ISO 15238:2025
(Main)Coal — Determination of total cadmium
Coal — Determination of total cadmium
This document specifies a procedure for the determination of the total cadmium mass fraction of coal.
Charbon — Dosage du cadmium total
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International
Standard
ISO 15238
Third edition
Coal — Determination of total
2025-07
cadmium
Charbon — Dosage du cadmium total
Reference number
© 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
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Preparation of sample . 2
8 Procedure . 3
8.1 Ashing of coal sample .3
8.2 Preparation of test solution .3
8.3 Preparation of blank solution . .3
8.4 Graphite-furnace atomic absorption analysis .3
8.4.1 Calibration . . .3
8.4.2 Measurement of standards .3
8.4.3 Measurement of test solution . .4
8.4.4 Measurement of blank solution .4
9 Expression of results . 4
9.1 Ash mass fraction . .4
9.2 Cadmium mass fraction .4
10 Precision . 5
10.1 Repeatability limit .5
10.2 Reproducibility critical difference .5
11 Test report . 5
Bibliography . 6
iii
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 document 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 27, Coal and coke, Subcommittee SC 5, Methods
of analysis.
This third edition cancels and replaces the second edition (ISO 15238:2016), which has been technically
revised.
The main changes are as follows:
— the normative references have been updated;
— Formulae (1) and (2) have been modified.
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
International Standard ISO 15238:2025(en)
Coal — Determination of total cadmium
1 Scope
This document specifies a procedure for the determination of the total cadmium mass fraction of coal.
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 5068-2, Brown coals and lignites — Determination of moisture — Part 2: Indirect gravimetric method for
moisture in the analysis sample
ISO 11722, Solid mineral fuels — Hard coal — Determination of moisture in the general analysis test sample by
drying in nitrogen
ISO 13909-4, Coal and coke — Mechanical sampling — Part 4: Preparation of test samples of coal
ISO 18283, Coal and coke — Manual sampling
3 Terms and definitions
No terms and definitions are listed in this document.
...
FINAL DRAFT
International
Standard
ISO/FDIS 15238
ISO/TC 27/SC 5
Coal — Determination of total
Secretariat: SA
cadmium
Voting begins on:
2025-03-26
Voting terminates on:
2025-05-21
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 15238:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 15238:2025(en)
International
Standard
ISO/FDIS 15238
ISO/TC 27/SC 5
Coal — Determination of total
Secretariat: SA
cadmium
Voting begins on:
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 15238:2025(en) © ISO 2025
ii
ISO/FDIS 15238:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Preparation of sample . 2
8 Procedure . 3
8.1 Ashing of coal sample .3
8.2 Preparation of test solution .3
8.3 Preparation of blank solution . .3
8.4 Graphite-furnace atomic absorption analysis .3
8.4.1 Calibration . . .3
8.4.2 Measurement of standards .3
8.4.3 Measurement of test solution . .4
8.4.4 Measurement of blank solution .4
9 Expression of results . 4
9.1 Ash mass fraction . .4
9.2 Cadmium mass fraction .4
10 Precision . 5
10.1 Repeatability limit .5
10.2 Reproducibility critical difference .5
11 Test report . 5
Bibliography . 6
iii
ISO/FDIS 15238:2025(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 document 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 27, Coal and coke, Subcommittee SC 5, Methods
of analysis.
This third edition cancels and replaces the second edition (ISO 15238:2016), which has been technically
revised.
The main changes are as follows:
— the normative references have been updated;
— Formulae (1) and (2) have been modified.
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
FINAL DRAFT International Standard ISO/FDIS 15238:2025(en)
Coal — Determination of total cadmium
1 Scope
This document specifies a procedure for the determination of the total cadmium mass fraction of coal.
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 t
...
ISO/FDIS 15238
ISO/TC 27/SC 5
Secretariat: SA
Date: 2025-02-1003-11
Coal — Determination of total cadmium
FDIS stage
Warning for WD’s and CD’s
This document is not an ISO International Standard. It is distributed for review and comment. It is subject to change
without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which
they are aware and to provide supporting documentation.
ISO/DISFDIS 15238:20242025(en)
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 the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
E-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
iii
ISO/FDIS 15238:2025(en)
Contents
Foreword . Error! Bookmark not defined.
1 Scope . Error! Bookmark not defined.
2 Normative references . Error! Bookmark not defined.
3 Terms and definitions . Error! Bookmark not defined.
4 Principle. Error! Bookmark not defined.
5 Reagents . Error! Bookmark not defined.
6 Apparatus . Error! Bookmark not defined.
7 Preparation of sample . Error! Bookmark not defined.
8 Procedure . Error! Bookmark not defined.
8.1 Ashing of coal sample . Error! Bookmark not defined.
8.2 Preparation of test solution . Error! Bookmark not defined.
8.3 Preparation of blank solution . Error! Bookmark not defined.
8.4 Graphite-furnace atomic absorption analysis . Error! Bookmark not defined.
9 Expression of results . Error! Bookmark not defined.
9.1 Ash mass fraction . Error! Bookmark not defined.
9.2 Cadmium mass fraction . Error! Bookmark not defined.
10 Precision . Error! Bookmark not defined.
10.1 Repeatability limit . Error! Bookmark not defined.
10.2 Reproducibility critical difference . Error! Bookmark not defined.
11 Test report . Error! Bookmark not defined.
Foreword . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Preparation of sample . 2
8 Procedure . 3
8.1 Ashing of coal sample . 3
8.2 Preparation of test solution . 3
8.3 Preparation of blank solution . 3
8.4 Graphite-furnace atomic absorption analysis . 3
9 Expression of results . 4
9.1 Ash mass fraction . 4
9.2 Cadmium mass fraction . 4
10 Precision . 5
10.1 Repeatability limit . 5
10.2 Reproducibility critical difference . 5
11 Test report . 5
iv
ISO/DISFDIS 15238:20242025(en)
Bibliography . 6
v
ISO/FDIS 15238:2025(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 document 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.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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 5, Methods
of analysis.
This third edition cancels and replaces the second edition (ISO 15238:2016), which has been technically
revised.
The main changes are as follows:
— — the normative references have been updated;
— — Formulae (1) and (2)Formulae (1) and (2) have been modified.
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.htmlwww.iso.org/members.html.
vi
ISO/FDIS 15238:2025(en)
Coal — Determination of total cadmium
1 Scope
This document specifies a procedure for the determination of the total cadmium mass fraction of coal.
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 5068-2, Brown coals and lignites — Determination of moisture — Part 2: Indirect gravimetric method for
moisture in the analysis sample
ISO 11722, Coal and coke — CoalSolid mineral fuels — Hard coal — Determination of moisture in the general
analysis test sample by drying in nitrogen
ISO 13909-4, Coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples of coal
ISO 18283, Coal and coke — Manual sampling
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminologicalterminology 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/
— ISO Online browsing platform: available at https://www.iso.org/obp
4 Principle
The coal sample is ashed, followed by dissolution of the ash in a mixture of hydrochloric, nitric and
hydrofluoric acids. The cadmium species present are quantified by graphite furnace atomic absorption
spectroscopy.
This procedure has not been validated with coals that spontaneously ignite. Prior to use with such sample
types, users should validate the method.
5 Reagents
WARNING — Care shall be exercised when handling the reagents, many of which are toxic and
corrosive.
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade.
ISO/FDIS 15238:2025(en)
5.1 5.1 Water, conforming to the requirements of Grade 1 of ISO 3696.
5.2 5.2 Aqua regia solution. Mix 1 part volume fraction of concentrated nitric acid solution
(relative density 1,42), 3 parts volume fraction of concentrated hydrochloric acid solution (relative density
1,19), and 1 part volume fraction of water.
5.3 5.3 Concentrated hydrofluoric acid solution (relative density 1,15).
WARNING — Hydrofluoric acid is an extremely aggressive chemical which shall be handled with care.
5.4 5.4 Boric acid solution, saturated. Dissolve 60 g of boric acid in 1 l of hot water, cool and allow
to stand for 3 d before decanting the clear solution.
5.5 5.5 Cadmium standard stock solution, 10 µg/ml. Prepare the stock solution from a high
purity metal oxide or salt, having a purity greater than 99,9 %. Dilute to volume with 1 % volume fraction
nitric acid solution.
The cadmium standard stock solution may also be prepared from commercially available certified cadmium
solution.
5.6 5.6 Cadmium standard solution, 0,1 µg/ml. Dilute 10,0 ml of cadmium standard stock
solution (5.5) to 1,0 l with 1 % volume fraction nitric acid solution.
6 Apparatus
6.1 6.1 Balance, capable of determining mass by weighing to the nearest 0,1 mg.
6.2 6.2 Silica or platinum combustion crucible (45 mm × 35 mm × 14 mm).
6.3 6.3 Muffle furnace, with a temperature control.
6.4 6.4 Plastic bottles, made of high density polyethylene (HDPE) or fluorinated ethylene propylene
(FEP), of 125 ml capacity, with screw-cap lids, capable of withstanding 130 °C when sealed and containing
liquid.
6.5 6.5 Volumetric flasks, made of high density polyethylene (HDPE) or fluorinated ethylene
propylene (FEP), of 100 ml capacity.
6.6 6.6 Water bath.
6.7 6.7 Graphite-furnace atomic absorption spectrometer, with background correction.
7 Preparation of sample
The test sample shall be prepared in accordance with ISO 13909-4 or ISO 18283, as appropriate. Ensure that
the moisture of the sample is in equilibrium with the laboratory atmosphere, exposing it if necessary, in a thin
layer for the minimum time required to achieve equilibrium.
Before commencing the determination, mix the equilibrated sample for at le
...
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