ISO 24894:2026

International
Standard
ISO 24894
First edition
Analysis of natural gas —
2026-01
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
Reference number
© ISO 2026
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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 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
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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
International Standard ISO 24894:2026(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 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.
Al ·· c (1)
where
A is the absorbance;
-1 -1
εε
is the molar absorption coefficient (M cm );
l is the optical path length (cm);
c is the molar concentration (mol/L or M).

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. Hydroge
...