ISO 19929:2017

INTERNATIONAL ISO
STANDARD 19929
First edition
2017-03
Plastics — Determination of average
molecular mass and mixture ratio
of poly(ethylene glycol) and its
derivatives by MALDI-TOF-MS
Plastiques — Détermination de la masse moléculaire moyenne et
du rapport de mélange du poly(éthylène glycol) et de ses dérivés par
MALDI-TOF-MS
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles . 3
5 Reagents . 3
6 Apparatus . 4
7 Procedure. 5
7.1 General . 5
7.2 Sample preparation . 5
7.2.1 General. 5
7.2.2 Preparation of polymer standard mixtures . 6
7.2.3 Preparation of polymer/matrix/salt solutions . 6
7.2.4 Deposition of the sample on the sample plate (target) . 6
7.2.5 Preparation of biopolymer/matrix solutions . 7
7.3 Instrument settings . 7
7.4 Spectra recording . 8
8 Data acquisition and processing . 8
8.1 General . 8
8.2 Calibration of mass axis . . 8
8.2.1 General. 8
8.2.2 Calibration of mass axis using synthetic polymer standards . 9
8.2.3 Calibration of mass axis using biopolymer standards . 9
8.2.4 Self-calibration method . 9
8.3 Generation of mass calibration curve . 9
8.4 Calibration of intensity axis . 9
9 Expression of results .10
9.1 Calculation of molecular mass distribution (MMD).10
9.2 Calculation of the number-average molecular mass .10
9.3 Calculation of peak area .10
9.4 Constructing calibration curve for intensity .10
9.5 Calculation of mass ratio .11
10 Precision .11
11 Test report .11
11.1 General .11
11.2 Apparatus .11
11.3 Calibration .11
11.4 Results .11
Annex A (normative) Calibrants .12
Bibliography .13
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
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electrotechnical standardization.
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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
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URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties.
iv © ISO 2017 – All rights reserved

Introduction
For quality control and research of polymeric materials, it is important to know the composition of
polymer mixtures with different terminal groups. In contrast to traditional methods such as liquid
chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
(MALDI-TOF-MS) is a rapid and effective method to characterize polymer mixtures because of its high
mass resolution. It can also be applied to quantitation of mixtures of different polymers. Interlaboratory
comparisons of quantitative MALDI-TOF-MS performed for mixtures of PEG and its derivatives can
ensure standardized conditions of measurement. Standardization of quantitative MALDI-TOF-MS may
promote increasing applications of this analytical technique.
INTERNATIONAL STANDARD ISO 19929:2017(E)
Plastics — Determination of average molecular mass and
mixture ratio of poly(ethylene glycol) and its derivatives by
MALDI-TOF-MS
1 Scope
This document specifies a general method for determining the average molecular mass and mixture
ratio of poly(ethylene glycol) (PEG) and its derivatives with different end groups by matrix-assisted
laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). It is applicable to PEG
−1 −1
and its derivatives with molecular masses from 500 g mol to 20 000 g mol . The composition is
calculated by means of a calibration curve constructed using standard polymer mixtures, where the
peak area ratio is plotted versus the mass ratio. This document can be applied to other polymers with
monomeric unit similar to PEG.
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 10927:2011, Plastics — Determination of the molecular mass and molecular mass distribution of polymer
species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472, ISO 10927 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
MALDI-TOF-MS
technique in which the separation is based on different flight times in a field free flight tube depending on
the mass of formed polymer ions after ionization by a laser, desorption and acceleration by high voltage
3.2
peak area
A
sum of peak areas, A , where A is an area under the curve of the mass, M , associated with the j-th
ij ij ij
species of polymer i
Note 1 to entry: As Figure 1 a) shows, integration for peak area, A , should be performed over all isotopes related
ij
to the j-th species. If the software is not able to integrate all isotopic peaks, the peak area of the most abundant
isotopic peak can be used instead [see Figure 1 b)]. For data handling, see ISO 10927:2011, 6.7.
ISO 19929:20
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