ISO 21257:2024
(Main)Plastics — Polymer polyols for use in the production of polyurethanes — Determination of the residual acrylonitrile and styrene monomer content by gas chromatography
Plastics — Polymer polyols for use in the production of polyurethanes — Determination of the residual acrylonitrile and styrene monomer content by gas chromatography
This document specifies a method for the determination of the residual acrylonitrile monomer and styrene monomer in polymer polyols by gas chromatography.
Plastiques — Polyols polymères pour la production de polyuréthanes — Détermination de la teneur résiduelle en monomères d'acrylonitrile et de styrène par chromatographie en phase gazeuse
General Information
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Standards Content (Sample)
International
Standard
ISO 21257
Second edition
Plastics — Polymer polyols for use
2024-10
in the production of polyurethanes
— Determination of the residual
acrylonitrile and styrene monomer
content by gas chromatography
Plastiques — Polyols polymères pour la production de
polyuréthanes — Détermination de la teneur résiduelle en
monomères d'acrylonitrile et de styrène par chromatographie en
phase gazeuse
Reference number
© ISO 2024
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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 materials . 1
6 Apparatus . 2
7 Preparation of calibration solution and sample solution . 3
7.1 General .3
7.2 Method A for using OT column .3
7.2.1 Preparation of internal standard solution .3
7.2.2 Preparation of calibration solutions .3
7.2.3 Preparation of sample solution .3
7.3 Method B for using packed column .3
7.3.1 Preparation of internal standard solution .3
7.3.2 Preparation of calibration solutions .4
7.3.3 Preparation of sample solution .4
8 Procedure . 4
8.1 Gas chromatographic procedure .4
8.2 Measurement of sample solutions and calibration solutions .5
8.3 Evaluation of gas chromatographic peak .5
9 Expression of the results . 6
9.1 Preparation of the calibration curve .6
9.2 Calculation of results from a calibration graph .7
9.3 Calculation of results from a single-point calibration .8
9.4 Acceptability of results and measurement sensitivity .8
10 Precision . 8
11 Test report . 9
Annex A (informative) Typical analytical conditions . 10
Annex B (informative) Typical examples of GC chromatogram .12
Annex C (informative) Precision . 14
Bibliography .15
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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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
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting
materials.
This second edition cancels and replaces the first edition (ISO21257:2018), of which it constitutes a minor
revision. The changes are as follows:
— the title has been changed to plural form to read: "Plastics — Polymer polyols for use in the production
of polyurethanes — Determination of the residual acrylonitrile and styrene monomer content by gas
chromatography";
— in 7.2.1, 7.2.2, 7.2.3, 7.3.1, 7.3.2 and 7.3.3, “to the nearest 1 mg” have been changed to “to the nearest
0,1 mg”;
— in 8.3 Table 4, the table title has been changed to “Table 4 — Typical retention times of acrylonitrile,
styrene, internal standard and solvent with typical operating conditions in Annex A”.
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
Polymer polyols are defined as very fine and stable dispersions of solid, vinylic polymers (for example,
acrylonitrile/styrene copolymers are typical) in liquid polyether polyols.
Polymer polyol is used to improve the physical properties of seat cushions, especially hardness. Because the
toxicity of acrylonitrile and styrene is high, it is important to establish an analytical method to determine
residual amounts of these reactants.
The importance of residual toxicity has increased with the use of polyurethane foam, etc. which comes in
contact with food and skin. This document is intended to help manufacturers evaluate the safety of their
products.
v
International Standard ISO 21257:2024(en)
Plastics — Polymer polyols for use in the production of
polyurethanes — Determination of the residual acrylonitrile
and styrene monomer content by gas chromatography
1 Scope
This document specifies a method for the determination of the residual acrylonitrile monomer and styrene
monomer in polymer polyols by gas chromatography.
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 472, Plastics — Vocabulary
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 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
The polymer polyol sample is dissolved in a suitable solvent. This sample solution is then analysed using gas
chromatography with internal standardization. The amounts of residual acrylonitrile monomer and styrene
monomer are determined from peak areas using a previously established calibration curve.
NOTE Because of the high molecular weight of substances which are part of the polymer polyol, and because these
are injected directly into the chromatograph, injector contamination can occur which leads to erroneous results.
Monitor the condition of the chromatographic parts and clean or replace as necessary.
An injector liner packed with glass wool has been used to improve vaporization and ease of cleaning.
5 Reagents and materials
5.1 Solvent, use analytical-grade methanol, N, N-dimethylformamide, tetrahydrofuran, dipropylene
glycol monomethyl ether or toluene.
Other solvents can also be used if suitable results are obtained for the retention time, thermal stability and
separation performance.
5.2 Internal standard, shall be selected based on the retention times of the volatile materials contained
in the polymer polyol sample and the solvent.
Recommended combinations of solvent from 5.1 and internal standard are methanol and 2-methyl1-propanol,
N, N-dimethylformamide and ethylbenzene, dipropylene glycol monomethyl ether and bromobenzene.
Other combinations are also possible if the retention times, thermal stability and separation performance
are suitable.
5.3 Carrier gases and fuel gases for gas chromatograph.
Use helium or nitrogen as carrier gas, hydrogen as fuel gas, dry air as supporting fuel g
...
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