1、BS ISO 22412:2017Particle size analysis Dynamic light scattering (DLS)BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 22412:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 22412:2017. It supersedes BS 3406-8:1997 and
2、 BS ISO 22412:2008 which are withdrawn.The UK participation in its preparation was entrusted to Technical Committee LBI/37, Particle characterization including sieving.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport
3、to include all the necessary 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 88273 9 ICS 19.120 Compliance with a British Standard cannot confer immunity from legal obligations.T
4、his British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 22412:2017 ISO 2017Particle size analysis Dynamic light scattering (DLS)Analyse granulomtrique Di
5、spersion lumineuse dynamique (DLD)INTERNATIONAL STANDARDISO22412Second edition2017-02Reference numberISO 22412:2017(E)BS ISO 22412:2017ISO 22412:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no pa
6、rt 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 ISOs member b
7、ody 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.iso.orgBS ISO 22412:2017ISO 22412:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definiti
8、ons . 14 Symbols and units . 35 Principle 46 Apparatus . 57 Test sample preparation 77.1 General . 77.2 Concentration limits . 77.3 Checks for concentration suitability. 78 Measurement procedure 89 Evaluation of results 109.1 General 109.2 Correlation analysis . 119.2.1 Cumulants method 119.2.2 Dist
9、ribution calculation algorithms . 119.3 Frequency analysis . 1210 System qualification and quality control .1310.1 System qualification 1310.2 Quality control of measurement results 1310.3 Method precision and measurement uncertainty .1411 Test report 14Annex A (informative) Theoretical background 1
10、6Annex B (informative) Guidance on potential measurement artefacts and on ways to minimize their influence .25Annex C (informative) Online measurements 28Annex D (informative) Recommendations for sample preparation .29Bibliography .33 ISO 2017 All rights reserved iiiContents PageBS ISO 22412:2017ISO
11、 22412:2017(E)ForewordISO (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
12、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) o
13、n 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
14、. 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
15、 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
16、 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 assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technical
17、Barriers to Trade (TBT) see the following URL: www .iso .org/ iso/ foreword .html. This document was prepared by Technical Committee ISO/TC 24, Particle characterization including sieving, Subcommittee SC 4, Particle characterization. This second edition of ISO 22412 cancels and replaces ISO 22412:2
18、008 and ISO 13321:1996.iv ISO 2017 All rights reservedBS ISO 22412:2017ISO 22412:2017(E)IntroductionParticle size analysis in the submicrometre size range is performed on a routine basis using the dynamic light scattering (DLS) method, which probes the hydrodynamic mobility of the particles. The suc
19、cess of the technique is mainly based on the fact that it provides estimates of the average particle size and size distribution within a few minutes, and that user-friendly commercial instruments are available. Nevertheless, proper use of the instrument and interpretation of the result require certa
20、in precautions.Several methods have been developed for DLS. These methods can be classified in several ways:a) by the difference in raw data acquisition (autocorrelation, cross-correlation and frequency analysis);b) by the difference in optical setup (homodyne versus heterodyne mode);c) by the angle
21、 of observation.In addition, instruments show differences with respect to the type of laser source and often allow application of different data analysis algorithms (e.g. cumulants, NNLS, CONTIN, etc.). ISO 2017 All rights reserved vBS ISO 22412:2017BS ISO 22412:2017Particle size analysis Dynamic li
22、ght scattering (DLS)1 ScopeThis document specifies the application of dynamic light scattering (DLS) to the measurement of average hydrodynamic particle size and the measurement of the size distribution of mainly submicrometre-sized particles, emulsions or fine bubbles dispersed in liquids. DLS is a
23、lso referred to as “quasi-elastic light scattering (QELS)” and “photon correlation spectroscopy (PCS),” although PCS actually is one of the measurement techniques.This document is applicable to the measurement of a broad range of dilute and concentrated suspensions. The principle of dynamic light sc
24、attering for a concentrated suspension is the same as for a dilute suspension. However, specific requirements for the instrument setup and specification of test sample preparation are required for concentrated suspensions. At high concentrations, particle-particle interactions and multiple light sca
25、ttering can become dominant and can result in apparent particle sizes that differ between concentrated and dilute suspensions.2 Normative referencesThe 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
26、 references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 9276-1, Representation of results of particle size analysis Part 1: Graphical representationISO 9276-2, Representation of results of particle size
27、 analysis Part 2: Calculation of average particle sizes/diameters and moments from particle size distributions3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.ISO and IEC maintain terminological databases for use in standardization at the following
28、addresses: IEC Electropedia: available at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp3.1particleminute piece of matter with defined physical boundariesNote 1 to entry: A physical boundary can also be described as an interface.Note 2 to
29、entry: A particle can move as a unit.SOURCE: ISO 26824:2013, 1.1, modifiedINTERNATIONAL STANDARD ISO 22412:2017(E) ISO 2017 All rights reserved 1BS ISO 22412:2017ISO 22412:2017(E)3.2average hydrodynamic diameterxDLShydrodynamic diameter that reflects the central value of the underlying particle size
30、 distributionNote 1 to entry: The average particle diameter is either directly determined without calculation of the particle size distribution, or calculated from the computed intensity-, volume- or number-weighted particle size distribution or from its fitted (transformed) density function. The ex
31、act nature of the average particle diameter depends on the evaluation algorithm.Note 2 to entry: The cumulants method yields a scattered light intensity-weighted harmonic mean particle diameter, which is sometimes also referred to as the “z-average diameter.”Note 3 to entry: Arithmetic, geometric an
32、d harmonic mean values can be calculated from the particle size distribution according to ISO 9276-2.Note 4 to entry: Mean values calculated from density functions (linear abscissa) and transformed density functions (logarithmic abscissa) may significantly differ (ISO 9276-1).Note 5 to entry: xDLSal
33、so depends on the particle shape and the scattering vector (and thus on the angle of observation, laser wavelength and refractive index of the suspension medium).3.3polydispersity indexPIdimensionless measure of the broadness of the size distributionNote 1 to entry: The PI typically has values less
34、than 0,07 for a monodisperse test sample of spherical particles.3.4scattering volumevolume defined by the intersection of the incident laser beam and the scattered light intercepted by the detector3.5scattered intensityintensity of the light scattered by the particles in the scattering volume3.6coun
35、t ratephotocurrentIsnumber of photon pulses per unit time Note 1 to entry: It is also a photodetector current which is proportional to the scattered intensity as measured by a detector.3.7validationproof with reference material that a measurement procedure is acceptable for all elements of its scope
36、Note 1 to entry: Evaluation of trueness requires a certified reference material.3.8reference materialRMmaterial, sufficiently homogeneous and stable with respect to one or more specified properties, which has been established to be fit for its intended use in a measurement processSOURCE: ISO Guide 3
37、0:2015, 2.1.1, modified2 ISO 2017 All rights reservedBS ISO 22412:2017ISO 22412:2017(E)3.9certified reference materialCRMreference material characterized by a metrologically valid procedure for one or more specified properties, accompanied by a certificate that provides the value of the specified pr
38、operty, its associated uncertainty, and a statement of metrological traceabilitySOURCE: ISO Guide 30:2015, 2.1.2, modified3.10qualificationproof with reference material that an instrument is operating in agreement with its specifications4 Symbols and unitsC() normalized distribution function of deca
39、y rates or characteristic frequenciesdimensionlessDTtranslational diffusion coefficient metres squared per secondm2/sDccollective diffusion coefficient metres squared per secondm2/sDsself-diffusion coefficient metres squared per secondm2/sf frequency, f = /(2 ) hertz Hzg(1)() normalized electric fie
40、ld correlation function dimensionlessG(2)() scattered intensity correlation function arbitrary unitsG(j) normalized distribution function of the individual decay rate jarbitrary unitsIsscattered intensity, count rate, photocurrent arbitrary unitsI0intensity of the incident light arbitrary unitsM num
41、ber of steps in the histogram dimensionlessn refractive index of the suspension medium dimensionlessP() power spectrum arbitrary unitsPI polydispersity index dimensionlessQint,iscattered light intensity-weighted amount of particles in size fraction i, i.e. xi1 25/ . It is recommended that both estim
42、ates of the baseline A are determined and that the largest of both is retained. However, for relative differences between the two estimates of the baseline larger than 103times the smallest value, measurement shall be discarded for further analysis.The range of values to be retained for yj = y(j) sh
43、all correspond to a range in G2(j) A of G2(1) A G2(j) A G2(1) A/100 with at least one value smaller than G2(1) A/50. All values of G2(j) A in this range must be positive; otherwise, the measurement shall be discarded for further analysis.Finally, the number m of values of yjin the acceptable range s
44、hall be at least 20.The parameters a0, a1and a2are determined by least-squares fitting of the experimental estimates of y(j) to Formula (A.15) whereby the following function is minimized in Formula (A.18):sa aa wy aa ajjmjj012101 222,()=+()= (A.18)In Formula (A.18), the normalized weighting factor w
45、jaccounts for the nonlinear transformation of the raw data G2into the values for y(j).The average particle diameter xDLSis calculated from a1by Formula (A.19):xakTnDLS=()1342102pipisin /(A.19)where20 ISO 2017 All rights reservedBS ISO 22412:2017ISO 22412:2017(E)k is the Boltzmann constant;T is the a
46、bsolute temperature; is the viscosity of the suspension medium;n is the refractive index of the suspension medium; is the scattering angle;0is the laser wavelength in vacuo.The polydispersity index PI is related to a2and a1by Formula (A.20):PI = 2a2/ a12(A.20)The actual value of the intercept B is c
47、omputed from a0and A by Formula (A.21):B = exp(2a0)/A (A.21)and is to be compared to the maximum value obtainable in the given experimental conditions, Bmax. Autocorrelation measurements for which the ratio B/Bmax Is. At high concentrations, and thus high Is, be careful to ensure that I0 Is at the d
48、etector is met. Mixing of the modes combines power spectra with different characteristic frequencies, 0, in the heterodyne mode and 2 0in the homodyne mode.The characteristic frequency, 0, is inversely proportional to the particle diameter x, the temperature T, the laser wavelength 0, the scattering
49、 angle and the viscosity of the medium and represents the half power point of the spectrum as shown in Formula (A.24).pi02211632=()xkTsin (A.24)Figure A.2 plots the power spectrum for different particle sizes in the heterodyne mode. The inverse relationship of the characteristic frequency with particle size is evident.KeyA amplitude, arbitrary unitsf frequency, in HzFigure A.2 Power spectra for different particle sizes in the heterodyne mode22
