ISO/TS 5973:2024
(Main)Laser diffraction measurements — Good practice
Laser diffraction measurements — Good practice
This document gives guidance on the determination criteria for when laser diffraction is the most appropriate method for the analysis of samples, the appropriate preparation of samples, the verification of the correct functioning of instruments, the interpretation of data, and the assessment of data quality. This document focuses on the practical steps needed to obtain results of good quality, rather than on theoretical considerations, and covers not only the measurement of solid particles (in wet and dry measurement configurations), but also emulsions and bubbles. Result variation expectations of real samples are also considered in this document.
Mesures par diffraction laser — Bonnes pratiques
General Information
Standards Content (Sample)
Technical
Specification
ISO/TS 5973
First edition
Laser diffraction measurements —
2024-07
Good practice
Mesures par diffraction laser — Bonnes pratiques
Reference number
© ISO 2024
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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 4
5 Laser diffraction experiment and measurement . 4
6 Information recommended collecting prior to analysis . 5
6.1 Sample information .5
6.2 Desired outcome of analysis . .6
6.3 Other sample considerations .7
6.4 Best sampling practice prior to laser diffraction measurements .8
6.4.1 General .8
6.4.2 Sampling of powders .8
6.4.3 Sampling of emulsions and suspensions .9
6.4.4 Sampling of sprays, gas bubbles and aerosols .9
6.4.5 Improving sampling in the instrument .10
7 Samples not appropriate for analysis by laser diffraction .10
8 Additional guidance on optical properties of samples .11
8.1 Coloured samples .11
8.2 Porous samples .11
8.3 Mixtures .11
8.4 Mie, Fraunhofer and incorrect use of refractive index .11
9 Repeatability, intermediate precision and reproducibility .12
9.1 General . 12
9.2 Key measurands . 12
9.3 Instrument repeatability . 12
9.4 Method repeatability (under repeatability conditions) . 13
9.5 Intermediate precision and reproducibility (under intermediate precision/
reproducibility conditions).14
9.6 Summary table of experiments detailed in 9.3 through 9.5 . 15
9.7 When is tighter or wider control needed? . 15
9.8 What are the most appropriate control parameters? . 15
10 Interpretation of light scattering and assessment of data quality .15
10.1 Background stability and alignment quality . 15
10.2 Multiple scattering .16
10.3 Non-smooth scattering patterns .16
11 Interpretation of trends in measurement data .16
11.1 General .16
11.2 Dispersion (wet measurements) .16
11.3 Dissolution (wet measurements) .17
11.4 Agglomeration (wet measurements) .17
11.5 Size decreasing on successive measurements (dry measurements) .17
11.6 Random variation (wet measurements) .17
11.7 Other causes of poor repeatability (wet and dry measurements).17
12 Orthogonal techniques for laser diffraction .18
12.1 Image analysis.18
12.2 Dynamic light scattering .18
iii
13 Validation, installation qualification, operational qualification and performance
qualification . 19
Annex A (informative) Characterization data approach to laser diffraction measurements .20
Bibliography .23
iv
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 24, Particle characterization including sieving,
Subcommittee SC 4, Particle characterization.
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.
v
Introduction
The laser diffraction technique has evolved such that it is now a dominant method for determination of
particle size distributions (PSDs). The success of the technique is because it can be applied to a wide variety
of particulate systems. The technique is fast and can be automated, and a variety of commercial instruments
are available. Nevertheless, the proper use of the instrument and the interpretation of the results require
caution. ISO 13320 has had multiple revisions to date and covers the principles of the technology and
information on evaluating the accuracy of the instrument with a view to qualification. ISO 13320 does not,
however, cover the use of the technology on samples in great detail, and therefore, this document is intended
to be used in conjunction with ISO 13320, as this document provides practical advice for the measurement of
real samples, guidance on obtaining consistent results with good quality data and data interpretation.
vi
Technical Specification ISO/TS 5973:2024(en)
Laser diffraction measurements — Good practice
1 Scope
This document gives guidance on the determination criteria for when laser diffraction is the most
appropriate method for the analysis of samples, the appropriate preparation of samples, the verification of
the correct functioning of instruments, the interpretation of data, and the assessment of data
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.