ISO 21863:2020

INTERNATIONAL ISO
STANDARD 21863
First edition
2020-11
Water quality — Determination of
alkylmercury compounds in water —
Method using gas chromatography-
mass spectrometry (GC-MS) after
phenylation and solvent extraction
Qualité de l'eau — Détermination des composés alkyl mercure dans
l'eau — Méthode par chromatographie gazeuse et spectrométrie de
masse (CG-SM) après phénylation et extraction par solvant
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Interferences . 2
5.1 Interferences with sampling, sample storage and sample preparation . 2
5.2 Interferences with GC-MS . 2
6 Reagents and standards . 2
7 Apparatus and materials. 4
8 Sample collection, preservation and storage. 5
9 Procedure. 5
9.1 Sample preparation . 5
9.1.1 pH-adjustment of water sample . 5
9.1.2 Phenylation and solvent extraction . 6
9.1.3 Dehydration of toluene extract . 6
9.2 Preparation of samples for GC-MS . 6
9.3 Optimization of operating condition for GC-MS . 6
9.4 Identification of individual substances with GC-MS . 6
9.5 Blank tests . 7
10 Calibration . 7
10.1 General requirements . 7
10.2 Performance test of GC-MS . 7
10.3 Calibration with internal standard . 8
10.3.1 General requirement . 8
10.3.2 Procedure of calibration . 8
10.4 Spike recovery test of target substances . 9
11 Calculation . 9
11.1 Calculation of results after calibration with internal standards . 9
11.2 Treatment of results lying outside the calibration range .10
11.3 Quality checks for internal standardization .10
12 Expression of results .10
13 Test report .11
Annex A (informative) Example of operating condition of GC-MS .12
Annex B (informative) Examples of mass chromatograms and mass spectra of phenylated
alkylmercury by GC-MS .13
Annex C (informative) The use of sodium tetrapropylborate as an alternative derivatizing
[4]
agent .16
Annex D (informative) The use of GC-AFS as an alternative detector .17
Annex E (informative) Performance data .20
Bibliography .21
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.
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iv © ISO 2020 – All rights reserved

Introduction
This document specifies a method for the determination of alkylmercury compounds in water by gas
chromatography-mass spectrometry (GC-MS) after phenylation and solvent extraction.
Alkylmercury has high toxicity that causes Minamata disease in the heavy exposure as discovered
at Minamata City in Japan in 1956. Methylmercury in wastewater from an acetaldehyde acetic acid
manufacturing plant was identified as a causative substance. Subsequent investigation revealed that
ethylmercury poisoning has a similar toxic effect as methylmercury. Japanese government set an
effluent standard and an environment standard for alkylmercury.
Minamata Convention on Mercury was adopted by over 140 countries in 2013 for prevention of global
environmental pollution and health damage caused by mercury, and entered into force in 2017. The
convention states that each party shall identify the relevant point source categories and take measures
including the set of release limit values and the use of best available techniques and best environmental
practices. It should be noted that the released inorganic mercury is partially converted to alkylmercury
by biochemical processes of microorganism in water and sediment. Alkylmercury is concentrated in
biota through food chain, and consequently the risk to higher organism increases.
This document will be beneficial to evaluate the risk of alkylmercury from water and to control the
anthropogenic releases of alkylmercury from the relevant point sources.
INTERNATIONAL STANDARD ISO 21863:2020(E)
Water quality — Determination of alkylmercury
compounds in water — Method using gas chromatography-
mass spectrometry (GC-MS) after phenylation and solvent
extraction
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 in accordance with this document
be carried out by suitably qualified staff.
1 Scope
This document specifies a method for the determination of alkylmercury compounds in filtered water
samples by gas chromatography-mass spectrometry after phenylation and solvent extraction.
This method is applicable to determination of individual methylmercury (MeHg) and
ethylmercury (EtHg) compounds in surface water and waste water.
The method can be applied to samples containing 0,2 μg/l to 10 μg/l of each compound as mercury
mass. Depending on the matrix, the method may also be applicable to higher concentrations after
suitable dilution of the sample or reduction in sample size.
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 — Sa
...