ISO 625:2025
(Main)Coal and coke — Determination of carbon and hydrogen — Liebig method
Coal and coke — Determination of carbon and hydrogen — Liebig method
This document specifies a method of determining the total carbon and the total hydrogen in coal and coke, by the Liebig method.
Charbon et coke — Dosage du carbone et de l'hydrogène — Méthode de Liebig
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International
Standard
ISO 625
Third edition
Coal and coke — Determination
2025-08
of carbon and hydrogen —
Liebig method
Charbon et coke — Dosage du carbone et de l'hydrogène —
Méthode de Liebig
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
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
6 Apparatus . 2
7 Preparation of the apparatus . 7
7.1 Preparation of the combustion tube .7
7.2 Conditioning of the combustion tube .8
7.3 Conditioning of the absorption train .8
8 Preparation of test sample . 9
9 Procedure . 9
10 Blank test . 9
11 Expression of results . 10
11.1 Total carbon .10
11.2 Organic carbon .10
11.3 Total hydrogen .10
11.4 Total hydrogen mass fraction, less that present as moisture .11
11.5 Additional information.11
12 Precision .11
12.1 Repeatability limit .11
12.2 Reproducibility limit .11
13 Test report .11
Annex A (informative) Derivation of factors used in calculations .12
Bibliography . 14
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 625:1996), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 625:1996/Cor. 1:1996.
The main changes are as follows:
— the normative references have been updated;
— the mandatory terms and definitions clause (Clause 3) has been added and subsequent clauses have been
renumbered;
— Clause 5 has been updated;
— Figures 1, 2, 3 and 4 have been updated;
— Clause 9 has been updated;
— Clause 11 has been revised;
— the test report has been updated;
— Annex A has been revised.
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
An alternative method to the one specified in this document is given in ISO 609.
v
International Standard ISO 625:2025(en)
Coal and coke — Determination of carbon and hydrogen —
Liebig method
1 Scope
This document specifies a method of determining the total carbon and the total hydrogen in coal and coke,
by the Liebig method.
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 687, Coke — Determination of moisture in the general analysis test sample
ISO 925, Solid mineral fuels — Determination of carbonate carbon content — Gravimetric method
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 13909-6, Coal and coke — Mechanical sampling — Part 6: Preparation of test samples of coke
ISO 18283, Coal and coke — Manual sampling
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
A known mass of coal or coke is burnt in a current of oxygen in a tube impervious to gases, the products of
the incomplete combustion being further burnt over copper oxide; all the hydrogen is converted to water
and all the carbon to carbon dioxide. These products are absorbed by suitable reagents and determined
gravimetrically. Oxides of sulfur are retained by lead chromate, chlorine by a silver gauze roll and oxides of
nitrogen by granular manganese dioxide.
The results include the carbon in the carbonates and the hydrogen combined in the moisture and in the water
of constitution of silicates. A determination of moisture is carried out at the same time, and an appropriate
correction is applied to the hydrogen value obtained by combustion. A determination of carbon dioxide may
also be made and the total carbon value corrected for the presence of mineral carbonates.
5 Reagents and materials
WARNING — Care shall be exercised when handling reagents, many of which are toxic.
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
distilled water or water of equivalent purity.
5.1 Magnesium perchlorate, anhydrous, with a particle size of less than 1,2 mm and preferably in the
size range from 1,2 mm to 0,7 mm.
WARNING — Determine any local regulations when disposing of exhausted magnesium perchlorate
prior to use. Regeneration of magnesium perchlorate shall not be attempted, owing to the risk of
explosion.
5.2 Sodium hydroxide on an inert base, preferably of a coarse grading, for example 3,0 mm to 1,5 mm,
but not finer than the grading 1,2 mm to 0,7 mm, and preferably of the self-indicating type.
5.3 Manganese dioxide, granular, 1,2 mm to 0,7 mm.
Manganese dioxide in the granular form and the size required can be prepared as follows.
Dissolve manganese sulfate in water and boil the solution. Make the solution alkaline with ammonium
hydroxide (5.10) and add solid ammonium persulfate (5.11), in small portions, to the boiling solution until
precipitation is complete. Filter through a hardened fast-filter paper, wash with water by decantation, then
with dilute sulfuric acid (5.12) and finally with water until acid-free. Transfer the moist precipitate to a
mortar (6.11) and place in an oven until most of the water has evaporated, but the powder is still damp.
Press the mass into a cake with a pestle (6.11), using firm pressure. Complete the drying, break up the cake
cautiously and sieve to separate the 1,2 mm to 0,7 mm size.
5.4 Copper gauze, of mesh approximately 1 mm and 10 mm wide.
5.5 Copper oxide, wire form, chopped to particles approximately 3 mm long with a diameter of
approximately 0,2 mm.
5.6 Lead chromate, fused, size range 2,4 mm to 1,2 mm.
5.7 Pure silver gauze, of mesh approximately 1 mm, made of wire approximately 0,3 mm in diameter.
5.8 Oxygen, hydrogen-free, preferably prepared from liquid air and
...
FINAL DRAFT
International
Standard
ISO/FDIS 625
ISO/TC 27/SC 5
Coal and coke — Determination
Secretariat: SA
of carbon and hydrogen — Liebig
Voting begins on:
method
2025-05-09
Voting terminates on:
2025-07-04
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 625:2025(en) © ISO 2025
FINAL DRAFT
ISO/FDIS 625:2025(en)
International
Standard
ISO/FDIS 625
ISO/TC 27/SC 5
Coal and coke — Determination
Secretariat: SA
of carbon and hydrogen —
Voting begins on:
Liebig method
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 625:2025(en) © ISO 2025
ii
ISO/FDIS 625:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
6 Apparatus . 2
7 Preparation of the apparatus . 7
7.1 Preparation of the combustion tube .7
7.2 Conditioning of the combustion tube .8
7.3 Conditioning of the absorption train .8
8 Preparation of test sample . 9
9 Procedure . 9
10 Blank test . 9
11 Expression of results . 10
11.1 Total carbon .10
11.2 Organic carbon .10
11.3 Total hydrogen .10
11.4 Total hydrogen mass fraction, less that present as moisture .11
11.5 Additional information.11
12 Precision .11
12.1 Repeatability limit .11
12.2 Reproducibility limit .11
13 Test report .11
Annex A (informative) Derivation of factors used in calculations .12
Bibliography . 14
iii
ISO/FDIS 625:2025(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 625:1996), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 625:1996/Cor. 1:1996.
The main changes are as follows:
— the normative references have been updated;
— the mandatory terms and definitions clause (Clause 3) has been added and subsequent clauses have been
renumbered;
— Clause 5 has been updated;
— Figures 1, 2, 3 and 4 have been updated;
— Clause 9 has been updated;
— Clause 11 has been revised;
— the test report has been updated;
— Annex A has been revised.
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
ISO/FDIS 625:2025(en)
Introduction
An alternative method to the one specified in this document is given in ISO 609.
v
FINAL DRAFT International Standard ISO/FDIS 625:2025(en)
Coal and coke — Determination of carbon and hydrogen —
Liebig method
1 Scope
This document specifies a method of determining the total carbon and the total hydrogen in coal and coke,
by the Liebig method.
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 687, Coke — Determination of moisture in the general analysis test sample
ISO 925, Solid mineral fuels — Determination of carbonate carbon content — Gravimetric method
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 13909-6, Coal and coke — Mechanical sampling — Part 6: Preparation of test samples of coke
ISO 18283, Coal and coke — Manual sampling
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
A known mass of coal or coke is burnt in a current of oxygen in a tube impervious to gases, the products of
the incomplete combustion being further burnt over copper oxide; all the hydrogen is converted to water
and all the carbon to carbon dioxide. These products are absorbed by suitable reagents and determined
gravimetrically. Oxides of sulfur are retained by lead chromate, chlorine by a silver gauze roll and oxides of
nitrogen by granular manganese dioxide.
The results include the carbon in the carbonates and the hydrogen combined in the moisture and in the water
of constitution of silicates. A determination of moisture is carried out at the same time, and an appropriate
correction is applied to the hydrogen value obtained by combustion. A determination of carbon dioxide may
also be made and the total carbon value corrected for the presence of mineral carbonates.
ISO/FDIS 625:2025(en)
5 Reagents and materials
WARNING — Care shall be exercised when handling reagents, many of which are toxic.
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
distilled water or water of equivalent purity.
5.1 Magnesium perchlorate, anhydrous, with a particle size of less than 1,2 mm and preferably in the
size range from 1,2 mm to 0,7 mm.
WARNING — Determine any local regulations when disposing of exhausted magnesium perchlorate
prior to use. Regeneration of magnesium perchlorate shall not be attempted, owing to the risk of
explosion.
5.2 Sodium hydroxide on an inert base, preferably of a coarse grading, for example 3,0 mm to 1,5 mm,
but not finer than the grading 1,2 mm to 0,7 mm, and preferably of t
...
Style Definition
ISO/FDIS 625
...
Formatted: Right: 1.5 cm, Bottom: 1 cm, Gutter: 0 cm,
ISO/TC 27/SC 5/WG 2
Header distance from edge: 1.27 cm, Footer distance
from edge: 1.27 cm, Not Different first page header
Secretariat: SA
ISO/FDIS 625:2024:2024(en)
DATEDate: 2025-03-1904-24
Formatted
...
Formatted: Font: Bold, English (United Kingdom)
Coal and coke — Determination of carbon and hydrogen — Liebig
Formatted: Cover Title_A1
method
Formatted
...
FDIS stage
ISO/FDIS 625:2025(en)
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
Formatted: Default Paragraph Font
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'sISO’s member body in the country of the requester.
ISO Copyright Officecopyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Formatted: zzCopyright address, Adjust space between
Phone: + 41 22 749 01 11
Latin and Asian text, Adjust space between Asian text
Email: E-mail: copyright@iso.org
and numbers
Website: www.iso.org
Formatted: zzCopyright address, Adjust space between
Latin and Asian text, Adjust space between Asian text
Published in Switzerland.
and numbers
ii
ISO/FDIS 625:2025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
6 Apparatus . 2
7 Preparation of the apparatus . 9
7.1 Preparation of the combustion tube. 9
7.2 Conditioning of the combustion tube . 11
7.3 Conditioning of the absorption train . 11
8 Preparation of test sample . 11
9 Procedure . 12
10 Blank test . 12
11 Expression of results . 12
11.1 Total carbon . 12
11.2 Organic carbon . 13
11.3 Total hydrogen . 13
11.4 Total hydrogen mass fraction, less that present as moisture . 13
11.5 Additional information . 14
12 Precision . 14
12.1 Repeatability limit . 14
12.2 Reproducibility limit . 14
13 Test report . 14
Annex A (informative) Derivation of factors used in calculations . 15
Bibliography . 18
iii
ISO/FDIS 625:2025(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 625:1996), which has been technically revised.
It also incorporates the Technical Corrigendum ISO 625:1996/Cor. 1:1996.
The main changes are as follows:
— — the normative references have been updated;
— — the mandatory terms and definitions clause (Clause 3(Clause 3)) has been added and subsequent
clauses have been renumbered;
— Clause 5— the Clause 5 has been updated;
— Figures 1, 2— Figures 1,2 ,3, 3 and 44 have been updated;
— Clause 9— Clause 9 has been updated;
— Clause 11— Clause 11 has been revised;
— — the test report has been updated;
— Annex A— Annex A has been revised.
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
ISO/FDIS 625:2025(en)
Introduction
An alternative method to thatthe one specified in this document is given in ISO 609.
v
ISO/FDIS 625:2025(en)
Formatted
...
Formatted
...
Formatted
...
Coal and coke — Determination of carbon and hydrogen — Liebig
Formatted
...
method
Formatted
...
Formatted
...
1 Scope
Formatted
...
This document specifies a method of determining the total carbon and the total hydrogen in coal and coke, by Formatted
...
the Liebig method.
Formatted
...
Formatted
...
2 Normative references
Formatted
...
The following documents are referred to in the text in such a way that some or all of their content constitutes
Formatted
...
requirements of this document. For dated references, only the edition cited applies. For undated references,
Formatted
...
the latest edition of the referenced document (including any amendments) applies.
Formatted
...
ISO 687, Coke — Determination of moisture in the general analysis test sample
Formatted
...
ISO 925, Coal and cokeSolid mineral fuels — Determination of carbonate carbon dioxide content — Gravimetric Formatted
...
method
Formatted
...
Formatted
...
ISO 5068--2, Brown coals and lignites — Determination of moisture — Part 2: Indirect gravimetric method
for moisture in the analysis sample Formatted
...
Formatted
...
ISO 11722, Solid mineral fuels — Hard coal — Determination of moisture in the general analysis test sample
Formatted
by drying in nitrogen .
Formatted
...
ISO 13909--4, Coal and coke — Mechanical sampling — Part 4: Coal — Preparation of test samples of coal
Formatted
...
ISO 13909--6, Coal and coke — Mechanical sampling — Part 6: Coke— Preparation of test samples of coke
Formatted
...
Formatted
...
ISO 18283, Coal and coke — Manual sampling
Formatted
...
3 Terms and definitions Formatted
...
Formatted
...
No terms and definitions are listed in this document.
Formatted
...
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
Formatted
...
Formatted
...
— — ISO Online browsing platform: available at https://www.iso.org/obp
Formatted
...
— — IEC Electropedia: available at https://www.electropedia.org/
Formatted
...
Formatted
...
4 Principle
Formatted
...
A known mass of coal or coke is burnt in a current of oxygen in a tube impervious to gases, the products of the
Formatted
...
incomplete combustion being further burnt over copper oxide; all the hydrogen is converted to water and all
Formatted
...
the carbon to carbon dioxide. These products are absorbed by suitable reagents and determined
gravimetrically. Oxides of sulfur are retained by lead chromate, chlorine by a silver gauze roll and oxides of
Formatted
...
nitrogen by granular manganese dioxide.
Formatted
...
Formatted
The results include the carbon in the carbonates and the hydrogen combined in the moisture and in the water .
of constitution of silicates. A determination of moisture is carried out at the same time, and an appropriate
Formatted
...
correction is applied to the hydrogen value obtained by combustion. A determination of carbon dioxide may
Formatted
...
also be made and the total carbon value corrected for the presence of mineral carbonates.
Formatted
...
ISO/FDIS 625:2025(en)
5 Reagents and materials
WARNING — Care shall be exercised when handling reagents, many of which are toxic.
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
distilled water or water of equivalent purity.
5.1 5.1 Magnesium perchlorate, anhydrous, with a particle size of less than 1,2 mm and preferably
in the size range from 1,2 mm to 0,7 mm.
WARNING — Determine any local regulations when disposing of exhausted magnesium perchlorate
prior to use. Regeneration of magnesium perchlorate shall not be attempted, owing to the risk of
explosion.
5.2 5.2 Sodium hydroxide on an inert base, preferably of a coarse grading, for example 3,0 mm
to 1,5 mm, but not finer than the grading 1,2 mm to 0,7 mm, and preferably of the self-indicating type.
5.3 5.3 Manganese dioxide, granular, 1,2 mm to 0,7 mm.
Manganese dioxide in the granular form and the size required can be prepared as follows.
Dissolve manganese sulfate in water and boil the solution. Make the solution alkaline with ammonium
hydroxide (5.10(5.10)) and add solid ammonium persulfate, (5.11(5.11)) in small portions, to the boiling
solution until precipitation is complete. Filter through a hardened fast-filter paper, wash with water by
decantation, then with dilute sulfuric acid (5.12(5.12)) and finally with water until acid-free. Transfer the
moist precipitate to a mortar (6.11(6.11)) and place in an oven until most of the water has evaporated, but the
powder is still damp. Press the mass into a cake with a pestle (6.11(6.11),), using firm pressure. Complete the
drying, break up the cake cautiously and sieve to separate the 1,2 mm to 0,7 mm size.
5.4 5.4 Copper gauze, of mesh approximately 1 mm and 10 mm wide.
5.5 5.5 Copper oxide, wire form, chopped to particles approximately 3 mm long with a diameter of
approximately 0,2 mm.
5.6 5.6 Lead chromate, fused, size range 2,4 mm to 1,2 mm.
5.7 5.7 Pure silver gauze, of mesh approximately 1 mm, made of wire approximately 0,3 mm in
diameter.
5.8 5.8 Oxygen, hydrogen-free, preferably prepared from liquid air and not by electrolysis.
Electrolytically prepared oxygen shall be passed over red-hot copper oxide before use to remove any trace of
hydrogen.
5.9 5.9 Glass wool.
5.10 5.10 Ammonium hydroxide, concentrated solution, mass fraction no
...
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