SIST EN 16339:2025

SLOVENSKI STANDARD
01-junij-2025
Nadomešča:
SIST EN 16339:2013
Zunanji zrak - Metoda za določanje koncentracije dušikovega dioksida z
difuzijskim vzorčenjem
Ambient air - Method for the determination of the concentration of nitrogen dioxide by
diffusive sampling
Außenluft - Bestimmung der Konzentration von Stickstoffdioxid mittels Passivsammler
Air ambiant - Méthode pour la détermination de la concentration du dioxyde d'azote au
moyen d'échantillonneurs par diffusion
Ta slovenski standard je istoveten z: EN 16339:2025
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 16339
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2025
EUROPÄISCHE NORM
ICS 13.040.20 Supersedes EN 16339:2013
English Version
Ambient air - Method for the determination of the
concentration of nitrogen dioxide by diffusive sampling
Air ambiant - Méthode de détermination de la Außenluft - Bestimmung der Konzentration von
concentration en dioxyde d'azote au moyen Stickstoffdioxid mittels Passivsammler
d'échantillonneurs par diffusion
This European Standard was approved by CEN on 24 February 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 16339:2025 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 Description of samplers. 8
4.1 Principle . 8
4.2 Diffusive samplers . 9
4.2.1 Description . 9
4.2.2 Preparation . 9
4.2.3 Storage of samplers before and after sampling . 10
4.2.4 Chemical interferences . 10
4.3 Protective devices . 10
4.3.1 General . 10
4.3.2 Protective shelter . 10
4.3.3 Protective filter . 11
4.4 Instructions for use . 11
5 Analysis. 11
5.1 General . 11
5.2 Colorimetric method . 12
5.2.1 General . 12
5.2.2 Calibration . 12
5.2.3 Extraction . 12
5.2.4 Analysis. 13
5.3 Ion chromatography method . 13
5.3.1 General . 13
5.3.2 Calibration . 13
5.3.3 Extraction . 13
5.3.4 Analysis. 14
6 Calculation of the concentration of nitrogen dioxide . 14
6.1 Diffusive sampling rate . 14
6.2 Mass concentration . 15
6.3 Conversion to standard conditions of temperature and pressure . 16
7 Quality control/quality assurance . 16
8 Measurement strategy . 17
8.1 Calibration of the diffusive sampling rate . 17
8.2 Siting criteria . 18
8.3 Use of replicates . 18
8.4 Exposure. 18
8.5 Co-location sites . 18
8.6 Auxiliary information . 19
9 Performance requirements and measurement uncertainty . 19
10 Report . 19
Annex A (normative) Description of tube-type samplers . 21
Annex B (informative) Description of other samplers . 27
Annex C (informative) Estimation of the diffusive sampling rate of the samplers . 32
Annex D (informative) Measurement uncertainty . 37
Annex E (informative) Reagents and equipment for analysis . 47
Annex F (informative) Validation data of the use of protective devices . 50
Bibliography . 51

European foreword
This document (EN 16339:2025) has been prepared by Technical Committee CEN/TC 264 “Air quality”,
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.
This document will supersede EN 16339:2013.
A list of the significant technical changes compared to EN 16339:2013 can be found in Annex G.
— 4.2 and Annex A: examples of demonstration of equivalence with respect to the reference method
are provided;
— 4.3 and Annex F: protective devices have been described including the advantages over the
conventional design of samplers;
— Annex D: More contemporary data included for the equivalence method determination of the
measurement uncertainty;
— Annex D: Sampling rates have been updated.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations 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.
Introduction
EU Directive 2008/50/EC [1] stipulates that European Union Member States apply measurement
methods for air quality pollutants (fixed measurement, modelling, indicative measurement, objective
estimation) and associated Data Quality Objectives (DQO), depending on concentrations observed in
different situations. Diffusive sampling is most often used as “indicative measurement”. The methodology
described in this document has been developed to ensure the possibility for diffusive sampling to partially
substitute and supplement fixed monitoring (where the reference method being that described in
EN 14211 [2] is used) as a tool for the assessment of nitrogen dioxide (NO ) with corresponding DQO.
Instead of the reference method, users may employ any other method which has been demonstrated to
be equivalent according to the Guide for the Demonstration of Equivalence (GDE) [3]
Diffusive sampling is an attractive alternative to fixed monitoring by reference methodology (described
in EN 14211) for the measurement of NO . This is due to:
— small size of diffusive samplers;
— no requirement for electric power;
— potential for covering areas with a high spatial density;
— cost effectiveness.
Consequently, diffusive samplers can partially substitute and supplement fixed monitoring as a means
for the assessment of air quality, provided that they fulfil the specific DQO given in [1].
Passive samplers can be used for indicative measurements to complement air quality networks, improve
modelling techniques and other air quality assessments, such as NO concentrations for comparing with
UNECE Critical Levels (annual mean of 30 µg NO /m , expressed as a NO equivalent) for the protection
x 2
of vegetation and natural ecosystems [4] [5] [6].
A demonstration of equivalence according to [3] has been performed by the North Rhein-Westphalia
state agency for nature, environment and consumer protection (LANUV) [7]. Some studies have
compared NO annual average concentrations measured by chemiluminescence and by diffusive
samplers [8], [9], [10] and [11]. These have shown the potential of diffusive sampling to meet the data
quality objective of 15 % expanded uncertainty for fixed measurements [1].
The methodology described in this document can be applied to obtain air quality information with a
relatively high spatial density that can be used to complement the appropriate siting of fixed monitoring
stations, or in the validation of dispersion models.
This document has been prepared based on the findings of reviews of implemented diffusive samplers in
the European Union [12].
The methodology described in this document may also be used to determine NO in indoor air.
Appropriate strategies for NO measurement in indoor air are described in EN ISO 16000-15 [13].
1 Scope
This document specifies a method for the sampling of NO in ambient air using diffusive sampling
followed by extraction and analysis by colourimetry or ion chromatography (IC). It can be used for the
NO measurement in a concentration range of approximately 3 µg/m to 130 µg/m [12]. A sample is
typically collected for a period of 1 to 4 weeks [14], with exposure periods depending on the design of
the samplers and the concentration levels of NO .
Several sorbents can be used for trapping NO in ambient air using a diffusive sampler [15]. This
document specifies the application of triethanolamine as the reagent.
This document describes the application of a tube-type sampler (with either a cylindrical or a slightly
conical tube), a badge-type sampler and a radial-type sampler.
The relative expanded uncertainty of NO measurements performed using these tube-type diffusive
samplers can potentially be lower than 25 % for individual measurements. When aggregating results to
form annual average values, the relative expanded uncertainty can be further reduced to levels below
15 % due to the reduction of random effects on uncertainty [9].
NOTE NO passive samplers are also employed to measure NO with the addition of an oxidant to convert
2 x
ambient NO into NO . A second NO sampler is also deployed without the oxidant and the concentration of NO is
2 2
determined from the difference of the two samplers [16].
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 13528-2, Ambient air quality - Diffusive samplers for the determination of concentrations of gases and
vapours - Requirements and test methods - Part 2: Specific requirements and test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
sampling period
period of time for which the measuring procedure yields a single value
[SOURCE: EN 482:2021 [17]]
3.2
combined standard uncertainty
standard measurement uncertainty [3.11] that is obtained using the individual standard measurement
uncertainties associated with the input quantities in a measurement model
[SOURCE: JGCM 200:2012, 2.31 [18]]
3.3
efficiency of extraction
ratio of the mass of analyte desorbed from a sampling device to that applied
[SOURCE: EN 13528-2:2002 [19]]
3.4
diffusive sampler
device which is capable of taking samples of gases from the atmosphere at a rate controlled by a physical
process such as gaseous diffusion through a static air layer or a porous material and/or permeation
through a membrane, but which does not involve the active movement of air through the device
Note to entry: Active normally refers to the pumped movement of air.
[SOURCE: EN 13528-1:2002, 3.6 [20], modified, Note 2 to entry deleted.]
3.5
diffusive sampling rate
rate at which the diffusive sampler collects a particular gas from the atmosphere
Note 1 to entry: The diffusive sampling rate is usually expressed in volume flow units of (m /h), (ml/min) or
(cm /min).
3 3
−8
Note 2 to entry: cm /min may be converted to SI units of m /s by factor 1,67 × 10 .
Note 3 to entry: The term “diffusive sampling rate” is sometimes referred to as “diffusive uptake rate”.
3.6
expanded measurement uncertainty
expanded uncertainty
product of a combined standard measurement uncertainty and a factor larger than the number one
Note 1 to entry: The factor depends upon the type of probability distribution of the output quantity in a
measurement model and on the selected coverage probability.
Note 2 to entry: The term “factor” in this definition refers to a coverage factor.
[SOURCE: JCGM 200:2012, 2.35 [18]]
3.7
field blank
sealed sampler drawn from the same batch as the samplers being used for NO monitoring, which is
taken unopened to the field, remains closed during the sampling period at the measurement location and
is returned together with exposed samplers after the sampling is completed
Note 1 to entry: This blank is only used for quality control purposes.
Note 2 to entry: A transport blank is considered to be a special case of a field blank. A transport blank is taken to
the exposure site, left unopened and returned to the laboratory immediately after placement or collection of the
-
samplers. Transport blanks may be used when regular field blanks reveal an unacceptable level of nitrite (NO ) to
investigate the possibility of contamination of samplers during transport.
3.8
laboratory blank
sealed sampler drawn from the same batch as the samplers being used for NO monitoring which is
stored in the laboratory for the duration of the sampling period and is analysed at the same time as the
returned exposed samplers
3.9
mass concentration
mean concentration during the sampling period (averaging time) which is expressed in µg/m
3.10
measurement uncertainty
uncertainty (of measurement)
non-negative parameter characterizing the dispersion of the quantity values being attributed to a
measurand, based on the information used
Note to entry: For footnotes to the definition the reader is referred to the parent document JGCM 200:2012.
[SOURCE: JCGM 200:2012, 2.26 [18]]
3.11
standard measurement uncertainty
standard uncertainty
measurement uncertainty expressed as a standard deviation
[SOURCE: JCGM 200:2012, 2.30 [18]]
4 Description of samplers
4.1 Principle
The diffusive sampler is exposed to air for a measured time period, i.e. the exposure time. Controlled by
the sampler’s specific diffusive sampling rate, NO migrates through the sampler diffusion path and is
collected as nitrite by reaction with triethanolamine (TEA). The nitrite formed in the sampler is
subsequently extracted and analysed in a laboratory. Based on the amount of nitrite determined, the
diffusive sampling rate and the exposure time, the time-integrated average concentration of NO can be
calculated.
A number of pathways have been proposed for the reaction of nitrogen dioxide with triethanolamine.
More details can be found in [21].
The diffusive sampling rate is determined either by calculation based on Fick’s first law of diffusion or
through calibration by exposure to standard atmospheres, and/or by field comparison of diffusive
samplers measurements with measurements carried out using the EU reference method (EN 14211).
This latter approach has been described in [8], [9], [10] and [22]. Values of and formulas to calculate
diffusive sampling rates associated with different diffusive samplers are given in Annex C.
NOTE The theory of performance of diffusive samplers is given in EN 13528-3 [23, under revision] together
with information on possible saturation of the sorbent, the effect of transients and the effect of face velocity. This
document explains the dependence of diffusive sampling rates on the concentration level of pollutants and sampling
time.
4.2 Diffusive samplers
4.2.1 Description
In general, three types of diffusive samplers are available with different designs: tube-type, radial-type
and badge-type:
— Descriptions of the tube-type sampler with cylindrical and with conical tube are given in Annex A.
The descriptions hold for sampler designs that have a proven practical validity.
— A radial-type sampler exists and is widely used in the EU. Validation data are available for this
sampler [12], [24]. The sampler is described in the informative B.1.
— A badge-type NO diffusive sampler exists that is based on the application of triethanolamine.
Validation data are available for this sampler [12], [25], and [26]. The sampler is described in the
informative B.2.
The sampler may include a protective device (4.3) in order to reduce environmental effects during
sampling.
When a protective device is considered an integral part of the sampler, the performance of the sampler
shall be validated including the protective device.
4.2.2 Preparation
The preparation of the sampler consists of the coating of a support with triethanolamine from a solution
in water, methanol or acetone.
TEA is coated onto a suitable support. Supports that have been demonstrated to be suitable in practice
are (see Annex A):
— a series (2 or 3) of circular stainless steel grids with a fine mesh size;
— a cylindrical stainless steel grid with a fine mesh size;
— a cellulose-fibre filter.
To this TEA solution a wetting agent may be added to facilitate the coating (see 4.2.2.4). In principle, one
of the procedures specified in Annex A shall be used for the coating.
Preparation procedures are taken from references describing tube-type samplers with a cylindrical tube.
Three preparation methods are given in Annex A. These preparation methods have proven to be effective
in practice. Other methods may be used provided that their suitability has been satisfactorily
demonstrated.
All reagents used shall not contain nitrite impurities higher than the laboratory blank values.
4.2.2.1 Triethanolamine (TEA)
Purity ≥ 99 %. TEA has a melting point of approximately 20 °C depending on its purity. When using
volumetric techniques for measuring quantities of TEA, the TEA should be handled at temperatures well
above its melting point. Alternatively, gravimetry may be used.
4.2.2.2 Acetone
Purity ≥ 99,9 %. For the preparation of TEA coating solutions.
4.2.2.3 Ultrapure water
For the preparation of TEA coating solutions. Its conductivity shall be equal or less than 0,1 µS/cm.
4.2.2.4 Wetting agent compound
A wetting agent, for example polyoxyethyleneglycol dodecyl ether, CAS no. 9002-92-0 [27], [28], may be
used for the preparation of TEA coating solutions.
NOTE This compound is commonly denominated as “Brij® 35” .
4.2.3 Storage of samplers before and after sampling
Manufacturer’s instructions for storage and sealing shall be followed.
Typically, samplers are stored in the dark under controlled conditions below room temperature in order
to minimize any undesired reactions.
Although samples may be stable for up to 4 months [29] when stored under the above conditions, it is
strongly recommended to analyse the samples as soon as possible after exposure.
If samples are not stored in accordance with the recommendations, including during travel, the end user
shall regularly check the impact on the quality of the measurements from the analysis of the appropriate
blanks.
4.2.4 Chemical interferences
Nitrous acid and peroxyacetyl nitrate are the major chemical interferences of sorption by
triethanolamine. However, in ambient air monitoring both contaminants are generally present at low
concentrations relative to NO . Moreover, these species can also interfere with the measurement of NO
2 2
when applying the EU reference method for NO monitoring based on chemiluminescence (see [2] [30]).
4.3 Protective devices
4.3.1 General
Protective devices are used to reduce the measurement uncertainty with NO diffusive samplers.
Protective shelters or protective filters can be used, alone or in combination.
NOTE The combined use of shelters and filters demonstrated equivalence to the reference method according
to the Directive (study LANUV [7]).
Examples of validation data are given in Annex F.
Protective devices shall be used consistently over time when measuring at a specific site for a prolonged
period, or over space when performing monitoring campaigns, in order to ensure the internal consistency
of sampler behaviour.
4.3.2 Protective shelter
It is strongly recommended to use a protective shelter to prevent:
— the entrance of particulate matter (PM) or water droplets (rain) into the sampler during sampling;
— exposure to direct sunlight;

Brij® is a trademark of ICI America Inc. This information is given for the convenience of users of this document
and does not constitute an endorsement by CEN of the product named.
— exposure to high wind velocities.
NOTE 1 EN 13528-3 [23, under revision] gives general recommendations for the design of protective devices.
NOTE 2 In Annex A protective devices are described for the tube-type samplers; in Annex B protective devices
are described for the other samplers.
4.3.3 Protective filter
It is strongly recommended to use a protective filter at the air inlet of the diffusive sampler to prevent or
reduce:
— the effect of wind on the diffusive sampling rate, e.g. wind-shortening;
— biological contamination;
— PM contamination.
In literature the term ‘membrane’ is commonly and interchangeably used for a filter. The user should
ensure that the relevant term has been applied correctly to the devices deployed.
NOTE In Annex A protective filters are described for the different samplers. Examples of protective filters
include a gas permeable, hydrophobic filter, or a stainless steel mesh across the air inlet.
The manufacturer’s recommended filter shall be used if available. Otherwise, the end user shall check any
alternative used against the reference method to ensure that there are no sample losses of NO .
Typically, the diffusive sampling rate is reduced when applying a filter at the open end of the sampler.
Metal meshes are also used to reduce wind-induced effects [31].
4.4 Instructions for use
The manufacturer shall make available a manual or instruction sheet for the handling of the samplers.
These shall be followed in order to ensure proper operation of the sampler. Samplers shall be deployed
vertically with the air inlet end (open or covered with a protective filter) facing the ground.
5 Analysis
5.1 General
-
There are two commonly used methods employed to analyse for nitrite (NO ) in the aqueous extract:
— colourimetry after derivatization of the nitrite, using the Griess-Saltzman method [27] [32];
— ion chromatography [28].
The mass of nitrite on the exposed samplers is related directly to NO
2.
Further details about reagents and equipment are described in Annex E.
For each technique employed, a calibration curve shall be established by performing linear regression of
the analytical responses observed against the concentrations of nitrite in the standard solutions. For each
concentration except zero the lack of fit of linearity of the calibration curve shall be calculated from the
relative residuals of the regression formula as:
a+⋅bc
i
δ 1− (1)
i
y
i
where
δ is the relative residual of the regression for calibration standard i;
i
Y is the analytical response for the analysis of calibration standard i;
i
a is the intercept of the linear regression formula;
b is the slope of the linear regression formula;
c is the concentration of nitrite in calibration standard i.
i
The relative residuals shall fulfil the requirements given in Table D.1.
If matrix effects are observed, calibration standards shall be prepared in diffusive samplers with TEA.
The detection limit is 3 times the relative standard deviation of the mean laboratory blank value. The
quantification limit is typically in the range between 6 to 10 times the relative standard deviation of the
mean laboratory blank value.
5.2 Colorimetric method
5.2.1 General
The Griess-Saltzman derivatization method consists of reacting nitrite with a mixture of sulphanilamide
and N-(naphthyl-1) ethylenediamine dihydrochloride in dilute orthophosphoric acid (see Annex E). The
absorbance of the azo dye formed is measured between 537 nm and 542 nm.
5.2.2 Calibration
Calibration shall be performed by analysing a series of solutions of nitrite in mixed reagent.
A full calibration shall include at least 6 calibration standards. It is recommended to use concentrations
of the calibration standards of zero (this refers to the colorimetric reagent), 0,1 µg/ml, 0,2 µg/ml,
0,4 µg/ml, 0,6 µg/ml, 0,8 µg/ml and 1,0 µg/ml of nitrite. Higher concentrations are not recommended
because of potential problems with linearity [33].
The expanded uncertainty of all diluted nitrite standards shall be equal to or less than 2 %. All potential
sources of uncertainty shall be included in the calculation (e.g. impurities, volumes of all glassware used,
uncertainty of nitrite concentration in a certified sodium nitrite solution).
5.2.3 Extraction
The extraction shall be performed by adding the colorimetric reagent to the TEA support.
NOTE In practice, when applying colourimetry, the derivatization agent solution is directly used for extraction.
The samples shall be secured against NO2 contamination from the laboratory air during extraction (e.g.
by using caps for the extraction vessels or samplers).
The extraction shall be carried out by using a vortex mixer or vibrating tray, followed by at least 1 h of
standing at ambient temperature for colour development, avoiding exposure to direct sunlight.
If the extraction can be made by other means, the laboratory will have to prove that other means are
sufficient to extract the whole. This shall be done in accordance with the requirements on the desorption
efficiency in EN 13528-2.
A vertical movement is needed to reach a good mixing state.
The extraction conditions and extract stabilities are given in Table 1.
=
Table 1 — Extraction conditions and extract stabilities for analysis by colourimetry
Sampler type Type and volume of Extraction conditions Extract stability
extract
Tube-type sampler 3 ml of mixed reagent Agitate by vortex mixing 2 days at 0 °C - 4 °C
with a cylindrical tube in the sampler (see for about 15 s immediately avoiding exposure
Annex E) after adding the reagents. to direct sunlight
Another possibility to
Tube-type sampler 2 ml of mixed reagent
extract the tubes is to use a
with a slightly conical in the sampler (see
vibrating tray for 10 min to
tube Annex E)
30 min.
Be sure that no air bubbles
are present in the solution
to be analysed
5.2.4 Analysis
Set up the colourimeter in accordance with the manufacturer’s instructions. Set the measurement
wavelength between 537 nm and 542 nm.
NOTE A commonly used wavelength is 540 nm. However, the use of other wavelengths within the above range
has been reported in guidance documents and protocols (see [12]).
Use a calibrated colourimeter to analyse derivatized samples and blanks. Determine the responses of the
samples and blanks and calculate from the calibration function the mass of nitrite in the desorbed
samples and blanks.
If the instrument response to a sample exceeds the calibration range, the sample shall be diluted with
mixed reagent to bring its concentration within the calibration range.
5.3 Ion chromatography method
5.3.1 General
For ion chromatography, the extraction of nitrite is performed in the sampler by adding a suitable eluent.
5.3.2 Calibration
Calibration shall be performed by analysing a series of solutions of nitrite in water or eluent.
A full calibration shall include at least 6 calibration standards.
For ion chromatography it is recommended to use concentrations of the calibration standards of
0,0 µg/ml, 0,1 µg/ml, 0,2 µg/ml, 0,4 µg/ml, 0,8 µg/ml, 1,5 µg/ml and 2,0 µg/ml of nitrite. The nitrite
concentrations shall be traceable to primary standards. The uncertainty requirement shall follow the
approach described in Clause 5.2.2
5.3.3 Extraction
The extraction shall be performed by adding ultrapure water or eluent to the TEA support. The volume
of the extraction solution is given in Table 2.
The samples shall be secured against NO contamination from the laboratory air during extraction (e.g.
by using caps for the extraction vessels or samplers).
The extraction shall be carried out by using a vortex shaker or vibrating tray.
Extraction can be made by other means, the laboratory will have to prove that other means are sufficient
to extract the whole. This shall be done in accordance with the requirements on the desorption efficiency
in EN 13528-2.
The reported stabilities of the extracts are given in Table 2.
Table 2 — Extraction conditions and extract stabilities for analysis by ion chromatography
Sampler type Type and volume of Extraction conditions Extract stability
extract
Tube-type sampler 5 ml of water or Agitate by vortex One week in the dark
with both a cylindrical eluent shaking for about 1 at
and a slightly conical min to 2 min. Another 0 °C - 4 °C
tube possibility is to use a
vibrating tray for 10
min to 30 min
5.3.4 Analysis
Set up the ion chromatograph in accordance with the manufacturer’s instructions. Use a calibrated ion
chromatograph to analyse samples and blanks. Determine the responses of the samples and blanks and
calculate from the calibration function the mass of nitrite in the desorbed samples and blanks.
If the instrument response to a sample exceeds the calibration range, the sample shall be diluted with
water or eluent to bring its concentration within the calibration range.
The expanded uncertainty of all diluted nitrite standards shall be equal to or less than 2 %. All potential
sources of uncertainty shall be included in the calculation (e.g. impurities, volumes of all glassware used,
uncertainty of nitrite concentration in a certified sodium nitrite solution).
Stock standard solutions of 1 000 µg/ml can be purchased as certified solutions from different
manufacturers or can be prepared by the laboratory.
6 Calculation of the concentration of nitrogen dioxide
6.1 Diffusive sampling rate
The diffusive sampling rate for the type of diffusive sampler is needed to calculate the mass concentration
of NO in ambient air. The diffusive sampling rate is determined by the geometry (see C.1.) of the diffusive
sampler and is proportional to the diffusion coefficient of NO in ambient air:
v= f D (2)
( )
where
v 3
is the diffusive sampling rate in m /h;
D 2
is the diffusion coefficient in m /h.
The diffusion coefficient (see [35]) is a function of temperature and pressure:
n+−1 1
D= f T , P (3)
( )
where
D 2
is the diffusion coefficient in m /h;
T is the temperature in K;
P is the pressure in kPa;
n is an empirically determined parameter, with 0,5 < n < 1,0.
Hence, the diffusive sampling rate is a function of temperature and pressure [23, under revision]:
n+−1 1
v= f T , P (4)
( )
The reference conditions, i.e. temperature and pressure, to which the diffusive sampling rate relates, need
to be known as those conditions are reflected in the mass concentration. If actual temperature and
pressure during the sampling time deviate from the reference conditions of the diffusive sampling rate
and data of average temperature and/or pressure is available, the diffusive sampling rate shall be
corrected using Formula (5):
1,81
  
P
T
ref
  
v=υ ⋅ ⋅ (5)
ref
  
TP
ref  
where
υ is the diffusive sampling rate at actual conditions in m /h;
υ is the diffusive sampling rate at reference conditions in m /h;
ref
T is the average temperature during exposure in K;
T is the reference temperature at which the diffusive sampling rate is given in K;
ref
P is the average pressure during exposure in kPa;
P is the reference pressure at which the diffusive sampling rate is given in kPa.
ref
NOTE 1 Reference conditions of a diffusive sampling rate typically refer to the annual mean conditions of a
region or country if determined by calibration in the field. Diffusive sampling rates which were determined in the
laboratory or available from commercial suppliers of diffusive samplers often refer to standard conditions, such as
293 K and 101,3 kPa.
NOTE 2 The pressure difference is typically small and can often be neglected. At higher altitudes, for example in
the mountains, the pressure difference can be considerable.
6.2 Mass concentration
The mass concentration of NO in ambient air under actual conditions of sampling is calculated using
Formula (6):
mm−
s b
(6)
C=
e⋅⋅vt
where
C 3
is the mass concentration of NO at ambient conditions in µg/m ;
m is the mass of nitrite found in the sample in µg;
s
m is the mass of nitrite found in the mean laboratory blank in µg;
b
υ
is the sampler diffusive sampling rate at actual conditions of sampling in m /h;
e is the efficiency of extraction of nitrite;
t is the sampling time in h.
NOTE It is not necessary to include the efficiency of extraction of nitrite if this efficiency is shown not be
significantly different from 100 % or if it is already included into the estimation of the diffusive sampling rate.
6.3 Conversion to standard conditions of temperature and pressure
The mass concentration of NO in air is calculated at the ambient temperature and pressure during
exposure using Formula (6). This mass concentration shall be referred to at standard conditions of
temperature and pressure, as required by [1], using Formula (7):
T 101,3
cc=⋅⋅ (7)
STP
293 P
where
c 3
STP is the concentration of NO at standard temperature and pressure in µg/m ;
c 3
is the concentration of NO at ambient conditions in µg/m ;
T is the average temperature during exposure in K;
P is the average pressure during exposure in kPa.
7 Quality control/quality assurance
For each series of analyses, the following control checks shall be performed and recorded. Corrective
actions shall be taken in case of exceedance of limits set by the user, in order to ensure the quality of the
NO measurement results.
a) Analysis of transport blanks and/or field blanks to detect contamination of samplers during
transport, in the field and during subsequent storage prior to analysis;
b) Analysis of calibration check solutions to determine instrument drift and appropriate re-calibration
intervals. The calibration check shall be carried out using at least 3 points (zero, 50 % of calibration
range and full scale) at the start of each day that samplers are analysed to detect any drift of the
analytical system during a series of analyses.
At regular intervals, the following control checks shall be performed and registered. Corrective actions
shall be taken in case of exceedance of limits set by the user, in order to ensure the quality of the NO
measurement results.
c) Analysis of reagent solutions to determine variations of reagent blank levels;
d) Analysis of laboratory blanks to detect contamination in the preparation or storage of samplers; at
least one sampler shall be analysed for each newly prepared batch of samplers;
NOTE 1 The use of replicate laboratory blanks can be adopted to identify outliers.
e) Determination of nitrite extraction efficiency by spiking coated samplers with known masses of
nitrite followed by the determination of their recoveries [e.g. see 11]; the nitrite shall be injected
directly onto the TEA support;
NOTE 2 Not required if already taken into account when determining the sampling rate, e.g. by calibration
in the field
f) Duplicate analysis of sample extracts to check analytical repeatability;
g) Analysis of samples taken in parallel at one field site to check method precision;
h) Checking the sensitivity of the analytical method used (e.g. the slope of the calibration curve). For
NO monitoring campaigns with diffusive samplers, it is necessary to implement other quality
control checks that will ensure proper analysis over time such as participation in prof
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