ISO 25095-2:2026

Propylene oxide for industrial use — Part 2: Determination of aldehydes by liquid chromatography

This document specifies a test method for determination of aldehydes in propylene oxide by liquid chromatography. This document is applicable to the determination of aldehydes in propylene oxide for industrial use, including formaldehyde, acetaldehyde, propionaldehyde and acrolein. The concentration for each aldehyde ranges from 0,5 mg/kg to 100 mg/kg.

Titre manque — Partie 2: Titre manque

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
• Current Stage: 6060 - International Standard published
• Start Date: 17-Mar-2026
• Due Date: 24-Oct-2027
• Completion Date: 17-Mar-2026

Overview

ISO 25095-2:2026 - Propylene oxide for industrial use - Part 2: Determination of aldehydes by liquid chromatography establishes a standardized test method for accurately determining aldehyde content in propylene oxide using liquid chromatography. This international standard is designed specifically for the industrial sector, with scope for quantifying key aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and acrolein within a concentration range of 0.5 mg/kg to 100 mg/kg.

By following ISO 25095-2:2026, laboratories and manufacturers can ensure consistent, reliable measurement of aldehyde impurities, supporting better product quality, safety, and regulatory compliance in propylene oxide products.

Key Topics

• Test Methodology: The primary method involves reacting sample aldehydes with 2,4-dinitrophenylhydrazine (DNPH) in acidic buffer, then separating and quantifying the resulting derivatives using liquid chromatography with ultraviolet or diode array detection.
• Scope of Aldehydes: The standard covers the determination of formaldehyde, acetaldehyde, propionaldehyde, and acrolein, which are important for monitoring product purity and safety in industrial propylene oxide.
• Sample Preparation & Handling: Clear procedures for sample preparation, including the use of analytical-grade reagents, buffer solutions, and safe sampling in accordance with referenced ISO standards.
• Equipment Requirements: Utilizes widely available laboratory instruments such as liquid chromatographs, chromatographic workstations, micro-injectors, analytical balances, reaction bottles, and temperature-controlled water baths.
• Result Calculation: Specifies calculation formulas for individual and total aldehyde concentrations in mg/kg, supporting consistent reporting.
• Precision and Repeatability: Defines both repeatability and reproducibility limits to ensure confidence in laboratory results.
• Reporting Requirements: Specifies what information must be included in test reports for transparency and traceability.

Applications

The practical value of ISO 25095-2:2026 lies in its application across the chemical and petrochemical industries where propylene oxide is produced or utilized. Key applications include:

• Quality Assurance in Manufacturing: Ensures products meet industry and customer specifications by controlling levels of harmful aldehyde impurities.
• Regulatory Compliance: Supports compliance with health, safety, and environmental regulations relating to volatile organic compounds in industrial chemicals.
• Process Control: Provides chemical manufacturers with reliable methods for routine process monitoring and troubleshooting by identifying variations in aldehyde content.
• Product Safety: Contributes to safer handling, storage, and transportation of propylene oxide by facilitating the detection of reactive aldehydes.
• Third-party and Contract Testing: Standardizes testing procedures across independent laboratories, leading to consistent and comparable results regardless of laboratory location.

Related Standards

To ensure comprehensive and compliant laboratory practices, ISO 25095-2:2026 is used alongside several other international standards, including:

• ISO 3165: Sampling of chemical products for industrial use - Ensures proper safety and representativeness in sample collection.
• ISO 3170: Manual sampling of hydrocarbon liquids - Outlines best practices for sampling volatile liquid chemicals.
• ISO 3696: Water for analytical laboratory use - Specifies grades and test methods for water quality in analytical procedures.
• ISO 6353-2: Reagents for chemical analysis - Details required specifications for chemical reagents used in testing.

Implementing ISO 25095-2:2026 in conjunction with these related standards supports a robust, reliable framework for the determination of aldehydes in industrial propylene oxide using liquid chromatography, contributing to higher product quality, regulatory compliance, and enhanced safety across the supply chain.

Standards Content (Sample)

International
Standard
ISO 25095-2
First edition
Propylene oxide for industrial
2026-03
use —
Part 2:
Determination of aldehydes by
liquid 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 . 2
7 Sampling . 3
8 Procedure . 3
8.1 Recommended column and operating conditions .3
8.2 Drawing of standard curves .3
8.3 Preparation of sample solution .4
8.4 Preparation of blank solution . .4
8.5 Determination .4
9 Calculation and expression of results . 4
10 Precision . 5
11 Test report . 5
Annex A (informative) Blank test and purification of 2, 4-dinitrophenylhydrazine (DNPH) . 6
Annex B (informative) Representative chromatogram for aldehyde derivatives . 7

iii
Foreword
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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
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ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
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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 25095-2:2026(en)
Propylene oxide for industrial use —
Part 2:
Determination of aldehydes by liquid 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 determination of aldehydes in propylene oxide by liquid
chromatography.
This document is applicable to the determination of aldehydes in propylene oxide for industrial use,
including formaldehyde, acetaldehyde, propionaldehyde and acrolein. The concentration for each aldehyde
ranges from 0,5 mg/kg to 100 mg/kg.
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 3165:1976, Sampling of chemical products for industrial use — Safety in sampling
ISO 3170:2025, Hydrocarbon Liquids — Manual sampling
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 6353-2, Reagents for chemical analysis — Part 2: Specifications — First series
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological 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 certain mass of the sample is reacted with excessive 2, 4-dinitrophenylhydrazine (hereafter referred to
as DNPH) in acidic buffer solution at 40 °C, in which the aldehydes (such as formaldehyde, acetaldehyde,
propionaldehyde, acrolein, and so on) and ketones (such as acetone) are converted into the corresponding
aldehydes-DNPH or ketones-DNPH (such as formaldehyde-DNPH, acetaldehyde-DNPH, propionaldehyde-
DNPH, acrolein-DNPH, acetone-DNPH, and so on). The reacted sample solution is injected into liquid
chromatograph to separate each component, which is detected by ultraviolet detector or diode array
detector and quantified by external standard method.

5 Reagents and materials
Unless otherwise specified, use only reagents of recognized analytical grade.
The standard solutions, impurity standard solutions, preparations and products used in the test method
shall be prepared in accordance with ISO 6353-2 when no other requirements are specified.
5.1 Water, in accordance with grade I as defined in ISO 3696. Dissolved gas needs to be removed by
ultrasound before use.
©1)
5.2 Acetonitrile, CAS No. 75-05-8, chromatographically pure.
5.3 DNPH, CAS No. 119-26-6, with mass fraction no less than 99 % and the concentration of each aldehyde-
DNPH is no
...