prEN 717-1
(Main)Wood-based panels - Determination of formaldehyde release - Part 1: Formaldehyde emission by the chamber method
Wood-based panels - Determination of formaldehyde release - Part 1: Formaldehyde emission by the chamber method
This document specifies a chamber method with three options of test chambers for the determination of the formaldehyde emission from wood-based panels in terms of the steady-state concentration in a climate chamber under defined conditions, which relate to typical conditions in real-life. This chamber method can also be applied to the estimation of formaldehyde concentrations under various conditions in practice, by the use of mathematical models.
This document can also be used for the testing of formaldehyde emissions of products other than wood-based panels.
Holzwerkstoffe - Bestimmung der Formaldehydabgabe - Teil 1: Formaldehydabgabe nach der Prüfkammer-Methode
Diese Europäische Norm legt ein Verfahren für die Bestimmung der Formaldehydabgabe von Holzwerkstoffen fest, mittels der Ausgleichskonzentration in einer Klimakammer unter definierten, praxisnahen Bedingungen. Als Optionen werden drei Prüfkammertypen beschrieben. Diese Prüfkammermethode erlaubt auch die Schätzung von Formaldehydkonzentrationen unter verschiedenen Praxisbedingungen mittels mathematischer Modelle.
Dieses Dokument kann außerdem zur Prüfung der Formaldehydabgabe bei anderen Erzeugnissen als Holzwerkstoffen verwendet werden.
Panneaux à base de bois - Détermination du dégagement de formaldéhyde - Partie 1 : Emission de for-maldéhyde par la méthode à la chambre
Le présent document spécifie une méthode à la chambre avec trois options de chambre d’essai pour la détermination de l’émission de formaldéhyde des panneaux à base de bois à une concentration à l’état stable dans une chambre climatisée dans des conditions définies qui se rapportent à des conditions moyennes représentatives de la réalité courante. Cette méthode à la chambre peut aussi être appliquée pour l’estimation des concentrations de formaldéhyde dans différentes conditions de la pratique, ceci par utilisation de modèles mathématiques.
Le présent document peut être également utilisé pour soumettre à essai des dégagements de formaldéhyde de produits autres que les panneaux à base de bois.
Lesne plošče - Ugotavljanje sproščanja formaldehida - 1. del: Sproščanje formaldehida po komorni metodi
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-februar-2026
Lesne plošče - Ugotavljanje sproščanja formaldehida - 1. del: Sproščanje
formaldehida po komorni metodi
Wood-based panels - Determination of formaldehyde release - Part 1: Formaldehyde
emission by the chamber method
Holzwerkstoffe - Bestimmung der Formaldehydabgabe - Teil 1: Formaldehydabgabe
nach der Prüfkammer-Methode
Panneaux à base de bois - Détermination du dégagement de formaldéhyde - Partie 1 :
Emission de for-maldéhyde par la méthode à la chambre
Ta slovenski standard je istoveten z: prEN 717-1
ICS:
79.060.01 Lesne plošče na splošno Wood-based panels in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2025
ICS 79.060.01 Will supersede EN 717-1:2004
English Version
Wood-based panels - Determination of formaldehyde
release - Part 1: Formaldehyde emission by the chamber
method
Panneaux à base de bois - Détermination du Holzwerkstoffe - Bestimmung der Formaldehydabgabe
dégagement de formaldéhyde - Partie 1 : Emission de - Teil 1: Formaldehydabgabe nach der Prüfkammer-
for-maldéhyde par la méthode à la chambre Methode
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 112.
If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
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. prEN 717-1:2025 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Principle . 7
5 Reagents . 7
5.1 General. 7
5.2 Acetylacetone solution . 7
5.3 Ammonium acetate solution . 7
5.4 Formaldehyde standard solution. 7
6 Apparatus . 8
6.1 Test chamber . 8
6.1.1 General. 8
6.1.2 Test chamber materials . 8
6.1.3 Air-tightness of the chamber . 8
6.1.4 Air circulation in the test chamber . 8
6.1.5 Air exchange facilities . 8
6.1.6 Clean air supply of the test chamber . 8
6.1.7 Temperature and relative humidity regulating systems . 8
6.1.8 Equipment for monitoring of test conditions . 9
6.2 Air sampling system . 9
6.2.1 General. 9
6.2.2 Equipment . 9
6.3 Equipment for chemical analysis . 9
6.4 Equipment for verification of air exchange rate. 10
7 Test pieces . 10
8 Procedure . 10
8.1 Test conditions . 10
8.2 Verification of test conditions . 10
8.2.1 Clean air supply of the test chamber . 10
8.2.2 Air-tightness of the test chamber . 10
8.2.3 Temperature and relative humidity control system . 11
8.2.4 Air exchange . 11
8.2.5 Air velocity in the chamber . 11
8.2.6 Performance of the chamber . 11
8.3 Chamber preparation . 11
8.4 Preparation of test pieces . 12
8.4.1 General. 12
8.4.2 Large chambers (see A.1) . 12
8.4.3 Small chambers (see A.2 and A.3) . 12
8.5 Loading and starting procedure . 12
8.6 Air sampling and analysis . 12
8.7 Test duration . 13
9 Determination of formaldehyde emission . 13
9.1 General . 13
9.2 Principle . 13
9.3 Procedure . 13
9.4 Calibration curve . 13
9.4.1 General . 13
9.4.2 Formaldehyde standard solution . 13
9.4.3 Fomaldehyde calibration solution . 14
9.4.4 Determination of the calibration curve . 14
9.5 Calculation of the amount of absorbed formaldehyde . 14
9.6 Calculation of the formaldehyde emission . 15
10 Determination of the steady-state emission value . 15
11 Expression of results . 15
12 Test report . 16
Annex A (normative) Test chambers . 18
Annex B (normative) Determination of air exchange rate . 25
Annex C (normative) Determination of the steady-state emission value . 27
Annex D (informative) Analytical procedure for the fluorimetric determination of
formaldehyde content . 31
Bibliography . 33
European foreword
This document (prEN 717-1:2025) has been prepared by Technical Committee CEN/TC 112 “Wood-
based panels”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 717-1:2004.
a) analytical procedures according to EN ISO 12460-2 in 9.1 added;
b) expression of test results in Clause 11 changed;
c) document series for determination of formaldehyde in the European foreword updated.
This document is one of a series, which specifies methods for determining formaldehyde potential in or
formaldehyde release from wood-based panels. The other documents of this series are:
— EN ISO 12460-2, Wood-based panels — Determination of formaldehyde release — Part 2: Small-
scale chamber method (ISO 12460-2)
— EN ISO 12460-3, Wood-based panels — Determination of formaldehyde release — Part 3: Gas
analysis method (ISO 12460-3)
— EN ISO 12460-5, Wood-based panels — Determination of formaldehyde release — Part 5: Extraction
method (called the perforator method) (ISO 12460-5)
— EN 717-3, Wood-based panels — Determination of formaldehyde release — Part 3: Formaldehyde
release by the flask method.
This document is based on CEN report CR 213 “Particleboards — Determination of Formaldehyde
Emission under Specified Conditions” and COST Project 613: Indoor Air Quality and its Impact on Man,
Report No. 2: “Formaldehyde emission from wood-based materials: Guideline for the determination of
steady state concentrations in test chambers”.
Introduction
Each testing institute is responsible for the quality of the test procedure. To ensure the reproducibility of
the test results, it is recommended to participate in a round-robin test for calibration at least once a year.
1 Scope
This document specifies a chamber method with three options of test chambers for the determination of
the formaldehyde emission from wood-based panels in terms of the steady-state concentration in a
climate chamber under defined conditions, which relate to typical conditions in real-life. This chamber
method can also be applied to the estimation of formaldehyde concentrations under various conditions
in practice, by the use of mathematical models.
This document can also be used for the testing of formaldehyde emissions of products other than wood-
based panels.
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.
EN 326-1, Wood-based panels - Sampling, cutting and inspection - Part 1: Sampling and cutting of test pieces
and expression of test results
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
volume of the chamber
total air volume of the unloaded chamber, including recirculating ventilation ducts, expressed in cubic
metres (m )
3.2
loading factor
ratio of the total surface area of the test piece, excluding the area of the edges, to the volume of the
2 3
chamber, expressed in square metres per cubic metre (m /m )
3.3
air exchange rate
3 3
quotient of air volume passing through the chamber per hour (m /h) and the chamber volume (m )
3.4
air velocity
velocity of the air near the surface of test pieces in the chamber in metres per second (m/s)
3.5
steady-state
state when the formaldehyde emission of the wood-based panels is quasi constant under the test
conditions, this means that the formaldehyde concentration in the chamber remains constant
Note 1 to entry: In practice, a true steady-state is not achievable because formaldehyde is emitted irreversibly. This
document defines a steady-state condition for the purpose of the test (see Clause 10).
3.6
emission value
the steady-state formaldehyde concentration in the chamber, obtained under constant temperature,
relative humidity, loading factor and air exchange rate, expressed by mass to volume in milligrams
formaldehyde per cubic metre air (mg/m )
Note 1 to entry: At 23 °C and 1 013 hPa, the following relationship exists for formaldehyde:
— 1 ppm (parts per million) = 1,24 mg/m
— 1 mg/m = 0,81 ppm (parts per million)
4 Principle
Test pieces of known surface area, are placed in a chamber, in which the temperature, relative humidity,
air velocity and exchange rate are controlled at defined values. Formaldehyde emitted from the test
pieces mixes with the air in the chamber. The air in the chamber is sampled periodically. The
formaldehyde concentration is determined by drawing air from the chamber through gas washing bottles
containing water, which absorbs the formaldehyde. The formaldehyde concentration in the water is
determined. The concentration of formaldehyde in the chamber atmosphere is calculated from the
concentration in the water in the gas washing bottles and the volume of the sampled air. It is expressed
in milligrams per cubic metre (mg/m ). Sampling is periodically continued until the formaldehyde
concentration in the chamber has reached a steady-state.
NOTE The influences of temperature, relative humidity, loading factor and air exchange rate on the
formaldehyde concentration in the chamber atmosphere can be described by formulas (e.g. Andersen formula). An
interrelation between the structure of the test pieces, especially of their surfaces and the air velocity is also apparent
but cannot be exactly described by a formula.
5 Reagents
5.1 General
Reagents and water of recognised analytical purity shall be used for the analysis.
5.2 Acetylacetone solution
4 ml acetylacetone are added to a 1 000 ml volumetric flask and made up to the mark with water.
5.3 Ammonium acetate solution
200 g ammonium acetate are dissolved in water in a 1 000 ml volumetric flask and made up to the mark.
NOTE Commercially prepared solutions can be used.
5.4 Formaldehyde standard solution
Standard iodine solution c(l ) = 0,05 mol/l
Standard sodium thiosulphate solution c(Na S O ) = 0,1 mol/l
2 2 3
Standard sodium hydroxide solution c(NaOH) = 1 mol/l
Standard sulphuric acid solution c(H SO ) = 1 mol/l
2 4
6 Apparatus
6.1 Test chamber
6.1.1 General
This document applies to different test chambers for formaldehyde emission testing which are described
in Annex A.
General specifications and requirements which apply to all types of test chambers included in this
document are given in 6.1.2 to 6.1.8.
6.1.2 Test chamber materials
Materials used for the inner walls and ducts of test chambers shall have a smooth surface, which, prior to
testing, can be effectively cleaned with water. The surface shall be as inert and non-absorptive as possible
to formaldehyde.
NOTE Proven materials are stainless steel or aluminium (sandblasted or polished), glass and some types of
plastics (PVC, PMMA).
6.1.3 Air-tightness of the chamber
The test chamber shall be air-tight in order to avoid uncontrolled air exchange.
The criteria of air-tightness are given in 8.2.2.
6.1.4 Air circulation in the test chamber
The test chamber shall contain facilities (such as fan systems) capable of maintaining:
— intensive air mixing in the chamber;
— an air velocity of 0,1 m/s to 0,3 m/s at the surface of the test pieces (see 8.2.5).
6.1.5 Air exchange facilities
The test chamber shall contain air inlet and/or outlet facilities capable of regulating the air flow and thus
the rate of air exchange (replacement of chamber air by clean, conditioned air) with an error limit of 5 %
at an air exchange rate of 1/h.
Precautions shall be taken to ensure that the clean air inlet and the air circulation system are adequately
placed to ensure sufficient mixing and that ambient air cannot enter into the air outlet, even during
sampling.
6.1.6 Clean air supply of the test chamber
Equipment capable of providing clean air with a maximum formaldehyde content of 0,006 mg/m
(0,005 ppm).
6.1.7 Temperature and relative humidity regulating systems
Equipment capable of maintaining the temperature and the relative humidity in the test chamber within
the following limits:
— Temperature: (23 ± 0,5) °C
— Relative humidity: (45 ± 3) %
6.1.8 Equipment for monitoring of test conditions
Measuring equipment and recording facilities capable of continuous or frequent monitoring of the
specified test conditions with an error limit as follows:
— Temperature: 0,1 °C
— Relative humidity: 1 %
— Air exchange rate: 0,03/h
— Air velocity: 0,05 m/s
6.2 Air sampling system
6.2.1 General
Figure 1 shows the principle of a sampling system for the determination of the formaldehyde
concentration in the chamber air. The sampling tube shall be placed either in the air outlet, or inside the
chamber, close to the air outlet.
NOTE Other sampling systems can be used, provided it can be shown that they give equivalent results.
6.2.2 Equipment
6.2.2.1 General
The air sampling system consists of the following components which are given in Figure 1. The numbers
in brackets refer to the numbers in Figure 1:
6.2.2.2 Sampling tube (1).
6.2.2.3 Two 100 ml gas washing bottles, containing water, for absorption and subsequent
determination of formaldehyde (2).
6.2.2.4 Silica absorber for drying the air (3).
6.2.2.5 Gas flow valve (4).
6.2.2.6 Gas sampling pump (5).
6.2.2.7 Gas flow meter (6).
6.2.2.8 Gas meter (including a thermometer) for measuring the volume of air (7).
6.2.2.9 Air pressure meter (8).
6.3 Equipment for chemical analysis
6.3.1 Spectrophotometer, suitable for use with cells with a path-length of at least 50 mm and capable
of measuring absorbance at 412 nm.
6.3.2 Water bath, capable of maintaining a temperature of (40 ± 1) °C.
6.3.3 Six volumetric flasks, 100 ml (calibrated at 20 °C).
6.3.4 Two volumetric flasks, 1 000 ml (calibrated at 20 °C).
6.3.5 Bulb pipettes, 5 ml, 10 ml, 15 ml, 20 ml, 25 ml, 50 ml, and 100 ml (calibrated at 20 °C).
6.3.6 Microburette.
6.3.7 At least three flasks, 50 ml, with stoppers.
6.3.8 Balance, scale interval 0,001 g.
6.4 Equipment for verification of air exchange rate
6.4.1 Compressed-gas cylinder with tracer-gas.
6.4.2 Detector for continuous monitoring of tracer-gas.
6.4.3 Recorder.
NOTE Dinitrogen monoxide (N O) with infrared (IR) detection has proved to be suitable.
7 Test pieces
Sample the test pieces according to the general principles of EN 326-1 and cut them to a size which
2 3
corresponds to a total loading rate of 1 m /m (see Annex A). Wrap the test pieces hermetically
immediately after cutting and leave them wrapped until the start of the test.
8 Procedure
8.1 Test conditions
The following conditions shall be maintained in the chamber throughout the test:
— Temperature (23 ± 0,5) °C;
— Relative humidity (45 ± 3) %;
2 3
— Loading factor (1,0 ± 0,02) m /m ;
— Air exchange rate (1,0 ± 0,05)/h;
— Air velocity at the surface of the test pieces (see 8.2.5) (0,1 to 0,3) m/s.
8.2 Verification of test conditions
8.2.1 Clean air supply of the test chamber
When determined in accordance with Clause 9, the formaldehyde content of the air supplied to the
chamber shall not exceed 0,006 mg/m (0,005 ppm).
8.2.2 Air-tightness of the test chamber
In order to avoid uncontrolled air exchange by intrusion of ambient air, the test chamber shall be
operated at a slight over-pressure.
Air-tightness shall be checked regularly, either by pressure drop measurements or by comparison of
simultaneous measurement of flow rates at the inlet and the outlet ports, or by measuring tracer gas
dilution.
The test chamber is considered sufficiently air-tight if at least one of the following requirements is
fulfilled:
− 2
— the air leakage is less than 10 × chamber volume per minute at an overpressure of 1 000 Pa;
— the inlet and outlet air flow differ by less than 2 %;
— the tracer gas dilution is less than 0,05/h.
8.2.3 Temperature and relative humidity control system
The temperature shall be controlled either by placing the test chamber within a location controlled to the
appropriate temperature, or by controlling the temperature within the chamber.
In the latter case, the chamber walls shall be insulated effectively to avoid condensation of moisture on
their inner surface.
Control of relative humidity shall be made either by external humidity control of the clean air supply, or
internal humidity control of the air within the chamber. In the latter case, precautions shall be taken to
avoid condensation, or spray of water, inside the chamber.
Temperature and relative humidity shall be monitored either continuously, or frequently, and
independently of the air conditioning system. Sensors shall be placed in a representative position inside
the chamber.
After loading the chamber, any initial deviations of temperature and relative humidity due to ambient air
and unconditioned test pieces shall be recorded.
8.2.4 Air exchange
The clean and conditioned air supply to the chamber shall either be monitored continuously, or
frequently. Suitable methods are specified in Annex A.
The air exchange rate shall not vary by more than 0,05 exchanges of air per hour.
The effective air exchange rate shall be regularly checked, by using either a calibrated gas meter, or the
tracer gas procedure described in Annex B.
8.2.5 Air velocity in the chamber
Prior to testing, the air velocity in the test chamber loaded with test pieces shall be set to a value between
0,1 m/s and 0,3 m/s, measured at representative positions not more than 20 mm from the surface of the
test pieces.
NOTE Hot wire or film anemometers calibrated in the range of 0 m/s to 0,5 m/s are suitable for air velocity
measurement.
The positions of the measuring points depend upon the volume of chamber and the type of air flow.
Air velocity shall be measured at a minimum of 4 positions in large chambers (≥ 12 m ) and at a minimum
3 3
of 2 positions in small chambers (1 m or 0,225 m ).
8.2.6 Performance of the chamber
The performance of the test chamber can be tested by a procedure described by [7].
8.3 Chamber preparation
Set the chamber to the conditions given in 8.1. The determination (see 8.6) of the formaldehyde
concentration in the empty chamber (“background-level”) shall be carried out not less than 1 h after
establishing the test conditions according to 8.1.
If the formaldehyde concentration in the chamber atmosphere is 0,006 mg/m or lower, the chamber can
be loaded with the test pieces.
If the formaldehyde concentration is higher than 0,006 mg/m , the chamber shall be purged by running
empty to reduce the formaldehyde concentration to the accepted background level of 0,006 mg/m . If
necessary, dust and other particles from the bottom shall be removed and the walls and other interior
surfaces of the chamber shall be cleaned before starting the air cleaning procedure.
8.4 Preparation of test pieces
8.4.1 General
Unwrap the test pieces, seal the edges if necessary and place the test pieces in the chamber. The ratio of
the length of open (unsealed) edges U related to the surface area A shall be U/A = 1,5 m/m .
NOTE As a result of the constant ratio U/A = 1,5 m/m the percentage of open edges area related to the surface
area depends on the thickness of the test piece, as shown in the following examples:
Panel thickness Ratio of the open edge area to total surface
area
10 mm 1,5 %
19 mm 2,8 %
32 mm 4,8 %
8.4.2 Large chambers (see A.1)
Edge sealing shall not be done for the 1 m × 2 m test pieces tested in large chambers (≥ 12 m ). The
perimeter, i. e the length of open (unsealed) edges U for 1 m × 2 m pieces is 6 m and the surface area A is
2 2
4 m . Thus the ratio of U/A is 1,5 m/m .
8.4.3 Small chambers (see A.2 and A.3)
In order to obtain the same ratio of U/A = 1,5 m/m for smaller test pieces in small chambers, partial edge
sealing is necessary. This sealing should be done using self-adhesive aluminium tape.
3 3
NOTE The length of edges to be sealed is given in A.2.3 for 1 m chambers and in A.3.3 for 0,225 m chambers.
8.5 Loading and starting procedure
Place the test pieces in the test chamber. They shall be vertical and approximately in the centre of the
chamber, with their surfaces parallel to the direction of the air flow and separated by not less than
200 mm (see Figures A.1 to A.5 and A.7). The first air sampling shall be made not less than 3 h after
loading the chamber and starting the test procedure.
8.6 Air sampling and analysis
Add at least 25 ml of water to each of the two gas washing bottles and connect them to the apparatus (see
6.2 and Figure 1). Sample the air from the chamber periodically by passing a minimum of 120 l, at a rate
of approximately 2 l/min, through the gas washing bottles. Pipette 10 ml of each of the absorption
solutions into a 50 ml flask and add 10 ml acetylacetone solution (see 5.2) and 10 ml of ammonium
acetate solution (see 5.3). Stopper the flasks and determine the formaldehyde content of the solutions
according to Clause 9.
The volume of air to be sampled depends on its formaldehyde concentration. With photometric
determination the procedure described above is suitable for concentrations higher than 0,005 mg/m .
For determination of lower concentrations, the volume of the sampled air should be increased and/or
the volume of the air sample solution reduced. The sensitivity of the analysis can also be increased by
using a fluorimetric determination of the reaction product (diacetyldihydrolutidine) instead of a
photometric determination.
8.7 Test duration
The sampling procedure is repeated twice a day until enough data are available to calculate the steady-
state (see Annex C).
The time interval between the two samplings shall be more than 3 h.
9 Determination of formaldehyde emission
9.1 General
The formaldehyde content of the aqueous solutions from each sampling period shall be determined
photometrically by the acetylacetone method.
NOTE 1 To enhance the sensitivity of the analysis, the formaldehyde content can also be determined
fluorimetrically (procedure see Annex D).
NOTE 2 The determination according to ISO 16000-3 (DNPH) can also be used.
NOTE 3 Analytical procedures as specified in EN ISO 12460-2 for the acetylacetone method, the DNPH method
and the laser absorption method (LAS) can also be used.
9.2 Principle
The determination is based on the Hantzsch reaction in which formaldehyde reacts with ammonium ions
and acetylacetone to yield diacetyldihydrolutidine (DDL) (see Figure 2). DDL has an absorption
maximum at 412 nm. The reaction is specific to formaldehyde.
9.3 Procedure
Heat the stoppered flasks (see 8.6) for 15 min in a water bath at (40 ± 1) °C. The solutions are then stored
at room temperature for 1 h, protected against the influence of light. The absorbance of the sol
...
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