ISO 21438-3
(Main)Workplace atmospheres — Determination of inorganic acids by ion chromatography — Part 3: Hydrofluoric acid and particulate fluorides
Workplace atmospheres — Determination of inorganic acids by ion chromatography — Part 3: Hydrofluoric acid and particulate fluorides
ISO 21438-3:2010 specifies a method for the determination of the time-weighted average mass concentration of soluble particulate fluorides and hydrofluoric acid (HF) in workplace air by collection of the particulate fluorides on a pre-filter and HF on an alkali-impregnated filter and analysis by ion chromatography. The method is only applicable to determination of particulate fluorides that are soluble using the sample preparation procedure specified. For aerosol sampling, the method is applicable to the personal sampling of the inhalable fraction of airborne particles, as defined in ISO 7708, and to static (area) sampling. The method is applicable to the determination of masses of 0,005 mg to at least 1,25 mg of particulate fluorides per sample and 0,012 5 mg to at least 1,2 mg of HF per sample. The concentration range of particulate fluorides and HF in air for which the measuring procedure is applicable is determined by the sampling method selected by the user. For a 120 l air sample, the working range is approximately 0,04 mg m-3 to at least 10 mg m-3 for particulate fluorides and approximately 0,13 mg m-3 to at least 10 mg m-3 for HF. HF can react with co-sampled particulate matter on the pre-filter, causing an interference on the measured concentration.
Air des lieux de travail — Détermination des acides inorganiques par chromatographie ionique — Partie 3: Acide fluorhydrique et fluorures particulaires
L'ISO 21438-3:2010 spécifie une méthode pour la détermination de la concentration en masse moyenne, pondérée en fonction du temps, en fluorures particulaires solubles et en acide fluorhydrique (HF) dans l'air des lieux de travail, par prélèvement des fluorures particulaires sur un préfiltre et de l'HF sur un filtre imprégné d'alcali et par analyse par chromatographie ionique. La méthode est applicable uniquement à la détermination des fluorures particulaires qui sont solubles en utilisant le mode opératoire spécifié pour la préparation des échantillons. En cas de prélèvement d'aérosol, la méthode est applicable au prélèvement individuel de la fraction inhalable des particules en suspension dans l'air, comme défini dans l'ISO 7708, ainsi qu'au prélèvement à point fixe. La méthode est applicable à la détermination de masses comprises entre 0,005 mg et au moins 1,25 mg de fluorures particulaires par échantillon et entre 0,012 5 mg et au moins 1,2 mg d'HF par échantillon. L'étendue des concentrations en fluorures particulaires et en HF dans l'air pour laquelle cette méthode de mesurage s'applique, est déterminée par la méthode de prélèvement choisie par l'utilisateur. Pour un échantillon de 120 l d'air, l'étendue de mesure se situe approximativement entre 0,04 mg m‑3 et au moins 10 mg m‑3 pour les fluorures particulaires et approximativement entre 0,13 mg m‑3 et au moins 10 mg m‑3 pour l'HF. L'HF peut réagir avec la matière particulaire co-échantillonnée sur le préfiltre, causant une interférence sur la concentration mesurée.
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Standards Content (Sample)
FINAL DRAFT
International
Standard
ISO/FDIS 21438-3
ISO/TC 146/SC 2
Workplace atmospheres —
Secretariat: ANSI
Determination of inorganic acids by
Voting begins on:
ion chromatography —
2025-09-29
Part 3:
Voting terminates on:
2025-11-24
Hydrofluoric acid and particulate
fluorides
Air des lieux de travail — Détermination des acides inorganiques
par chromatographie ionique —
Partie 3: Acide fluorhydrique et fluorures particulaires
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Reference number
ISO/FDIS 21438-3:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 21438-3:2025(en)
International
Standard
ISO/FDIS 21438-3
ISO/TC 146/SC 2
Workplace atmospheres —
Secretariat: ANSI
Determination of inorganic acids by
Voting begins on:
ion chromatography —
Part 3:
Voting terminates on:
Hydrofluoric acid and particulate
fluorides
Air des lieux de travail — Détermination des acides inorganiques
par chromatographie ionique —
Partie 3: Acide fluorhydrique et fluorures particulaires
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ii
ISO/FDIS 21438-3:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Requirement . 3
6 Reagents . 3
7 Apparatus . 4
7.1 Sampling equipment .4
7.2 Laboratory apparatus .5
8 Occupational exposure assessment . 6
9 Sampling . 6
9.1 Preliminary considerations .6
9.1.1 Selection and use of samplers .6
9.1.2 Sampling period .6
9.1.3 Effect of temperature and pressure on flow rate measurements .7
9.1.4 Sample handling .7
9.2 Preparation for sampling .8
9.2.1 Cleaning of samplers .8
9.2.2 Loading the samplers with filters .8
9.2.3 Setting the volumetric flow rate .8
9.2.4 Field blanks .8
9.3 Sampling position .9
9.3.1 Personal sampling .9
9.3.2 Static sampling .9
9.4 Collection of samples .9
9.5 Transportation .10
9.5.1 Samplers that collect either airborne particles or gases, or both, on the filter.10
9.5.2 Sampler with an internal filter cassette.10
9.5.3 Samplers of the disposable cassette type .10
9.5.4 Transport of samples to the laboratory .10
10 Analysis . .10
10.1 General .10
10.2 Preparation of test and calibration solutions .10
10.2.1 General .10
10.2.2 Selection of sample preparation method .10
10.2.3 Preparation of test solutions .10
10.2.4 Preparation of calibration solutions .11
10.3 Instrument analysis .11
10.4 Estimate of limits of detection (LODs) and limits of quantification (LOQs) . 12
10.4.1 Estimation of the instrumental limit of detection . 12
10.4.2 Estimation of the method limits of detection and limits of quantification . 12
10.5 Quality control . 12
10.5.1 Reagent blanks and laboratory blanks . 12
10.5.2 Quality control solutions . 12
10.5.3 Certified reference materials . 13
10.6 Measurement uncertainty . 13
11 Expression of results .13
12 Method performance . 14
iii
ISO/FDIS 21438-3:2025(en)
12.1 Sampling efficiency and sample storage .14
12.1.1 HF .14
12.1.2 Particulate fluorides .14
12.1.3 Humidity .14
12.2 Limit of quantification . 15
12.3 Upper limits of the measuring range . 15
12.4 Bias and precision . 15
12.4.1 Analytical bias . 15
12.4.2 Analytical precision . . . 15
12.5 Uncertainty of sampling and analysis method . 15
12.6 Interferences . 15
13 Test report .15
Annex A (informative) Temperature and pressure correction . 17
Annex B (informative) Filter materials .20
Bibliography .21
iv
ISO/FDIS 21438-3:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace
atmospheres.
This second edition cancels and replaces the first edition (ISO 21438-3:2010), which has been technically
revised.
The main changes are as follows:
— the normative references in Clause 2 has been updated;
— terms present in ISO 18158 have been removed from Clause 3;
— the reagents for electronically suppressed ion chromatography have been removed from Clause 6;
— Clause 8 has been reduced by referencing relevant standards;
— Figure 1 has been added.
A list of all parts in the ISO 21438 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO/FDIS 21438-3:2025(en)
Introduction
The health of workers in many industries is at risk through exposure by inhalation of hydrofluoric acid
and particulate fluorides. Industrial hygienists and other public health professionals need to determine
the effectiveness of measures taken to control workers' exposure, and this is generally achieved by making
workplace air measurements. This document provides a method for making valid exposure measurements
for hydrofluoric acid and particulate fluorides in use in industry. It is intended for agencies concerned with
health and safety at work; industrial hygienists and other public health professionals; analytical laboratories;
industrial users of hydrofluoric acid and particulate fluorides, and their workers.
The execution of the provisions and the interpretation of the results obtained with the use of this document
are entrusted to appropriately qualified and experienced people.
vi
FINAL DRAFT International Standard ISO/FDIS 21438-3:2025(en)
Workplace atmospheres — Determination of inorganic acids
by ion chromatography —
Part 3:
Hydrofluoric acid and particulate fluorides
1 Scope
This document specifies a method for the determination of the time-weighted average mass concentration
of soluble particulate fluorides and hydrofluoric acid (HF) in workplace air by collection of the particulate
fluorides on a pre-filter and HF on an alkali-impregnated filter and analysis by ion chromatography.
This method is only applicable to determination of particulate fluorides that are soluble using the sample
preparation procedure specified.
For aerosol sampling, this method is applicable to the personal sampling of the inhalable fraction of airborne
particles, as defined in ISO 7708, and to static (area) sampling.
The method is applicable to the determination of masses of 0,005 mg to at least 1,25 mg of particulate
fluorides per sample and 0,015 mg to at least 1,2 mg of HF per sample.
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 3696, Water for analytical laboratory use — Specification and test methods
ISO 7708, Air quality — Particle size fraction definitions for health-related sampling
ISO 8655-1, Piston-operated volumetric apparatus — Part 1: Terminology, general requirements and user
recommendations
ISO 8655-2, Piston-operated volumetric apparatus — Part 2: Pipettes
ISO 8655-6, Piston-operated volumetric apparatus — Part 6: Gravimetric reference measurement procedure for
the determination of volume
ISO 18158, Workplace air — Terminology
ISO 20581:2016, Workplace air — General requirements for the performance of procedures for the measurement
of chemical agents
EN 13205, Workplace atmospheres — Assessment of performance of instruments for measurement of airborne
particles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18158 and the following apply.
ISO/FDIS 21438-3:2025(en)
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
blank solution
solution prepared by taking a reagent blank, laboratory blank or field blank through the same procedure
used for sample dissolution (3.5)
3.2
calibration blank solution
calibration solution (3.3) prepared without the addition of any working standard solution (3.9)
Note 1 to entry: The concentration of fluoride in the calibration blank solution is taken to be zero.
3.3
calibration solution
solution prepared by dilution of the working standard solution (3.9), containing an analyte at concentrations
that are suitable for use of the analytical instrument calibration blank
3.4
extraction solution
solvent or solution used to solubilise the analyte(s) of interest
3.5
sample dissolution
process of obtaining a solution containing fluoride from a sample, which can involve complete dissolution of
the sample
3.6
sample solution
solution prepared from a sample by the process of sample dissolution (3.5)
Note 1 to entry: A sample solution can require further operations, for example dilution, in order to produce a test
solution (3.8) that is ready for analysis.
3.7
stock standard solution
solution, used for preparation of the calibration solutions (3.3), containing fluoride at a certified concentration
that is traceable to national standards
3.8
test solution
blank solution (3.1) or sample solution (3.6) that has been subjected to all operations required to bring it into
a state in which it is ready for analysis
Note 1 to entry: The blank test solution is the blank solution and the sample test solution is the sample solution if these
solutions are not subjected to any further operations before analysis.
3.9
working standard solution
solution, prepared by dilution of the stock standard solution (3.7), that contains fluoride at a concentration
that is better suited for preparation of calibration solutions (3.3) than the concentration of fluoride in the
stock standard solution
4 Principle
A known volume of air is drawn through a pre-filter and an alkali-impregnated filter mounted in an inhalable
sampler (7.1.1) to collect particulate fluorides and HF. Particulate fluorides are collected on the pre-filter
and HF is collected on the alkali-impregnated filter.
ISO/FDIS 21438-3:2025(en)
The pre-filter and alkali-impregnated filter are extracted separately with water or eluent (see 10.2.1),
without heating, to solubilize the fluorides.
Aliquots of the sample solution are subjected to ion chromatography in order to separate the extracted
fluoride from other anions. Following this separation, fluoride is measured using a conductivity detector.
Analytical results are obtained by plotting the measured conductivity as a function of concentration. They
can be used for assessment of occupational exposure to fluorides and HF in air.
5 Requirement
The measuring procedure shall conform with the performance requirements for procedures for measuring
chemical agents in air given in ISO 20581.
6 Reagents
Use only reagents of recognized analytical grade and only water as specified in ISO 20581. It is advisable to
check the blank values of all chemicals before use.
NOTE The presence of acetate or formate in reagents can cause a significant interference on fluoride detection.
6.1 Water, from a purification system that delivers ultrapure water of grade 1 in accordance with the
requirements of ISO 3696.
NOTE State of art water purification systems deliver water of grade 1 with higher quality than specified in
ISO 3696 (e.g. resistivity greater than 18 MΩ·cm).
6.2 Sodium carbonate (Na CO ), anhydrous, with a mass fraction greater than 99,9 %.
2 3
6.3 Sodium carbonate impregnation solution, for impregnation of 37 mm diameter filters.
The solution concentration (in g/l) and impregnation volume (in μl) are given in Table 1 for cellulose ester
filters and for quartz fibre filters.
Table 1 — Solution concentration and impregnation volume
Filter type Solution concentration Impregnation volume Reference
g/l μl
Cellulose ester 79,5 240 [13]
Quartz fibre 50 500 [14]
Adjustments can be made to the solution concentration as needed; however, corresponding adjustments
to the impregnation volume are required to ensure that the amount of Na CO impregnated on the filter
2 3
remains the same.
6.4 Fluoride standard solutions.
6.4.1 Fluoride stock standard solution.
Use a commercial standard solution with a certificate of its concentration, for example 1 000 mg/l, traceable
to national standards. Observe the manufacturer's expiry date or recommended shelf-life. If necessary,
dilute the standard solution (e.g. from 1 000 mg/l to 100 mg/l) to prepare the stock solution.
6.4.2 Fluoride calibration solutions.
Pipette appropriate volumes of the stock solution to create the calibration. The calibration range shall be
in accordance with the measuring range described in ISO 20581:2016, 5.4.4. A multi-point (the number of
ISO/FDIS 21438-3:2025(en)
points to be consistent with the quality system of the laboratory) calibration shall be constructed within the
linear range of the analytical method.
6.4.3 Fluoride check standard.
Use a certified reference material (CRM) as described in 10.5.3 with a certificate of its concentration, for
example 100 mg/l for fluoride, traceable to national standards. Observe the manufacturer's expiry date or
recommended shelf life.
6.4.4 Fluoride check standard working solution.
The check-standard working solution should be in the middle of the calibration range. Pipette a proper
volume of fluoride check standard (6.3.3) to create a check standard with the water (6.1). Prepare this
solution fresh for every calibration. If necessary, create a check-standard working solution for fluoride
separately.
7 Apparatus
7.1 Sampling equipment
7.1.1 Samplers, designed to collect the inhalable fraction of airborne particles, suitable for mounting a
pre-filter and an alkali-impregnated filter separated by a spacer, manufactured from a material that does
not react with HF. The performance of samplers shall be in accordance with EN 13205 where specific size-
selective fractions are stipulated.
The operating instructions supplied by the manufacturer should be consulted to find out whether particulate
matter deposited on the internal surfaces of the sampler forms part of the sample.
If samplers have an internal filter cassette, this shall also be manufactured from a material that does not
react with HF.
NOTE 1 Materials which do not react with acids, from which samplers and internal filter cassettes can be
manufactured, include polytetrafluoroethylene (PTFE) and other fluorinated polymers, polyvinyl chloride (PVC),
polyethylene, polypropylene and polycarbonate.
NOTE 2 Some inhalable samplers are designed to collect the inhalable fraction of airborne particles on the filter and
any particulate matter deposited on the internal surfaces of the sampler is not of interest. Other inhalable samplers are
designed such that airborne particles which pass through the entry orifice(s) match the inhalable convention, in which
case particulate matter deposited on the internal surfaces of the sampler does form part of the sample. However, all
[20]
samplers collect particles on the inner surface of the sampler .
[12]
NOTE 3 CEN/TR 15230 gives examples of inhalable samplers with the potential to meet the requirements of EN
13205, including published reports on their performance.
NOTE 4 In general, personal samplers for collection of the inhalable fraction of airborne particles do not exhibit the
same size-selective characteristics if used for static sampling.
7.1.2 Filters, of a diameter suitable for use with the samplers (7.1.1).
7.1.2.1 Pre-filters, for sampling particulate fluorides, with a collection efficiency ≥99 % for particles with
a 0,3 µm diffusion diameter, manufactured from a material that does not react with HF.
Refer to Clause B.1 for guidance on suitable materials from which pre-filters can be manufactured.
7.1.2.2 Sampling filters, for sampling HF, impregnated with sodium carbonate, for example:
7.1.3 Spacers, of a diameter suitable for use with the samplers (7.1.1) for separating the pre-filters
(7.1.2.1) and HF sampling filters (7.1.2.2), manufactured from an inert material that does not react with the
ISO/FDIS 21438-3:2025(en)
acids and on which the acids are not adsorbed, for example polypropylene sleeves, PTFE-coated screens or
polystyrene rings.
[3]
7.1.4 Sampling pumps, according to ISO 13137 should be used.
If the sampling pump is used outside the range of conditions specified in ISO 13137 appropriate action should
be taken to ensure that the performance requirements are met. For instance, at sub-zero temperatures it
can be necessary to keep the pump warm.
7.1.5 Flowmeter, portable, with an accuracy that is sufficient to enable the volumetric flow rate to be
measured to within ± 5 %.
The calibration of the flowmeter shall be checked against a primary standard, i.e. a flowmeter whose
accuracy is traceable to national standards. If appropriate (see 9.1.3), record the atmospheric temperature
and pressure at which the calibration of the flowmeter was checked.
It is advisable that the flowmeter used is capable of measuring the volumetric flow rate to within ±2 % or better.
7.1.6 Ancillary equipment:
— flexible tubing, for example silicone of an outer diameter of 10 mm and an inner diameter of 6 mm for
making a leakproof connection from the samplers to the sampling pumps without compressing as a
result of the pressure difference between ambient atmosphere and the in-line vacuum at the used flow
−1
rate of 1 l min ;
— belts or harnesses, which the sampling pump can conveniently fix for personal sampling;
— tweezers, manufactured from or tipped with PTFE, for handling filters;
— filter transport cassettes, or similar, if required (see 9.5), in which to transport samples to the laboratory;
— thermometer, of range 0 °C to 50 °C, graduated in divisions of at least 1 °C or less, for the measurement of
atmospheric temperature; for applications at temperatures below freezing, the range of the thermometer
shall extend to the appropriate desired range;
— barometer, suitable for measurement of atmospheric pressure, if required.
7.2 Laboratory apparatus
CAUTION — Fluorides are found ubiquitously in the environment. This can lead to elevated blanks so
it is especially important to take great care that all disposable plastic labware is checked for fluoride
contamination and that all reusable laboratory apparatus is thoroughly clean before use.
7.2.1 Disposable gloves, impermeable, to avoid the possibility of contamination from the hands and to
protect them from contact with toxic and corrosive substances. PVC gloves are suitable.
7.2.2 Plastic labware:
— one-mark volumetric flasks, e.g. example polymethylpentene (PMP);
— screw-cap polyethylene vessels, proper for the extraction of collected sample filters;
— beakers, of appropriate capacity;
— disposable membrane filters, of PTFE, with pore size of 0,45 µm, for use in ion chromatography;
— disposable syringes, of appropriate capacity, appropriate needles;
— autosampler vials, of appropriate capacity.
ISO/FDIS 21438-3:2025(en)
7.2.3 Piston-operated volumetric instruments, of capacities of 50 µl to 10 ml, conforming with the
requirements of ISO 8655-1 and tested in accordance with ISO 8655-6; pipettors conforming with the
requirements of ISO 8655-2, as an alternative to one-mark pipettes for the preparation of standard solutions,
calibration solutions and dilution of samples.
7.2.4 Ultrasonic bath, preferably with a timer, suitable for use in the ultrasonic extraction method for
soluble particulate fluorides and hydrofluoric acid.
7.2.5 Ion chromatograph, having the following listed components inclusive. Components and tubing that
come into contact with the sample solution or eluent shall, as far as possible, be comprising inert materials,
e.g. polyetheretherketone (PEEK):
— pump, capable of delivering a constant flow within the range 0,1 ml/min to 5 ml/min at a pressure of
15 MPa to 150 MPa;
— eluent generation system, for producing an eluent suitable for use with the selected separator column, as
an alternative to use of a manually prepared eluent (e.g. see Reference [15]);
— sample injection system, comprising a low dead-volume, non-metallic valve fitted with a sample loop, for
injecting the sample solution into the eluent stream;
— guard and separator column, packed with high capacity pellicular anion exchange resin, suitable for
resolving fluorides from other inorganic anions;
— suppressor module (chemically suppressed or electronically suppressed) for ion chromatography,
suitable for use with the separator column;
— conductivity detector, flow through, low volume, with a non-metallic flow path.
8 Occupational exposure assessment
[10] [9]
Refer to relevant ISO 20581, EN 689 , and ASTM E1370 for guidance on how to develop an appropriate
assessment strategy and for general guidance on measurement strategy.
9 Sampling
9.1 Preliminary considerations
9.1.1 Selection and use of samplers
Select samplers (7.1.1) in accordance with the requirements of the applicable limit value. Size selective
samplers shall collect the appropriate fraction of airborne particles as defined in ISO 7708 and confirmed
by testing (e.g. using EN 13205). If possible, the samplers selected should be manufactured from conducting
material, since samplers manufactured from non-conducting material have electrostatic properties that can
influence representative sampling.
Use the samplers at their design flow rate and in accordance with the instructions provided by the
[12]
manufacturer. See CEN/TR 15230 for further guidance.
NOTE Excessive flowrate leads to a decrease in the collection efficiency of HF vapour.
9.1.2 Sampling period
Select a sampling period that is appropriate for the measurement task (see Clause 8) but ensure that it is
long enough to enable particulate fluorides and HF to be determined with acceptable uncertainty at levels
of industrial hygiene significance. When high concentrations of airborne particles are anticipated, select
a sampling period that is not so long as to risk overloading the filter with particulate matter. For example,
estimate the minimum sampling time, t , in minutes, required to ensure that the amount collected is above
min
ISO/FDIS 21438-3:2025(en)
the lower limit of the measuring range of the analytical method when particulate fluorides or HF are present
in the test atmosphere at the appropriate multiple of its limit value (i.e. 0,1 times for an 8 h time-weighted
average limit value or 0,5 times for a short-term limit value), using Formula (1):
m
LOQ
t = (1)
min
××
qk ρ
V
LV
where
t is the minimum sampling time, in minutes;
min
m is the limit of quantification, given as the mass of the analyte on the sampling substrate, in
LOQ
micrograms;
q is the design flow rate, in litres per minute, of the sampler;
V
k is the appropriate multiple of the limit value;
ρ is the limit value, in milligrams per cubic metre.
LV
NOTE k is a variable depending on the source of the limit value. For example, k is 0,1 in France for an 8 h time-
weighted average limit value and for a short-term limit value. In Germany, k is 0,1 times for an 8 h time-weighted
average limit value but 0,5 times for a short-term limit value.
If the minimum sampling time is not short enough for the method to be useful for the intended measurement
task, consider the possibility of using a sampler designed to be used at a higher flow rate.
When high concentrations of airborne particles are anticipated, select a sampling period that is not so long
as to risk overloading the pre-filter with particulate matter.
When a high concentration of HF is anticipated, select a sampling period that is not so long as to risk
exceeding the maximum sampling capacity of the HF sampling filter. See References [13] and [14].
9.1.3 Effect of temperature and pressure on flow rate measurements
Refer to the manufacturer’s instructions to determine whether the indicated volumetric flow rate of the
flowmeter (7.1.5) is dependent upon temperature and pressure. Consider whether the difference between
the atmospheric temperature and pressure at the time of calibration of the flowmeter and during sampling
is likely to be great enough to justify making a correction to take this into account, for example, if the error
can be greater than ±5 %. If a correction is necessary, measure and record the atmospheric temperature and
pressure at which the calibration of the flowmeter was checked, and measure and record the atmospheric
temperature and pressure at the start and at the end of the sampling period (see 9.4).
NOTE An example of temperature and pressure correction for the indicated volumetric flow rate is given in
Clause A.1 for a constant pressure drop, variable area flowmeter.
Consider whether it is necessary to recalculate the concentration of particulate fluorides and HF in air to
[1]
reference conditions (see ISO 8756 ). If so, measure and record the atmospheric temperature and pressure
at the start and at the end of the sampling period (see 9.4) and use the formula given in Clause A.2 to apply
the necessary correction.
The concentration of HF in air is generally stated for actual environmental conditions (temperature,
pressure) at the workplace. If the concentration is to be compared with occupational exposure limit values
that are referenced at normal temperature and pressure, then the concentration should be stated at normal
temperature and pressure.
9.1.4 Sample handling
To minimize the risk of damage or contamination, only handle the pre-filters, HF sampling filters and spacers
in a clean area where the concentration of HF and particulate fluorides in air is as low as possible and only
handle filters using tweezers.
ISO/FDIS 21438-3:2025(en)
9.2 Preparation for sampling
9.2.1 Cleaning of samplers
Clean the samplers (7.1.1) before use. Dismantle the samplers, soak in detergent solution, rinse thoroughly
with water (7.1.3), wipe with absorbent tissue and allow to dry before reassembling. Alternatively, use a
laboratory washing machine.
NOTE Some samplers are single use and disposable and do not require cleaning before use.
9.2.2 Loading the samplers with filters
Load each clean sampler first with an impregnated sampling filter (7.1.2.2), then with a pre-filter (7.1.2.1),
separated with a spacer (7.1.3). A spacer can also be placed behind the HF sampling filter to support it.
Ensure that the configuration in which the filters are loaded leads to the sampled air passing first through
the pre-filter and then through the impregnated filter (see Figure 1). Label each sampler so that it can be
uniquely identified and seal with its protective cover or plug to prevent contamination.
Key
1 pre-filter
2 spacer (required)
3 impregnated sampling filter
4 spacer (optional)
5 direction of air flow through the sampler
Figure 1 — Filter loading configuration
9.2.3 Setting the volumetric flow rate
Perform the following in a clean area, where the concentrations of particulate fluorides and HF are minimal.
Connect each loaded sampler to a sampling pump (7.1.4) using flexible tubing (7.1.6), ensuring that no leaks
can occur. Remove the protective cover or plug from each sampler, switch on the sampling pump, attach the
flowmeter (7.1.5) to the sampler so that it measures the flow through the sampler inlet orifice(s) and set the
required volumetric flow rate. Switch off the sampling pump and seal the sampler with its protective cover
or plug to prevent contamination during transport to the sampling position.
If necessary, allow the sampling pump operating conditions to stabilize before setting the volumetric flow rate.
9.2.4 Field blanks
Retain as blanks one unused assembled sampler from each batch of 10 prepared, subject to a minimum of
three. Treat these in the same manner as those used for sampling in respect of storage and transport to and
from the sampling position but draw no air through the filters.
ISO/FDIS 21438-3:2025(en)
9.3 Sampling position
9.3.1 Personal sampling
Position the sampler in the worker's breathing zone, as close to the mouth and nose as is reasonably
practicable, for example fastened to the worker's lapel. Attach the sampling pump to the worker in a manner
that causes minimum inconvenience (e.g. to a belt around the waist) or place it in a convenient pocket.
Give consideration to whether the nature of the process is likely to result in a significant difference between
the actual exposure of the worker and the concentration of particulate fluorides and HF measured by a
sampler mounted on the lapel. If this is the case, make special arrangements to mount the sampler as close
as possible to the worker's nose and mouth.
9.3.2 Static sampling
If static sampling is carried out to assess the exposure of a worker in a situation where personal sampling
is not possible, position the sampler in the immediate vicinity of the worker and at breathing height. If in
doubt, take the sampling position to be the point where the risk of exposure is considered to be greatest.
If static sampling is carried out to characterize the background level of particulate fluorides and HF in the
workplace, select a sampling position that is sufficiently remote from the work processes, such that results
are not directly affected by particulate fluorides and HF from emission sources.
9.4 Collection of samples
When ready to begin sampling, remove the protective cover or plug from the sampler and switch on the
sampling pump. Record the time and volumetric flow rate at the sta
...
ISO/DISFDIS 21438-3:2025(en)
ISO/TC 146/SC 2 N1354
Secretariat: ANSI
Date: 2025-09-15
Workplace atmospheres — Determination of inorganic acids by
ion chromatography —
Part 3:
Hydrofluoric acid and particulate fluorides
Second edition
2025-01-10
ISO #####-#:####(X)
Air des lieux de travail — Détermination des acides inorganiques par chromatographie ionique —
Partie 3: Acide fluorhydrique et fluorures particulaires
FDIS stage
2 © ISO #### – All rights reserved
ISO/FDIS 21438-3:2025(en)
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'sISO’s member body in the country of the requester.
ISO Copyright Office copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email: E-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland.
iii
ISO/FDIS 21438-3:2025(en)
Contents
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 3
5 Requirement . 3
6 Reagents . 3
7 Apparatus . 4
7.1 Sampling equipment . 4
7.2 Laboratory apparatus . 6
8 Occupational exposure assessment . 7
9 Sampling . 7
9.1 Preliminary considerations . 7
9.2 Preparation for sampling . 8
9.3 Sampling position . 10
9.4 Collection of samples . 10
9.5 Transportation . 11
10 Analysis . 11
10.1 General. 11
10.2 Preparation of test and calibration solutions . 11
10.3 Instrument analysis . 12
10.4 Estimate of limits of detection (LODs) and limits of quantification (LOQs) . 13
10.5 Quality control . 13
10.6 Measurement uncertainty . 14
11 Expression of results . 15
12 Method performance . 16
12.1 Sampling efficiency and sample storage . 16
12.2 Limit of quantification . 17
12.3 Upper limits of the measuring range . 17
12.4 Bias and precision . 17
12.5 Uncertainty of sampling and analysis method . 17
12.6 Interferences . 17
13 Test report . 17
Annex A (informative) Temperature and pressure correction . 20
Annex B (informative) Filter materials . 26
Bibliography . 27
iv
ISO/FDIS 21438-3:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO documentsdocument should be noted. This document was drafted in accordance with the editorial rules
of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace
atmospheres.
This second edition cancels and replaces the first edition (ISO 21438-3:2010), which has been technically
revised.
The main changes are as follows:
—
— — the normative references in 2Clause 2 has been updated;
— — terms present in ISO 18158 have been removed from 3Clause 3;;
— — the reagents for electronically suppressed ion chromatography have been removed from 6Clause 6;;
— 8— Clause 8 has been reduced by referencing relevant standards;
— Figure 1— Figure 1 has been added.
A list of all parts in the ISO 21438 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO/FDIS 21438-3:2025(en)
Introduction
The health of workers in many industries is at risk through exposure by inhalation of hydrofluoric acid and
particulate fluorides. Industrial hygienists and other public health professionals need to determine the
effectiveness of measures taken to control workers' exposure, and this is generally achieved by making
workplace air measurements. This document provides a method for making valid exposure measurements for
hydrofluoric acid and particulate fluorides in use in industry. It is intended for agencies concerned with health
and safety at work; industrial hygienists and other public health professionals; analytical laboratories;
industrial users of hydrofluoric acid and particulate fluorides, and their workers.
The execution of the provisions and the interpretation of the results obtained with the use of this document
are entrusted to appropriately qualified and experienced people.
vi
ISO/FDIS 21438-3:2025(en)
Workplace atmospheres — Determination of inorganic acids by ion
chromatography —
Part 3:
Hydrofluoric acid and particulate fluorides
1 Scope
This document specifies a method for the determination of the time-weighted average mass concentration of
soluble particulate fluorides and hydrofluoric acid (HF) in workplace air by collection of the particulate
fluorides on a pre-filter and HF on an alkali-impregnated filter and analysis by ion chromatography.
This method is only applicable to determination of particulate fluorides that are soluble using the sample
preparation procedure specified.
For aerosol sampling, this method is applicable to the personal sampling of the inhalable fraction of airborne
particles, as defined in ISO 7708, and to static (area) sampling.
The method is applicable to the determination of masses of 0,005 mg to at least 1,25 mg of particulate fluorides
per sample and 0,015 mg to at least 1,2 mg of HF per sample.
The concentration range of particulate fluorides and HF in air for which the measuring procedure is applicable
is determined by the sampling method selected by the user. For a 120 l air sample, the measuring range is
3 3 3
approximately 0,04 mg/m to at least 10 mg/m for particulate fluorides and approximately 0,13 mg/m to at
least 10 mg/m for HF.
HF can react with co-sampled particulate matter on the pre-filter, causing an interference on the measured
concentration.
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 3696, Water for analytical laboratory use — Specification and test methods
ISO 7708, Air quality — Particle size fraction definitions for health-related sampling
ISO 8655--1, Piston-operated volumetric apparatus — Part 1: Terminology, general requirements and user
recommendations
ISO 8655--2, Piston-operated volumetric apparatus — Part 2: Pipettes
ISO 8655--6, Piston-operated volumetric apparatus — Part 6: Gravimetric reference measurement procedure for
the determination of volume
ISO 18158, Workplace air — Terminology
ISO 20581:2016, Workplace air — General requirements for the performance of procedures for the
measurement of chemical agents
ISO/FDIS 21438-3:2025(en)
EN 13205, Workplace atmospheres — Assessment of performance of instruments for measurement of airborne
particles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18158 and the following 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 3.1
blank solution
solution prepared by taking a reagent blank, laboratory blank or field blank through the same procedure used
for sample dissolution (3.5(3.5))
3.2 3.2
calibration blank solution
calibration solution (3.3(3.3)) prepared without the addition of any working standard solution (3.9(3.9))
Note 1 to entry: The concentration of fluoride in the calibration blank solution is taken to be zero.
3.3 3.3
calibration solution
solution prepared by dilution of the working standard solution (3.9(3.9),), containing an analyte at
concentrations that are suitable for use of the analytical instrument calibration blank
3.4 3.4
extraction solution
solvent or solution used to solubilise the analyte(s) of interest
3.5 3.5
sample dissolution
process of obtaining a solution containing fluoride from a sample, which can involve complete dissolution of
the sample
3.6 3.6
sample solution
solution prepared from a sample by the process of sample dissolution (3.5(3.5))
Note 1 to entry: A sample solution can require further operations, for example dilution, in order to produce a test solution
(3.8(3.8)) that is ready for analysis.
3.7 3.7
stock standard solution
solution, used for preparation of the calibration solutions (3.3(3.3),), containing fluoride at a certified
concentration that is traceable to national standards
3.8 3.8
test solution
blank solution (3.1(3.1)) or sample solution (3.6(3.6)) that has been subjected to all operations required to
bring it into a state in which it is ready for analysis
ISO/FDIS 21438-3:2025(en)
Note 1 to entry: The blank test solution is the blank solution and the sample test solution is the sample solution if these
solutions are not subjected to any further operations before analysis.
3.9 3.9
working standard solution
solution, prepared by dilution of the stock standard solution (3.7(3.7),), that contains fluoride at a
concentration that is better suited for preparation of calibration solutions (3.3(3.3)) than the concentration of
fluoride in the stock standard solution
4 Principle
A known volume of air is drawn through a pre--filter and an alkali-impregnated filter mounted in an inhalable
sampler (7.1.1(7.1.1)) to collect particulate fluorides and HF. Particulate fluorides are collected on the pre--
filter and HF is collected on the alkali-impregnated filter.
The pre--filter and alkali-impregnated filter are extracted separately with water or eluent (see 10.2.110.2.1),),
Commented [JS1]: This subclause number does not
without heating, to solubilize the fluorides. exist. Please review and revise.
Commented [MB2R1]: Changed to 10.2.1
Aliquots of the sample solution are subjected to ion chromatography in order to separate the extracted
fluoride from other anions. Following this separation, fluoride is measured using a conductivity detector.
Analytical results are obtained by plotting the measured conductivity as a function of concentration. They can
be used for assessment of occupational exposure to fluorides and HF in air.
5 Requirement
The measuring procedure shall conform with the performance requirements for procedures for measuring
chemical agents in air given in ISO 20581.
6 Reagents
Use only reagents of recognized analytical grade and only water as specified in ISO 20581. It is advisable to
check the blank values of all chemicals before use.
NOTE The presence of acetate or formate in reagents can cause a significant interference on fluoride detection. It is
therefore advisable to check that all reagents to be used have a negligible acetate and formate content.
6.1 6.1 Water, from a purification system that delivers ultrapure water of grade 1 in accordance with
the requirements of ISO 3696.
NOTE State of art water purification systems deliver water of grade 1 with higher quality than specified in ISO 3696
(e.g. resistivity greater than 18 MΩ•·cm).
6.2 6.2 Sodium carbonate (Na2CO3), anhydrous, with a mass fraction greater than 99,9 % mass
fraction.%.
6.3 6.2.1 Sodium carbonate impregnation solution, for impregnation of 37 mm diameter filters.
SolutionThe solution concentration (in g/l) and impregnation volume (in μl) are given in Table 1Table 1 for
cellulose ester filters and for quartz fibre filters.
ISO/FDIS 21438-3:2025(en)
Table 1 — Solution concentration and impregnation volume
Filter type Solution concentration Impregnation volume Reference
g/l μl
Cellulose ester 79,5 240 [0[14]]
Quartz fibre 50 500 [0[15]]
Adjustments can be made to the solution concentration as needed; however, corresponding adjustments to
the impregnation volume are required to ensure that the amount of Na CO impregnated on the filter remains
2 3
the same.
6.4 6.3 Fluoride standard solutions.
6.4.1 6.3.1 Fluoride stock standard solution.
Use a commercial standard solution with a certificate of its concentration, for example 1 000 mg/l, traceable
to national standards. Observe the manufacturer's expiry date or recommended shelf-life. If necessary, dilute
the standard solution (e.g. from 1 000 mg/l to 100 mg/l) to prepare the stock solution.
6.4.2 6.3.2 Fluoride calibration solutions.
Pipette appropriate volumes of the stock solution to create the calibration. The calibration range shall be in
accordance with the measuring range described in ISO 20581:2016, 5.4.4. A multi-point (the number of points
to be consistent with the quality system of the laboratory) calibration shall be constructed within the linear
range of the analytical method.
6.4.3 6.3.3 Fluoride check standard.
Use a Certified Reference Materialcertified reference material (CRM) as described in 10.5.3 10.5.3 with a
certificate of its concentration, for example 100 mg/l for fluoride, traceable to national standards. Observe the
manufacturer's expiry date or recommended shelf life.
6.4.4 6.3.4 Fluoride check standard working solution.
The check-standard working solution should be in the middle of the calibration range. Pipette a proper volume
of fluoride check standard (6.3.3) to create a check standard with the water (6.1(6.1).). Prepare this solution
fresh for every calibration. If necessary, create a check-standard working solution for fluoride separately.
7 Apparatus
7.1 Sampling equipment
7.1.1 7.1.1 Samplers, designed to collect the inhalable fraction of airborne particles, suitable for mounting
a pre-filter and an alkali-impregnated filter separated by a spacer, manufactured from a material that does not
[11]
react with HF. The performance of samplers shall be in accordance with EN 13205 where specific size-
selective fractions are stipulated.
The operating instructions supplied by the manufacturer should be consulted to find out whether particulate
matter deposited on the internal surfaces of the sampler forms part of the sample.
If samplers have an internal filter cassette, this shall also be manufactured from a material that does not react
with HF.
ISO/FDIS 21438-3:2025(en)
NOTE 1 Materials which do not react with acids, from which samplers and internal filter cassettes can be
manufactured, include polytetrafluoroethylene (PTFE) and other fluorinated polymers, polyvinyl chloride (PVC),
polyethylene, polypropylene and polycarbonate.
NOTE 2 Some inhalable samplers are designed to collect the inhalable fraction of airborne particles on the filter, and
any particulate matter deposited on the internal surfaces of the sampler is not of interest. Other inhalable samplers are
designed such that airborne particles which pass through the entry orifice(s) match the inhalable convention, in which
case particulate matter deposited on the internal surfaces of the sampler does form part of the sample. However, all
[ ]
samplers collect particles on the inner surface of the sampler 0 [21]. .
[ [13]]
NOTE 3 CEN/TR 15230 0 gives examples of inhalable samplers with the potential to meet the requirements of EN
[11]
13205, , including published reports on their performance.
NOTE 4 In general, personal samplers for collection of the inhalable fraction of airborne particles do not exhibit the
same size-selective characteristics if used for static sampling.
7.1.2 7.1.2 Filters, of a diameter suitable for use with the samplers (7.1.1(7.1.1).).
7.1.2.1 7.1.2.1 Pre-filters, for sampling particulate fluorides, with a collection
efficiency ≥99 % for particles with a 0,3 µm diffusion diameter, manufactured from a material that does not
react with HF.
Refer to Clause B.1Clause B.1 for guidance on suitable materials from which pre--filters can be manufactured.
7.1.2.2 7.1.2.2 Sampling filters, for sampling HF, impregnated with sodium carbonate, for
example 37 mm diameter cellulose nitrate filters impregnated with 240 µl of 79,5 g/l sodium
carbonate solution (6.2.1) (see Reference [14]), dried in a desiccator for a minimum of 8 h; or 37 mm
diameter binder-free quartz fibre filters impregnated with 500 µl of 50 g/l sodium carbonate solution
(6.2.1) (see Reference [15]).:
7.1.3 7.1.3 Spacers, of a diameter suitable for use with the samplers (7.1.1(7.1.1)) for separating the pre--
filters (7.1.2.1(7.1.2.1)) and HF sampling filters (7.1.2.2(7.1.2.2),), manufactured from an inert material that
does not react with the acids and on which the acids are not adsorbed, for example polypropylene sleeves,
PTFE-coated screens or polystyrene rings.
[ [3]]
7.1.4 7.1.4 Sampling pumps, according to ISO 13137 0 should be used.
If the sampling pump is used outside the range of conditions specified in ISO 13137 appropriate action should
be taken to ensure that the performance requirements are met. For instance, at sub-zero temperatures it can
be necessary to keep the pump warm.
7.1.5 7.1.5 Flowmeter, portable, with an accuracy that is sufficient to enable the volumetric flow rate to
be measured to within ± ± 5 %.
The calibration of the flowmeter shall be checked against a primary standard, i.e. a flowmeter whose accuracy
is traceable to national standards. If appropriate (see 9.1.39.1.3),), record the atmospheric temperature and
pressure at which the calibration of the flowmeter was checked.
It is advisable that the flowmeter used beis capable of measuring the volumetric flow rate to within ±2 % or
better.
7.1.6 7.1.6 Ancillary equipment:
— — Flexibleflexible tubing, for example silicone of an outer diameter of 10 mm and an inner diameter of
6 mm for making a leakproof connection from the samplers to the sampling pumps without compressing
as a result of the pressure difference between ambient atmosphere and the in-line vacuum at the used flow
−1
rate of 1 l min .;
ISO/FDIS 21438-3:2025(en)
— — Beltsbelts or harnesses, which the sampling pump can conveniently fix for personal sampling.;
— — Tweezerstweezers, manufactured from or tipped with PTFE, for handling filters.;
— — Filterfilter transport cassettes, or similar, if required (see 9.59.5),), in which to transport samples to
the laboratory.;
— — Thermometerthermometer, of range 0 °C to 50 °C, graduated in divisions of at least 1 °C or less, for the
measurement of atmospheric temperature. For; for applications at temperatures below freezing, the range
of the thermometer shall extend to the appropriate desired range.;
— — Barometerbarometer, suitable for measurement of atmospheric pressure, if required.
7.2 Laboratory apparatus
CAUTION — Fluorides are found ubiquitously in the environment. This can lead to elevated blanks so
it is especially important to take great care that all disposable plastic labware is checked for fluoride
contamination and that all reusable laboratory apparatus is thoroughly clean before use.
7.2.1 7.2.1 Disposable gloves, impermeable, to avoid the possibility of contamination from the hands and
to protect them from contact with toxic and corrosive substances. PVC gloves are suitable.
7.2.2 7.2.2 Plastic labware.:
— — Oneone-mark volumetric flasks, fore.g. example polymethylpentene (PMP));
— — Screwscrew-cap polyethylene vessels, proper for the extraction of collected sample filters.;
— — Beakersbeakers, of appropriate capacity.;
— — Disposabledisposable membrane filters, of PTFE, ofwith pore size of 0,45 µm, for use in ion
chromatography.;
— — Disposabledisposable syringes, of appropriate capacity, appropriate needles.;
— — Autosamplerautosampler vials, of appropriate capacity.
7.2.3 7.2.3 Piston-operated volumetric instruments, of capacities of 50 µl to 10 ml, conforming with
the requirements of ISO 8655-1, and tested in accordance with ISO 8655-6; pipettors, conforming with the
requirements of ISO 8655-2, as an alternative to one-mark pipettes for the preparation of standard solutions,
calibration solutions and dilution of samples.
7.2.4 7.2.4 Ultrasonic bath, preferably with a timer, suitable for use in the ultrasonic extraction method
for soluble particulate fluorides and hydrofluoric acid.
7.2.5 7.2.5 Ion chromatograph, having the following listed components inclusive. Components and
tubing that come into contact with the sample solution or eluent shall, as far as possible, be comprised
ofcomprising inert materials, for examplee.g. polyetheretherketone (PEEK).):
— — Pumppump, capable of delivering a constant flow within the range 0,1 ml/min to 5 ml/min at a
pressure of 15 MPa to 150 MPa.;
— — Eluenteluent generation system, for producing an eluent suitable for use with the selected separator
column, as an alternative to use of a manually prepared eluent (e.g. see Reference [0[16]).]);
— — Samplesample injection system, comprising a low dead-volume, non-metallic valve fitted with a
sample loop, for injecting the sample solution into the eluent stream.;
ISO/FDIS 21438-3:2025(en)
— — Guardguard and separator column, packed with high capacity pellicular anion exchange resin, suitable
for resolving fluorides from other inorganic anions.;
— — Suppressorsuppressor module (chemically suppressed or electronically suppressed) for ion
chromatography, suitable for use with the separator column.;
— — Conductivityconductivity detector, flow through, low volume, with a non-metallic flow path.
8 Occupational exposure assessment
[ [10]] [ [9]]
Refer to relevant ISO 20581, EN 689 0, , and ASTM E1370 0 for guidance on how to develop an
appropriate assessment strategy and for general guidance on measurement strategy.
9 Sampling
9.1 Preliminary considerations
9.1.1 Selection and use of samplers
Select samplers (7.1.1(7.1.1) according to) in accordance with the requirements of the applicable limit value.
Size selective samplers shall collect the appropriate fraction of airborne particles as defined in ISO 7708 and
[11]
confirmed by testing (e.g. using EN 13205 ).). If possible, the samplers selected should be manufactured
from conducting material, since samplers manufactured from non-conducting material have electrostatic
properties that can influence representative sampling.
Use the samplers at their design flow rate and in accordance with the instructions provided by the
[ [13]]
manufacturer. See CEN/TR 15230 0 for further guidance.
NOTE Excessive flowrate leads to a decrease in the collection efficiency of HF vaporvapour.
9.1.2 Sampling period
Select a sampling period that is appropriate for the measurement task (see Error! Reference source not
found.Clause 8)) but ensure that it is long enough to enable particulate fluorides and HF to be determined
with acceptable uncertainty at levels of industrial hygiene significance. When high concentrations of airborne
particles are anticipated, select a sampling period that is not so long as to risk overloading the filter with
particulate matter. For example, estimate the minimum sampling time, t , in minutes, required to ensure that
min
the amount collected is above the lower limit of the measuring range of the analytical method when particulate
fluorides or HF are present in the test atmosphere at the appropriate multiple of its limit value (i.e. 0,1 times
for an 8 h time-weighted average limit value or 0,5 times for a short-term limit value), using Error! Reference
source not found.Formula (1)::
(1)
𝑚
LOQ
𝑡 = (1)
min
𝑞 × 𝑘 × 𝜌
V
LV
where
t is the minimum sampling time, in minutes;
min
m is the limit of quantification, given as mass of the analyte on the sampling substrate, in
LOQ
micrograms;
q is design flow rate, in litres per minute, of the sampler;
V
ISO/FDIS 21438-3:2025(en)
k is the appropriate multiple of the limit value;
ρLV is the limit value, in milligrams per cubic metre.
tmin is the minimum sampling time, in minutes;
mLOQ is the limit of quantification, given as the mass of the analyte on the sampling substrate, in micrograms;
qV is the design flow rate, in litres per minute, of the sampler;
k is the appropriate multiple of the limit value;
ρ is the limit value, in milligrams per cubic metre.
LV
NOTE k is a variable depending on the source of the limit value. For example, k is 0,1 in France for an 8 h time-
weighted average limit value and for a short-term limit value. In Germany, k is 0,1 times for an 8 h time-weighted average
limit value but 0,5 times for a short-term limit value.
If the minimum sampling time is not short enough for the method to be useful for the intended measurement
task, consider the possibility of using a sampler designed to be used at a higher flow rate.
When high concentrations of airborne particles are anticipated, select a sampling period that is not so long as
to risk overloading the pre-filter with particulate matter.
When a high concentration of HF is anticipated, select a sampling period that is not so long as to risk exceeding
the maximum sampling capacity of the HF sampling filter. See References [0[14]] and [0[15].].
9.1.3 Effect of temperature and pressure on flow rate measurements
Refer to the manufacturer’s instructions to determine whether the indicated volumetric flow rate of the
flowmeter (7.1.5(7.1.5)) is dependent upon temperature and pressure. Consider whether the difference
between the atmospheric temperature and pressure at the time of calibration of the flowmeter and during
sampling is likely to be great enough to justify making a correction to take this into account, for example, if the
error can be greater than ±5 %. If a correction is necessary, measure and record the atmospheric temperature
and pressure at which the calibration of the flowmeter was checked, and measure and record the atmospheric
temperature and pressure at the start and at the end of the sampling period (see 9.49.4).).
NOTE 1 An example of temperature and pressure correction for the indicated volumetric flow rate is given in
Clause A.1Clause A.1 for a constant pressure drop, variable area flowmeter.
Consider whether it is necessary to recalculate the concentration of particulate fluorides and (HF) in air to
[ [1] ]
reference conditions (see ISO 8756 0 ). ). If so, measure and record the atmospheric temperature and
pressure at the start and at the end of the sampling period (see 9.49.4)) and use the formula given in
Clause A.2Clause A.2 to apply the necessary correction.
NOTE 2 The concentration of HF in air is generally stated for actual environmental conditions
(temperature, pressure) at the workplace. If the concentration is to be compared with occupational exposure
limit values that are referenced at normal temperature and pressure, then the concentration should be stated
at normal temperature and pressure.
9.1.4 Sample handling
To minimize the risk of damage or contamination, only handle the pre--filters, HF sampling filters, and spacers
in a clean area where the concentration of HF and particulate fluorides in air is as low as possible and only
handle filters using tweezers.
ISO/FDIS 21438-3:2025(en)
9.2 Preparation for sampling
9.2.1 Cleaning of samplers
Clean the samplers (7.1.1(7.1.1)) before use. Dismantle the samplers, soak in detergent solution, rinse
thoroughly with water (7.1.3(7.1.3),), wipe with absorbent tissue and allow to dry before reassembling.
Alternatively, use a laboratory washing machine.
NOTE Some samplers are single use and disposable and do not require cleaning before use.
9.2.2 Loading the samplers with filters
Load each clean sampler first with an impregnated sampling filter (7.1.2.2(7.1.2.2),), then with a pre--filter
(7.1.2.1(7.1.2.1),), separated with a spacer (7.1.3(7.1.3).). A spacer can also be placed behind the HF sampling
filter to support it. Ensure that the configuration in which the filters are loaded leads to the sampled air passing
first through the pre-filter and then through the impregnated filter (see Figure 1Figure 1).). Label each
sampler so that it can be uniquely identified and seal with its protective cover or plug to prevent
contamination.
Key
1 pre-filter
2 spacer (required)
3 impregnated sampling filter
4 spacer (optional)
5 direction of air flow through the sampler
1 pre-filter
2 spacer (required)
3 impregnated sampling filter
4 spacer (optional)
5 direction of air flow through the sampler
Figure 1 — Filter loading configuration
9.2.3 Setting the volumetric flow rate
Perform the following in a clean area, where the concentrations of particulate fluorides and HF are minimal.
ISO/FDIS 21438-3:2025(en)
Connect each loaded sampler to a sampling pump (7.1.4(7.1.4)) using flexible tubing (7.1.6(7.1.6),), ensuring
that no leaks can occur. Remove the protective cover or plug from each sampler, switch on the sampling pump,
attach the flowmeter (7.1.5(7.1.5)) to the sampler so that it measures the flow through the sampler inlet
orifice(s) and set the required volumetric flow rate. Switch off the sampling pump and seal the sampler with
its protective cover or plug to prevent contamination during transport to the sampling position.
If necessary, allow the sampling pump operating conditions to stabilize before setting the volumetric flow rate.
9.2.4 Field blanks
Retain as blanks one unused assembled sampler from each batch of 10 prepared, subject to a minimum of
three. Treat these in the same manner as those used for sampling in respect of storage and transport to and
from the sampling position but draw no air through the filters.
9.3 Sampling position
9.3.1 Personal sampling
Position the sampler in the worker's breathing zone, as close to the mouth and nose as is reasonably
practicable, for example fastened to the worker's lapel. Attach the sampling pump to the worker in a manner
that causes minimum inconvenience, for example (e.g. to a belt around the waist,) or place it in a convenient
pocket.
Give consideration to whether the nature of the process is likely to result in a significant difference between
the actual exposure of the worker and the concentration of particulate fluorides and HF measured by a
sampler mounted on the lapel. If this is the case, make special arrangements to mount the sampler as close as
possible to the worker's nose and mouth.
9.3.2 Static sampling
If static sampling is carried out to assess the exposure of a worker in a situation where personal sampling is
not possible, position the sampler in the immediate vicinity of the worker and at breathing height. If in doubt,
take the sampling position to be the point where the risk of exposure is considered to be greatest.
If static sampling is carried out to characterize the background level of particulate fluorides and HF in the
workplace, select a sampling position that is sufficiently remote from the work processes, such that results are
not directly affected by particulate fluorides and HF from emission sources.
9.4 Collection of samples
When ready to begin sampling, remove the protective cover or plug from the sampler and switch on the
sampling pump. Record the time and volumetric flow rate at the start of the sampling period. If the sampling
pump is fitted with an integral timer, check that this is reset to zero. Measure the atmospheric temperature
and pressure at the start of the sampling period using the thermometer and barometer (7.1.6(7.1.6)) and
record the measured values.
NOTE If the temperature or pressure at the sampling position is different from that where the volumetric flow rate
was set (see 9.2.39.2.3),), the volumetric flow rate can change and can require re-adjustment before sampling.
At the end of the sampling period (see 9.1.29.1.2),), record the time and calculate the duration of the sampling
period. Check the malfunction indicator or the reading on the integral timer, if fitted, and consider the sample
to be invalid if there is evidence that the sampling pump was not operating properly throughout the sampling
period. Measure the volumetric flow rate at the end of the sampling period using the flowmeter and record
the measured value. Measure the atmospheric temperature and pressure at the end of the sampling period
using the thermometer and barometer and record the measured values.
ISO/FDIS 21438-3:2025(en)
Carefully record the sample identity and all relevant sampling data (see 13Clause 13).). Calculate the mean
volumetric flow rate by averaging the volumetric flow rates at the start and at the end of the sampling period
and, if appropriate (see 9.1.39.1.3),), calculate the mean atmospheric temperature and pressure. Calculate the
volume of air sampled, in litres, at atmospheric temperature and pressure, by multiplying the mean flow rate,
in litres per minute, by the duration, in minutes, of the sampling period.
If the post-sampling verification of flow rate is within ± ± 5 % of the measured value prior to sampling, then it
is possible to use the pre-sampling volumetric flow rate or to calculate the mean volumetric flow rate by
averaging the volumetric flow rates at the start and at the end of the sampling period.
If the post-sampling flow rate differs by more than 5 % from the pre-sampling flow rate, the sample should
either be considered invalid, or flagged with calculation of concentrations using both flow rate values and
consideration of both values. However, samplers of selective size fractions are required to operate within
a ±5 % range of a nominal flow rate so the sample shall be considered invalid since a pre- to post-sampling
deviation of greater than ± ± 5 % will be outside of the allowed range.
9.5 Transportation
9.5.1 Samplers that collect either airborne particles and/or gases, or both, on the filter
For samplers that collect airborne particles and/or gases on the filter (7.1.1(7.1.1),), remove the filter from
each sampler, place in a labelled filter transport cassette (7.1.6(7.1.6)) and close with a lid. Alternatively,
transport samples to the laboratory in the samplers in which they were collected. Take particular care to
prevent the collected sample from coming into contact with the walls of the transport container.
9.5.2 Sampler with an internal filter cassette
For samplers with an internal filter cassette (see NOTE 4 in 7.1.1to 7.1.1),), remove the filter cassette from
each sampler and fasten with its lid or transport clip.
9.5.3 Samplers of the disposable cassette type
For samplers of the disposable cassette type, transport the samples to the laboratory in the samplers in which
they were collected.
9.5.4 Transport of samples to the laboratory
Transport the samples to the laboratory in a container which has been designed to prevent damage to the
samples in transit and which has been labelled to ensure proper handling.
Ensure that the documentation which accompanies the samples is suitable for a “chain of custody” to be
[ [6] ]
established (e.g. see ASTM D4840 0 ). ).
10 Analysis
10.1 General
CAUTION — Use suitable personal protective equipment (including suitable gloves, face shield or
safety glasses, etc.) while carrying out the analysis.
10.2 Preparation of test and calibration solutions
10.2.1 General
Filter each sample solution through a 0,45 µm PTFE filter, for example by using a disposable syringe,
dispensing each filtrate into an individual, labelled, autosampler vial (see 7.2.27.2.2).).
ISO/FDIS 21438-3:2025(en)
10.2.110.2.2 Selection of sample preparation method
Decide whether to use water (6.1(6.1)) or eluent (depending on the analytical technique and separator column
used) to prepare test solutions for determination of particulate fluorides and HF.
10.2.210.2.3 Preparation of test solutions
Open each filter cassette or sampler (see 9.59.5)) and transfer both filters into individual, labelled screw-cap
vessels or beakers using clean tweezers (7.2.2(7.2.2),), ensuring that the side of the pre-filter on which the
particulate fluoride sample was collected is facing upwards. Follow the same procedure for the blank filters
(see 9.2.49.2.4).).
Pipette 5,0 ml of water (6.1(6.1) or eluent (10.1.1)) into each screw-cap vessel or beaker.
Swirl gently to mix the contents, ensuring that the filter remains completely immersed. Sonicate for 15 min in
an ultrasonic bath and then allow the immersed filters to sit for 1 h at room temperature, swirling or agitating
occasionally.
Some samplers are designed such that airborne particles which pass through the entry orifice(s) constitute
the inhalable or respirable fraction; in which case any particulate material deposited on the internal surfaces
of th
...
PROJET FINAL
Norme
internationale
ISO/FDIS 21438-3
ISO/TC 146/SC 2
Air des lieux de travail —
Secrétariat: ANSI
Détermination des acides
Début de vote:
inorganiques par chromatographie
2025-09-29
ionique —
Vote clos le:
2025-11-24
Partie 3:
Acide fluorhydrique et fluorures
particulaires
Workplace atmospheres — Determination of inorganic acids by
ion chromatography —
Part 3: Hydrofluoric acid and particulate fluorides
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
INDUSTRIELLES, TECHNOLOGIQUES ET COM-MERCIALES,
AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
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SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTATION
NATIONALE.
Numéro de référence
ISO/FDIS 21438-3:2025(fr) © ISO 2025
PROJET FINAL
ISO/FDIS 21438-3:2025(fr)
Norme
internationale
ISO/FDIS 21438-3
ISO/TC 146/SC 2
Air des lieux de travail —
Secrétariat: ANSI
Détermination des acides
Début de vote:
inorganiques par chromatographie
2025-09-29
ionique —
Vote clos le:
2025-11-24
Partie 3:
Acide fluorhydrique et fluorures
particulaires
Workplace atmospheres — Determination of inorganic acids by
ion chromatography —
Part 3: Hydrofluoric acid and particulate fluorides
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSERVATIONS,
NOTIFICATION DES DROITS DE PROPRIÉTÉ DONT ILS
AURAIENT ÉVENTUELLEMENT CONNAISSANCE ET À
FOURNIR UNE DOCUMENTATION EXPLICATIVE.
DOCUMENT PROTÉGÉ PAR COPYRIGHT
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
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AINSI QUE DU POINT DE VUE DES UTILISATEURS, LES
Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette
PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE CONSIDÉRÉS
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Publié en Suisse Numéro de référence
ISO/FDIS 21438-3:2025(fr) © ISO 2025
ii
ISO/FDIS 21438-3:2025(fr)
Sommaire Page
Avant-propos .v
Introduction .vi
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 2
4 Principe. 3
5 Exigence. 3
6 Réactifs . 3
7 Appareillage . 4
7.1 Matériel de prélèvement .4
7.2 Matériel de laboratoire .6
8 Évaluation de l’exposition professionnelle . 7
9 Prélèvement . 7
9.1 Considérations préliminaires .7
9.1.1 Sélection et utilisation des dispositifs de prélèvement .7
9.1.2 Durée du prélèvement .7
9.1.3 Effets de la température et de la pression sur les mesures du débit .8
9.1.4 Manipulation des échantillons .8
9.2 Préparation du prélèvement .8
9.2.1 Nettoyage des dispositifs de prélèvement .8
9.2.2 Mise en place des filtres dans les dispositifs de prélèvement .8
9.2.3 Réglage du débit volumétrique .9
9.2.4 Blancs de terrain .9
9.3 Point de prélèvement .9
9.3.1 Prélèvement sur opérateur .9
9.3.2 Prélèvement à point fixe .10
9.4 Prélèvement des échantillons .10
9.5 Transport .10
9.5.1 Dispositifs de prélèvement recueillant des gaz ou des particules en suspension
dans l’air, ou les deux, sur le filtre .10
9.5.2 Dispositifs de prélèvement à cassette porte-filtre interne .11
9.5.3 Dispositifs de prélèvement avec cassette à usage unique .11
9.5.4 Transport des échantillons au laboratoire .11
10 Analyse .11
10.1 Généralités .11
10.2 Préparation des solutions d’essai et d’étalonnage .11
10.2.1 Généralités .11
10.2.2 Choix de la méthode de préparation des échantillons .11
10.2.3 Préparation des solutions d’essai .11
10.2.4 Préparation des solutions d’étalonnage . 12
10.3 Analyse instrumentale . 12
10.4 Estimation des limites de détection (LD) et des limites de quantification (LQ) . 13
10.4.1 Estimation de la limite de détection instrumentale . 13
10.4.2 Estimation des limites de détection et des limites de quantification de la
méthode . 13
10.5 Contrôle de la qualité . 13
10.5.1 Blancs de réactifs et blancs de laboratoire . 13
10.5.2 Solutions de contrôle qualité . 13
10.5.3 Matériaux de référence certifiés .14
10.6 Incertitude de mesure .14
iii
ISO/FDIS 21438-3:2025(fr)
11 Expression des résultats .15
12 Performances de la méthode .15
12.1 Efficacité de prélèvement et conservation des échantillons . 15
12.1.1 HF . 15
12.1.2 Fluorures particulaires . 15
12.1.3 Humidité . 15
12.2 Limite de quantification .16
12.3 Limites supérieures de la gamme de mesure .16
12.4 Biais et fidélité .16
12.4.1 Biais analytique .16
12.4.2 Fidélité analytique .16
12.5 Incertitude de la méthode de prélèvement et d’analyse .16
12.6 Interférences .16
13 Rapport d’essai . 17
Annexe A (informative) Correction de température et de pression . 19
Annexe B (informative) Matériaux des filtres . .22
Bibliographie .23
iv
ISO/FDIS 21438-3:2025(fr)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes nationaux
de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est en général
confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude a le droit de faire
partie du comité technique créé à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec l’ISO participent également aux travaux. L’ISO collabore étroitement avec
la Commission électrotechnique internationale (IEC) en ce qui concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document
a été rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2
(voir www.iso.org/directives).
L’ISO attire l’attention sur le fait que la mise en application du présent document peut entraîner l’utilisation
d’un ou de plusieurs brevets. L’ISO ne prend pas position quant à la preuve, à la validité et à l’applicabilité de
tout droit de brevet revendiqué à cet égard. À la date de publication du présent document, l’ISO n’avait pas
reçu notification qu’un ou plusieurs brevets pouvaient être nécessaires à sa mise en application. Toutefois,
il y a lieu d’avertir les responsables de la mise en application du présent document que des informations
plus récentes sont susceptibles de figurer dans la base de données de brevets, disponible à l’adresse
www.iso.org/brevets. L’ISO ne saurait être tenue pour responsable de ne pas avoir identifié de tels droits de
brevet et averti de leur existence.
Les appellations commerciales éventuellement mentionnées dans le présent document sont données pour
information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion de
l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles techniques au
commerce (OTC), voir www.iso.org/avant-propos.
Le présent document a été élaboré par le comité technique ISO/TC 146, Qualité de l’air, sous-comité SC 2,
Atmosphères des lieux de travail.
Cette deuxième édition annule et remplace la première édition (ISO 21438-3:2010), qui a fait l’objet d’une
révision technique.
Les principales modifications sont les suivantes:
— mise à jour des références normatives à l’Article 2;
— suppression à l’Article 3 des termes présents dans l’ISO 18158;
— suppression à l’Article 6 des réactifs pour chromatographie ionique avec suppression électronique;
— réduction de l’Article 8 par référence aux normes pertinentes;
— ajout de la Figure 1.
Une liste de toutes les parties de la série ISO 21438 se trouve sur le site web de l’ISO.
Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent
document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes se
trouve à l’adresse www.iso.org/fr/members.html.
v
ISO/FDIS 21438-3:2025(fr)
Introduction
Dans de nombreuses industries, la santé des travailleurs est menacée en raison de l’exposition par inhalation
à l’acide fluorhydrique et aux fluorures particulaires. Les hygiénistes industriels et autres professionnels
de santé publique ont besoin de déterminer l’efficacité des mesures prises pour contrôler l’exposition
des travailleurs, ce qui se traduit en général par la réalisation de mesurages de l’air des lieux de travail.
Le présent document fournit une méthode permettant d’effectuer des mesurages d’exposition valides
pour l’acide fluorhydrique et les fluorures particulaires utilisés dans l’industrie. Il est destiné aux agences
concernées par l’hygiène et la sécurité au travail; aux hygiénistes industriels et aux autres professionnels
de la santé publique; aux laboratoires d’analyse; aux industriels utilisateurs d’acide fluorhydrique et de
fluorures particulaires et à leurs employés.
La mise en œuvre de ces dispositions et l’interprétation des résultats obtenus grâce à l’utilisation du présent
document sont confiées à des personnes dotées d’une qualification et d’une expérience appropriées.
vi
PROJET FINAL Norme internationale ISO/FDIS 21438-3:2025(fr)
Air des lieux de travail — Détermination des acides
inorganiques par chromatographie ionique —
Partie 3:
Acide fluorhydrique et fluorures particulaires
1 Domaine d’application
Le présent document spécifie une méthode de détermination de la concentration massique moyenne
pondérée dans le temps en fluorures particulaires solubles et en acide fluorhydrique (HF) dans l’air des
lieux de travail, par prélèvement des fluorures particulaires sur un préfiltre et de l’HF sur un filtre imprégné
d’alcali suivi d’une analyse par chromatographie ionique.
Cette méthode est applicable uniquement à la détermination des fluorures particulaires qui sont solubles en
utilisant le mode opératoire spécifié pour la préparation des échantillons.
En cas de prélèvement d’aérosol, cette méthode est applicable au prélèvement sur opérateur de la fraction
inhalable des particules en suspension dans l’air, comme défini dans l’ISO 7708, ainsi qu’au prélèvement à
point fixe.
La méthode est applicable à la détermination de masses comprises entre 0,005 mg et au moins 1,25 mg de
fluorures particulaires par échantillon et entre 0,015 mg et au moins 1,2 mg d’HF par échantillon.
2 Références normatives
Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur
contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour
les références non datées, la dernière édition du document de référence s’applique (y compris les éventuels
amendements).
ISO 3696, Eau pour laboratoire à usage analytique — Spécification et méthodes d'essai
ISO 7708, Qualité de l'air — Définitions des fractions de taille des particules pour l'échantillonnage lié aux
problèmes de santé
ISO 8655-1, Appareils volumétriques à piston — Partie 1: Définitions, exigences générales et recommandations
pour l'utilisateur
ISO 8655-2, Appareils volumétriques à piston — Partie 2: Pipettes
ISO 8655-6, Appareils volumétriques à piston — Partie 6: Mode opératoire de mesure gravimétrique de référence
pour la détermination de volumes
ISO 18158, Qualité de l'air — Terminologie
ISO 20581:2016, Air des lieux de travail — Exigences générales concernant les performances des procédures de
mesure des agents chimiques
EN 13205, Atmosphères des lieux de travail — Évaluation des performances des instruments de mesurage des
concentrations d’aérosols
ISO/FDIS 21438-3:2025(fr)
3 Termes et définitions
Pour les besoins du présent document, les termes et les définitions de l’ISO 18158 ainsi que les suivants
s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en normalisation,
consultables aux adresses suivantes:
— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp
— IEC Electropedia: disponible à l’adresse https:// www .electropedia .org/
3.1
solution de blanc
solution préparée à partir d’un blanc de réactifs, d’un blanc de laboratoire ou d’un blanc de terrain en
utilisant le même mode opératoire que pour la mise en solution de l’échantillon (3.5)
3.2
solution de blanc d’étalonnage
solution d’étalonnage (3.3) préparée sans ajout d’une solution étalon de travail (3.9)
Note 1 à l'article: La concentration d’ions fluorure dans la solution de blanc d’étalonnage est considérée comme nulle.
3.3
solution d’étalonnage
solution obtenue par dilution de la solution étalon de travail (3.9), contenant un analyte aux concentrations
appropriées au blanc d’étalonnage de l’instrument d’analyse
3.4
solution d’extraction
solvant ou solution utilisés pour solubiliser l’analyte ou les analytes étudiés
3.5
mise en solution de l’échantillon
processus permettant d’obtenir une solution contenant des ions fluorure à partir d’un échantillon, qui peut
impliquer la mise en solution complète de l’échantillon
3.6
solution d’échantillon
solution préparée, à partir d’un échantillon, au moyen du processus de mise en solution d’échantillon (3.5)
Note 1 à l'article: Une solution d’échantillon peut nécessiter plusieurs opérations, par exemple, une dilution, afin de
produire une solution d’essai (3.8) prête pour l’analyse.
3.7
solution étalon mère
solution, utilisée dans la préparation des solutions d’étalonnage (3.3), contenant des ions fluorure à une
concentration certifiée dont la traçabilité aux étalons nationaux est établie
3.8
solution d’essai
solution de blanc (3.1) ou solution d’échantillon (3.6) qui a été soumise à toutes les opérations nécessaires
pour l’amener à un état dans lequel elle est prête pour l’analyse
Note 1 à l'article: Si ces solutions ne sont pas soumises à d’autres traitements avant analyse, la solution d’essai à blanc
est la solution de blanc, et la solution d’échantillon est la solution d’essai.
3.9
solution étalon de travail
solution préparée par dilution de la solution étalon mère (3.7), contenant des ions fluorure à une concentration
mieux adaptée à la préparation des solutions d’étalonnage (3.3) que la concentration en fluorure de la solution
étalon mère
ISO/FDIS 21438-3:2025(fr)
4 Principe
Un volume connu d’air est prélevé à travers un préfiltre et un filtre imprégné d’alcali, installés dans un
dispositif de prélèvement de la fraction inhalable (7.1.1), pour recueillir les fluorures particulaires et l’HF.
Les fluorures particulaires sont collectés sur le préfiltre et l’HF est piégé sur le filtre imprégné d’alcali.
Le préfiltre et le filtre imprégné d’alcali sont extraits séparément à l’eau ou à l’éluant (voir 10.2.1),
sans chauffage, pour solubiliser les fluorures.
Des aliquotes de la solution d’échantillon sont traitées par chromatographie ionique pour séparer les
ions fluorure extraits des autres anions. À la suite de cette séparation, le fluorure est mesuré à l’aide d’un
détecteur conductimétrique.
Les résultats d’analyse sont obtenus en reportant la conductivité mesurée en fonction de la concentration.
Ils peuvent être utilisés pour évaluer l’exposition professionnelle aux fluorures et à l’HF dans l’air.
5 Exigence
La procédure de mesure doit satisfaire aux exigences de performance relatives aux méthodes de mesurage
des agents chimiques dans l’air des lieux de travail, telles que définies dans l’ISO 20581.
6 Réactifs
Utiliser uniquement des réactifs de qualité analytique reconnue et de l’eau telle que spécifiée dans l’ISO 20581.
Il est recommandé de vérifier les valeurs de blanc de tous les produits chimiques avant utilisation.
NOTE La présence d’acétate ou de formiate dans les réactifs peut interférer de manière significative avec la
détection des fluorures.
6.1 Eau, d’un système de purification délivrant de l’eau ultrapure de qualité 1, conformément aux
exigences de l’ISO 3696.
NOTE Les systèmes de purification actuels du marché fournissent de l’eau de qualité 1 affichant un niveau de
qualité supérieur à celui spécifié dans l’ISO 3696 (par exemple une résistivité supérieure à 18 MΩ·cm).
6.2 Carbonate de sodium (Na CO ), anhydre, d’une fraction massique supérieure à 99,9 %.
2 3
6.3 Solution de carbonate de sodium d’imprégnation, pour l’imprégnation de filtres de 37 mm de
diamètre.
La concentration de la solution (en g/l) et le volume d’imprégnation (en μl) sont indiqués dans le Tableau 1
pour les filtres en ester de cellulose et pour les filtres en fibres de quartz.
Tableau 1 — Concentration de la solution et volume d’imprégnation
Type de filtre Concentration de la solution Volume d’imprégnation Référence
g/l μl
Ester de cellulose 79,5 240 [13]
Fibre de quartz 50 500 [14]
Il est possible de modifier la concentration de la solution si besoin; cependant, il est nécessaire d’adapter le
volume d’imprégnation en conséquence de sorte à avoir la même quantité de Na CO imprégné sur le filtre.
2 3
ISO/FDIS 21438-3:2025(fr)
6.4 Solutions étalons de fluorure.
6.4.1 Solution étalon mère de fluorure.
Utiliser une solution étalon du commerce présentant une concentration certifiée (1 000 mg/l par exemple)
dont la traçabilité aux étalons nationaux est établie. Respecter la date d’expiration fixée par le fabricant ou
la durée de conservation recommandée. Si nécessaire, diluer la solution étalon (par exemple de 1 000 mg/l
à 100 mg/l) afin de préparer la solution mère.
6.4.2 Solutions d’étalonnage de fluorure.
Pipeter des volumes appropriés de la solution mère pour obtenir la droite d’étalonnage. Le domaine
d’étalonnage doit être conforme à la gamme de mesure décrite dans l’ISO 20581:2016, 5.4.4. Un étalonnage
à plusieurs points (nombre de points à déterminer selon le système qualité du laboratoire) doit être mis en
œuvre au sein du domaine de linéarité de la méthode d’analyse.
6.4.3 Étalon de référence de fluorure.
Utiliser un matériau de référence certifié (MRC) tel que défini en 10.5.3, de concentration certifiée
(par exemple 100 mg/l de fluorure) et dont la traçabilité aux étalons nationaux est établie. Respecter la date
d’expiration fixée par le fabricant ou la durée de conservation recommandée.
6.4.4 Solution de travail d’étalon de référence de fluorure.
Il convient que la solution de travail d’étalon de référence se trouve au milieu du domaine d’étalonnage.
À l’aide d’une pipette, introduire un volume approprié d’étalon de référence de fluorure (6.3.3) pour créer
un étalon de référence avec l’eau (6.1). Préparer cette solution extemporanément à chaque étalonnage.
Si nécessaire, préparer une solution de travail d’étalon de référence séparément pour le fluorure.
7 Appareillage
7.1 Matériel de prélèvement
7.1.1 Dispositifs de prélèvement, conçus pour recueillir la fraction inhalable des particules en
suspension dans l’air, permettant le montage d’un préfiltre et d’un filtre imprégné d’alcali séparés par un
intercalaire, fabriqués dans un matériau ne réagissant pas avec l’HF. Les performances des dispositifs de
prélèvement doivent être conformes à l’EN 13205 lorsque des fractions granulométriques spécifiques sont
stipulées.
Il convient de consulter la notice d’utilisation fournie par le fabricant pour déterminer si la matière
particulaire déposée sur les surfaces internes du dispositif de prélèvement fait partie de l’échantillon.
Si les dispositifs de prélèvement contiennent une cassette porte-filtre interne, celle-ci doit également être
fabriquée dans un matériau ne réagissant pas avec l’HF.
NOTE 1 Parmi les matériaux ne réagissant pas avec les acides, dans lesquels les dispositifs de prélèvement et les
cassettes porte-filtres internes peuvent être fabriqués, figurent le polytétrafluoroéthylène (PTFE) et autres polymères
fluorés, le polychlorure de vinyle (PVC), le polyéthylène, le polypropylène et le polycarbonate.
NOTE 2 Certains dispositifs de prélèvement de la fraction inhalable sont conçus pour recueillir la fraction inhalable
des particules en suspension dans l’air sur le filtre et la matière particulaire déposée sur les surfaces internes du
dispositif de prélèvement ne présente alors aucun intérêt. D’autres dispositifs de prélèvement de la fraction inhalable
sont conçus de sorte que les particules en suspension dans l’air qui passent dans les orifices d’entrée correspondent à la
convention inhalable, auquel cas la matière particulaire déposée sur les surfaces internes du dispositif de prélèvement
fait partie de l’échantillon. Cependant, tous les dispositifs de prélèvement recueillent des particules sur leur surface
[20]
interne .
[12]
NOTE 3 Le CEN/TR 15230 donne des exemples de dispositifs de prélèvement de la fraction inhalable susceptibles
de satisfaire aux exigences de l’EN 13205, y compris des rapports publiés sur leurs performances.
ISO/FDIS 21438-3:2025(fr)
NOTE 4 En général, les dispositifs de prélèvement individuels utilisés pour recueillir la fraction inhalable des
particules en suspension dans l’air n’ont pas les mêmes caractéristiques de sélection de taille s’ils sont utilisés pour un
prélèvement à point fixe.
7.1.2 Filtres, d’un diamètre compatible pour l’utilisation avec les dispositifs de prélèvement (7.1.1).
7.1.2.1 Préfiltres, pour le prélèvement des fluorures particulaires, dont l’efficacité de prélèvement
est ≥ 99 % pour les particules ayant un diamètre de diffusion de 0,3 µm, fabriqués dans un matériau ne
réagissant pas avec l’HF.
Se reporter à l’Article B.1 pour obtenir des recommandations relatives aux matériaux appropriés pour la
fabrication des préfiltres.
7.1.2.2 Filtres de prélèvement, pour le prélèvement de l’HF, imprégnés de carbonate de sodium,
par exemple:
7.1.3 Intercalaires, d’un diamètre compatible avec les dispositifs de prélèvement (7.1.1), destinés à
séparer les préfiltres (7.1.2.1) et les filtres de prélèvement de l’HF (7.1.2.2), fabriqués dans un matériau
inerte ne réagissant pas avec les acides et ne les adsorbant pas, par exemple, manchons en polypropylène ou
grilles revêtues de PTFE ou bagues en polystyrène.
[3]
7.1.4 Il convient d’utiliser des pompes de prélèvement conformes à l’ISO 13137 .
Si la pompe de prélèvement est utilisée en dehors du domaine des conditions spécifiées dans l’ISO 13137,
il convient de prendre des mesures appropriées pour s’assurer que les exigences de performance sont
satisfaites. Par exemple, à des températures inférieures à zéro, il peut se révéler nécessaire de maintenir la
pompe au chaud.
7.1.5 Débitmètre, portable, offrant une précision suffisante pour permettre de mesurer le débit
volumétrique à ±5 %.
L’étalonnage du débitmètre doit être vérifié par rapport à un étalon primaire, c’est-à-dire un débitmètre dont
la traçabilité de la précision aux étalons nationaux est établie. S’il y a lieu (voir 9.1.3), noter la température et
la pression atmosphériques auxquelles l’étalonnage du débitmètre a été vérifié.
Il est recommandé que le débitmètre utilisé soit capable de mesurer le débit volumétrique à ±2 % au
minimum.
7.1.6 Matériel auxiliaire:
— tuyau souple, par exemple en silicone, d’un diamètre extérieur de 10 mm et d’un diamètre intérieur
de 6 mm pour un raccordement étanche entre les dispositifs de prélèvement et les pompes de prélèvement
sans phénomène de compression découlant de la différence de pression entre l’atmosphère ambiante et
−1
la dépression créée dans le circuit au débit de 1 l min ;
— ceintures ou harnais, auxquels la pompe de prélèvement peut se fixer facilement en vue d’un prélèvement
sur opérateur;
— pinces, fabriquées ou recouvertes de PTFE, pour manipuler les filtres;
— cassettes de transport de filtres, ou dispositif analogue, si nécessaire (voir 9.5), permettant de transporter
les échantillons jusqu’au laboratoire;
— thermomètre, offrant une plage de lecture de 0 °C à 50 °C, graduée par divisions de 1 °C ou moins, pour
le mesurage de la température atmosphérique; pour des applications à des températures négatives,
la gamme du thermomètre doit s’étendre à la plage appropriée souhaitée;
— baromètre, adapté au mesurage de la pression atmosphérique si nécessaire.
ISO/FDIS 21438-3:2025(fr)
7.2 Matériel de laboratoire
ATTENTION — Les fluorures sont omniprésents dans l’environnement, ce qui peut se traduire par
des niveaux de blanc élevés. Il est donc particulièrement important de contrôler soigneusement
la verrerie de laboratoire en plastique à usage unique afin de déceler toute contamination aux
fluorures, et de nettoyer complètement tout le matériel de laboratoire réutilisable avant utilisation.
7.2.1 Gants à usage unique, imperméables, pour éviter toute possibilité de contamination par les mains
et pour les protéger de tout contact avec des substances toxiques et corrosives. Des gants en PVC sont
adéquats.
7.2.2 Matériel de laboratoire en plastique:
— fioles jaugées à un trait, par exemple en polyméthylpentène (PMP);
— récipients en polyéthylène à bouchon à vis, adaptés pour l’extraction des échantillons collectés sur les
filtres;
— béchers, de capacité appropriée;
— membranes filtrantes à usage unique, en PTFE, d’une porosité de 0,45 µm, destinées à la chromatographie
ionique;
— seringues jetables, de capacité appropriée, avec aiguilles adaptées;
— flacons de passeur automatique, de capacité appropriée.
7.2.3 Appareils volumétriques à piston, d’une capacité de 50 µl à 10 ml, conformes aux exigences de
l’ISO 8655-1 et soumis à essai conformément à l’ISO 8655-6; possibilité d’utiliser des pipettes conformes
aux exigences de l’ISO 8655-2, à la place des pipettes à un trait pour la préparation des solutions étalons,
des solutions d’étalonnage et la dilution des échantillons.
7.2.4 Cuve à ultrasons, de préférence équipée d’une minuterie, permettant d’appliquer la méthode
d’extraction par ultrasons des fluorures particulaires solubles et l’acide fluorhydrique.
7.2.5 Système de chromatographie ionique, composé des éléments énumérés ci-après. Les éléments et
les tuyaux de raccordement qui entrent en contact avec la solution d’échantillon ou l’éluant doivent, dans la
mesure du possible, être composés de matériaux inertes, par exemple du polyétheréthercétone (PEEK):
— pompe, pouvant fournir un débit constant sur une plage comprise entre 0,1 ml/min et 5 ml/min à une
pression de 15 MPa à 150 MPa;
— système de génération d’éluant, permettant de produire un éluant compatible avec la colonne de
séparation sélectionnée, comme alternative à l’utilisation d’un éluant préparé manuellement (voir par
exemple la Référence [15]);
— système d’injection d’échantillons, composé d’une vanne non métallique à faible volume mort, dotée
d’une boucle d’injection, conçue pour injecter la solution d’échantillon dans le flux d’éluant;
— colonne de garde et de séparation, remplie d’une résine pelliculaire échangeuse d’anions d’une grande
capacité, adaptée à la séparation des fluorures des autres anions inorganiques;
— module de suppression (chimique ou électronique) pour la chromatographie ionique, compatible avec la
colonne de séparation;
— détecteur conductimétrique, à flux continu, de faible volume, à circuit non métallique.
ISO/FDIS 21438-3:2025(fr)
8 Évaluation de l’exposition professionnelle
[10] [9]
Se reporter aux norme pertinentes ISO 20581, EN 689, et ASTM E1370 pour obtenir des
recommandations concernant la manière d’élaborer une stratégie d’évaluation appropriée, ainsi que des
recommandations générales relatives à la stratégie de mesure.
9 Prélèvement
9.1 Considérations préliminaires
9.1.1 Sélection et utilisation des dispositifs de prélèvement
Sélectionner des dispositifs de prélèvement (7.1.1) conformément aux exigences liées à la valeur limite
applicable. Les dispositifs de prélèvement sélectifs en taille de particules doivent collecter la fraction
appropriée des particules en suspension dans l’air, telle que définie dans l’ISO 7708 et être validés par
des essais (par exemple, selon l’EN 13205). Si possible, il convient d’utiliser des dispositifs de prélèvement
fabriqués à partir d’un matériau conducteur puisque les dispositifs de prélèvement fabriqués à partir
d’un matériau non conducteur possèdent des propriétés électrostatiques susceptibles d’influer sur la
représentativité du prélèvement.
Utiliser les dispositifs de prélèvement à leur débit nominal et conformément aux instructions fournies par le
[12]
fabricant. Voir le CEN/TR 15230 pour des recommandations supplémentaires.
NOTE Un débit excessif entraîne une diminution de l’efficacité de prélèvement des vapeurs d’HF.
9.1.2 Durée du prélèvement
Choisir une durée de prélèvement adaptée au mesurage (voir l’Article 8), mais veiller à ce qu’elle soit
suffisamment longue pour que le niveau d’incertitude obtenu lors de la détermination des fluorures
particulaires et de l’HF soit acceptable du point de vue de l’hygiène industrielle. Lorsque des concentrations
élevées de particules en suspension dans l’air sont attendues, choisir une durée de prélèvement qui ne soit
pas trop longue pour éviter tout risque de surcharge du filtre par la matière particulaire.
Calculer, par exemple, la durée minimale de prélèvement, t , en minutes, nécessaire pour que la quantité
min
prélevée soit supérieure à la limite inférieure de la gamme de mesure de la méthode d’analyse lorsque des
fluorures particulaires ou de l’HF sont présents dans l’atmosphère d’essai au multiple approprié de sa valeur
limite (c’est-à-dire 0,1 fois pour une valeur limite moyenne pondérée dans le temps de 8 h ou 0,5 fois pour
une valeur limite à court terme), à l’aide de la Formule (1):
m
LQ
t = (1)
min
qk××ρ
VLV
où
t est la durée minimale de prélèvement, en minutes;
min
m est la limite de quantification, donnée comme la masse d’analyte sur le substrat de prélèvement,
LQ
en microgrammes;
q est le débit nominal du dispositif de prélèvement, en litres par minute;
V
k est le multiple approprié de la valeur limite;
ρ est la valeur limite, en milligrammes par mètre cube.
LV
NOTE k est une variable qui dépend de l’origine de la valeur limite. Par exemple, k est égal à 0,1 en France pour
une valeur limite moyenne pondérée dans le temps de 8 h et pour une valeur limite à court terme. En Allemagne, k est
égal à 0,1 pour une valeur limite moyenne pondérée dans le temps de 8 h mais est égal à 0,5 pour une valeur limite à
court terme.
ISO/FDIS 21438-3:2025(fr)
Si la durée minimale de prélèvement n’est pas suffisamment courte pour que la méthode soit utilisable pour
le mesurage prévu, envisager la possibilité d’utiliser un dispositif de prélèvement conçu pour être utilisé à
un débit plus élevé.
Lorsque des concentrations élevées de particules en suspension dans l’air sont attendues, choisir une durée
de prélèvement qui ne soit pas trop longue pour éviter tout risque de surcharge du préfiltre par la matière
particulaire.
Lorsqu’une concentration élevée d’HF est prévisible, sélectionner une durée de prélèvement qui ne soit
pas trop longue pour éviter le risque d’excéder la capacité maximale du filtre de prélèvement d’HF. Voir les
Références [13] et [14].
9.1.3 Effets de la température et de la pression sur les mesures du débit
Se référer aux instructions du fabricant afin de déterminer si le débit volumétrique indiqué sur le
débitmètre (7.1.5) dépend de la température et de la pression. Examiner si la différence entre la température
et la pression atmosphériques au moment de l’étalonnage du débitmètre et celles lors du prélèvement est
susceptible d’être suffisamment importante pour justifier l’apport d’une correction, par exemple lorsqu’une
erreur supérieure à ±5 % est susceptible d’apparaître. Si une correction est nécessaire, mesurer et noter
la température et la pression atmosphériques auxquelles l’étalonnage du débitmètre a été vérifié. Mesurer
et noter également la température et la pression atmosphériques au début et à la fin de la période de
prélèvement (voir 9.4).
NOTE Un exemple de correction de température et de pression pour le débit volumétrique indiqué est donné à
l’Article A.1 pour un débitmètre à perte de charge constante et à section variable.
Déterminer s’il est nécessaire de recalculer la concentration en fluorures particulaires et en HF dans l’air
[1]
pour les conditions de référence (voir l’ISO 8756 ). Dans l’affirmative, mesurer et noter la température et
la pression atmosphériques au début et à la fin de la période de prélèvement (voir 9.4) et utiliser la formule
indiquée à l’Article A.2 pour appliquer la correction nécessaire.
La concentration en HF dans l’air est généralement indiquée pour les conditions environnementales
ambiantes (température, pression) sur le lie
...
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