ISO 25122

• Abstract:

  This document specifies a gas chromatographic (GC) method for the determination of traces of carbon monoxide and carbon dioxide in ethylene and propylene for industrial use. This document is applicable to ethylene and propylene having carbon monoxide and carbon dioxide concentrations greater than 0,5 mL/m3.

• Status: Not Published
• ICS: 71.040.40 - Chemical analysis
• ICS: 71.080.10 - Aliphatic hydrocarbons
• Technical Committee: ISO/TC 47 - Chemistry
• Drafting Committee: ISO/TC 47/WG 2 - Light Olefins
• Current Stage: 6000 - International Standard under publication
• Start Date: 09-Sep-2026
• Completion Date: 10-Oct-2026

ISO 25122 is an ISO standard for measuring traces of carbon monoxide and carbon dioxide in ethylene and propylene for industrial use. It specifies a gas chromatographic (GC) method for samples above 0.5 mL/m3, so laboratories can report low-level impurity content on the same basis. The document covers sampling, calibration, calculation, precision, quality assurance, and test reporting.

What does ISO 25122 specify?

ISO 25122 specifies a GC method for determining trace carbon monoxide and carbon dioxide in industrial ethylene and propylene. It applies to materials with carbon monoxide and carbon dioxide concentrations greater than 0.5 mL/m3.

The document is organized into clauses 1 to 13. These cover scope, normative references, principle, reagents and materials, apparatus, sampling, procedure, calculation, reporting, precision, quality assurance, and test report. In practice, that gives the user a complete laboratory method rather than only a detector setting or a calculation rule.

What are the key requirements of ISO 25122?

• Clause 4 - Measurement principle: ISO 25122 uses gas chromatography with a hydrogen flame ionization detector (FID), then converts carbon monoxide and carbon dioxide to methane in a methanizer before final detection. This matters because the method measures the impurities indirectly after conversion, so the chromatograph and methanizer must work together.

• Clause 5 - Reagents and materials: The method calls for high-purity nitrogen, hydrogen, and air, all dried and purified, plus a gas standard with known carbon monoxide and carbon dioxide content. The standard should be close to the sample level when possible, because calibration accuracy depends on matching the measurement range.

• Clause 6 - Apparatus and operating conditions: ISO 25122 allows two instrument configurations. Condition 1 uses one valve and two columns, while condition 2 uses two valves and three columns. Condition 2 improves separation from oxygen, which is important when oxygen could bias the carbon monoxide result.

• Clause 6 - Columns and methanizer: The document gives typical column types and operating conditions, including packed columns and a molecular sieve 13X column in condition 2. It also specifies a nickel catalytic methanizer heated to 350 °C to 400 °C. In practice, the analyst must set up the GC so that carbon monoxide and carbon dioxide are fully separated and fully converted.

• Clause 7 and Clause 8 - Sampling and procedure: Sampling follows ISO 7382 for ethylene and ISO 8563 for propylene. The method then uses 2 mL injections for calibration and sample measurement, with repeated measurements. For liquid propylene, the sample must be fully vaporized before introduction, which avoids losing dissolved gases.

• Clause 8 and Clause 9 - Calibration and calculation: Calibration uses a gas standard and requires the peak area difference between duplicate measurements to stay within 5% of the mean. Results are calculated by external standard comparison from peak areas. This means the method depends on stable repeat injections and good baseline control.

• Clause 10 to Clause 13 - Reporting, precision, quality assurance: ISO 25122 requires reporting the arithmetic mean of two measurements to the nearest 0.1 mL/m3. Clause 11 gives repeatability and reproducibility statements, Clause 12 requires periodic QC samples, and Clause 13 lists the minimum test report content. That supports routine release testing and internal quality control.

Who uses ISO 25122?

ISO 25122 is used by laboratories and quality assurance teams testing industrial ethylene and propylene. It is relevant where producers, plant laboratories, or contract laboratories need to verify trace carbon monoxide and carbon dioxide before product release, transfer, or further processing.

Which standards are used with ISO 25122?

• ISO 7382 - Sampling of ethylene in the liquid and gaseous phase.
• ISO 8563 - Sampling of propylene and butadiene in the liquid phase.

These referenced standards supply the sampling methods that ISO 25122 relies on before the GC analysis begins.

What does the ISO 25122 document contain?

ISO 25122 includes the full laboratory method structure: principle, reagent specifications, apparatus setup, sampling, calibration, sample measurement, calculation, reporting, precision, quality assurance, and test report requirements. It also includes two schematic instrument arrangements for the two operating conditions.

The document gives typical column arrangements and operating conditions in Table 1, plus typical chromatograms in Figures 3 and 4. Figure 1 and Figure 2 show the two valve-and-column configurations used for the two operating conditions.

Clause 9 provides the external-standard calculation approach, and Clause 11 provides precision statements for both analytes. Clause 13 lists the items that belong in the test report, including sample identification, the reference to ISO 25122, the result, any optional experimental conditions, any agreed deviations, and the test date.

International
Standard
First edition
Ethylene and propylene for
industrial use — Determination
of traces of carbon monoxide
and carbon dioxide — Gas
chromatographic method
PROOF/ÉPREUVE
Reference number
© ISO 2026
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
PROOF/ÉPREUVE
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
5.1 Nitrogen .2
5.2 Hydrogen .2
5.3 Air .2
5.4 Gas standard .2
6 Apparatus . 2
6.1 Gas Chromatography .2
6.2 Column .4
6.3 Methanizer .6
6.4 Data processing equipment .6
7 Sampling . 6
8 Procedure . 6
8.1 Preparation of Apparatus .6
8.2 Calibration .6
8.3 Sample measurement .7
9 Calculation . 7
10 Reporting . 7
11 Precision . 7
11.1 Repeatability (r) .7
11.2 Reproducibility (R) .7
12 Quality Assurance . 8
13 Test report . 8
PROOF/ÉPREUVE
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 47, Chemistry.
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.
PROOF/ÉPREUVE
iv
International Standard ISO 25122:2026(en)
Ethylene and propylene for industrial use — Determination
of traces of carbon monoxide and carbon dioxide — Gas
chromatographic method
1 Scope
This document specifies a gas chromatographic (GC) method for the determination of traces of carbon
monoxide and carbon dioxide in ethylene and propylene for industrial use.
This document is applicable to ethylene and propylene having carbon monoxide and carbon dioxide
concentrations greater than 0,5 mL/m .
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 7382, Ethylene for industrial use — Sampling in the liquid and the gaseous phase
ISO 8563, Propylene and butadiene for industrial use — Sampling in the liquid phase
3 Terms and definitions
No terms and definitions need to be defined 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
...

ISO/DISPRF 25122:2026(en)
ISO/TC 47
Secretariat: JISC
Date: 2026-06-1608-11
Ethylene and propylene for industrial use — Determination of traces
of carbon monoxide and carbon dioxide — — Gas chromatographic
method
PROOF
ISO/PRF 25122:2026(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 © ISO/DIS 25122 2026 – All rights reserved
ii
ISO/DISPRF 25122:2026(en)
Contents
Foreword . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 2
5.1 Nitrogen . 2
5.2 Hydrogen . 2
5.3 Air . 2
5.4 Gas standard . 2
6 Apparatus . 2
6.1 Gas Chromatography . 2
6.2 Column . 4
6.3 Methanizer . 7
6.4 Data processing equipment . 7
7 Sampling . 8
8 Procedure . 8
8.1 Preparation of Apparatus . 8
8.2 Calibration . 8
8.3 Sample measurement . 8
9 Calculation . 8
10 Reporting . 8
11 Precision . 9
11.1 Repeatability (r) . 9
11.2 Reproducibility (R) . 9
12 Quality Assurance . 9
13 Test report . 9

Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents and materials . 1
6 Apparatus . 2
7 Sampling . 6
8 Procedure . 7
9 Calculation . 7
10 Reporting . 7
11 Precision . 7
iii
ISO/PRF 25122:2026(en)
12 Quality Assurance . 8
13 Test report . 8
iv © ISO/DIS 25122 2026 – All rights reserved
iv
ISO/DISPRF 25122:2026(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 47, Chemistry.
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.

v
DRAFT International Standard ISO/DIS 25122:2026(en)

Ethylene and Propylenepropylene for Industrial Use industrial use —
Determination of Tracestraces of Carbon Monoxidecarbon monoxide
and Carbon Dioxidecarbon dioxide — Gas Chromatographic
Methodchromatographic method
1 Scope
This document specifies a gas chromatographic (GC) method for the determination of traces of carbon
monoxide and carbon dioxide in ethylene and propylene for industrial use.
This document is applicable to ethylene and propylene having carbon monoxide and carbon dioxide
concentrations greater than 0,5 mL/m .
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 7382, Ethylene for indus
...