ISO 16014-3:2019

Plastics - Determination of average molecular weight and molecular weight distribution of polymers using size-exclusion chromatography - Part 3: Low-temperature method

This document specifies a method for determining the average molecular weight and the molecular weight distribution of polymers by size-exclusion chromatography (SEC) using an organic eluent at a temperature lower than 60 °C (see Annex A). The average molecular weight and the molecular weight distribution are calculated from a calibration curve prepared using polymer standards. Therefore, this test method is classified as a relative method (see ISO 16014-1).

Plastiques — Détermination de la masse moléculaire moyenne et de la distribution des masses moléculaires de polymères par chromatographie d'exclusion stérique — Partie 3: Mesurage aux basses températures

General Information

• Status: Published
• Publication Date: 14-May-2019
• ICS: 83.080.01 - Plastics in general
• Technical Committee: ISO/TC 61/SC 5 - Physical-chemical properties
• Drafting Committee: ISO/TC 61/SC 5/WG 11 - Analytical methods
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Jun-2024
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 16014-3:2012 - Plastics - Determination of average molecular mass and molecular mass distribution of polymers using size-exclusion chromatography - Part 3: Low-temperature method
• Effective Date: 15-Dec-2017

Overview

ISO 16014-3:2019 specifies a low‑temperature size‑exclusion chromatography (SEC) method for determining the average molecular weight and molecular weight distribution of polymers. The procedure uses an organic eluent at temperatures below 60 °C and calculates molecular-weight values from a calibration curve prepared with polymer standards, so it is classified as a relative method (see ISO 16014-1). The standard covers reagents, apparatus, temperature and flow control, sample and standard preparation, data acquisition, result expression and precision requirements.

Key topics and technical requirements

• Principle: SEC separation with an organic mobile phase at <60 °C; molecular-weight distribution derived from a standards-based calibration curve.
• Calibration: Use polymer molecular‑weight standards covering the analysis range; when like‑chemistry standards are unavailable, universal calibration (ISO 16014-2) is an option.
• Columns and performance: Set of columns must meet performance criteria - total theoretical plate number > 15 000, resolution factor R > 1.5 near the polymer peak and asymmetry factor ≈ 1.00 ± 0.15.
• Temperature control: Columns must be maintained within ±0.5 K; detector and injector temperature control typically within ±1 K to ensure baseline and flow stability.
• Flow and pumping: Pumping system should maintain flow rate accuracy to within ±0.3%.
• Sample and standard preparation: Dissolution, optional gentle heating/shaking, filtration to protect columns (recommended filter pore size 0.2–1 µm). The standard provides guidance on concentrations and injection practices.
• Detectors and additives: Compatible detectors and possible eluent additives (e.g., LiBr, LiCl, or sodium trifluoroacetate) are described for specific polymers to avoid aggregation or improve solubility.
• Data handling: Instructions for acquisition, processing and reporting of average molecular weight and distribution parameters; precision and interlaboratory performance are addressed.

Applications and users

ISO 16014-3:2019 is used for:

• Routine quality control and batch release testing of polymer materials
• R&D and formulation development where low‑temperature eluents are required
• Material characterization in regulatory submissions, failure analysis and supplier qualification Typical users include polymer analytical labs, QC/QA teams, materials scientists, instrument manufacturers and standards organizations. Keywords: ISO 16014-3:2019, size‑exclusion chromatography, SEC low‑temperature method, molecular weight distribution, polymer analysis.

Related standards

• ISO 16014-1 - General principles for SEC polymer molecular‑weight determination
• ISO 16014-2 - Universal calibration method (alternative calibration approach)
• ISO 472 - Plastics vocabulary
• ISO 5725-1 / ISO 5725-2 - Accuracy, repeatability and reproducibility guidance

Use ISO 16014-3:2019 when SEC must be performed with organic eluents at controlled temperatures below 60 °C and when a standards-based, relative molecular‑weight method is appropriate.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 16014-3
Third edition
2019-05
Plastics — Determination of average
molecular weight and molecular
weight distribution of polymers using
size-exclusion chromatography —
Part 3:
Low-temperature method
Plastiques — Détermination de la masse moléculaire moyenne
et de la distribution des masses moléculaires de polymères par
chromatographie d'exclusion stérique —
Partie 3: Mesurage aux basses températures
Reference number
©
ISO 2019
© ISO 2019
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
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CH-1214 Vernier, Geneva
Phone: [phone]
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Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 2
7 Procedure. 3
7.1 Preparation of solutions of molecular weight standards . 3
7.2 Preparation of sample solutions . 4
7.3 Preparation of solutions for column performance evaluation . 4
7.4 Setting up the apparatus. 4
7.5 Operating parameters . 5
7.5.1 Flow rate . 5
7.5.2 Injection masses and injection volumes . 5
7.5.3 Column temperature . 5
7.5.4 Detector sensitivity . 5
7.6 Number of determinations . 5
8 Data acquisition and processing . 5
9 Expression of results . 6
10 Precision . 6
10.1 General . 6
10.2 Experimental conditions . 6
10.3 Results of interlaboratory tests . 7
11 Test report . 8
Annex A (informative) Further information on applicability of method . 9
Annex B (informative) Further information on reagents .10
Annex C (informative) Further information on interlaboratory tests .11
Bibliography .17
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 5, Physical-
chemical properties.
This third edition cancels and replaces the second edition (ISO 16014-3:2012), which has been
technically revised. The main changes compared to the previous edition are as follows:
— publication dates of references have been removed;
— molecular mass has been changed to molecular weight according to IUPAC rule.
A list of all parts in the ISO 16014 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 © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 16014-3:2019(E)
Plastics — Determination of average molecular weight
and molecular weight distribution of polymers using size-
exclusion chromatography —
Part 3:
Low-temperature method
1 Scope
This document specifies a method for determining the average molecular weight and the molecular
weight distribution of polymers by size-exclusion chromatography (SEC) using an organic eluent at a
temperature lower than 60 °C (see Annex A). The average molecular weight and the molecular weight
distribution are calculated from a calibration curve prepared using polymer standards. Therefore, this
test method is classified as a relative method (see ISO 16014-1).
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 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 16014-1, Plastics — Determination of average molecular weight and molecular weight distribution of
polymers using size-exclusion chromatography — Part 1: General principles
ISO 16014-2, Plastics — Determination of average molecular weight and molecular weight distribution of
polymers using size-exclusion chromatography — Part 2: Universal calibration method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and in ISO 16014-1 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
According to ISO 16014-1.
5 Reagents
5.1 Eluent.
For a general discussion of eluents, see ISO 16014-1.
For examples of eluents used for SEC measurements at temperatures < 60 °C, see Annex B.
NOTE Water is often used for SEC measurements on water-soluble polymers at temperatures < 60 °C, but it
is not suitable for use in this method.
5.2 Reagent for column evaluation, according to ISO 16014-1.
There are several low molecular weight compounds that can be used, for example ethylbenzene when
tetrahydrofuran is used as eluent or diethylene glycol when N,N-dimethylformamide is used as eluent
(see Annex B).
5.3 Molecular weight standards, according to ISO 16014-1.
Some examples of commercially available molecular weight standards are given in ISO 16014-1:2019,
Annex B.
5.4 Reagent for flow rate marker (internal standard), according to ISO 16014-1.
It is often very difficult to find a low molecular weight compound suitable for use as a flow rate marker
because it should not co-elute with the polymer peak, the system peak or the solvent peak.
Examples of compounds suitable for use as a flow rate marker are sulfur when tetrahydrofuran is used
as eluent and ethylbenzene when N,N-dimethylformamide is used as eluent.
5.5 Additives.
LiBr or LiCl, for example, is used as an additive in N,N-dimethylformamide to avoid aggregation of
polyacrylonitrile, and sodium trifluoroacetate is added to 1,1,1,3,3,3-hexafluoroisopropanol for SEC
measurements on polyamide.
6 Apparatus
6.1 General
A schematic diagram of an SEC system is shown in ISO 16014-1.
Either commercially available or assembled SEC systems may be used, provided they meet the component
requirements specified and have the capability to maintain a constant column temperature < 60 °C.
6.2 Eluent reservoir, according to ISO 16014-1.
It is not necessary to keep the reservoir at the same temperature as the columns.
6.3 Pumping system, according to ISO 16014-1.
In order to maintain the flow rate accurate to within ±0,3 %, the pumping system shall be kept at
a controlled temperature. It is, however, not necessary to keep the pumping system at the same
temperature as the columns.
2 © ISO 2019 – All rights reserved

6.4 Injector, according to ISO 16014-1.
In order to maintain an accurately known flow rate, the injector temperature-control equipment shall
be capable of keeping the injector at within ±1 K of the temperature set. It is not necessary to keep the
injector at the same temperature as the columns.
6.5 Columns, according to ISO 16014-1.
Organic or inorganic packing materials may be used. There are no limitations on particle size or shape.
The set of columns used shall have a total theoretical plate number > 15 000, and the resolution factor R
shall be > 1,5 close to the polymer peak. The asymmetry factor shall be within the range 1,00 ± 0,15. The
set of columns used should preferably cover the whole range of molecular weights being determined,
and the calibration curve shall be as linear as possible (the correlation factor shall be very close to 1).
Determination of the theoretical plate number, the resolution factor and the asymmetry factor of the
columns shall be carried out as described in ISO 16014-1.
The column temperature-control equipment shall be capable of keeping the columns within ± 0,5 K of
the temperature set, to ensure adequate reproducibility of the results.
6.6 Detector, according to ISO 16014-1.
The detector temperature-control equipment shall be capable of keeping the detector within ± 1 K of
the temperature set, in order to meet the requirements for flow rate and baseline stability (sensitivity).
It is recommended that the columns and detector be kept at the same temperature.
6.7 Tubing, according to ISO 16014-1.
The temperature of the tubing shall be kept constant to ensure that the column performance
requirements are met, but it is not necessary to keep the tubing at the same temperature as the column.
6.8 Temperature control.
Refer to 6.4 for the injector temperature-control equipment. And refer to 6.5 and 6.6 for the columns
and detector.
One of the important factors in SEC is that all components need to be kept at a constant temperature.
6.9 Recorder and plotter, according to ISO 16014-1.
6.10 Data-processing system, according to ISO 16014-1.
6.11 Other components.
In addition to the components described above, a column guard filter, pressure monitor, pulse damper
or related components may be used, if necessary.
7 Procedure
7.1 Preparation of solutions of molecular weight standards
The molecular weight standards used to prepare the calibration curve should preferably be selected
so as to cover the range of molecular weights of the polymer being analysed and so that there are at
least two standards in each molecular weight decade. Solutions may be prepared which contain more
than one narrow molecular weight distribution standard, but only when the standards are perfectly
separated from each other on the chromatogram.
A solution of mixed molecular weight standards containing standards of high molecular weight
(>1 000 000) might give peaks which are retarded and/or deformed because of the high viscosity of the
solution. In such cases, the solutions of high molecular weight standards shall be prepared separately.
If molecular weight standards having the same chemical structure as the polymer being analysed are
not available, the calibration curve may be prepared using standards consisting of a different type of
polymer, and a universal calibration curve prepared for this different type of polymer (according to
ISO 16014-2).
If gentle shaking and/or stirring or heating is required to accelerate dissolution, the time shall be as
short as possible to avoid any rupture of the polymer chains.
Filtration of the solutions is recommended to protect the column from clogging. In such cases,
membrane filters or sintered-metal filters with a pore size between 0,2 µm and 1 µm shall be used. If
solid material is observed on the filter, indicating incomplete dissolution, repeat the dissolution process.
If a membrane filter is used, the membrane and backing shall be inert to the solvent being used.
In general, use solutions within 48 h of preparation. However, longer storage times are allowed if the
solution is kept in a cool, dark place to prevent polymer degradation and solvent evaporation.
Recommended concentrations for solutions of molecular weight standards are as follows:
4 3
M < 5 × 10 0,4 mg/cm
p
4 6 3
5 × 10 ≤ M < 10 0,2 mg/cm
p
6 3
10 ≤ M 0,1 mg/cm
p
If a viscometric detector is used, higher molecular weight standard concentrations are required
in the lower molecular weight
...