Plastics -- Polymer polyols for use in the production of polyurethane -- 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.

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Status
Published
Publication Date
02-Oct-2018
Current Stage
6060 - International Standard published
Start Date
11-Sep-2018
Completion Date
03-Oct-2018
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ISO 21257:2018 - Plastics -- Polymer polyols for use in the production of polyurethane -- Determination of the residual acrylonitrile and styrene monomer content by gas chromatography
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INTERNATIONAL ISO
STANDARD 21257
First edition
2018-10
Plastics — Polymer polyols for use
in the production of polyurethane
— Determination of the residual
acrylonitrile and styrene monomer
content by gas chromatography
Reference number
ISO 21257:2018(E)
ISO 2018
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ISO 21257:2018(E)
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© ISO 2018

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Published in Switzerland
ii © ISO 2018 – All rights reserved
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ISO 21257:2018(E)
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 ................................................................................................................................................................................. 2

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 ........................................................................................................................... 4

7.3 Method B for using packed column ....................................................................................................................................... 4

7.3.1 Preparation of internal standard solution ................................................................................................. 4

7.3.2 Preparation of calibration solutions ............................................................................................................... 4

7.3.3 Preparation of sample solution ........................................................................................................................... 4

8 Procedure..................................................................................................................................................................................................................... 5

8.1 Gas chromatographic procedure ............................................................................................................................................. 5

8.2 Measurement of sample solutions and calibration solutions ......................................................................... 5

8.3 Evaluation of gas chromatographic peak ......................................................................................................................... 6

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 .......................................................................................... 9

10 Precision ....................................................................................................................................................................................................................... 9

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

© ISO 2018 – All rights reserved iii
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ISO 21257:2018(E)
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 documents 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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/patents).

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 61, Plastics, Subcommittee SC 12,

Thermosetting materials.

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 © ISO 2018 – All rights reserved
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ISO 21257:2018(E)
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.

Annexes A, B and C complement the main body of this document and not meant to be a normative part

of this document.
© ISO 2018 – All rights reserved v
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INTERNATIONAL STANDARD ISO 21257:2018(E)
Plastics — Polymer polyols for use in the production
of polyurethane — 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 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 http: //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 will lead 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.

© ISO 2018 – All rights reserved 1
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ISO 21257:2018(E)
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-methyl-

1-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 gas.

6 Apparatus
Normal laboratory equipment and the following apparatus are required.

6.1 Gas chromatograph, with flame ionization detector and capable of employing packed or open

tubular columns with either split or splitless injector. Typical operating conditions are described in

Annex A.
6.1.1 Injection port, for liquid samples.

When using open tubular column (hereafter called an OT column), an injection port with splitter may

be applicable.
6.1.2 Column and packing material.

The column diameter and length, as well as the packing material and liquid phase, are to be selected

based on consideration of column resolution (Re) and calibration curve linearity. Both packed columns

and OT (capillary) columns (hereafter referred to as OT columns) are acceptable.
Typical columns are described in Annex A.

— OT columns: The OT column are to be selected from suitable manufacturer(s), and then shall be

conditioned sufficiently.

— Packed columns: The packed column should be packed with the liquid phase and support particles

from suitable manufacturer(s), and then conditioned sufficiently.

6.1.3 Detector, hydrogen flame ionization detector (hereafter referred to as FID).

6.2 Data processor, selected based on suitability for recording the signals from the detector and

processing the chromatograms.

6.3 Sample injection syringe, micro-syringe with a volume range 1 μL to 50 μL. Manual and

autoinjector syringes are suitable.
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ISO 21257:2018(E)
6.4 Analytical balance, capable of measuring to 0,1 mg, is required.

6.5 One-mark volumetric flasks (hereafter volumetric flasks), as specified in ISO 1042.

Needed volumes are 50 mL and 500 mL.

6.6 Single-volume pipettes (hereafter volumetric pipettes), as specified in ISO 648.

Needed volumes are 0,5 mL, 1,0 mL, 2,0 mL 5,0 mL and 10,0 mL.

NOTE Graduated pipettes (ISO 835) and piston pipettes (ISO 8655) are also suitable.

7 Preparation of calibration solution and sample solution
7.1 General

Two sample preparation methods are described in 7.2 and 7.3. Method A is to be used for an OT-column

chromatograph and Method B is used for a packed-column chromatograph. The range of calibration

concentrations should be selected based on expected levels of acrylonitrile and styrene monomers.

Calibrations with 4 levels of each monomer are to be used.
7.2 Method A for using OT column
7.2.1 Preparation of internal standard solution

Into a 500 mL volumetric flask, weigh to the nearest 1 mg, the amount of internal standard specified in

Table 1. Add solvent to make 500 mL, stopper tightly and mix well. This solution is hereafter called the

internal standard solution.
7.2.2 Preparation of calibration solutions

Weigh the amounts of acrylonitrile and/or of styrene specified in Table 1, to the nearest 1 mg, into a

500 mL volumetric flask. Add solvent to make 500 mL, stopper tightly and mix well. This solution is

hereafter called the acrylonitrile/styrene solution.

Into a 50 mL volumetric flask, pipet 0,5 mL of the acrylonitrile/styrene solution and 5,0 mL of the

internal standard solution. Add solvent to make 50 mL, stopper tightly and mix well. Prepare three

additional solutions by pipetting
...

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