1、BS ISO 19929:2017Plastics Determination ofaverage molecular mass andmixture ratio of poly(ethyleneglycol) and its derivatives byMALDI-TOF-MSBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 19929:2017 BRITISH STANDARDNational forewordThis British Standard is the
2、 UK implementation of ISO 19929:2017.The UK participation in its preparation was entrusted to Technical Committee PRI/21, Testing of plastics.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessa
3、ry provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 89838 9 ICS 83.080.01 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard wa
4、s published under the authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 19929:2017 ISO 2017Plastics Determination of average molecular mass and mixture ratio of poly(ethylene glycol) and its deri
5、vatives by MALDI-TOF-MSPlastiques Dtermination de la masse molculaire moyenne et du rapport de mlange du poly(thylne glycol) et de ses drivs par MALDI-TOF-MSINTERNATIONAL STANDARDISO19929First edition2017-03Reference numberISO 19929:2017(E)BS ISO 19929:2017ISO 19929:2017(E)ii ISO 2017 All rights res
6、ervedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, 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 int
7、ranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww
8、.iso.orgBS ISO 19929:2017ISO 19929:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principles . 35 Reagents 36 Apparatus . 47 Procedure. 57.1 General . 57.2 Sample preparation 57.2.1 General 57.2.2 Preparation of polymer standard mixtures 67.2.3 Prepar
9、ation of polymer/matrix/salt solutions . 67.2.4 Deposition of the sample on the sample plate (target) 67.2.5 Preparation of biopolymer/matrix solutions . 77.3 Instrument settings . 77.4 Spectra recording 88 Data acquisition and processing 88.1 General . 88.2 Calibration of mass axis . 88.2.1 General
10、 88.2.2 Calibration of mass axis using synthetic polymer standards 98.2.3 Calibration of mass axis using biopolymer standards . 98.2.4 Self-calibration method . 98.3 Generation of mass calibration curve 98.4 Calibration of intensity axis . 99 Expression of results .109.1 Calculation of molecular mas
11、s distribution (MMD).109.2 Calculation of the number-average molecular mass .109.3 Calculation of peak area . 109.4 Constructing calibration curve for intensity 109.5 Calculation of mass ratio . 1110 Precision 1111 Test report 1111.1 General 1111.2 Apparatus . 1111.3 Calibration . 1111.4 Results . 1
12、1Annex A (normative) Calibrants .12Bibliography .13 ISO 2017 All rights reserved iiiContents PageBS ISO 19929:2017ISO 19929:2017(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Intern
13、ational 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
14、 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,
15、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
16、 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 declaration
17、s 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 on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity asses
18、sment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html.This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-ch
19、emical properties.iv ISO 2017 All rights reservedBS ISO 19929:2017ISO 19929:2017(E)IntroductionFor 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 chroma
20、tography, 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 compar
21、isons 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. ISO 2017 All rights reserved vBS ISO 19929:2017BS ISO
22、 19929:2017Plastics Determination of average molecular mass and mixture ratio of poly(ethylene glycol) and its derivatives by MALDI-TOF-MS1 ScopeThis document specifies a general method for determining the average molecular mass and mixture ratio of poly(ethylene glycol) (PEG) and its derivatives wi
23、th different end groups by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). It is applicable to PEG and its derivatives with molecular masses from 500 g mol1to 20 000 g mol1. The composition is calculated by means of a calibration curve constructed using s
24、tandard 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 referencesThe following documents are referred to in the text in such a way that some or all of their content constitute
25、s 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 VocabularyISO 10927:2011, Plastics Determination of the molecular mass and molecular mass
26、distribution of polymer species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS)3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 472, ISO 10927 and the following apply.ISO and IEC maintain terminological da
27、tabases 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/ obp3.1matrix-assisted laser desorption/ionization time-of-flight mass spectrometryMALDI-TOF-MStechnique in whi
28、ch 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 voltage3.2peak areaAsum of peak areas, Aij, where Aijis an area under the curve of the mass, Mij, associated
29、with the j-th species of polymer iNote 1 to entry: As Figure 1 a) shows, integration for peak area, Aij, should be performed over all isotopes related 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 instea
30、d see Figure 1 b). For data handling, see ISO 10927:2011, 6.7.INTERNATIONAL STANDARD ISO 19929:2017(E) ISO 2017 All rights reserved 1BS ISO 19929:2017ISO 19929:2017(E)a) Peak area of isotopic peaks b) Peak area or peak height of the most abundant isotopic peakKey1 “peak area”, Aij2 “peak height” of
31、the most abundant isotopic peak of PEG(n = 43)+Na+3 “peak area” of the most abundant isotopic peak of PEG(n = 43)+Na+X mass/chargeFigure 1 Definitions of peak area and peak height3.3molecular massMsum of the masses of atomsNote 1 to entry: The molecular mass of the j-th species, Mj, is also calculat
32、ed as the average mass of isotopes.Note 2 to entry: The terms “molecular weight” and “molar mass” are also used instead of “molecular mass”.3.4number-average molecular massMnmolecular mass defined as:MNMNjjjjjnNote 1 to entry: Njis the number of molecules of species j of molecular mass Mj.3.5weight-
33、average molecular massMwmolecular mass defined as:MNMNMjjjjjjw()()22 ISO 2017 All rights reservedBS ISO 19929:2017ISO 19929:2017(E)3.6z-average molecular massMzmolecular mass defined as:MNMNMjjjjjjz()()324 PrinciplesThe MALDI process involves the ablation and the ionization of an analyte dispersed i
34、n a small organic molecule matrix. The matrix shall be able to absorb the laser energy. A metal salt may be added to cationize the analyte. A polymer is co-crystallized or co-mixed with the matrix molecule and deposited on the target. A short duration UV laser pulse is used to ablate the matrix and
35、the analyte. The laser energy is transferred to the matrix molecules, causing them to vaporize. Analyte and matrix molecules leave the target surface in a plume. Due to the very short desorption time, polymer molecules do not degrade. The polymer in the ablation plume gains a cation and is accelerat
36、ed by a high voltage, drifts down the field free flight tube and is detected at the end of the flight tube. The time-of-flight of the species depends on their molecular masses, and needs to be calibrated with standards of known molecular masses. Biopolymers such as proteins are often used to this en
37、d.Ideally, the product of the ratio between the total sum of peak areas and that between number-average molecular mass is proportional to the mass ratio, i.e.AAMMkWW10101010=nn,(1)where Ai, Wiand Mn,iare sum of peak areas in MALDI-TOF-MS spectra, mass and number-average molecular mass of polymer i (
38、i = 0 or 1), respectively. The proportionality constant, k10, is experimental and generally depends on the combination of polymers with different chemical structures. Ideally, if no mass discrimination is observed, k10= 1.5 Reagents5.1 Matrices.-Cyano-4-hydroxycinnamic acid (CHCA) and 1,8,9-trihydro
39、xyanthracene (dithranol) are the recommended matrices for this method. Other matrices can be used after examining sufficient ionizing ability and solubility in solvents used. The procedure described in Clause 7 can be applied to examination of the ability and solubility. All materials should be at l
40、east 97 % pure. They should be stored in a freezer or refrigerator. They should be warmed up to room temperature right before use. Regulated reagents shall be handled in accordance with regulations.5.2 Salts.Lithium, sodium and potassium salts, e.g. iodides or trifluoroacetates, are recommended.5.3
41、Solvents.Methanol and tetrahydrofuran (THF) are recommended since they are good solvents of PEG and its derivatives. They also applied to polar polymers. The solvents should be at least 97 % pure. If the solvents are regulated, they should be treated safely. ISO 2017 All rights reserved 3BS ISO 1992
42、9:2017ISO 19929:2017(E)5.4 Molecular mass standards.The calibration of the mass axis should be done using biopolymers and/or synthetic polymers with known repeating units and defined end groups. The molecular mass of the standards shall be within the range of the molecular mass of the investigated p
43、olymer. The software of the mass spectrometer should be used for calibration. The list of recommended biopolymers and their molecular masses in Table A.1 shall be used.5.5 Mixed polymer standards.Polymers used for the calibration of mass ratios should have identical chemical repeating unit and simil
44、ar molecular mass distributions. The preparation of solutions of mixed polymer standards should be done using a balance.6 Apparatus6.1 GeneralA schematic diagram of a MALDI-TOF mass spectrometer is shown in Figure 2. Essential components are sample introduction chamber, a laser source, an ion source
45、, a flight tube with an acceleration region and an ion detector (linear detector). The instruments may have additionally an ion deflector and a reflector detector. Both commercially available TOF mass spectrometers and systems assembled in the laboratory may be used for this method, provided they me
46、et the required levels of performance.Key1 laser source 7 reflector (ion deflector)2 counter 8 linear detector3 optical system with beam splitter and attenuator 9 reflector detector4 sample introduction chamber 10 vacuum pump system5 target (ion source) 11 data recording6 ion acceleration optics 12
47、computerFigure 2 Schematic diagram of a MALDI-TOF mass spectrometer4 ISO 2017 All rights reservedBS ISO 19929:2017ISO 19929:2017(E)6.2 Sample introduction chamber/targetA MALDI sample consists of a film of the analyte, matrix and salt mixture deposited onto a metal sample plate. The entire plate and
48、 MALDI sample are often referred to as a MALDI target. The MALDI target is introduced into the spectrometer vacuum chamber from sample introduction chamber by either a manual or an automatic operation. The target is moveable, so that all sample spots are accessible by the laser beam.6.3 Laser source
49、The laser system comprises a pulsed laser, an attenuator which allows for the adjustment of the laser power, and a lens and mirror system to direct the laser beam onto the MALDI target. Some commercial instruments have beam splitters to direct a fraction of the laser light to a photodiode to start the timing for the TOF measurement. The wavelength of the laser should be in the absorption range of the matrices. Typically, UV-lasers are used.6.4 Flight tubeThe target is at a high voltage of se
