ISO/FDIS 24894

Analysis of natural gas — Determination of sulfur compounds — Determination of hydrogen sulfide by laser absorption spectroscopy

This document specifies a method for the determination of hydrogen sulfide content in natural gas by laser absorption spectroscopy. The analytical range expressed as mole fraction is 1×10−6 to 10×10−6.

Analyse du gaz naturel — Détermination des composés soufrés — Détermination du sulfure d’hydrogène par spectroscopie par absorption laser

General Information

• Status: Not Published
• ICS: 75.060 - Natural gas
• Technical Committee: ISO/TC 193/SC 1 - Analysis of natural gas
• Drafting Committee: ISO/TC 193/SC 1/WG 24 - Sulfur UV Fluorescence
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 22-Oct-2025
• Completion Date: 22-Oct-2025

Standards Content (Sample)

FINAL DRAFT
International
Standard
ISO/TC 193/SC 1
Analysis of natural gas —
Secretariat: NEN
Determination of sulfur compounds
Voting begins on:
— Determination of hydrogen
2025-10-22
sulfide by laser absorption
Voting terminates on:
spectroscopy
2025-12-17
Analyse du gaz naturel — Détermination des composés soufrés
— Détermination du sulfure d’hydrogène par spectroscopie par
absorption laser
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
FINAL DRAFT
International
Standard
ISO/TC 193/SC 1
Analysis of natural gas —
Secretariat: NEN
Determination of sulfur compounds
Voting begins on:
— Determination of hydrogen
sulfide by laser absorption
Voting terminates on:
spectroscopy
Analyse du gaz naturel — Détermination des composés soufrés
— Détermination du sulfure d’hydrogène par spectroscopie par
absorption laser
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
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 material . 2
5.1 Calibration gas .2
5.2 Methane .2
5.3 Absorption solution for hydrogen sulfide .3
6 Measurement device . 3
6.1 General requirements .3
6.2 Laser generator .3
6.3 Pretreatment system .3
6.3.1 Filter unit .3
6.3.2 Pressure control unit .3
6.3.3 Flow control unit .3
7 Sample . 3
8 Measurement . 4
8.1 Preparation .4
8.2 Calibration of analyser .4
8.2.1 Calibration frequency .4
8.2.2 Calibration procedure.4
8.2.3 Calibration method .4
9 Analysis . . 4
10 Precision and measurement uncertainty . 4
10.1 Repeatability .4
10.2 Uncertainty evaluation .5
11 Test report . 5
Annex A (informative) Example of statistical procedure for estimation of the repeatability . 6
Bibliography . 9

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 193, Natural gas, Subcommittee SC 1, Analysis
of natural gas.
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
Five methods for determination of sulfur compounds in natural gas already exist as International Standards:
ISO 16960, ISO 19739, ISO 20729, ISO 20676, ISO 11626.
Laser absorption spectroscopy is a more efficient method compared with chemical titration because it is
an optical and instrumental method. It offers a more convenient and more stable means to analyse H S in
natural gas.
v
FINAL DRAFT International Standard ISO/FDIS 24894:2025(en)
Analysis of natural gas — Determination of sulfur compounds
— Determination of hydrogen sulfide by laser absorption
spectroscopy
1 Scope
This document describes a method for the online determination of hydrogen sulfide content in natural gas by
laser absorption spectroscopy. The analytical range expressed as mole fraction is 1 μmol/mol to 50 μmol/mol.
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 6143, Gas analysis — Comparison methods for determining and checking the composition of calibration gas
mixtures
ISO 10715, Natural gas — Gas sampling
ISO 12963, Gas analysis — Comparison methods for the determination of the composition of gas mixtures based
on one- and two-point calibration
ISO 14532, Natural gas — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14532 apply.
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 sketch of the measuring principle is shown in Figure 1. The semiconductor laser generator generates a
laser beam: the laser beam goes through the sample in a gas chamber and reflects many times between the
high reflectivity mirrors at both ends. Then, the laser beam is detected by the photoelectric sensor. The
energy of the laser beam is attenuated because of the absorption by the te
...

ISO/FDIS 24894:2025(en)
ISO /TC 193/SC 1/WG 24
Secretariat: NEN
Date: 2025-08-25
Analysis of natural gas — Determination of sulfur compounds— —
Determination of hydrogen sulfide by laser absorption spectroscopy
Analyse du gaz naturel — Détermination des composés soufrés — Détermination du sulfure d’hydrogène par
spectroscopie par absorption laser
FDIS stage
ISO/DIS 10360-102FDIS 24894:2025(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
EmailE-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
ii
Contents
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and material . 3
6 Measurement device . 4
7 Sample . 4
8 Measurement . 4
9 Analysis . 5
10 Precision and measurement uncertainty . 5
11 Test report . 6
Annex A (informative) Example of statistical procedure for estimation of the repeatability . 7
Bibliography . 5

Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and material . 2
5.1 Calibration gas . 2
5.2 Methane . 2
5.3 Absorption solution for hydrogen sulfide . 2
6 Measurement device . 3
6.1 General requirements . 3
6.2 Laser generator . 3
6.3 Pretreatment system . 3
6.3.1 Filter unit . 3
6.3.2 Pressure control unit . 3
6.3.3 Flow control unit . 3
7 Sample . 3
8 Measurement. 3
8.1 Preparation . 3
8.2 Calibration of analyser . 4
8.2.1 Calibration frequency . 4
8.2.2 Calibration procedure . 4
8.2.3 Calibration method . 4
iii
ISO/DIS 10360-102FDIS 24894:2025(en)
9 Analysis . 4
10 Precision and measurement uncertainty . 4
11 Test report . 5
Annex A(informative)Example of statistical procedure for estimation of the repeatability . 6
Bibliography . 9

iv
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 documentsdocument 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 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 193, Natural gas, Subcommittee SC 1, Analysis
of natural gas.
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.www.iso.org/members.html.

v
ISO/DIS 10360-102FDIS 24894:2025(en)
Introduction
Five methods for determination of sulfur compounds in natural gas already exist as International Standards:
ISO 16960, ISO 19739, ISO 20729, ISO 20676, ISO 11626.
Laser absorption spectroscopy is a more efficient method compared with chemical titration because it is an
optical and instrumental method. It offers a more convenient and more stable means to analyse H S in natural
gas.
vi
Analysis of natural gas — Determination of sulfur compounds—
— Determination of hydrogen sulfide by laser absorption
spectroscopy
1 Scope
This document describes a method for the online determination of hydrogen sulfide content in natural
gas by laser absorption spectroscopy. The analytical range expressed as mole fraction is 1 μmol/mol to
50 μmol/mol.
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 6143, Gas analysis — Comparison methods for determining and checking the composition of
calibration gas mixtures
ISO 10715, Natural gas — Gas sampling
ISO 12963, Gas analysis — Comparison methods for the determination of the composition of gas mixtures
based on one- and two-point calibration
ISO 14532, Natural gas — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14532 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
4 Principle
A sketch of the measuring principle is shown in Figure 1.Error! Reference source not found. The
semiconductor laser generator generates a laser beam: the laser beam goes through the sample in a gas
chamber and reflects many times between the high reflectivity mirrors at both ends. Then, the laser
beam is detected by the photoelectric sensor. The energy of the laser beam is attenuated because of the
absorption by the test sample. The absorbance obeys the Beer-Lambert law. which describes the
relationship between the absorbance and the mole fraction of (in this case) hydrogen sulfide.
𝑨 = 𝜺 ∙ l ∙ c                (1)
A: Absorbance
𝜺 : Molar absorption coefficient (M-1cm-1)
l : Optical path length (cm)
c : Molar concentration (mol/L or M)
ISO/DIS 10360-102FDIS 24894:2025(en)

a b
3 3
𝐴 = 𝜀 ·  𝑙  ·  𝑐 (1)
where
Key
A is the absorbance
-1 -1
1 ana is the molar absorption coefficient (M cm )
Inserted Cells
lyti
cal
unit
𝜀
2 laseis the optical path length (cm)
r
gen
erat
orl
3 mir is the molar concentration (mol/L or M)
ror
c
4 gas chamber
5 sensor
a
Gas input.
b
Gas output.
Key
1 analytical unit
2 laser generator
3 mirror
4 gas chamber
5 sensor
a
Gas input.
b
Gas output.
Figure 1 — Working principle of the hydrogen sulfide laser absorption analyser
5 Reagents and material
5.1 Calibration gas
Calibration shall be performed in accordance with ISO 6143. Hydrogen sulfide calibration gas mixtures
suitable for the instrument range shall be selected in accordance with the calibration method used.
The balance gas of the hydrogen sulfide calibration gas mixture shall be methane. A matrix of natural
gas may be used as the balance gas instead of methane.
...