ISO 20289:2018

INTERNATIONAL ISO
STANDARD 20289
First edition
2018-03
Surface chemical analysis — Total
reflection X-ray fluorescence analysis
of water
Analyse chimique des surfaces — Analyse par fluorescence de rayons
X en réflexion totale d'eau
Reference number
©
ISO 2018
© ISO 2018
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Published in Switzerland
ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 3
5 Safety . 3
6 Interferences . 3
7 Apparatus . 3
7.1 General . 3
7.2 Labware . 4
7.3 Drying apparatus . 4
8 Reagents, standards and materials . 4
9 Sample preparation . 5
9.1 Environment . 5
9.2 Sample . 5
9.3 Specimen . 6
9.4 Sample carrier . 6
9.5 Trials/replicates . 6
9.6 Effect of residue mass, size and its position . 7
10 Procedure. 7
10.1 General . 7
10.2 Instrument calibration . 7
10.3 Detection limit . 7
10.4 TXRF measurements . 8
10.5 Spectra fitting . 8
10.6 Unknown samples . 8
11 Qualitative and quantitative analysis . 8
11.1 Identification of elements . 8
11.2 Quantification of elements . 8
11.3 Calculations . 9
11.4 Measurement uncertainty . 9
12 Quality control . 9
13 Precision and accuracy .10
14 Test report .10
Annex A (informative) Uncertainty in TXRF measurements .11
Annex B (informative) Validation of the method .15
Bibliography .19
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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URL: www .iso .org/ iso/ foreword .html.
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.
iv © ISO 2018 – All rights reserved

Introduction
Total reflection X-ray fluorescence (TXRF) spectroscopy is a surface sensitive technique which can be
used to obtain compositional information about different kinds of samples. ISO/TS 18507 provides the
guidelines for the characterization of biological and environmental samples with TXRF.
TXRF is suitable for quantitative elemental analysis of liquid samples deposited as thin films on clean
[1] [2]
and well-polished reflectors, by means of internal standard calibration .
This document provides guidance and requirements for the quantitative elemental analysis of water by
means of TXRF instrumentation.
INTERNATIONAL STANDARD ISO 20289:2018(E)
Surface chemical analysis — Total reflection X-ray
fluorescence analysis of water
1 Scope
This document provides a chemical method for technicians working with Total Reflection X-ray
Fluorescence (TXRF) instrumentation to perform measurements of water samples, according to
good practices, with a defined degree of accuracy and precision. Target users are identified among
laboratories performing routine analysis of large numbers of samples, which also comply with
ISO/IEC 17025.
This document specifies a method to determine the content of elements dissolved in water (for example,
drinking water, surface water and ground water). Taking into account the specific and additionally
occurring interferences, elements can also be determined in waste waters and eluates. Sampling,
dilution and pre-concentration methods are not included in this document.
Elements that can be determined with the present method may change according to the X-ray source of
the instrument. No health, safety or commercial aspects are considered herewith.
The working range depends on the matrix and the interferences encountered. In drinking water and
relatively unpolluted waters, the limit of quantification lies between 0,001 mg/l and 0,01 mg/l for most
of the elements. The working range typically covers concentrations between 0,001 mg/l and 10 mg/l,
depending on the element and predefined requirements.
Annex B reports, for example, the complete validation of the method of TXRF analysis of water
performed with instrumentation that has Mo as the X-ray source and uses Ga as the internal standard
for calibration.
Quantification limits of most elements are affected by blank contamination and depend predominantly
on the laboratory air-handling facilities available, on the purity of reagents and the cleanliness of
labware.
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 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and
sampling techniques
ISO 5667-3, Water quality — Sampling — Part 3: Guidance on the preservation and handling of water samples
ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 14706, Surface chemical analysis — Determination of surface elemen
...