das in diesem Dokument beschriebene Bestimmungsverfahren A für freien In-can-Formaldehyd ist für Pigment-Systeme nur bedingt geeignet, da die Eigenfärbung des Stoffes einen Einfluss auf den Nachweis haben kann.

Peintures et vernis - Dosage des agents de préservation dans les produits de peinture diluables à l’eau - Partie 1: Dosage du formaldéhyde libre en pot (ISO 7012-1:2025)

Barve in laki - Določanje konzervansov v premazih, topnih v vodi - 1. del: Določanje prostega formaldehida v pločevinki/posodi (ISO 7012-1:2025)

Ta dokument določa napravo in analitične metode za določanje vsebnosti prostega formaldehida v pločevinki/posodi premazov, topnih v vodi.
Ta dokument je mogoče uporabljati tudi za polimerne disperzije.
Metoda A za določanje prostega formaldehida v pločevinki/posodi, opisana v tem dokumentu, je le delno primerna za pigmentirane sisteme, saj lahko obarvanost materiala vpliva na zaznavanje.

General Information

• Status: Published
• Public Enquiry End Date: 01-Jun-2024
• Publication Date: 14-May-2025
• ICS: 87.040 - Paints and varnishes
• Technical Committee: IBLP - Paints and varnishes
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 29-Apr-2025
• Due Date: 04-Jul-2025
• Completion Date: 15-May-2025
• Ref Project: EN ISO 7012-1:2025 - Paints and varnishes - Determination of preservatives in water-dilutable coating materials - Part 1: Determination of in-can free formaldehyde (ISO 7012-1:2025)

Overview

EN ISO 7012-1:2025 - "Paints and varnishes - Determination of preservatives in water-dilutable coating materials - Part 1: Determination of in‑can free formaldehyde" is a CEN-adopted ISO method for the quantitative determination of in‑can free formaldehyde in water‑dilutable coatings. The standard applies to paints, varnishes and polymer dispersions, and is intended for routine laboratory measurement of residual formaldehyde used as or released from preservatives.

Key topics and technical requirements

• Scope and applicability
  • Quantitative measurement of in‑can free formaldehyde in water‑dilutable coating materials; applicable to polymer dispersions.
  • Limited suitability for pigmented systems - intrinsic coloration can interfere with detection.
• Analytical principles
  • Method A: Derivatization with acetylacetone (ACAC) followed by spectral photometric detection.
  • Method B: Derivatization with dinitrophenylhydrazine (DNPH) followed by LC separation and UV/VIS detection.
  • Method C: LC separation with post‑column derivatization (ACAC) and UV/VIS quantification.
• Laboratory setup and reagents
  • Requirements include general extraction apparatus, HPLC/UHPLC systems (for Methods B and C), appropriate columns and vials, post‑column reactor (Method C), and calibrated formaldehyde standards.
  • Reagents listed include formaldehyde stock and working solutions, and optional Carrez clarification reagents.
• Procedure and quality control
  • Detailed steps for sampling, extraction, derivatization, calibration, blank determination and sample measurement.
  • Precision data are addressed via repeatability (r) and reproducibility (R) concepts; the standard specifies how to calculate in‑can free formaldehyde content and perform quality checks.

Applications and users

• Who uses EN ISO 7012-1:2025:
  • Coating manufacturers and formulators verifying preservative content.
  • Quality control and analytical laboratories performing incoming/outgoing product testing.
  • R&D teams assessing preservative dynamics and product stability.
  • Regulatory, compliance and safety personnel monitoring formaldehyde levels for health and labeling requirements.
• Practical uses:
  • Routine QC of water‑dilutable paints, varnishes and polymer dispersions.
  • Stability and shelf‑life studies where monitoring free formaldehyde is required.
  • Verification of supplier claims and batch release testing.

Related standards

• Prepared by ISO/TC 35 “Paints and varnishes” and adopted by CEN as EN ISO 7012-1:2025. Laboratories should align this method with national regulation and other ISO/CEN standards on preservatives, analytical chemistry and safety data where applicable.

Keywords: EN ISO 7012-1:2025, in-can free formaldehyde, paints and varnishes, water-dilutable coating materials, preservative determination, ACAC, DNPH, liquid chromatography, photometric detection.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2025
Barve in laki - Določanje konzervansov v premazih, topnih v vodi - 1. del:
Določanje prostega formaldehida v pločevinki/posodi (ISO 7012-1:2025)
Paints and varnishes - Determination of preservatives in water-dilutable coating
materials - Part 1: Determination of in-can free formaldehyde (ISO 7012-1:2025)
Beschichtungsstoffe - Bestimmung von Konservierungsmitteln in wasserverdünnbaren
Beschichtungsstoffen - Teil 1: Bestimmung des freien Formaldehyds im Gebinde (ISO
7012-1:2025)
Peintures et vernis - Dosage des agents de préservation dans les produits de peinture
diluables à l’eau - Partie 1: Dosage du formaldéhyde libre en pot (ISO 7012-1:2025)
Ta slovenski standard je istoveten z: EN ISO 7012-1:2025
ICS:
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 7012-1
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2025
EUROPÄISCHE NORM
ICS 87.040
English Version
Paints and varnishes - Determination of preservatives in
water-dilutable coating materials - Part 1: Determination
of in-can free formaldehyde (ISO 7012-1:2025)
Peintures et vernis - Dosage des agents de préservation Beschichtungsstoffe - Bestimmung von
dans les produits de peinture diluables à l'eau - Partie Konservierungsmitteln in wasserverdünnbaren
1: Dosage du formaldéhyde libre en pot (ISO 7012- Beschichtungsstoffen - Teil 1: Bestimmung des freien
1:2025) Formaldehyds im Gebinde (ISO 7012-1:2025)
This European Standard was approved by CEN on 27 March 2025.

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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7012-1:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 7012-1:2025) has been prepared by Technical Committee ISO/TC 35 "Paints
and varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” the
secretariat of which is held by DIN.
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 October 2025, and conflicting national standards shall
be withdrawn at the latest by October 2025.
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 7012-1:2025 has been approved by CEN as EN ISO 7012-1:2025 without any
modification.
International
Standard
ISO 7012-1
First edition
Paints and varnishes —
2025-04
Determination of preservatives in
water-dilutable coating materials —
Part 1:
Determination of in-can free
formaldehyde
Peintures et vernis — Dosage des agents de préservation dans les
produits de peinture diluables à l’eau —
Partie 1: Dosage du formaldéhyde libre en pot
Reference number
ISO 7012-1:2025(en) © ISO 2025

ISO 7012-1:2025(en)
© ISO 2025
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]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 7012-1:2025(en)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
4.1 General .3
4.2 Equilibria of in-can free formaldehyde in the coating matrix .3
4.3 Equilibria of in-can free formaldehyde during extraction .3
4.4 Equilibria of in-can free formaldehyde during derivatization .3
4.5 Principle of Method A: Derivatization with acetylacetone (ACAC) combined with
photometric detection .3
4.5.1 Derivatization with ACAC.3
4.5.2 Detection and quantification with a spectral photometer .4
4.6 Principle of Method B: Derivatization with dinitrophenylhydrazine (DNPH) combined
with liquid chromatography (LC) separation and UV/VIS detection .4
4.6.1 Derivatization with DNPH .4
4.6.2 Separation, detection and quantification with LC-UV/VIS .4
4.7 Principle of Method C: Liquid chromatography (LC) separation followed by post-
column derivatization with ACAC and subsequent quantification with UV/VIS detection .4
4.7.1 Separation of free formaldehyde by liquid chromatography .4
4.7.2 Post-column derivatization with acetylacetone (ACAC) and quantification with
UV/VIS detection .4
5 Apparatus . 4
5.1 General .4
5.2 General apparatus .4
5.3 Apparatus for extraction .4
5.4 Apparatus for method A .5
5.5 Apparatus for method B .5
5.5.1 LC [HPLC or ultra-performance liquid chromatography (UHPLC)] system .5
5.5.2 Appropriate column .5
5.5.3 Vials .5
5.6 Apparatus for method C .6
5.6.1 LC [HPLC or ultra-performance liquid chromatography (UHPLC)] system with
post-column reactor .6
5.6.2 Appropriate column (e.g. RPC8, RPC18 column) .6
6 Reagents and materials . 6
6.1 General .6
6.2 General reagents .6
6.2.1 Demineralized water .6
6.2.2 Formaldehyde solution .6
6.2.3 Formaldehyde stock solution .6
6.2.4 Formaldehyde working solutions for calibration .6
6.2.5 Carrez solutions (optional) .7
6.3 Method A: Reagents for derivatization with ACAC .7
6.4 Method B: Reagents for derivatization with DNPH .7
6.5 Method C: Reagents for post-column derivatization with ACAC .7
6.6 Reagents for titration of formaldehyde standard .8
7 Procedure . 8
7.1 Sampling .8
7.2 Extraction .8
7.3 Analysis and detection of Method A .9
7.3.1 Procedure for derivatization with ACAC .9
7.3.2 Photometric analysis of calibration solutions .9

iii
ISO 7012-1:2025(en)
7.3.3 Sample measurement for photometric analysis .10
7.3.4 Quantification of the in-can free formaldehyde content .10
7.4 Analysis and detection of Method B .10
7.4.1 Procedure for derivatization with DNPH .10
7.4.2 Operation conditions .11
7.4.3 Blank determination .11
7.4.4 Analysis of calibration solution .11
7.4.5 Sample measurement .11
7.4.6 Quality check . 12
7.4.7 Calculation of in-can free formaldehyde content . 12
7.5 Analysis and detection of Method C . 12
7.5.1 Operation conditions . 12
7.5.2 Blank determination . 12
7.5.3 Analysis of calibration solution . 12
7.5.4 Sample measurement . 13
7.5.5 Quality check . 13
7.5.6 Calculation of in-can free formaldehyde content . 13
8 Precision . 14
8.1 General .14
8.2 Repeatability limit, r . .14
8.3 Reproducibility limit, R .14
9 Test report . 14
Annex A (normative) Titration methods for the determination of formaldehyde content.16
Annex B (informative) Example of HPLC conditions for method B .18
Annex C (informative) Example of HPLC conditions for method C . 19
Annex D (informative) Results of the interlaboratory test .20
Bibliography .21

iv
ISO 7012-1:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 16,
Chemical analysis, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 139, Paints and varnishes, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 7012 series can be found on the ISO website.
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.

v
International Standard ISO 7012-1:2025(en)
Paints and varnishes — Determination of preservatives in
water-dilutable coating materials —
Part 1:
Determination of in-can free formaldehyde
1 Scope
This document specifies the apparatus and analytical methods for determining the concentration of in-can
free formaldehyde in water-dilutable coating materials.
This document can also be applied to polymer dispersions.
The determination method A for in-can free formaldehyde described in this document is only of limited
suitability for pigmented systems, as the inherent coloration of the material can have an influence on the
detection.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their 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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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/
3.1
ready for use
state of a product when it is mixed in accordance with the manufacturer’s instructions in the correct
proportions and thinned if required using the correct thinners so that it is ready for application by the
approved method
[SOURCE: ISO 11890-2:2020, 3.7]
3.2
in-can free formaldehyde content
concentration of formaldehyde which is available in the coating as an in-can preservative (3.9) as determined by:
— method A of this document, i.e. photometric detection after derivatization with acetylacetone;

ISO 7012-1:2025(en)
— method B of this document, i.e. liquid chromatography detection after derivatization with DNPH
(2,4-dinitrophenyl-hydrazine); or
— method C of this document i.e. liquid chromatography detection with post-column derivatization with
acetylacetone; where water is used as an extraction solvent for all three methods
Note 1 to entry: In-can free formaldehyde content corresponds to the amount of formaldehyde in milligrams, based
on 1 kg of coating material (3.4) or polymer dispersion, which is available unbound in the sample at the time of
derivatization.
Note 2 to entry: Since the free formaldehyde is in equilibrium with bound formaldehyde and the equilibrium can
be influenced by the solvent, the content of free formaldehyde in water can differ from that in another solvent. This
definition for in-can free formaldehyde content is only valid with respect to water as the extraction solvent.
3.3
in-can total formaldehyde content
concentration of free and bound formaldehyde in the coating material (3.4)
3.4
coating material
DEPRECATED: coating
product, in liquid, paste or powder form, that, when applied to a substrate, forms a layer possessing
protective, decorative and/or other specific properties
[SOURCE: ISO 4618:2023, 3.48]
3.5
water-dilutable coating material
water-reducible coating material
water-based coating material
water-borne coating material
water-thinnable coating material
DEPRECATED: water paint
coating material (3.4) whose viscosity is reduced by the addition of water
[SOURCE: ISO 4618:2023, 3.272]
3.6
formaldehyde depot substance
compound that releases formaldehyde over a long period of time
3.7
extinction
attenuation of a light beam traversing a medium through absorption and scattering
Note 1 to entry: Extinction depends on the wavelength of the radiation.
[SOURCE: ISO 13320:2020, 3.1.9]
3.8
preservative
substance that prevents the growth of undesirable microorganisms
[SOURCE: ISO 8124-7:2015, 3.6]
3.9
in-can preservative
biocide used to prevent growth of microorganisms during storage of a stock solution of a coating material
(3.4) or water-based coating material (3.5)
[SOURCE: ISO 4618:2023, 3.141]

ISO 7012-1:2025(en)
4 Principle
4.1 General
This document describes three methods for the determination of in-can free formaldehyde in coating
materials which have been validated to show comparable results for selected samples with respect to their
comparability limits statistically for methods A and B and with a single comparison for method C.
4.2 Equilibria of in-can free formaldehyde in the coating matrix
When a formaldehyde depot substance is added to a coating material, equilibrium is established between
the formaldehyde bound to the formaldehyde depot substance and the in-can free formaldehyde. This
equilibrium depends on the pH value, the coating matrix, the formaldehyde depot substance and the
temperature. Furthermore, in water-dilutable coating materials, there is also equilibrium between the in-can
free formaldehyde and the matrix itself. The in-can free formaldehyde can undergo a variety of equilibrium
reactions, e.g. with water to form a hydrate or with other formaldehyde molecules to form trimers.
A distinction shall be made in a coating material between the in-can total formaldehyde content and the in-
can free formaldehyde content. In this document, the in-can free formaldehyde content is understood to be
the formaldehyde concentration determined by either:
— method A, i.e. derivatization with acetylacetone and subsequent photometric detection and quantification;
— method B, i.e. derivatization with DNPH and subsequent detection and quantification with liquid
chromatography-ultraviolet/visible light detector (LC-UV/VIS) analysis; or
— method C, i.e. liquid chromatography (LC) separation followed by post-column derivatization with
acetylacetone and subsequent quantification with ultraviolet/visible light detector (UV/VIS) detection.
4.3 Equilibria of in-can free formaldehyde during extraction
In addition to the equilibria in the coating matrix mentioned in 4.2, during extraction, the equilibrium of in-
can free formaldehyde is also affected by the extraction solvent.
Depending on the nature of the extraction solvent, the sample/solvent ratio, extraction time and pH value,
the equilibrium of bound and free in-can formaldehyde can be shifted to either side. Therefore, it is crucial
to select the appropriate extraction solvent and extraction conditions.
4.4 Equilibria of in-can free formaldehyde during derivatization
The in-can free formaldehyde in the extract (or after chromatographic separation) is derivatized by
chemical reaction with a derivatizing agent. The reaction is also an equilibrium reaction. To ensure complete
derivatization, an excess of derivatization agent is added.
4.5 Principle of Method A: Derivatization with acetylacetone (ACAC) combined with
photometric detection
4.5.1 Derivatization with ACAC
In order to enable photometric detection of formaldehyde, derivatization shall be carried out. Derivatization
introduces a chromophore after reaction with formaldehyde, which has the property to absorb ultraviolet
(UV) or visible (VIS) light.
The derivatization is performed prior to the photometric analysis (pre-column derivatization).
In-can free formaldehyde is derivatised to 3,5-diacetyl-1,4-dihydrolutidine by using ACAC and ammonium
ions (Hantzsch reaction). The absorption maximum of the compound is at a wavelength of 412 nm.

ISO 7012-1:2025(en)
4.5.2 Detection and quantification with a spectral photometer
A spectral photometer is applied to quantify the formaldehyde-ACAC reaction product, which, in turn, can
be used to calculate the concentration of in-can free formaldehyde in the coating matrix.
4.6 Principle of Method B: Derivatization with dinitrophenylhydrazine (DNPH) combined
with liquid chromatography (LC) separation and UV/VIS detection
4.6.1 Derivatization with DNPH
The in-can free formaldehyde can be derivatized with DNPH leading to the formation of a compound that
can be separated by liquid chromatography and detected with a UV/VIS-detector at 360 nm.
4.6.2 Separation, detection and quantification with LC-UV/VIS
Liquid chromatography is applied to separate the different aldehyde-DNPH reaction products. Subsequent
UV/VIS detection is used to identify and quantify the concentration of the formaldehyde-DNPH reaction
product, which enables the calculation of the in-can free formaldehyde content in the coating sample.
If derivatization with DNPH is used, the determination of in-can free formaldehyde content shall be
performed by LC-UV/VIS analysis, since the reaction with DNPH is also sensitive to other aldehydes, which
can interfere when using a determination with a spectral photometer.
4.7 Principle of Method C: Liquid chromatography (LC) separation followed by post-column
derivatization with ACAC and subsequent quantification with UV/VIS detection
4.7.1 Separation of free formaldehyde by liquid chromatography
Liquid chromatography is performed prior to derivatization. It is applied to separate free formaldehyde
from all other components present in the water extract to avoid interferences in the detection.
4.7.2 Post-column derivatization with acetylacetone (ACAC) and quantification with UV/VIS
detection
To enable detection of the separated formaldehyde, derivatization is performed as described in 4.5.1, in
this case by mixing ACAC to the column outlet. Quantification is done in-line with UV/VIS detection at the
maximum absorption of the formaldehyde ACAC reaction product, i.e. 412 nm.
5 Apparatus
5.1 General
The usual laboratory apparatus and, in particular, the following apparatus stated in 5.2 to 5.6 shall be used.
5.2 General apparatus
5.2.1 Precision scale, capable of weighing to an accuracy of 0,000 1 g.
5.2.2 Suitable volumetric flasks for calibration, with ground-glass stoppers.
5.2.3 Suitable pipettes.
5.3 Apparatus for extraction
5.3.1 Centrifuge, capable of producing a clear supernatant.

ISO 7012-1:2025(en)
NOTE A rotation speed of (5 000 - 20 000) revolutions per minute (r/min) has been found suitable.
5.3.2 Tubes for centrifuge, capable of withstanding the acceleration.
5.3.3 Ultrafiltration centrifuge tubes, if necessary.
5.3.4 Volumetric glassware (flask or graduated cylinder), with a suitable volume and ground-glass
stoppers.
NOTE For standard conditions, often 25 ml glassware is used.
5.3.5 Disposable filter, e.g. with a pore size of 0,2 µm, and syringes.
5.4 Apparatus for method A
5.4.1 Spectral photometer, capable for a wavelength of 412 nm.
5.4.2 Suitable cuvettes.
5.5 Apparatus for method B
5.5.1 LC [HPLC or ultra-performance liquid chromatography (UHPLC)] system
This LC system shall be equipped with:
— a sample injection system,
— a solvent pumping system capable of mixing solvents,
— a sample compartment capable of maintaining the required temperature,
— a temperature-controlled column compartment,
— a UV-VIS detector [or optionally a diode array detector (DAD)],
— a degassing system, and
— data processing software.
An LC system that is capable of performing at the flows, pressures, controlled temperatures, sample volumes,
and other requirements of the standard shall be used.
5.5.2 Appropriate column
Reverse phase C18 particle columns were used to develop this test method. Any column that achieves
adequate resolution may be used. The retention times and order of elution can change depending on the
column used and shall be monitored. An example of an appropriate column is a RPC8 or RPC18 column.
5.5.3 Vials
These vials shall be made of chemically inert material (e.g. glass) and able to be sealed with a suitable cap,
e.g. a septum cap (with a rubber membrane coated with polytetrafluoroethylene) or pre-slit cap.
NOTE A cap is suitable if no interferences appear in the analysis coming from the cap.

ISO 7012-1:2025(en)
5.6 Apparatus for method C
5.6.1 LC [HPLC or ultra-performance liquid chromatography (UHPLC)] system with post-column reactor
Use an LC system as described in 5.5.1, an isocratic solvent delivery system is sufficient. For the post-column
derivatization, a second isocratic pump is required. In addition, a mixing system comprising of a T-piece and
a reaction coil [preferably of stainless steel 1,5 m length, 0,02 inch (about 0,5 mm) I.D.] in a housing that can
be heated to 95 °C shall be used.
5.6.2 Appropriate column (e.g. RPC8, RPC18 column)
Use a C18-type of column that is compatible with 100 % aqueous mobile phase.
6 Reagents and materials
6.1 General
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade.
6.2 General reagents
6.2.1 Demineralized water
Demineralized water shall be of grade 1 in accordance with ISO 3696. Since demineralized water can lead to
microbial contamination, it is recommended to use demineralized water with low microbial contamination
[colony forming units (CFU) < 100], or to test that a microbial contamination of the demineralized water
has no influence on the measurement result. Formaldehyde as a preservative can potentially react with
microorganisms.
6.2.2 Formaldehyde solution
The formaldehyde solution content shall be (30 – 40) % mass fraction.
6.2.3 Formaldehyde stock solution
A stock solution of formaldehyde with a concentration of approximately 1 g/l is prepared by diluting a
suitable amount of a (30 – 40) % mass fraction of formaldehyde solution (6.2.2) with demineralized water;
weigh to the nearest of 0,001 g.
To determine the exact formaldehyde content of the formaldehyde solution or any stock solution diluted from
the original formaldehyde solution, use one of the titration methods as given in Annex A (i.e. the iodometric
method specified in A.1 or the pH-value method specified in A.2).
6.2.4 Formaldehyde working solutions for calibration
Starting from the formaldehyde stock solution (6.2.3), different dilution steps are performed to cover the
working range of the instrument, for example from 0,1 mg/l to 100 mg/l, corresponding to the respective
contents in the product under test of approximately 0,1 mg/kg to 100 mg/kg.
The calibration is carried out by the external standard method.
Prepare calibration solutions for at least five calibration points, including blank point.
NOTE If commercially available certified formaldehyde stock solution is used, calibration solutions are prepared
in volumetric flasks by diluting the stock solution with water.

ISO 7012-1:2025(en)
6.2.5 Carrez solutions (optional)
6.2.5.1 Carrez I solution (optional)
Dissolve 3,6 g of potassium hexacyanoferrate (II) trihydrate in 100 ml of deionized water.
6.2.5.2 Carrez II solution (optional)
Dissolve 7,2 g of zinc sulfate heptahydrate in 100 ml of deionized water.
6.3 Method A: Reagents for derivatization with ACAC
6.3.1 Ammonium acetate, ≥ 99,0 % mass fraction.
6.3.2 ACAC (2,4-pentandione).
6.3.3 Acetic acid, ≥ 99,5 % mass fraction.
6.3.4 Acetylacetone reagent, prepared by weighing 75 g of ammonium acetate (6.3.1) into a 500 ml
volumetric flask, then adding 1 ml of ACAC (6.3.2) and 1,5 ml acetic acid (6.3.3), and filling up to 500 ml with
demineralized water (6.2.1).
NOTE The acetyl acetone reagent is not chemically stable. It can be used for determinations at room temperature
for a maximum of 14 days.
6.4 Method B: Reagents for derivatization with DNPH
6.4.1 DNPH powder.
6.4.2 Acetonitrile.
6.4.3 Citric acid monohydrate.
6.4.4 Sodium citrate tribasic dehydrate.
6.4.5 NaOH, 1 mol/ l.
6.4.6 O-phosphoric acid, 85 % mass fraction.
6.4.7 Citrate buffer solution, 1 mol/l, pH 3, prepared by dissolving 16,8 g of citric acid monohydrate
(6.4.3) and 5,9 g of sodium citrate tribasic dihydrate (6.4.4) in 100 ml of deionized water (6.2.1), and adjusted
to pH 3 with 1 mol/l NaOH (6.4.5) and indicator paper.
6.4.8 DNPH solution, prepared by weighing to the nearest 10 mg, 0,3 g of DNPH (6.4.1) into a 50 ml
volumetric flask (5.3.4), adding a sufficient amount of acetonitrile (6.4.2) to dissolve the DNPH and 0,5 ml
of phosphoric acid (6.4.6). Subsequently, fill up to the mark with acetonitrile and homogenize. The resulting
solution is diluted by a factor of 10 prior to use.
6.5 Method C: Reagents for post-column derivatization with ACAC
6.5.1 Ammoniumacetate, ≥ 99,0 % mass fraction.
6.5.2 ACAC, (2,4-pentandione) ≥ 99,0 % mass fraction.

ISO 7012-1:2025(en)
6.5.3 Acetic acid, ≥ 99,5 % mass fraction.
6.5.4 ACAC post-column reagent, prepared by weighing into a 500 ml volumetric flask (5.3.4) 31 g of
ammonium acetate (6.5.1), adding 2,5 ml of ACAC (6.5.2) and 3,75 ml of acetic acid (6.5.3), filling up to 500 ml
with demineralized water (6.2.1), and mixing thoroughly to completely dissolve.
NOTE The ACAC reagent is not chemically stable. It can be used for determinations at room temperature for a
maximum of 14 days.
6.6 Reagents for titration of formaldehyde standard
6.6.1 General
The following reagents in 6.6.2 and 6.6.3 shall be used to perform the titration of the formaldehyde standard
in order to determine the formaldehyde concentration in accordance with the methods given in Annex A.
6.6.2 Reagents for iodometric method
Reagents used for iodometric method (see A.1) are as follows:
a) Formaldehyde solution, content (30 – 40) % mass fraction
b) Solution of iodine in water, 0,05 mol/l
c) Hydrochloric acid, c(HCl) = 1 mol/l
d) Solution of starch, 1 % mass fraction
e) Solution of sodium thiosulfate in water, c(Na S O ) = 0,1 mol/l
2 2 3
6.6.3 Reagents for pH-value method
Reagents used for pH-value method (see A.2) are as follows:
a) Formaldehyde solution, content (30 – 40) % mass fraction
b) Sodium hydroxide solution water, c(NaOH) = 1 mol/l
c) Hydrochloric acid, c(HCl) = 0,1 mol/l
d) Anhydrous sodium sulfite, ≥ 98 % mass fraction
7 Procedure
7.1 Sampling
Prepare the sample as specified in ISO 1513 for testing in the “ready for use” state.
Take at least duplicate representative samples of the product to be tested (or of each product in the case of a
multi-coat system), as specified in ISO 15528 and prepare each sample for testing.
7.2 Extraction
Weigh, to the nearest of 0,001 g, (2,5 ± 0,3) g of water-dilutable coating material into a volumetric glassware
(5.3.4) of 25 ml. Fill up to 25 ml with demineralized water (6.2.1).
Completely homogenize the sample by either shaking (typically 2 min is sufficient) or mechanical stirring
(typically 10 min is sufficient). The entire mixture or an aliquote is transferred into a centrifuge tube (5.3.2)
no later than 1 h after the previous step. The tube is sealed and centrifuged with an appropriate speed for
at least 20 min to obtain a transparent solution as far as possible. If turbidity occurs, the supernatant can be

ISO 7012-1:2025(en)
filtered through a 0,2 µm disposable filter (5.3.5) before derivatization. Alternatively, use an ultrafiltration
centrifuge tube (5.3.3). If the solution is turbid after filtration and centrifugation, re-weigh the sample and
dilute it with the Carrez solutions (6.2.5) instead of water. The ratio between the two solutions shall be 1:1.
For example, weigh 2,5 g of sample and add 2 ml of Carrez I (6.2.5.1) and 2 ml of Carrez II (6.2.5.2), shake for
15 min to 20 min and centrifuge.
Freezing or centrifugation at low temperature, e.g. from −1 °C to 5 °C, makes the sample easier to filter prior to
derivatization step. This ensures the sample is clear and is particularly useful if the solution remains turbid.
7.3 Analysis and detection of Method A
7.3.1 Procedure for derivatization with ACAC
Mix equal volumes of the extract derived from 7.2 and ACAC reagent (6.3.4). Let the mixture stand at room
...