ISO 23971:2025
(Main)Surface chemical analysis — X-ray fluorescence analysis of particulate matter filters
Surface chemical analysis — X-ray fluorescence analysis of particulate matter filters
This document gives guidance on sample preparation, and on qualitative and quantitative determination of elements in particulate matter collected on filtering membranes (PM filter) by energy dispersive X-ray Fluorescence (EDXRF) in different geometrical configurations. This document does not apply to PM filter sampling. This document only applies to the analysis of X-ray emission from filters that are probed using an X-ray beam as the exciting source. X-ray emissions generated by electron microscope are excluded[1]. This document is applicable under a range of contexts including, but not limited to, those highlighted in the introduction. The described method is generally applicable for the determination of elements with atomic number higher than 11 (Na) and having a deposited mass on the filter greater than 10 ng. The elements that can be identified and the detection limits depend on the specific instrumental configuration employed. Various types of filtering membranes (filter) materials can be used, such as glass fibre, quartz fibre, cellulose, nylon, polycarbonate (PC) and polytetrafluoroethylene (PTFE). The entire filter, or portions of various sizes thereof, can be submitted for analysis. NOTE Reference free analysis, based on fundamental parameters is excluded, as the nature of the PM filter samples means that the parameters are not sufficiently well defined.
Titre manque
General Information
Standards Content (Sample)
International
Standard
ISO 23971
First edition
Surface chemical analysis — X-ray
2025-11
fluorescence analysis of particulate
matter filters
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 5
5 Safety . 5
6 Preliminary remarks . 5
7 Measurements . 7
8 Filter materials and interferences . 7
9 Sample preparation and handling . 7
10 Qualitative Analysis . 8
10.1 Identification of analytes .8
10.2 Determination of the analyte net intensities .9
10.3 Determination of LOD .9
11 Quantitative analysis . 9
11.1 Certified reference material, reference material and calibration sample .9
11.2 Calibration curve .10
11.3 Uncertainty budget .10
11.4 Precision and accuracy .11
12 Quality check .11
13 Test analysis report .11
Annex A (informative) Contributions to the uncertainty budget .13
Annex B (informative) Calibration procedure . 14
Annex C (informative) International interlaboratory comparison .20
Bibliography .27
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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This document was prepared by Technical Committee ISO/TC 201, Surface Chemical Analysis, Subcommittee
SC 10, X-ray Reflectometry (XRR) and X-ray Fluorescence (XRF) Analysis.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv
Introduction
Air pollution originates from both natural sources (volcanoes, dust winds) and anthropogenic activities
(industry, transportation, agricultural, household). It represents a major health, environmental, societal,
and economic burden. Particulate matter (PM) is one of the six primary pollutants in the air and its danger
varies depending on the size, concentration, and composition of the particles. Various sampling approaches
and analytical requirements have been applied to the study of PMs according to the specific frameworks for
and under which samples are collected, for instance for monitoring ambient air quality, workplace air, or
stationary source emissions. Air filtering membrane (PM filter) remains the preferred sampling substrate.
PM concentration in the volume of sampled air is determined gravimetrically by weighing filters collected
from air monitoring stations, which can also perform size fraction selection. PM chemical composition,
physical properties, and biological content are determined by analysing the whole or part of the PM filter.
The most widely used analytical techniques for determining the elemental composition, mainly for metals
and metalloids in PM filters are atomic absorption and inductively coupled plasma-based spectroscopies
(AAS and ICP). These methods are destructive as they require the complete solubilization of the solid
samples in a liquid mixture. Energy dispersive X-ray fluorescence (EDXRF) is an alternative technique to
the above mentioned for elemental analysis, which is non-destructive, with lower environmental impact,
and which does not require sample solubilization or the use of gasses for operation. Several International
Standards exist and describe methods for elemental analysis based on AAS and ICP, while only a few non
International Standards describe methods based on XRF techniques.
This document is developed in response to a worldwide demand to use green and environmentally
sustainable analytical methods according to the 2030 Agenda for Sustainable Development. This document
supports the use of energy dispersive XRF based techniques for elemental analysis of PM filters, targeting
the Sustainable Development Goals (SDGs) 11, 12, 14, 15.
v
International Standard ISO 23971:2025(en)
Surface chemical analysis — X-ray fluorescence analysis of
particulate matter filters
1 Scope
This document gives guidance on sample preparation, and on qualitative and quantitative determination
of elements in particulate matter collected on filtering membranes (PM filter) by energy dispersive X-ray
Fluorescence (EDXRF) in different geometrical configurations. This document does not apply to PM filter
sampling. This document only applies to the analysis of X-ray emission from filters that are probed using an
[1]
X-ray beam as the exciting source. X-ray emissions generated by electron microscope are excluded .
This document is applicable under a range of contexts including, but not limited to, those highlighted in the
introduction. The described method is generally applicable for the determination of elements with atomic
number higher than 11 (Na) and having a deposited mass on the filter greater than 10 ng. The elements that
can be identified and the detection limits depend on the specific instrumental configuration employed.
Various types of filtering membranes (filter) materials can be used, such as glass fibre, quartz fibre, cellulose,
nylon, polycarbonate (PC) and polytetrafluoroethylene (PTFE). The entire filter, or portions of various sizes
thereof, can be submitted for analysis.
NOTE Reference free analysis, based on fundamental parameters is excluded, as the nature of the PM filter
samples means that the parameters are not sufficiently well defined.
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 18115-1, Surface chemical analysis — Vocabulary — Part 1: General terms and terms used in spectroscopy
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18115-1 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
absorption
attenuation of X-rays passing through matter, arising primarily from photoelectric absorption for X-ray
energies
3.2
absorption correction
matrix correction arising from the loss of X-ray intensity from an element due to photoelectric absorption
with all elements within the sample while passing through it to the detector
3.3
accuracy
systematic deviation of a measured parameter from a reference value for that parameter
3.4
background
non-characteristic component of an X-ray spectrum, sum of all detector artefacts and radiation contributions
arising from scattering of the primary radiation, emissions from the sample carrier, the sample, the ambient
atmosphere, or detector system
Note 1 to entry: In total refection X-ray fluorescence (TXRF), the Bremsstrahlung (3.6) contributes to the background
of the measured spectrum. It can be reduced considerably with good monochromatizating of the incident beam, but
this is often i
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