CEN/TR 10377:2023

Guidelines for the preparation of standard routine methods with wavelength-dispersive X-ray fluorescence spectrometry

X-ray Fluorescence Spectrometry (XRF) has been used for several decades as an important analytical tool for production analysis. XRF is characterised by its speed and high precision over a wide concentration range and since the technique in most cases is used as an relative method the limitations are often connected to the quality of the calibration samples. The technique is well established and most of its physical properties are well known.

Lignes directrices pour la préparation de méthodes de routine utilisant la spectrométrie de fluorescence X à dispersion de longueur d'onde

Le présent document est destiné à être utilisé pour l'analyse des métaux et des alliages (principalement les aciers), mais il est également applicable à d'autres matériaux bien que les techniques de préparation des échantillons soient diffèrentes. L'objet du présent document est de décrire les concepts et les modes opératoires généraux pour l'étalonnage et l'analyse par XRF.

Navodilo za pripravo standardnih postopkov z valovno-disperzno rentgensko fluorescenčno spektrometrijo

Fluorescenčna spektrometrija (XRF) se že več desetletij uporablja kot pomembno analitično orodje za analizo proizvodnje. Za fluorescenčno spektrometrijo je značilno, da je z njo mogoče hitro in zelo natančno analizirati širok razpon koncentracij. Ker se ta tehnika večinoma uporablja kot relativna metoda, so njene omejitve pogosto povezane s kakovostjo vzorcev za umerjanje. Ta tehnika je dobro uveljavljena, večina njenih fizičnih lastnosti pa je dobro znana.

General Information

• Status: Published
• Publication Date: 27-Jun-2023
• ICS: 77.040.30 - Chemical analysis of metals
• Technical Committee: ECISS/TC 102 - Methods of chemical analysis for iron and steel
• Drafting Committee: CEN/TC 459/SC 2/WG 2 - Routine methods for the analysis of steel by spark OES
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 28-Jun-2023
• Due Date: 30-Aug-2023
• Completion Date: 28-Jun-2023
• Mandate: M/BC/CEN/89/10 - ECISS - 3rd programme
• Ref Project: SIST-TP CEN/TR 10377:2023 - Guidelines for the preparation of standard routine methods with wavelength-dispersive X-ray fluorescence spectrometry

Relations

• Replaces: CR 10299:1998 - Guidelines for the preparation of standard routine methods with wavelength-dispersive X-ray fluorescence spectrometry
• Effective Date: 28-Oct-2020

Overview

CEN/TR 10377:2023 - "Guidelines for the preparation of standard routine methods with wavelength-dispersive X‑ray fluorescence spectrometry" is a CEN Technical Report that gives practical guidance on developing routine WDXRF (wavelength‑dispersive X‑ray fluorescence) methods. Focused primarily on the analysis of metals and alloys (notably steels), the document explains measurement principles, instrument components, calibration strategies, validation, performance criteria and radiation protection. It updates and supersedes CR 10299:1999 and was prepared by CEN/TC 459/SC 2.

Keywords: CEN/TR 10377:2023, wavelength-dispersive XRF, WDXRF, XRF calibration, metals analysis, steels, routine methods.

Key topics and technical requirements

• Measurement principle: Prepare a clean, uniform sample surface, irradiate with X‑rays, disperse secondary radiation with crystals and measure characteristic wavelengths with detectors; results referenced to calibration curves built from certified reference materials (CRMs) and reference materials (RMs).
• Instruments & components: Guidance on tube types (end‑window vs side‑window), anode materials (Rh, Cr, Mo, W, Au, Ag and double‑anode options) and trade‑offs. Typical equipment capabilities described (acceleration voltages up to ~100 kV); recommended vacuum conditions for stable analysis (pressure < 40 Pa for light elements).
• Sample handling: Emphasis on sampling, sample preparation and use of spinners to minimize striation/heterogeneity effects.
• Signal corrections & evaluation: Dead‑time correction, background correction, line interference and inter‑element correction models.
• Calibration strategy: Selecting calibration and recalibration samples, optimizing geometry (2Θ), tube voltage/current, detector conditions, filter use, minimum counting times and regression calculation approaches.
• Validation & performance: Procedures for assessing trueness and precision, limits of detection/quantification (LOD/LOQ/LLD), sensitivity and Background Equivalent Concentration (BEC), repeatability/reproducibility, monitoring and maintenance.
• Safety: Radiation protection requirements for XRF instrumentation and measurement workspaces.

Practical applications

• Routine composition analysis and process control in steel and alloy production
• Quality control and acceptance testing in manufacturing and foundries
• Certification and conformity testing laboratories using WDXRF for fast, high‑precision elemental results
• Development of standardized lab procedures and method documentation for industrial analytics

Keywords: production analysis, alloy composition, quality control, WDXRF method validation.

Who should use this standard

• Analytical chemists and laboratory managers implementing WDXRF methods
• QC/QA teams in metallurgy and materials production
• Instrument manufacturers and service engineers preparing method documentation
• Standards developers and accreditation bodies specifying routine XRF procedures

Related standards and references

• Supersedes CR 10299:1999 (now TR 10377:2023)
• References ISO/IEC terminologies (IEC Electropedia, ISO OBP) for terms and definitions
• Useful when combined with laboratory accreditation and CRM documentation for method traceability

For implementers, CEN/TR 10377:2023 is a practical reference to design robust WDXRF routine methods, optimize instrument settings, ensure valid calibrations and meet performance and safety requirements.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2023
Navodilo za pripravo standardnih postopkov z valovno-disperzno rentgensko
fluorescenčno spektrometrijo
Guidelines for the preparation of standard routine methods with wavelength-dispersive
X-ray fluorescence spectrometry
Ta slovenski standard je istoveten z: CEN/TR 10377:2023
ICS:
71.040.50 Fizikalnokemijske analitske Physicochemical methods of
metode analysis
77.040.30 Kemijska analiza kovin Chemical analysis of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 10377
TECHNICAL REPORT
RAPPORT TECHNIQUE
June 2023
TECHNISCHER REPORT
ICS 77.040.30 Supersedes CR 10299:1998
English Version
Guidelines for the preparation of standard routine
methods with wavelength-dispersive X-ray fluorescence
spectrometry
This Technical Report was approved by CEN on 12 June 2023. It has been drawn up by the Technical Committee CEN/TC 459/SC
2.
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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 10377:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Principle . 8
5 Instruments. 8
5.1 General. 8
5.2 Tubes . 9
5.3 Vacuum system . 10
5.4 Sample spinner . 10
5.5 Filters . 10
5.6 Collimators . 10
5.7 Crystals . 11
5.8 Detectors . 11
5.9 Sequential- simultaneous instruments . 12
6 Sampling and sample preparation . 12
7 Evaluation methods . 13
7.1 Dead time correction . 13
7.2 Background correction . 13
7.3 Line interference, correction models . 13
7.4 Inter-element effects, correction models . 14
8 Calibration strategy . 15
8.1 General. 15
8.2 Optimizing 2Θ . 15
8.3 Selecting the optimum conditions for detectors . 15
8.4 Selecting the optimum tube voltage and current . 15
8.5 Selecting the minimum measuring times . 15
8.6 Selecting the calibration samples . 15
8.7 Selecting the recalibration samples . 16
8.8 Measuring of calibration samples . 16
8.9 Regression calculations . 16
9 Validation of method (trueness and precision) . 17
10 Performance criteria . 17
10.1 General. 17
10.2 Checking the precision . 17
10.3 Performance monitoring . 17
10.4 Maintenance . 18
11 Radiation protection . 18
Annex A (informative) Example of assessment of Sensitivity (S), Background Equivalent
Concentration (BEC), Background (Bg), Limit of Detection (LOD), Limit of
Quantification (LOQ) and Lower Limit of Detection (LLD) . 19
Annex B (informative) Example of an assessment of line interference . 21
Annex C (informative) Example of performance criteria obtained under repeatability
conditions . 22
Bibliography . 23

European foreword
This document (CEN/TR 10377:2023) has been prepared by Technical Committee CEN/TC 459/SC 2
“Methods of chemical analysis for iron and steel”, the secretariat of which is held by SIS.
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 CR 10299:1999.
In comparison with the previous edition, the following modifications have been made:
— Conversion of the document from a CEN Report (CR) to a Technical Report (TR);
— Title: reworded;
— Clause 1, “Purpose of the guideline” split in “Introduction” and “Scope”;
— Definition 3.3, deleted;
— Definition 3.4, deleted;
— Definition 3.9, updated;
— Definition 3.10, updated;
— Definition 3.11, updated;
— Definition 3.12, updated;
— Renumbering of Clauses 2, 4, 5, 6, 7, 8, 9 and 10;
— Annex A updated and became “Bibliography”;
— Annex B, became Annex A;
— Annex C, became Annex B;
— Annex D, became Annex C;
— Annex E, withdrawn.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
Introduction
X-ray Fluorescence Spectrometry (XRF) has been used for several decades as an important analytical
tool for routine analysis. XRF is characterized by its speed and high precision over wide content ranges.
Since the technique in most cases is used as a relative method, its limitations are often connected to
the quality of the calibration samples.
The technique is well established and most of its physical properties are well known.
1 Scope
This document is intended to be used for the analysis of metals and alloys (namely steels), but it can
also be applicable to other materials although the sample preparation techniques differ. The purpose
of this document is to describe general concepts and the procedures for calibration and analysis by
XRF.
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 terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
calibration
calculation of the best fit of net intensities and contents from a number of calibration samples to a
calibration curve
3.2
recalibration
calculation of new calibration constants with a few number of samples, selected from the calibration
samples
Note 1 to entry: Calibration samples using the apparent contents calculated in 3.1
Note 2 to entry: To compensate for the day-to-day variations of the instrument a set of recalibration samples is
measured; either one with a low and one with a high content for each element (two-point recalibration) or one
with a high content only for each element (one-point recalibration). The intensities are compared to the initial
intensities recorded during the calibration procedure and recalibration coefficients are calculated. Calibration
constants are not changed.
3.3
background equivalent concentration
BEC
quantity of analyte which, when subjected to excitation, provides a net intensity equal to the spectral
background
3.4
limit of detection
LOD
minimum content at which the signal generated by a given element can be positively recognised above
any background signals with a specified degree of certainty
3.5
lower limit of detection
LLD
minimum content at which the signal generated by a given element can be positively recognised above
any background signals with a specified degree of certainty
Note 1 to entry: The related calculations are based only on the counting statistical error
3.7
limit of quantification
LOQ
smallest content that can be determined with a specified degree of certainty
3.8
repeatability conditions
conditions where independent test results are obtained with the same method on identical test items
in the same laboratory by the same operator using the same equipment within short intervals of time
[SOURCE: ISO 5725-1:1994]
3.9
reproducibility conditions
conditions where test results are obtained with the same method on identical test items in different
laboratories with different operators using different equipment
[SOURCE: ISO 5725-1:1994]
3.10
accuracy
closeness of agreement between test result and accepted reference value
Note 1 to entry: The term accuracy, when applied to a set of test results, involves a combination of random
components and a common systematic error or bias component.
[SOURCE: ISO 5725-1:1994]
3.11
trueness
closeness of agreement between the average value obtained from a large series of test results and an
accepted reference value
Note 1 to entry: The measure of trueness is usually expressed in terms of bias.
Note 2 to entry: Trueness has been referred to as “accuracy of the mean”. This usage is not recommended.
[SOURCE: ISO 5725-1:1994]
3.12
sensitivity, S
difference in intensities between a sample with a high content and one with a low content divided by
the difference in content
Note 1 to entry: Sensitivity is expressed as counts per second per percent.
4 Principle
The sample is prepared to a clean uniform surface and then irradiated by an X-ray beam of high energy.
The secondary X-rays produced are dispersed by means of crystals and the intensities are measured
by detectors at selected characteristic wavelengths. The measuring time is set to reach below a
specified statistical counting error.
Contents of the elements are calculated by relating the measured intensities of test samples to
calibration curves established with certified reference materials (CRMs) and reference materials
(RMs).
5 Instruments
5.1 General
The principle of two different concepts of X-ray fluorescence spectrometer is shown in Figures 1 and
2.
Key
1 Sample
2 Spinner
3 Detector
4 Tube
5 Crystal
6 Primary collimator
7 Secondary collimator
Figure 1 — Spectrometer geometry of sequential instruments
Key
1 Sample
2 Spinner
3 Detector
4 Tube
5 Crystal
6 Source slit
7 Detector slit
Figure 2 — Spectrometer geometry of simultaneous instruments
5.2 Tubes
Two different types of X-ray tubes are used: side-window tubes or end-window tubes.
Table 1 gives a comparison of these two types. More favourable measuring conditions are usually
obtained for light elements with an end-window tube due to the thinner window.
Table 1 - Comparison of end window and side window tubes

End window tubes Side window tubes
Cooling Two cooling circuits: One cooling circuit:
a) Direct cooling with deionized water; Direct cooling with tap water.
b) Indirect cooling with tap water.
Window Slight thermal stressing: Greater thermal stressing:
Thinner window. Thicker window.
Service life 20 000 h 5 000 h
As target material, different high-purity elements like Rh, Ag, W, Cr or Au are used. For the analysis of
steels rhodium is usually used as a multipurpose tube with good excitation conditions for all elements
of interest. If possible, it is suggested that the target material (anode) is not made of an element to be
determined. The applicability of the usual anode materials is summarized in Table 2.
The X-ray tube produces a continuous spectrum and a characteristic spectra depending on the selected
anode material. For optimum excitation, a maximum excitation energy at least two to three times
above the corresponding absorption edge of the element line to be determined is recommended.
At present, equipment is available which can be operated with acceleration voltages up to 100 kV and
maximum power of 3 kW. The limitations of the apparatus are given either by the high-voltage supply
or the X-ray tube used. The use of acceleration voltages above 60 kV is only of advantage in a few cases
e.g. for determining the trace elements in heavy materials.
The radiation from the sample is emitted uniformly in all directions. The sample volume, from where
the characteristic lines for an element can be determined is proportional to its mass number. Light
elements are only penetrating a thin layer of the sample.
Table 2 - Anode materials for X-ray tubes and their fields of application
Anode material Application
Rh Good excitation conditions for light and heavy elements.
Cr Good excitation conditions for light elements, especially for K, Ca and Ti.
Not so good for heavy elements.
Mo Good excitation conditions for heavy elements, especially for Rb and Sr.
W Good excitation conditions for heavy elements, especially for Fe and Ni.
Au Good excitation conditions for heavy elements, especially for Cu and Zn.
Ag Equivalent to Rh. Ag is used if Rh lines interfere with an element to be
determined.
Double anode Different applications according to the anode materials.
5.3 Vacuum system
During the measurement, the sample is moved to the spectrometer chamber. It is important that light
elements (Z < 20) are measured in vacuum as the absorption losses in air are so high that a meaningful
measurement is no longer possible. For the analysis of metal alloys, it is recommended to measure all
elements in vacuum in order to keep the instrument in stable conditions. A pressure less than 40 Pa is
required.
5.4 Sample spinner
Most instruments are equipped with a sample spinner in order to avoid effects from grinding
striations. If that is not the case, it is suggested that the samples are oriented in such a way that the
relation between the X-ray beam and the grinding striations are always the same from measurement
to measurement.
5.5 Filters
If the anode consists of an element identical to one of the elements to be determined a filter has to be
inserted in front of the exit window on the tube in order to eliminate the characteristic lines from the
tube. The efficiency of a filter depends on the material and thickness. A filter made of titanium or
aluminium is often used to eliminate the characteristic lines from a chromium tube. When a filter is
used, the sensitivity of the element to be determined will decrease several times. Sometimes a filter
could be used to increase the peak to background ratio for heavy elements in low concentrations. Many
instruments are supplied with a filter changer containing filters of different materials and thicknesses.
5.6 Collimators
In the flat crystal system (Figure 1) only a portion of the secondary radiation is selected by a primary
collimator and the parallel beam falls into the plane surface of the crystal. The resolution of the
spectrometer is affected not only by the crystals used, but also by the collimation of the radiation. The
finer the collimator selected, the better is the resolution, but the lower is the intensity measured. Most
sequential spectrometers of this type are supplied with at least two collimators, coarse and fine.
In a curved crystal geometry (Figure 2) the use of collimators is not necessary since the light is focused
on the detector by a slit system.
5.7 Crystals
In order to isolate individual characteristic lines emitted by the sample, large single crystals are used
as dispersion media. To cover the usual wavelength range (0,2 Å to 15 Å), crystals with different
interplanar spacing (d-value) are used.
The analysing crystals commonly used are listed in Table 3. To cover the whole wavelength range a
minimum of three crystals is required: LiF(200), PE and TlAP or a multilayer for light elements.
Table 3 Crystals and their fields of application
For the
2 d values
Crystal Lattice planes measurement of the
(nm)
Kα-lines of
Lithium fluoride (LiF) (220) 0,2848 Ti, V, Cr, Mn, Fe, Co, Ni
Lithium fluoride (LiF) (200) 0,4027 K, Ca, Ti, V, Cr, Mn, Fe,
Co, Ni, Cu, Zn, As, Sr, V
Germanium (Ge) (111) 0,6532 P, S, Cl
Pyrolytic graphite (002) 0,6715 P, S, Cl
(PG)
Pentaerythritol (PE) (002) 0,8742 Al, Si, P, S, Cl
Ammonium (101) 1,0642 Mg, Na
dihydrogen
phosphate (ADP)
Thallium hydrogen (100) 2,575 F, Na, Mg, Al
phtalate (TIAP)
Multi-layer crystal –- Variable Elements Z < 11
5.8 Detectors
The selected fluorescent radiation intensity in the spectrometer is recorded by means of appropriate
counters (flow counter, gas counter, and scintillation counter). As the sensitivity of the various
counters is a function of the energy of the radiation to be measured, it is important that the most
suitable counter is used for the particular element line in simultaneous apparatus.
With sequential apparatus, flow and scintillation counters are generally used at the same time and are
connected in series (tandem connection).
For elements with atomic number less than 25 the flow counter is used and for atomic number higher
than 30 the scintillation counter is used.
For atomic numbers between 25 and 30 both counters are used in tandem, if possible. In simultaneous
instruments gas counters filled with krypton or xenon are often used for atomic numbers between 20
and 40.
Counters can record only a limited number of pulses per unit of time, because the measuring process
for each pulse requires a fixed amount of time which is in the order of 1 µs to 100 µs. Other pulses
cannot be detected in this time. It is defined as dead time, τ. Therefore, it is important that care is taken
to ensure that the maximum pre-set pulse rate is not exceeded. This is possible, for example, by
connecting attenuation filters (in simultaneous equipment) or decreasing the tube current. Otherwise,
there will be no linearity between the intensity of the X-ray radiation and the pulse rate measured.
The dead time of the counters can have an effect from a pulse rate of approximately 10 pulses per
second. However, higher pulse rates can be used if the instrument is supplied with an electronic dead
time corrector.
The counters used register pulses at different intensities as a function of the energy of the X-ray
radiation. Therefore, specific pulses or energies can be filtered out by the selection of an electronic
“window” (Pulse Height Discriminator). This pulse height discrimination eliminates interfering pulses.
5.9 Sequential- simultaneous instruments
The X-ray fluorescence apparatus can be subdivided into two categories: sequential and simultaneous.
Simultaneous apparatus has several fixed goniometers (channels) arranged around the sample so that
the individual element intensities are measured at the same time with the same excitation conditions.
Each channel is optimized for each element. Sequential instruments offer the flexibility to optimize the
measuring conditions independently for each of the selected elements and the corresponding
background. The goniometer can be set to a pre-defined angle (5° to
...