ISO 25095-1:2026

Propylene oxide for industrial use — Part 1: Determination of purity and trace impurities by gas chromatography

This document specifies a test method for the determination of propylene oxide and trace impurities in propylene oxide for industrial use by gas chromatography. This document is suitable for the determination of propylene oxide which is produced by ethylbenzene co-oxidation (PO/SM), isobutane co-oxidation (PO/TBA), cumene co-oxidation (CHPPO), hydrogen peroxide oxidation (HPPO) and chlorohydrin. This document is applicable for determination of propylene oxide with a purity ≥ 99,70 % and impurity content ≥ 0,000 3 %.

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General Information

• Status: Published
• Publication Date: 16-Mar-2026
• ICS: 71.040.40 - Chemical analysis
• ICS: 71.080.99 - Other organic chemicals
• Technical Committee: ISO/TC 47 - Chemistry
• Drafting Committee: ISO/TC 47 - Chemistry
• Current Stage: 6060 - International Standard published
• Start Date: 17-Mar-2026
• Due Date: 14-Jun-2027
• Completion Date: 17-Mar-2026

Overview

ISO 25095-1:2026, Propylene oxide for industrial use - Part 1: Determination of purity and trace impurities by gas chromatography is an international standard that specifies a gas chromatographic test method for analyzing the purity and detecting trace impurities in propylene oxide intended for industrial use. Suitable for products manufactured via various industrial processes-including ethylbenzene co-oxidation (PO/SM), isobutane co-oxidation (PO/TBA), cumene co-oxidation (CHPPO), hydrogen peroxide oxidation (HPPO), and the chlorohydrin process-this standard ensures reliable quality assessment for propylene oxide with a purity of 99.70% or higher and impurity content as low as 0.0003%.

This ISO standard is vital for laboratories, quality control teams, and manufacturers who need standardized, reproducible procedures for assessing chemical product integrity, particularly within the chemical and petrochemical industries.

Key Topics

• Scope and Applicability

  • Defines a chromatographic method for the quantification of propylene oxide and its trace impurities.
  • Applicable to products from several primary commercial production routes.
  • Targeted for high-purity material (≥99.70% propylene oxide).

• Analytical Method

  • Employs gas chromatography (GC) with a flame ionization detector (FID).
  • Utilizes corrected peak-area normalization for quantitative assessments.
  • Requires subtraction of water and total aldehydes for final purity calculations using referenced standards.

• Sampling and Safety

  • Stresses the importance of representative sampling as per relevant ISO standards (ISO 3165, ISO 3170).
  • Provides guidance on required laboratory safety and approved practices for handling volatile, flammable chemicals.

• Test Reporting

  • Outlines required elements for test reports, including sample identification, reference to ISO 25095-1:2026, calculated results, deviations, unusual observations, and test dates.
  • Stipulates standards for repeatability and reproducibility to assure result reliability across laboratories.

Applications

This standard has significant practical value in several industrial and laboratory settings:

• Quality Assurance in Propylene Oxide Production

  • Enables manufacturers to verify product purity and ensure compliance with customer and regulatory requirements.
  • Essential in process control settings to identify process deviations that may introduce unwanted impurities.

• Third-party and Internal Laboratory Testing

  • Provides commercial testing laboratories with a validated method for customer sample analysis.
  • Supports reproducible and comparable results between different laboratories due to standardized procedures.

• Regulatory Compliance and Product Certification

  • Facilitates certification processes where a proven method for impurity determination is needed for global trade.

• Research and Development

  • Supports R&D groups in assessing new production methods for propylene oxide, validating purity, and characterizing impurity profiles.

• End-Use Industries

  • Ensures safety and product quality in downstream applications such as the production of polyurethanes, glycols, and solvents, where impurity levels can critically affect end-product performance.

Related Standards

For comprehensive quality control and laboratory practice, the following related ISO standards are referenced or recommended:

• ISO 760: Determination of water - Karl Fischer method (General method)
• ISO 3165: Sampling of chemical products for industrial use - Safety in sampling
• ISO 3170: Hydrocarbon liquids - Manual sampling
• ISO 25095-2: Propylene oxide for industrial use - Part 2: Determination of aldehydes by liquid chromatography

These standards collectively support a robust, safe, and internationally harmonized approach to testing, ensuring accuracy and comparability in the determination of propylene oxide purity and trace impurities.

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By implementing ISO 25095-1:2026, organizations benefit from a trusted, globally recognized method for evaluating industrial propylene oxide, assuring product quality, process control, and regulatory readiness.

Standards Content (Sample)

International
Standard
ISO 25095-1
First edition
Propylene oxide for industrial
2026-03
use —
Part 1:
Determination of purity and trace
impurities by gas chromatography
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
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
6 Apparatus . 3
7 Sampling . 3
8 Procedure . 3
8.1 Preparation of apparatus .3
8.2 Test .4
9 Calculation of relative correction factors . 4
10 Calculation of results . 4
11 Expression of results . 5
12 Repeatability and reproducibility . 5
12.1 Repeatability limit .5
12.2 Reproducibility limit .5
13 Test report . 6
Annex A (informative) Representative chromatograms. 7
Annex B (informative) Reference retention time, effective carbon number and relative
correction factor for each component. 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
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has been established has the right to be represented on that committee. International organizations,
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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)
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Any trade name used in this document is information given for the convenience of users and does not
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This document was prepared by Technical Committee ISO/TC 47, Chemistry.
A list of all parts in the ISO 25095 series can be found on the ISO website.
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 25095-1:2026(en)
Propylene oxide for industrial use —
Part 1:
Determination of purity and trace impurities by gas
chromatography
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all the safety problems, if any, associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices.
1 Scope
This document specifies a test method for the determination of propylene oxide and trace impurities in
propylene oxide for industrial use by gas chromatography.
This document is suitable for the determination of propylene oxide which is produced by ethylbenzene co-
oxidation (PO/SM), isobutane co-oxidation (PO/TBA), cumene co-oxidation (CHPPO), hydrogen peroxide
oxidation (HPPO) and chlorohydrin. This document is applicable for determination of propylene oxide with a
purity ≥ 99,70 % and impurity content ≥ 0,000 3 %.
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 760, Determination of water — Karl Fischer method (General method)
ISO 3165:1976, Sampling of chemical products for industrial use — Safety in sampling
ISO 3170:2025, Hydrocarbon Liquids — Manual sampling
ISO 25095-2, Propylene oxide for industrial use—Part 2: determination of aldehydes by Liquid chromatography
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
Propylene oxide and impurities in a sample are separated by a gas chromatograph (GC) under propriate
conditions and detected by flame ionization detector (FID). Quantification is achieved by corrected peak-
area normalization, the content of propylene oxide can be calculated after deducting water and total
aldehydes, which are difficult to measure by GC/FID .

5 Reagents and materials
Unless otherwise specified, use only reagents of recognized analytical grade. If there are impurities to be
considered other than those listed as follows, appropriate reagents can be used.
©1)
5.1 Propylene, CAS No. 115-07-1.
5.2 Methanol solution of dimethyl ether, CAS No. 115-10-6.
5.3 Methanol, CAS No. 67-56-1.
5.4 n-Pentane, CAS No. 109-66-0.
5.5 Acetaldehyde, CAS No. 75-07-0.
5.6 Ethylene oxide, CAS No. 75-21-8.
5.7 Methyl formate, CAS No. 107-31-3.
5.8 Furan, CAS No. 110-00-9.
5.9 2-Methylpentane, CAS No. 43133-95-5.
5.10 iso-Propanol, CAS No. 67-63-0.
5.11 Dimethoxymethane, CAS No. 109-87-5.
5.12 n-Hexane, CAS No. 110-54-3.
5.13 Propylene oxide, CAS No. 75-56-9.
5.14 Propionaldehyde, CAS No. 123-38-6.
5.15 Acrolein, CAS No. 107-02-8.
5.16 Acetone, CAS No. 67-64-1.
5.17 iso-Octane, CAS No. 540-84-1.
5.18 Benzene, CAS No. 71-43-2.
5.19 Ethylene glycol monomethyl ether, CAS No. 109-86-4.
5.20 1, 2-Dichloropropane, CAS No. 78-87-5.
5.21 n-Octane, CAS No. 111-65-9.
5.22 Ethylene glycol, CAS No. 107-21-1.
1) CAS Registry Number® is a trademark of CAS corporation. This information is given for the convenience of users of
this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if
they can be shown to lead to the same results.

5.23 1-Methoxy-2-propanol, CAS No. 107-98-2.
5.24 1, 2-Propylene glycol, CAS No. 57-55-6.
5.25 Ethylbenzene, CAS No. 100-41-4.
5.26 1, 3-Propanediol, CAS No. 504-63-2.
5.27 iso-Propylbenzene, CAS No. 98-82-8.
5.28 Hydrogen, CAS No. 1333-74-0, with volume fraction of no less than 99,99 %, being dried and purified
by
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