EN ISO 23320:2022

SLOVENSKI STANDARD
01-september-2022
Nadomešča:
SIST EN 838:2010
Zrak na delovnem mestu - Plini in pare - Zahteve za vrednotenje merilnih
postopkov z difuzijskimi vzorčevalniki (ISO 23320:2022)
Workplace air - Gases and vapours - Requirements for evaluation of measuring
procedures using diffusive samplers (ISO 23320:2022)
Luft am Arbeitsplatz - Gase und Dämpfe - Anforderungen an die Evaluierung von
Messverfahren mit Diffusionssammlern (ISO 23320:2022)
Air des lieux de travail - Gazes et vapeurs - Exigences pour l'évaluation des procédures
pour le mesurage à l'aide de dispositifs de prélèvement par diffusion (ISO 23320:2022)
Ta slovenski standard je istoveten z: EN ISO 23320:2022
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 23320
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2022
EUROPÄISCHE NORM
ICS 13.040.30 Supersedes EN 838:2010
English Version
Workplace air - Gases and vapours - Requirements for
evaluation of measuring procedures using diffusive
samplers (ISO 23320:2022)
Air des lieux de travail - Gazes et vapeurs - Exigences Luft am Arbeitsplatz - Gase und Dämpfe -
pour l'évaluation des procédures pour le mesurage à Anforderungen an die Evaluierung von Messverfahren
l'aide de dispositifs de prélèvement par diffusion (ISO mit Diffusionssammlern (ISO 23320:2022)
23320:2022)
This European Standard was approved by CEN on 13 March 2022.

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, Turkey 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
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 23320:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 23320:2022) has been prepared by Technical Committee ISO/TC 146 "Air
quality" in collaboration with Technical Committee CEN/TC 137 “Assessment of workplace exposure to
chemical and biological agents” 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 November 2022, and conflicting national standards
shall be withdrawn at the latest by November 2022.
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 supersedes EN 838:2010.
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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 23320:2022 has been approved by CEN as EN ISO 23320:2022 without any modification.

INTERNATIONAL ISO
STANDARD 23320
First edition
2022-04
Workplace air — Gases and vapours
— Requirements for evaluation of
measuring procedures using diffusive
samplers
Air des lieux de travail — Gazes et vapeurs — Exigences pour
l'évaluation des procédures pour le mesurage à l'aide de dispositifs de
prélèvement par diffusion
Reference number
ISO 23320:2022(E)
ISO 23320:2022(E)
© ISO 2022
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 23320:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.1
5 Types of samplers. 3
6 Requirements . 3
6.1 General . 3
6.2 Sampler requirements . 3
6.2.1 Nominal uptake rate . 3
6.2.2 Air velocity/sampler orientation . 3
6.2.3 Sampler leak test . 4
6.2.4 Shelf life . 4
6.2.5 Sampler identification (for commercially available diffusive samplers) . 4
6.2.6 Marking . . . 4
6.2.7 Instructions for use. 4
6.3 Measuring procedure requirements . 5
6.3.1 Sampling procedure requirements . 5
6.3.2 Analytical procedure requirements . 5
6.3.3 Expanded uncertainty . 6
6.3.4 Method description . 6
7 General test conditions .7
7.1 Reagents . 7
7.2 Apparatus . 7
7.3 Independent method . 7
7.4 Generation of a calibration gas mixture . 8
7.4.1 General . 8
7.4.2 Determination of mass concentration. 8
8 Test methods . 9
8.1 General . 9
8.2 Sampler test methods . 9
8.2.1 Determination of (nominal) uptake rate . 9
8.2.2 Air velocity . . . 10
8.2.3 Sampler leak test . 11
8.2.4 Shelf life (for Type A impregnated supports) . . 11
8.2.5 Sampler identification .12
8.2.6 Marking . . 12
8.2.7 Instructions for use.12
8.3 Measuring procedure test methods .12
8.3.1 Determination of the sampling conditions .12
8.3.2 Analytical procedure test methods . 13
8.3.3 Method recovery and method precision . 15
8.4 Uncertainty of measurement . 17
8.4.1 Identification of random and non-random uncertainty components . 17
8.4.2 Estimation of individual uncertainty components . 17
8.4.3 Calculation of expanded uncertainty . 19
9 Test report .19
Annex A (informative) Fundamentals of diffusive sampling .20
Annex B (informative) Estimation of uncertainty of measurement .23
iii
ISO 23320:2022(E)
Annex C (informative) Calculation of uptakes rates from diffusion coefficients .33
Annex D (informative) Example of estimation of expanded uncertainty .35
Bibliography .38
iv
ISO 23320:2022(E)
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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 146, Air quality, Subcommittee SC 2,
Workplace atmospheres, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 137, Assessment of workplace exposure to chemical and biological agents,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO 23320:2022(E)
Introduction
This document provides a framework for assessing the performance of procedures for measuring
gases and vapours against the general requirements for the performance of procedures for measuring
chemical agents in workplace atmospheres as specified in ISO 20581. These performance criteria
include maximum values of expanded uncertainty achievable under prescribed laboratory conditions
for the methods to be used.
This document enables manufacturers and users of diffusive samplers and developers and users of
procedures for measuring gases and vapours to adopt a consistent approach to method validation.
This document is based on EN 838:2010, published by the European Committee for Standardization
(CEN) and is also complementary to ISO 16107.
vi
INTERNATIONAL STANDARD ISO 23320:2022(E)
Workplace air — Gases and vapours — Requirements
for evaluation of measuring procedures using diffusive
samplers
1 Scope
This document specifies performance requirements and test methods under prescribed laboratory
conditions for the evaluation of diffusive samplers (see Reference [1]) and of procedures using these
samplers for the determination of gases and vapours in workplace atmospheres (see Reference [2]).
This document is applicable to diffusive samplers and measuring procedures using these samplers,
such as ISO 16200-2 and ISO 16017-2, in which sampling and analysis are carried out in separate stages.
This document is not applicable to
— diffusive samplers which are used for the direct determination of concentrations, and
— diffusive samplers which rely on sorption into a liquid.
This document addresses requirements for method developers and/or manufacturers.
NOTE For the purposes of this document a manufacturer can be any commercial or non-commercial entity.
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 20581, Workplace air — General requirements for the performance of procedures for the measurement
of chemical agents
ISO 22065, Workplace air — Gases and vapours — Requirements for evaluation of measuring procedures
using pumped samplers
ISO 18158, Workplace air — Terminology
ISO 8655-2, Piston-operated volumetric apparatus — Part 2: Piston pipettes
ISO 8655-6, Piston-operated volumetric apparatus — Part 6: Gravimetric methods for the determination
of measurement error
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18158 and ISO 20581 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols and abbreviated terms
ISO 23320:2022(E)
NOTE See 8.4 and Annex C for symbols used in conjunction with uncertainty of measurement only.
A cross-sectional area of sorption surface, in square centimetres (cm )
CRM certified reference material
2 −1
D diffusion coefficient of an analyte, in square centimetres per minute (cm ∙ min )
a
2 −1
D diffusion coefficient of analyte 1, in square centimetres per minute (cm ∙ min )
a1
2 −1
D diffusion coefficient of analyte 2, in square centimetres per minute (cm ∙ min )
a2
l length of static air layer in sampler (or equivalent for permeation types), in centimetres (cm)
m mass of analyte desorbed from blank sampler, in nanograms (ng)
b
m mass of analyte desorbed, in nanograms (ng)
d
m mass of the analyte which can diffuse to a suitable sorbent within a certain time, i.e. the mass
s
uptake of a diffusive sampler, in nanograms (ng)
−1

m mass loss from permeation tube, in micrograms per minute (µg ∙ min )
−1
M molar mass of analyte, in grams per mole (g ∙ mol )
a
n number of replicate samples
OELV occupational exposure limit value
p actual pressure of the test atmosphere sampled, in kilopascals (kPa)
at
R recovery
R analytical recovery
an
RH relative humidity of the test atmosphere sampled, in percent (%)
t exposure time, in minutes (min)
e
T temperature of the test atmosphere sampled, in Kelvin (K)
at
3 −1

uptake rate, in cubic centimetres per minute (cm ∙ min )
U
d
−1 −1
uptake rate, in nanograms per parts per million (volume fraction) per minute (ng ∙ ppm ∙ min )
 ′
U
()
d
3 −1

uptake rate of analyte 1, in cubic centimetres per minute (cm ∙ min )
U
d1
3 −1

uptake rate of analyte 2, in cubic centimetres per minute (cm ∙ min )
U
d2
−1

v
flow rate into the exposure chamber, for example, in litres per minute (l ∙ min )
β mass concentration of the analyte in the calibration gas mixture, in milligrams per cubic metre
a
−3
(mg ∙ m )
mass concentration in parts per million (ppm);
′
β
()
a
β mass concentration of the given analyte at the beginning of the diffusion layer (i.e. at the distance
a1
−3
l from the surface of the sorbent), in milligrams per cubic metre (mg ∙ m )
ISO 23320:2022(E)
β mass concentration of the given analyte at the end of the diffusion layer (i.e. at the surface of
a2
−3
the sorbent), in milligrams per cubic metre (mg ∙ m )
mean mass concentration of the analyte recovered from the test gas atmosphere, in milligrams
β
a,R
−3
per cubic metre (mg ∙ m );
−3
β mass concentration of the calibration gas mixture, in milligrams per cubic metre (mg ∙ m )
cg
ϑ temperature of the test atmosphere sampled, in degree Celsius (°C)
at
K coefficient of variation (CV)(The predecessor term "relative standard deviation" is deprecated and
v
has been replaced by the term "coefficient of variation". See also ISO 3534-1:2006, 2.38, Note 2.)
−1
ø volume fraction of the analyte, in microlitres per litre (µl ∙ l )
a
5 Types of samplers
Samplers for gases and vapours can be divided into type A samplers and type B samplers:
Type A samplers rely on sorption onto a solid or onto a support impregnated with a reagent, desorption
with solvent, and subsequent analysis of the desorbate. They are usually made of polypropylene or
glass and consist of one or more sorbent layers and contain an active sorbent (e.g. activated carbon) or a
support impregnated with reagent.
Type B samplers rely on sorption onto a solid or onto a support impregnated with a reagent, thermal
desorption, and analysis of the desorbate. They are usually made of glass or metal, are sealed with
removable fittings and consist of one or more beds of sorbent (e.g. porous polymer resin).
6 Requirements
6.1 General
Some requirements (see 6.2) shall be initially verified by the manufacturer once for each type of
sampler. Other requirements (see 6.3) shall be verified for each combination sampler/chemical agent.
Measuring procedures shall meet the requirements for measuring procedures specified in 6.3. When
use of a sampler for measurement of a particular gas or vapour is claimed, the sampler shall meet the
requirements specified in 6.2.
NOTE 1 No useful performance requirements can be given for the effect of interferents (with the exception
of relative humidity). The effect of interferents is difficult to predict for a non-ideal sorbent without adsorption
isotherm data on mixed systems which is normally unavailable. However, the user of diffusive samplers is
cautioned that the adsorption of water vapour on certain sorbents, e.g. activated carbon and silica gel, can have a
large effect on sampler capacity and analytical recovery.
NOTE 2 Because of the known effect of pressure on diffusion coefficients, a pressure test is not necessary.
6.2 Sampler requirements
6.2.1 Nominal uptake rate
The nominal uptake rate and the coefficient of variation shall be provided by the manufacturer in
accordance with 8.2.1 and Annex A.
6.2.2 Air velocity/sampler orientation
The manufacturer shall test the working range of air velocity and the influence of sampler orientation
in accordance with 8.2.2.
ISO 23320:2022(E)
6.2.3 Sampler leak test
When tested in accordance with 8.2.3, any additional analyte determined above the blank value (see
6.3.2.3) shall be less the one-third of the calculated mass uptake by the sampler for 30 min exposure to
a concentration of 0,1 OELV.
6.2.4 Shelf life
The manufacturer shall specify the shelf life of the diffusive sampler when stored in its original package.
During this period the sampler shall fulfil all requirements.
6.2.5 Sampler identification (for commercially available diffusive samplers)
Samplers shall be uniquely identified.
6.2.6 Marking
Diffusive samplers shall be marked with at least the following:
a) manufacturer's name;
b) product identification;
c) batch identification;
d) shelf life (if applicable);
e) number of this document.
If required due to limited space, the marking may be placed on the packaging of the diffusive sampler.
However, the manufacturer's name and product identification shall be indicated on the diffusive
sampler.
6.2.7 Instructions for use
The instructions for use supplied with the diffusive sampler shall be written in the principal language(s)
used in the countries where the diffusive sampler is to be marketed. Where appropriate, the instructions
for use shall contain directly and by reference to an online document, at least the following information:
a) designated use (general purpose for a number of gases and vapours or, specific, for a particular gas
or vapour, see 6.1);
b) blank value (only when used for a particular gas or vapour, see 6.1);
c) nominal uptake rate for the substances for which the diffusive sampler is intended to use;
d) directions for proper handling of the diffusive sampler, including opening and closing;
e) general information on the principle of use, for example, sorbent type, reaction of the reagent
impregnated solid, desorption method;
f) information on storage and transport;
g) air velocity range in which the sampler can be used;
h) orientation;
i) information on health or environmental hazards and method of disposal.
The general information on the principle of use can be given in additional literature.
ISO 23320:2022(E)
6.3 Measuring procedure requirements
6.3.1 Sampling procedure requirements
6.3.1.1 Sampling time
Sampling time shall be established according to concentration range of the compounds of interest over
which measurements are to be made, i.e. up to two times the OELV, see ISO 20581, and taking into
account the nominal or theoretical uptake rate.
6.3.1.2 Bias due to the selection of a non-ideal sorbent (back diffusion)
When tested in accordance with 8.3.1.1, the bias shall be ≤ 10 %.
6.3.1.3 Uptake rate
If it is possible to calculate the ideal steady-state value in accordance with 8.2.1, the nominal uptake
rate, determined in accordance with 8.2.1, shall be within ±25 % of the steady-state value.
6.3.1.4 Storage conditions after sampling
The storage conditions after sampling shall be specified. When tested in accordance with 8.3.1.3, the
mean value of the recovery after storage shall not differ by more than 10 % from the value before
storage.
6.3.2 Analytical procedure requirements
6.3.2.1 Limit of quantification
The limit of quantification as determined in 8.3.2.1 for long-term OELVs shall be lower than the mass
collected by the sampler at a concentration of 0,1 OELV for 8 h.
The limit of quantification for short-term OELVs shall be lower than the mass collected by the sampler
at a concentration of 0,5 OELV for 15 min.
If the sampler is to be used for shorter reference periods, the limit of quantification also shall be able to
be measured at those periods.
6.3.2.2 Analytical recovery
When tested in accordance with 8.3.2.2 the analytical recovery R shall be
an
for type A samplers: R ≥ 75 % with K ≤ 10 % at each loading, and
an v
for type B samplers: R ≥ 95 % with K ≤ 10 % at each loading.
an v
Where the analytical recovery cannot be achieved the user shall take care that the measuring procedure
meets all other requirements of this document and ISO 20581.
6.3.2.3 Blank value
In order to obtain acceptable values for the quantification limit of the method, the blank value of the
sampling media should be as low as technically possible.
The blank value as tested in 8.3.2.3 shall be less than the limit of quantification as determined in
accordance with 8.3.2.1 or otherwise it can be subtracted from the result, but the standard deviation of
the blank value will contribute to the expanded uncertainty of the measuring procedure.
ISO 23320:2022(E)
Where it is known that the blank value is significant and varies between batches of samplers, it shall be
checked on each batch of samplers.
To eliminate any contamination which could occur during storage before use Type B samplers should
be cleaned before sampling by taking them through the thermal desorption procedure.
This cleaning process should be carried out as close as possible to the time when the samplers will be
used.
6.3.3 Expanded uncertainty
When tested in accordance with 8.3 the expanded uncertainty calculated in accordance with 8.4 shall
meet the requirements given in ISO 20581.
The expanded uncertainty requirement shall be met from 10 °C to 40 °C and at relative humidities from
20 % to 80 %. Above 30 °C the use of correction factors is permitted to meet this requirement.
In addition, the performance criteria should also be met under a wider variety of environmental
influences, representative of workplace conditions.
6.3.4 Method description
6.3.4.1 Scope of the measuring procedure
The scope of the measuring procedure shall include information on the following:
a) principle of the method;
b) chemical agents covered by the measuring procedure;
c) analytical technique used;
d) working ranges;
e) chemical agents for which the measuring procedure is known to be adequate but not completely
validated according to this document, especially in case of compounds of the same chemical family
or homologous series;
f) chemical agents for which the measuring procedure is known to be inadequate;
g) any known interferences.
6.3.4.2 Method performance
The measuring procedure shall comprise information about method performance, including the
following:
a) the chemical agents for which measuring procedure has been shown to be effective;
b) the range of concentrations of chemical agents in air, sample volume, uptake rates, exposure time
and range of environmental conditions over which the measuring procedure has been shown to
meet the performance criteria for expanded uncertainty prescribed in ISO 20581;
c) the limit of quantification of the measuring procedure for chemical agents of interest;
d) full details of any known interferences, including suitable and sufficient information on how to
minimise their effects.
ISO 23320:2022(E)
6.3.4.3 Apparatus and reagents
With regard to apparatus and reagents the measuring procedure shall
a) specify that the diffusive sampler used complies with the provisions of this document,
b) specify the required characteristics of analytical instruments to be used,
c) specify the quality of the reagents to be used.
6.3.4.4 Safety information
The measuring procedure shall provide suitable and sufficient information on the safety hazards
associated with the reagents and equipment used.
7 General test conditions
7.1 Reagents
Use reagents of analytical grade, where possible.
7.2 Apparatus
Usual laboratory apparatus and the following:
7.2.1 Dynamic system for generating, pre-mixing and delivering a known concentration of a test gas
or vapour in air (see ISO 6145-1, ISO 6145-4, ISO 6145-6 and ISO 6145-10), including at least:
— an exposure chamber constructed of inert materials such as glass or polytetrafluorethylene (PTFE),
through which the generated test atmosphere is passed, of sufficient capacity to accommodate
simultaneously at least six test samplers and six samplers of one independent method (see 7.3)
positioned in such a manner that there is no interference between each sampler;
— provisions for measuring, controlling and varying the air flow rate through the chamber and the
concentration, temperature and relative humidity of the calibration gas mixture.
NOTE It is also possible to use a smaller exposure chamber and to carry out repeat experiments to obtain at
least six pairs of data.
7.2.2 Micropipettes or syringes, for applying known volumes of standard solutions, conforming
with the requirements of ISO 8655-2 and with a calibration checked in accordance with ISO 8655-6.
7.2.3 Instruments for analysing the gas, vapour or a characteristic reaction product collected
by either the test sampler or an independent sampling method.
7.3 Independent method
The concentration of the generated calibration gas mixture in the exposure chamber shall be verified
as follows:
a) by an independent method, which has been validated using an established protocol, for example a
pumped sampler method, bubbler method, or a different diffusive sampler method; or
b) by using an independently calibrated on-line instrument, e.g. a flame ionization detector, or an
infrared spectrometer.
If a pumped sampler procedure is used as the independent method, the method shall conform with all
requirements of ISO 22065.
ISO 23320:2022(E)
7.4 Generation of a calibration gas mixture
7.4.1 General
Set up a calibration gas mixture (see ISO 6141, ISO 6143, ISO 6144 and Reference [3]) at the concentration
and values of temperature, relative humidity, etc. specified in the appropriate test methods in Clause 8.
Ensure that the flow rate into the exposure chamber exceeds the combined sampling rate of all samplers
by at least 25 %.
7.4.2 Determination of mass concentration
7.4.2.1 Calculate the mass concentration of the calibration gas mixture,β , given in milligrams per
cg
−3
cubic metre (mg ∙ m ), from the test atmosphere generation parameters. For example, for a permeation
cell system, the delivered mass concentration is:

m
β = (1)
cg

v
where
−1

m is the mass loss from permeation tube, in micrograms per minute (µg ∙ min );
−1

v
is the flow rate into the exposure chamber, for example, in litres per minute (l ∙ min ).
NOTE 1 The example does not give a preference for permeation systems for generating calibration gas
mixtures of gases and vapours.
NOTE 2 This value is the calculated inlet value of the exposure chamber concentration.
7.4.2.2 Measure the mass concentrations at the inlet and outlet of the exposure chamber using the
independent method described in 7.3 with all samplers within the test chamber, including both the test
and independent method functioning.
Determine whether the measured outlet mass concentration differs by more than 5 % from the
measured inlet mass concentration. If it does, then the calibration gas mixture generation system shall
be changed e.g. by increasing the flow rate or chamber volume, until the difference is less than 5 %.
When the difference is less than 5 %, calculate the mean mass concentration in the test atmosphere
within the exposure chamber either from the mean of the calculated inlet and outlet values, or from the
mean calculated inlet value adjusted for (half of) the experimentally determined depletion.
7.4.2.3 Determine the mean mass concentration of the test atmosphere within the exposure chamber
experimentally using the results of the independent method described in 7.3. A correction may be
applied for any known bias in the independent method.
Compare the experimentally determined mass concentration with the calculated value (see 7.4.2.2). If
the experimentally determined value is within ±10 % of the calculated value of the mass concentration
of the delivered test atmosphere, take the calculated value as the true value. If this requirement is not
met, then make adjustments or use an alternative generation method or verify the independent method.
If it is not possible to calculate the mass concentration of the calibration gas mixture, for example, for
reactive gases, the value determined by the independent method shall be used as the true value.
ISO 23320:2022(E)
8 Test methods
8.1 General
If it is known in advance that a certain type of diffusive sampler is unaffected by an environmental
influence, then the relevant tests in 8.3.3.1 to 8.3.3.5 may be modified to examine only the factors likely
to have an influence.
If not otherwise specified in the test procedure, the sampler orientation shall be as specified by the
manufacturer.
There are different levels of evaluation. These levels are specified as follows:
a) level 1: A measuring procedure evaluated for the analyte of interest in accordance with the
normative part of this document;
b) level 2: A measuring procedure deemed to be compliant with the normative part of this document
on the basis that the analyte of interest is an analogue within a homologous series, both upper and
lower members of which have been tested and shown to comply with level 1. Such an evaluation shall
include at least the nominal uptake rate determination as specified in 8.2.1 and the determination
of the analytical recovery as specified in 8.3.2.2.
NOTE 1 Some special groups of substances (for example toluene, xylenes) usually isomers, can be treated as
homologous when it is known that their chemical and physical properties are very similar.
NOTE 2 To reduce the number of experiments a factorial design can be applied, see References [4] to [7].
8.2 Sampler test methods
8.2.1 Determination of (nominal) uptake rate
Expose a set of six diffusive samplers to a test atmosphere under the following exposure conditions:
— concentration: 1 OELV;
— time: 4 h;
— relative humidity: (50 ± 5) %;
— temperature: 20 °C to 25 °C;
−1
— air velocity: 0,5 m ∙ s .
Analyse the diffusive samplers by reference to standard solutions or to samplers spiked with known
amounts of analyte.
Calculate the (nominal) uptake rate according to Formula (2):
mm−
db

U = (2)
d
Rt××β
an ae
where
3 −1

is the uptake rate, in cubic centimetres per minute (cm ∙ min );
U
d
m is the mass of analyte desorbed, in nanograms (ng);
d
m is the mass of analyte desorbed from blank sampler, in nanograms (ng);
b
R is the analytical recovery.
an
ISO 23320:2022(E)
β is the mass concentration of the analyte in the calibration gas mixture, in milligrams per cubic
a
−3
metre (mg ∙ m )
t is the exposure time, in minutes (min)
e
−6 
NOTE 1 If the mass concentration is given as 10 (parts per million), use (β )' and (U )' instead of β and
a d a

U .
d
Calculate the mean (nominal) uptake rate and the coefficient of variation.
NOTE 2 For the calculation of uptake rates from diffusion coefficients see Annex C.
8.2.2 Air velocity
The manufacturer is responsible for ensuring that this test is carried out for at least one chemical agent.
Expose a set of six diffusive samplers to a test atmosphere under the following exposure conditions:
— concentration: 1 OELV;
— time: 4 h;
— relative humidity: (50 ± 5) %;
— temperature: 20 °C to 25 °C;
−1 −1
— air velocity: 0,01 m ∙ s to 4,0 m ∙ s ;
— sampler orientation: to be tested parallel and perpendicular to the flow direction.
Analyse the set by reference to standard solutions or to samplers spiked with known amounts of
analyte.
Calculate the observed mass concentration (see 8.3.3.1) and plot the mean value against air velocity,
assuming linear flow. Determine the air velocity corresponding to an observed mass concentration of
about 90 % and 110 % of its maximal (plateau) value for each sampler orientation (see Figure 1). Test
the samplers and use under conditions where air velocities are in the range of the plateau area.
As the influence of air movement on diffusive sampler performance is dependent on sampler geometry
and not on the analyte selected, it is necessary to perform this test only on a given diffusive sampler
using a representative chemical agent.
Samplers which are intended only for personal monitoring need to be tested only over the range from
−1 −1 −1 −1
0,1 m ∙ s to 1,5 m ∙ s (indoor workplaces only) or over the range from 0,1 m ∙ s to 4,0 m ∙ s (indoor
or outdoor workplaces).
ISO 23320:2022(E)
Key
X air velocity around diffusive sampler 1 minimum air velocity
Y observed mass concentration of the analyte 2 maximum air velocity
a
β at plateau.
a
Figure 1 — Typical relationship between air velocity and observed mass concentration for
diffusive samplers
8.2.3 Sampler leak test
Expose a set of six s
...