ISO 24384:2024

International
Standard
ISO 24384
First edition
Water quality — Determination of
2024-02
chromium(VI) and chromium(III)
in water — Method using liquid
chromatography with inductively
coupled plasma mass spectrometry
(LC-ICP-MS) after chelating
pretreatment
Qualité de l'eau — Dosage du chrome (VI) et du chrome (III)
dans l'eau — Méthode par spectrométrie de masse avec plasma à
couplage inductif (LC-ICP-MS) après un prétraitement par agents
de chélation
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Interferences . 2
5.1 General .2
5.2 Samples .2
5.3 Sample storage and sample preparation .2
5.4 Chelating pretreatment .2
5.5 LC-ICP-MS measurements .2
6 Reagents and standards . . 3
7 Apparatus . 5
8 Sampling, preservation and storage of samples . 6
9 Procedure . 7
9.1 Sample preparation .7
9.1.1 pH-adjustment of water sample .7
9.1.2 Chelating pretreatment .7
9.2 Optimization of operating condition for LC-ICP-MS .7
9.3 Identification of Cr(VI) and Cr(III) on LC-ICP-MS .8
9.4 Blank value measurements .8
10 Calibration . 8
10.1 General requirements .8
10.2 Calibration covering the total procedure .9
10.3 Recovery test of target substances .10
11 Calculation . 10
11.1 Use of the calibration curve to determine the result .10
11.2 Calculation of results after calibration .10
11.3 Treatment of results lying outside the calibration range .11
12 Expression of results .11
13 Test report .11
Annex A (informative) Example of an operating condition of LC-ICP-MS and chromatogram of
Cr(VI) and Cr(III) in the case of PDCA-chelating pretreatment .12
Annex B (informative) Example of operating condition of LC-ICP-MS and chromatograms of
Cr(VI) and Cr(III) in the case of EDTA-chelating pretreatment . 14
Annex C (informative) Performance data .16
Bibliography .18

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods.
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
Introduction
Chromium (Cr) exists in natural resources and is also widely used in industries as plating agents, paints,
dyes, catalysts, and dietary supplements. The Cr(VI) compounds are highly harmful and recognized to
be a human carcinogen. The Cr(III) compounds are recently used as a substitute for Cr(VI) compounds in
industries, e.g. plating. In wastewater, surface water, or drinking water, chromium mainly exists in two
oxidation states: +3 [Cr(III)] and +6 [Cr(VI)]. However, the proportion between Cr(VI) and Cr(III) is quite
variable. Therefore, the determination of the individual oxidation states of chromium is crucial to evaluate
and control the risk of chromium to human and environmental health. This document will be beneficial to
perform a robust, simple, and rapid determination of chromium of the individual oxidation states.

v
International Standard ISO 24384:2024(en)
Water quality — Determination of chromium(VI)
and chromium(III) in water — Method using liquid
chromatography with inductively coupled plasma mass
spectrometry (LC-ICP-MS) after chelating pretreatment
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is
the responsibility of the user to establish appropriate safety and health practices.
IMPORTANT — It is absolutely essential that tests conducted according to this document be carried
out by suitably qualified staff.
1 Scope
This document specifies a method for the determination of hexavalent chromium [Cr(VI)] and trivalent
chromium [Cr(III)] in water by liquid chromatography with inductively coupled plasma mass spectrometry
(LC-ICP-MS) after chelating pretreatment.
This method is applicable to the determination of Cr(VI) and Cr(III) dissolved in wastewater, surface
water, groundwater, or drinking water from 0,20 μg/l to 500 μg/l of each compound as chromium (Cr)
mass. Samples containing Cr at concentrations higher than the working range can be analysed following
appropriate dilution of the 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 8466-1, Water quality — Calibration and evaluation of analytical methods — Part 1: Linear calibration
function
3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Principle
The chemical forms of various Cr(III) species in water samples are unified to a stable Cr(III) complex by
a chelating pretreatment with 2,6-pyridinedicarboxylic acid (PDCA) or ethylenediaminetetraacetic acid
[1][2]
(EDTA) after adjusting the sample solution pH to 6,9 ± 0,1. Liquid chromatography combined with
inductively coupled plasma mass spectrometry (LC-IC
...