SIST EN ISO 18227:2026

SLOVENSKI STANDARD
01-april-2026
Nadomešča:
SIST EN 15309:2007
Trdni matriksi v okolju - Določanje elementne sestave z rentgensko fluorescenčno
spektrometrijo (ISO 18227:2025)
Environmental solid matrices - Determination of elemental composition by X-ray
fluorescence spectrometry (ISO 18227:2025)
Feststoffe in der Umwelt - Bestimmung der elementaren Zusammensetzung durch
Röntgenfluoreszenz (ISO 18227:2025)
Matrices solides environnementales - Détermination de la composition élémentaire par
spectrométrie de fluorescence X (ISO 18227:2025)
Ta slovenski standard je istoveten z: EN ISO 18227:2025
ICS:
13.030.10 Trdni odpadki Solid wastes
13.080.10 Kemijske značilnosti tal Chemical characteristics of
soils
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 18227
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2025
EUROPÄISCHE NORM
ICS 13.080.10 Supersedes EN 15309:2007
English Version
Environmental solid matrices - Determination of elemental
composition by X-ray fluorescence spectrometry (ISO
18227:2025)
Matrices solides environnementales - Détermination Feststoffe in der Umwelt - Bestimmung der
de la composition élémentaire par spectrométrie de elementaren Zusammensetzung durch
fluorescence X (ISO 18227:2025) Röntgenfluoreszenz (ISO 18227:2025)
This European Standard was approved by CEN on 8 December 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18227:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 18227:2025) has been prepared by Technical Committee ISO/TC 190 "Soil
quality" in collaboration with Technical Committee CEN/TC 444 “Environmental characterization of
solid matrices” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by June 2026, and conflicting national standards shall be
withdrawn at the latest by June 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 15309:2007.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 18227:2025 has been approved by CEN as EN ISO 18227:2025 without any modification.

International
Standard
ISO 18227
Second edition
Environmental solid matrices —
2025-12
Determination of elemental
composition by X-ray fluorescence
spectrometry
Matrices solides environnementales — Détermination de la
composition élémentaire par spectrométrie de fluorescence X
Reference number
ISO 18227:2025(en) © ISO 2025
ISO 18227:2025(en)
© ISO 2025
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
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or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 18227:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Safety remarks . 3
5 Principle . 3
6 Apparatus . 3
7 Reagents . 4
8 Interferences and sources of error . 5
9 Sample preparation . 5
9.1 General .5
9.2 Drying and determination of dry mass .5
9.3 Preparation of pressed pellet .6
9.4 Preparation of fused beads .6
10 Procedure . 7
10.1 Analytical measurement conditions .7
10.1.1 Wavelength dispersive instruments .7
10.1.2 Intensities and background corrections .7
10.1.3 Counting time .7
10.1.4 Energy dispersive instruments .7
10.1.5 Intensities and background corrections .7
10.2 Calibration .7
10.2.1 General .7
10.2.2 General calibration procedure .8
10.2.3 Internal standard correction using Compton (incoherent) scattering method .8
10.2.4 Fundamental parameter approach .9
10.2.5 Fundamental or theoretical influence coefficient method .9
10.2.6 Empirical alpha correction.10
10.2.7 Calibration procedure for trace elements using the pressed pellet method .10
10.2.8 Calibration procedure for major and minor oxides using the fused bead method . 12
10.3 Analysis of the samples . 13
11 Quality control .13
11.1 Drift correction procedure . 13
11.2 Blank test . 13
11.3 Reference materials . 13
11.4 Performance data .14
12 Calculation of the result . 14
13 Test report . 14
Annex A (informative) Semi-quantitative screening analysis of waste, sludge and soil samples .15
Annex B (informative) Examples for operational steps of the sample preparation for soil and
waste samples .18
Annex C (informative) Suggested analytical lines, crystals and operating conditions .24
Annex D (informative) List of reference materials applicable for XRF analysis .26
Annex E (informative) Validation .27
Bibliography .37

iii
ISO 18227:2025(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 documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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 190, Soil quality, Subcommittee SC 3, Chemical
and physical characterization, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 444, Environmental characterization of solid matrices, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 18227:2014), which has been technically
revised.
The main changes are as follows:
— the contents of the two almost identical standards ISO 18277:2014 and EN 15309:2007 have been
combined;
— normative references have been revised.
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.

iv
ISO 18227:2025(en)
Introduction
X-ray fluorescence (XRF) spectrometry is a fast and reliable method for the quantitative analysis of the total
content of certain elements within different matrices.
The quality of the results obtained depends very closely on the type of instrument used, e.g. bench top
or high performance, energy dispersive or wavelength dispersive instruments. When selecting a specific
instrument several factors should be considered, such as the matrices to be analysed, elements to be
determined, detection limits required and the measuring time. The quality of the results depends on the
element to be determined and on the surrounding matrix.
Due to the wide range of matrix compositions and the lack of suitable reference materials in the case of
inhomogeneous matrices such as waste, it is generally difficult to set up a calibration with matrix- matched
reference materials.
Therefore, this document describes two different procedures:
— a quantitative analytical procedure required for homogeneous solid waste, soil and soil-like material,
where the calibration is based on matrix-matched standards;
— an optional XRF screening method for solid and liquid material as waste, sludge and soil in Annex A
which provides a total element characterization at a semi-quantitative level, where the calibration is
based on matrix-independent calibration curves, previously set up by the manufacturer.

v
International Standard ISO 18227:2025(en)
Environmental solid matrices — Determination of elemental
composition by X-ray fluorescence spectrometry
1 Scope
This document specifies the procedure for a quantitative determination of major and trace element
concentrations in homogeneous solid waste, soil, soil-like material and sludge by energy dispersive X-ray
fluorescence (EDXRF) spectrometry or wavelength dispersive X-ray fluorescence (WDXRF) spectrometry
using a calibration with matrix-matched standards.
This document is applicable for the following elements: Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni,
Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, Sn, Sb, Te, I, Cs, Ba, Ta, W, Hg, Tl, Pb, Bi, Th and U. Concentration
levels between a mass fraction of approximately 0,000 1 % and 100 % can be determined depending on the
element and the instrument used.
An optional XRF screening method for solid and liquid material as waste, sludge and soil is added in Annex A
which provides a total element characterization at a semi-quantitative level, where the calibration is based
on matrix-independent calibration curves, previously set up by the manufacturer.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
absorption edge
jump of the mass absorption coefficient at a specific wavelength or energy
3.2
analytical line
specific characteristic X-ray spectral line of the atom or ion of the analyte used for determination of the
analyte content
3.3
continuous radiation
electromagnetic radiation produced by the acceleration of a charged particle, such as an electron, when
deflected by another charged particle, such as an atomic nucleus
3.4
Compton-line
spectral line due to incoherent scattering (Compton-effect) occurring when the incident X-ray photon strikes
an atom without promoting fluorescence
Note 1 to entry: Energy is lost in the collision and therefore the resulting scattered X-ray photon is of lower energy
than the incident X-ray photon.

ISO 18227:2025(en)
3.5
drift correction monitor
physically stable sample used to correct for instrumental drift
3.6
fused bead
analyte sample prepared by dissolution in a flux
3.7
liquid sample
analyte sample submitted as a solution for direct measurement in the sample cup
3.8
mass absorption coefficient
constant describing the fractional decrease in the intensity of a beam of X-radiation as it passes through an
absorbing medium
Note 1 to entry: This is expressed in cm /g.
Note 2 to entry: The mass absorption coefficient is a function of the wavelength of the absorbed radiation and the
atomic number of the absorbing element.
3.9
powder sample
analyte sample submitted as a powder for direct measurement in the sample cup
3.10
precision
closeness of agreement between independent test results obtained under stipulated conditions
Note 1 to entry: Precision depends only on the distribution of random errors and does not relate to the true value or
the specified value.
Note 2 to entry: The measure of precision is usually expressed in terms of imprecision and computed as a standard
deviation of the test results. Less precision is reflected by a larger standard deviation.
Note 3 to entry: Quantitative measures of precision depend critically on the stipulated conditions. Repeatability and
reproducibility conditions are particular sets of extreme conditions.
[SOURCE: ISO 3534-2:2006, 3.3.4]
3.11
pressed pellet
analyte sample prepared by pressing milled material into a disk
3.12
primary X-ray
X-ray by which the sample is radiated
3.13
quality control sample
stable sample with known contents used to monitor instrument and calibration performance
EXAMPLE Certified reference material (CRM).
3.14
X-ray fluorescence radiation
emission of characteristic X-rays from a sample that has been bombarded by high-energy X-rays or gamma rays

ISO 18227:2025(en)
4 Safety remarks
Anyone dealing with waste and sludge analysis shall be aware of the typical risks that this kind of material
presents irrespective of the parameter to be determined. Waste and sludge samples can contain hazardous
substances, e.g. toxic, reactive, flammable, and infectious substances, which could potentially undergo
either biological or chemical reaction, or both. Consequently, these samples should be handled with special
care. The gases that can be produced by microbiological or chemical activity are potentially flammable and
pressurize sealed bottles. Bursting bottles are likely to result in hazardous shrapnel, dust and/or aerosol.
The user shall be aware of national regulations applicable to hazard handling.
The user shall be aware of national regulations relevant to radiation protection.
The person responsible for managing or supervising the operation of X-ray equipment shall provide evidence
of his knowledge of radiation protection as defined in national regulations.
5 Principle
After a suitable preparation, if necessary, the sample is introduced into an XRF-spectrometer and excited
by primary X-rays. The intensities of the secondary fluorescent energy lines specific for each element are
measured and the elemental composition of the sample is determined by reference to previously established
calibration graphs or equations and applying corrections for inter-element effects. The calibration equations
and inter-element corrections are established using either pure reagents or series of internal or reference
materials, or both, provided they meet all the requirements of the relevant preparation technique.
6 Apparatus
6.1 X-ray fluorescence spectrometer, which shall be able to analyse the elements listed in the scope of
this document.
The following types of X-ray fluorescence spectrometers are applicable:
— energy dispersive X-ray fluorescence (EDXRF) spectrometer that achieves the dispersion of the emitted
X-ray fluorescence radiation by an energy dispersive detector;
— wavelength dispersive X-ray fluorescence (WDXRF) spectrometer that achieves the dispersion of the
emitted X-ray fluorescence radiation by diffraction by a crystal or a synthetic multilayer.
The spectrometer consists of a number of components:
— primary X-ray source, an X-ray tube with a high voltage generator;
— a sample holder;
— detector unit including electronic equipment;
— source modifiers to modify the shape or intensity of the source spectrum or the beam shape (e.g. source
filters, secondary targets, polarizing targets, collimators, focussing optics).
The detector unit is different for WDXRF and for EDXRF spectrometers. WDXRF spectrometers take
advantage of the dispersion of the emitted radiation by scattering by a crystal or a synthetic multilayer. The
detector should not be capable of energy discrimination. EDXRF spectrometers use an energy dispersive
detector. Pulses of current from the detector, which are a measure of the energy of the incoming X-rays, are
segregated into channels according to energy using a multi-channel analyser (MCA). The spectrometer is
capable to measure under vacuum, helium-atmosphere (7.3) or nitrogen- atmosphere (7.4).
NOTE 1 The use of a high-energy X-ray tube increases the potential for losses of volatile analytes from samples by
heating in the spectrometer during analysis.

ISO 18227:2025(en)
NOTE 2 The new generation of EDXRF spectrometers takes advantage of the polarizing target theory resulting in a
significant decrease of the background scattering, and therefore lower limits of detection can be achieved (comparable
to WDXRF).
6.2 Analytical balance, readable and accurate to 0,001 g.
6.3 Drying oven, thermostatically controlled and capable of maintaining a temperature of (105 ± 5) °C.
6.4 Grinding mill, capable of grinding dried materials to a required particle size without contaminating
the samples with compounds to be determined, preferable with walls made of agate, corundum or zircon.
6.5 Pellet preparation equipment, manual or automatic pellet press, capable of providing a pressure of
at least 100 kN.
6.6 Aluminium cup: supporting backing cup for pressed pellets.
6.7 Fusion apparatus: electric, gas or high frequency induction furnace that can be heated up to a fixed
temperature of between 1 000 °C and 1 250 °C.
6.8 Fusion crucibles: crucibles made of non-wetting platinum alloy (with a mass fraction of 95 % Pt and a
mass fraction of 5 % Au is suitable).
Lids, if used, shall be made from platinum alloy.
NOTE Certain metal sulfides (so called platinum poisons) affect the platinum crucibles in which the sample is melted.
6.9 Casting moulds: non-wetting platinum alloy (with a mass fraction of 95 % Pt and a mass fraction of
5 % Au is suitable).
7 Reagents
The reagents mentioned are used as carrier material.
7.1 Binder: liquid or solid binder free of analytes of interest.
Solid materials can contain a certain amount of moisture, which shall be compensated for.
NOTE Different types of binders can be used. A binder commonly used is wax.
7.2 Flux: solid flux free of analytes of interest.
Solid materials can contain a certain amount of moisture, which shall be compensated for (e.g. ISO 12677 for
compensation for moisture in flux).
NOTE Different type of fluxes can be used. Fluxes commonly used are lithium metaborate, lithium tetraborate or
mixtures of both.
7.3 Helium, purity ≥ 99,996 % by volume.
7.4 Nitrogen, purity ≥ 99,996 % by volume.

ISO 18227:2025(en)
8 Interferences and sources of error
The container in which the sample is delivered and stored can be a source of error. Its material shall be
chosen according to the elements to be determined.
NOTE Elemental Hg can penetrate polyethylene walls very rapidly in both directions. In the case of glass
containers, contamination can be observed for some elements e.g. Al, As, Ba, Ce, K, Na and Pb.
Interferences in X-ray fluorescence spectrometry are due to spectral line overlaps, matrix effects, spectral
artefacts and particle size or mineralogical effects.
Spectral line overlaps occur when an analytical line cannot be resolved from the line of a different element.
Corrections for these interferences are made using the algorithms provided with the software.
Matrix effects occur when the X-ray fluorescence radiation from the analyte element is absorbed or enhanced
by other elements in the sample before it reaches the detector. In the case of complex matrices these effects
generally shall be corrected.
Spectral artefacts, e.g. escape peaks, sum peaks, pulse pile up lines, dead time, and continuous radiation
correction, are accounted for by the provided software. Spectral artefacts differ for energy dispersive and
wavelength dispersive XRF spectrometry.
Particle size effects can be reduced by milling the sample, and both particle size and mineralogical effects
can be eliminated by preparing bead samples. For quantitative analysis, the same sample preparation
procedure is applied to both the standards and the samples to be analysed.
9 Sample preparation
9.1 General
In analysis by XRF spectrometry the sample preparation step is crucial as the quality of the sample
preparation strongly influences the accuracy of the results.
For quantitative analysis of solid samples, pressed pellets or fused beads shall be prepared. The pressed
pellet method should be applied for the quantification of trace elements and shall be applied for the
quantification of volatile elements, and the fused bead method should be applied for the determination of
non-volatile major and minor elements.
NOTE 1 The preparation of fused beads eliminates effects due to particle size and mineralogy.
The conditions of the preparation of fused beads shall be adapted to the matrix properties. Otherwise, the
preparation of fused beads can be difficult or can cause problems in case of waste-like matrices such as
sludges.
For a given calibration the same preparation method shall be used throughout, for both samples and
standards.
NOTE 2 Depending on the sample type other sample preparation methods can be applied according to Annex B.
For precise quantitative measurements, homogeneous and representative test portions shall be used. If not
otherwise specified, pre-treatment and preparation of test portions should be carried out according to the
appropriate clauses of e.g. ISO 11464, EN 15002 or EN 16179. The particle size of the sample can strongly
affect the precision of the measurement. The particle size should preferably be smaller than 150 µm.
Particle size smaller than 80 µm is recommended for the analysis of low atomic mass elements when using
the pressed pellet method.
9.2 Drying and determination of dry mass
If not otherwise specified, the determination of the dry mass should be carried out according to e.g.
ISO 11465 or EN 15934.
ISO 18227:2025(en)
9.3 Preparation of pressed pellet
After drying (6.3) and milling or grinding the sample (6.4), a pellet is prepared in the pellet press (6.5).
Before pressing, the sample shall be mixed and homogenized with a binder (7.1) in a ratio of sampler:binder
of 10:1 by mass. For the preparation of 40 mm in diameter pellets, approximately 10,0 g of sample is taken;
for 32 mm in diameter pellets, approximately 4,5 g of sample is required. The amount of binder in the pellet
shall be taken into account for the dilution factor. The sample should be pressed in an aluminium cup (6.6)
as support.
NOTE 1 Different types of binders can be used. A binder commonly used is wax. In the case of a liquid binder the
pellet is placed in an oven to evaporate organic solvent.
NOTE 2 Different dilution factors can be used.
9.4 Preparation of fused beads
After drying (6.3) and milling or grinding the sample (6.4), a fused bead is prepared using the fusion
apparatus (6.7).
Ignite the sample at 1 025 °C ± 25 °C until constant mass is reached. Determine the loss on ignition at the
chosen temperature to correct for volatile elements or compounds being released during ignition of the
sample, or both.
NOTE 1 The ignition temperature can vary depending on the sample matrix.
Because of the wide applicability of the fused bead technique, various fluxes and modes of calibration are
permitted providing they have been demonstrated to be able to meet certain criteria of reproducibility,
sensitivity and accuracy.
For application of alkaline fusion technique (e.g. selection of flux, fusion temperature, and additives)
ISO 14869-2 or CEN/TR 15018 should be used.
NOTE 2 Fluxes commonly used are lithium metaborate, lithium tetraborate or mixtures of both.
NOTE 3 Loss of volatile elements, e.g. As, Br, Cd, Cl, Hg, I, S, Sb, Se, and Tl, can occur during the fusion process. Also,
Cu can be volatile if a bromide-releasing agent is used.
The flux (7.2) is added to the ignited material in a dilution ratio of sample:flux of 1:5 by mass. For the
preparation of 40 mm in diameter beads, approximately 1,6 g of ignited sample is taken; for 32 mm in
diameter beads, approximately 0,8 g of ignited sample is required. The amount of flux in the bead shall be
taken into account for the dilution factor. The same sample preparation procedure and ratio of sample to
flux shall be used for samples and standards. The beads produced should be visually homogeneous and
transparent.
Non-ignited material can be used to prepare beads but, nevertheless, loss of ignition shall be determined
and shall be taken into account in the calculation of the results. It should be noted that non-ignited material
can contain compounds that can damage the platinum crucibles during fusion.
NOTE 4 Different dilution factors can be used.
After fusion in a platinum-gold crucible (6.8) the melt is poured into a casting mould (6.9) to make a bead.
Beads can deteriorate because of adverse temperature and humidity conditions, so they should be stored in
desiccators.
ISO 18227:2025(en)
10 Procedure
10.1 Analytical measurement conditions
10.1.1 Wavelength dispersive instruments
The suggested analytical lines and operating conditions are given in Table C.1 of Annex C. The settings are
strongly dependent on the spectrometer configuration, e.g. the type of X-ray tube (Rh, Cr), tube power,
available crystals, and type of collimators.
10.1.2 Intensities and background corrections
For the determination of trace elements, the measured intensities shall be background-corrected. The
measured background positions should be free of spectral line interferences. The net peak intensity I,
expressed as the number of counts per second of the element of interest, is calculated as the difference
between the measured peak intensity of the element and the background intensity as in Formula (1):
II=− I (1)
pb
where
I is the count rate of the element i, expressed as the number of counts per second;
p
I is the background count rate of the element i, expressed as the number of counts per second.
b
10.1.3 Counting time
The minimum counting time is the time necessary to achieve an uncertainty (2σ %), which is less than the
desired precision of the measurement. Choose a reference material with a concentration level in the middle
of the working range and measure the count rate. The counting time for each element can be calculated
according to Formula (2):
100 1
t =⋅ (2)
2σ %
II−
pb
where
t is the total counting time for the peaks and background, in seconds;
2σ% is the relative target precision at a confidence level of 95 %, expressed as percentage.
10.1.4 Energy dispersive instruments
The suggested analytical lines and operating conditions are given in Table C.2 of Annex C. The settings are
strongly dependent on the spectrometer configuration, e.g. type of X-ray tube (Rh, Pd), tube power, available
targets, and type of filters.
10.1.5 Intensities and background corrections
Deconvolution of the spectra and background correction are needed when analysing the samples with
overlapping lines. Usually, XRF instruments are supplied with a specific software module for that purpose.
10.2 Calibration
10.2.1 General
The calibration procedure is similar for energy dispersive and wavelength dispersive techniques. In general
calibration is established by using matrix-adapted reference materials. The calibration equations and inter-
element corrections are calculated by the software of the instrument. An accuracy check is performed with
CRMs or samples with known composition.

ISO 18227:2025(en)
Different procedures for correcting matrix effects can be used according to the analytical accuracy required:
— The scattered radiation method is based on the principle that the intensities of the analyte line and of
the Compton line are affected in the same proportion due to the overall mass absorption coefficient of
the sample. This linear relationship holds when all analytes are at low concentrations (trace elements)
and their absorption coefficients are not affected by an adjacent absorption edge. In this case an internal
Compton correction can be used. Aside from that, a correction method using the Compton intensity
with mass absorption coefficients (MAC) is also applicable. In this method, the intensities of the major
elements are measured to apply a jump edge correction for the analysed trace elements.
— Correction using the fundamental parameter (FP) approach.
— Correction using theoretical correction coefficients (alphas) taking basic physical principles, instrumental
geometry, etc. into account.
— Correction using empirical correction coefficients (alphas) based on regression analysis of standards
with known elemental concentrations.
10.2.2 General calibration procedure
For calibration purposes analyte lines of samples of known composition shall be measured. Formula (3)
implies a linear relationship between the intensity and the concentration.
Ca=+aI⋅ (3)
ii,,01ii
where
C is the concentration of the element of interest i, expressed as mg/kg or percentage dry matter;
i
a is the offset of the calibration curve;
i,0
a is the slope of the calibration curve;
i,1
I is the net intensity of the element of interest i, expressed as counts per second.
i
Matrix effects shall be taken into account in X-ray spectrometry according to Formula (4):
Ca=+aM⋅ (4)
ii,,M 01i,
where
C is the concentration of the element of interest i after matrix correction, expressed as mg/kg or
i,M
percentage dry matter;
M is the correction term due to the matrix effects.
The matrix effect correction term can consist of an internal standard Compton correction method (10.2.3)
or can be calculated from mathematical models (10.2.4, 10.2.5 or 10.2.6).
10.2.3 Internal standard correction using Compton (incoherent) scattering method
The measured intensity of incoherent scattering can be used directly to compensate for matrix effects or
indirectly for the determination of the effective mass absorption coefficient μ to correct for matrix effects.
The compensation for matrix effects is based on a combination of sample preparation and experimental
intensity data but not on fundamental and experimental parameters.

ISO 18227:2025(en)
The Compton scatter method can be expressed according to Formula (5):
 I   I 
inc,,r iu
CC=⋅ ⋅ (5)
   
iu,,i r
I I
ir, inc,u
   
where
C is the concentration of the element of interest i of the sample u, expressed as mg/kg or
iu,
percentage dry matter;
C is the concentration of the element of interest i of the calibration reference material r, expressed
i ,r
as mg/kg or percentage dry matter;
I is the intensity of the incoherent Compton-line element of the calibration reference material r,
inc,r
expressed as counts per second;
I is the intensity of the element of interest i of the calibration reference material r, expressed as
i ,r
counts per second;
I is the intensity of the element of interest i of the sample u, expressed as counts per second;
iu,
I is the intensity of the incoherent Compton-line of the sample u, expressed as counts per second.
inc,u
10.2.4 Fundamental parameter approach
The fundamental parameter approach uses the physical processes forming the basis of X-ray fluorescence
emission and scattering to construct a theoretical model for the correction of matrix effects in practice.
The correction term M is calculated from first principle expressions. These are derived from basic X-ray
physics and contain physical constants and parameters that include absorption and scattering coefficients,
fluorescence yield, primary spectral distributions and spectrometry geometry. The use of scattered
radiation (Compton or Rayleigh, or both) allows the determination of matrix effects caused by sample
elements that cannot be measured directly. The calculation of analyte concentrations in samples is based on
making successively better estimates of composition by an iteration procedure. These iteration cycles are
performed until the difference between the compared results is below a defined value.
NOTE The algorithm used for the procedure is usually implemented in the manufacturer’s software.
10.2.5 Fundamental or theoretical influence coefficient method
The fundamental influence coefficient method encompasses any mathematical expression relating emitted
intensities and concentrations in which the influence coefficients are defined and derived explicitly in terms
of fundamental parameters.
The calculation of the concentration from the intensities is performed by linear regression whereby the net
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