CEN ISO/TS 24672:2024
(Main)Nanotechnologies - Guidance on the measurement of nanoparticle number concentration (ISO/TS 24672:2023)
Nanotechnologies - Guidance on the measurement of nanoparticle number concentration (ISO/TS 24672:2023)
This document provides an overview of the methods used to determine the nanoparticle number concentration in liquid dispersions and aerosols. The methods described are the ensemble measurement techniques of differential centrifugal sedimentation (DCS), multi-angle dynamic light scattering (MDLS), small-angle X-ray scattering (SAXS) and ultraviolet-visible spectroscopy (UV-vis) and the particle counting methods of particle tracking analysis (PTA), resistive pulse sensing (RPS), single particle inductively coupled plasma mass spectrometry (spICP-MS), condensation particle counter (CPC), and differential mobility analysing system (DMAS). This document provides information on the use of each technique, along with considerations on sample preparation, advantages and limitations.
Nanotechnologien - Leitfaden für die Messung der Konzentration von Nanopartikeln (ISO/TS 24672:2023)
Nanotechnologies - Conseils pour la mesure de la concentration en nombre de nanoparticules (ISO/TS 24672:2023)
Nanotehnologije - Navodilo za merjenje številčnosti koncentracije nanodelcev (ISO/TS 24672:2023)
Ta dokument vsebuje pregled metod za določanje številčnosti koncentracije nanodelcev v tekočih disperzijah in aerosolih. Opisane so naslednje metode: tehnike skupinskega merjenja, tj. diferencialna centrifugalna sedimentacija (DCS), dinamično sipanje svetlobe pod več koti (MDLS), sipanje rentgenskih žarkov pod majhnim kotom (SAXS) in ultravijolično-vidna spektroskopija (UV-vis) ter metode štetja delcev, tj. analiza sledenja delcev (PTA), uporovno pulzno zaznavanje (RPS), masna spektrometrija posameznih delcev z induktivno sklopljeno plazmo (spICP-MS), kondenzacijski števec delcev (CPC) in sistem za analizo diferencialne mobilnosti (DMAS). Ta dokument vsebuje informacije o uporabi posamezne tehnike ter vidike glede priprave vzorcev, prednosti in omejitev.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2024
Nanotehnologije - Navodilo za merjenje številčnosti koncentracije nanodelcev
(ISO/TS 24672:2023)
Nanotechnologies - Guidance on the measurement of nanoparticle number
concentration (ISO/TS 24672:2023)
Nanotechnologien - Leitfaden für die Messung der Konzentration von Nanopartikeln
(ISO/TS 24672:2023)
Nanotechnologies - Conseils pour la mesure de la concentration en nombre de
nanoparticules (ISO/TS 24672:2023)
Ta slovenski standard je istoveten z: CEN ISO/TS 24672:2024
ICS:
07.120 Nanotehnologije Nanotechnologies
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN ISO/TS 24672
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
September 2024
TECHNISCHE SPEZIFIKATION
ICS 07.120
English Version
Nanotechnologies - Guidance on the measurement of
nanoparticle number concentration (ISO/TS 24672:2023)
Nanotechnologies - Conseils pour la mesure de la Nanotechnologien - Leitfaden für die Messung der
concentration en nombre de nanoparticules (ISO/TS Konzentration von Nanopartikeln (ISO/TS
24672:2023) 24672:2023)
This Technical Specification (CEN/TS) was approved by CEN on 9 September 2024 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.
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United Kingdom.
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CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 24672:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
The text of ISO/TS 24672:2023 has been prepared by Technical Committee ISO/TC 229
"Nanotechnologies” of the International Organization for Standardization (ISO) and has been taken over
as CEN ISO/TS 24672:2024 by Technical Committee CEN/TC 352 “Nanotechnologies” the secretariat of
which is held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO/TS 24672:2023 has been approved by CEN as CEN ISO/TS 24672:2024 without any
modification.
TECHNICAL ISO/TS
SPECIFICATION 24672
First edition
2023-11
Nanotechnologies — Guidance on the
measurement of nanoparticle number
concentration
Nanotechnologies — Conseils pour la mesure de la concentration en
nombre de nanoparticules
Reference number
ISO/TS 24672:2023(E)
ISO/TS 24672:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
ISO/TS 24672:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 4
5 Overview . 5
5.1 General . 5
5.2 Comparison of different techniques . 5
5.3 Considerations when selecting a technique . 8
5.3.1 General . 8
5.3.2 Type of particles. 8
5.3.3 Number concentration range . 9
5.3.4 Accuracy and precision . 9
5.3.5 Other factors . 10
5.4 Unit for nanoparticle number concentration . 10
6 Ensemble techniques . .11
6.1 Differential centrifugal sedimentation . 11
6.1.1 General . 11
6.1.2 Sample specifications .12
6.1.3 Technical aspects .12
6.1.4 Sources of uncertainty and challenges . 14
6.1.5 Outlook .15
6.2 Multi-angle dynamic light scattering . 15
6.2.1 General .15
6.2.2 Sample specifications . .15
6.2.3 Technical aspects . 16
6.2.4 Sources of uncertainty and challenges . 17
6.2.5 Outlook . 17
6.3 Small-angle X-ray scattering . 17
6.3.1 General . 17
6.3.2 Sample specifications . 18
6.3.3 Technical aspects . 18
6.3.4 Sources of uncertainty and challenges . 20
6.3.5 Outlook . 20
6.4 Ultraviolet-visible spectroscopy . 20
6.4.1 General .20
6.4.2 Sample specifications . . 21
6.4.3 Technical aspects . 21
6.4.4 Sources of uncertainty and challenges . 22
6.4.5 Outlook .23
7 Particle counting techniques .23
7.1 Particle tracking analysis .23
7.1.1 General .23
7.1.2 Sample specifications . .23
7.1.3 Technical aspects . 24
7.1.4 Sources of uncertainty and challenges . 24
7.1.5 Outlook . 25
7.2 Resistive pulse sensing . 25
7.2.1 General . 25
7.2.2 Sample specifications . 26
7.2.3 Technical aspects . 27
iii
ISO/TS 24672:2023(E)
7.2.4 Sources of uncertainty and challenges .28
7.2.5 Outlook .28
7.3 Single particle inductively coupled plasma mass spectrometry .28
7.3.1 General .28
7.3.2 Sample specifications .29
7.3.3 Technical aspects .29
7.3.4 Sources of uncertainty and challenges . 33
7.3.5 Outlook . 33
7.4 Condensation particle counter and differential mobility analysing system .34
7.4.1 General .34
7.4.2 Sample specifications .34
7.4.3 Technical aspects . 35
7.4.4 Sources of uncertainty and challenges . 37
7.4.5 Outlook .38
Annex A (informative) Summary of VAMAS international interlaboratory studies .40
Annex B (informative) General guidance on sample preparation for suspensions containing
nanoparticles .43
Bibliography .46
iv
ISO/TS 24672:2023(E)
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
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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
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database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
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Any trade name used in this document is information given for the convenience of users and does not
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 229, Nanotechnologies.
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
ISO/TS 24672:2023(E)
Introduction
Nanoparticle number concentration refers to the number of nanoparticles per unit of volume or mass
in a sample. It is an important measurand when analysing dispersions containing nanoparticles.
Nanoparticle number concentration is also considered a useful metric for supporting materials
toxicological assessments. Furthermore, the capability to accurately measure nanoparticle number
concentration can help industry to increase product manufacturing quality control and implement
quality assurance. Currently, in most applications, nanoparticle number concentration is estimated
from indirect mass-balance considerations and validated direct techniques for this measurand are
required.
This document provides an overview of commonly used methods for the measurement of nanoparticle
number concentration. These are the ensemble measurement techniques of differential centrifugal
sedimentation (DCS) (line start incremental disc-type centrifugal liquid sedimentation), multi-
angle dynamic light scattering (MDLS), small-angle X-ray scattering (SAXS) and ultraviolet-visible
spectroscopy (UV-vis) and the particle counting techniques of particle tracking analysis (PTA),
resistive pulse sensing (RPS), single particle inductively coupled plasma mass spectrometry (spICP-
MS), condensation particle counter (CPC), and differential mobility analysing system (DMAS).
This document focuses on the analysis of nanoparticles in suspensions (liquid dispersions) but also
addresses aerosols measured using a CPC or a DMAS. Particles on surfaces or incapsulated in solid
materials are not covered in this document. Nanoparticles rather than nano-objects are discussed as
most techniques use the spherical approximation model to measure particle diameter which is more
applicable to nanoparticles as opposed to nanofibres and nanoplates. Most of the techniques discussed
can also analyse particles of size greater than the nanoscale.
This document provides guidance to help users to select the most appropriate techniques for
nanoparticle number concentration measurements suitable for their applications.
vi
TECHNICAL SPECIFICATION ISO/TS 24672:2023(E)
Nanotechnologies — Guidance on the measurement of
nanoparticle number concentration
1 Scope
This document provides an overview of the methods used to determine the nanoparticle number
concentration in liquid dispersions and aerosols. The methods described are the ensemble measurement
techniques of differential centrifugal sedimentation (DCS), multi-angle dynamic light scattering
(MDLS), small-angle X-ray scattering (SAXS) and ultraviolet-visible spectroscopy (UV-vis) and the
particle counting methods of particle tracking analysis (PTA), resistive pulse sensing (RPS), single
particle inductively coupled plasma mass spectrometry (spICP-MS), condensation particle counter
(CPC), and differential mobility analysing system (DMAS). This document provides information on the
use of each technique, along with considerations on sample preparation, advantages and limitations.
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 80004-1, Nanotechnologies – Vocabulary — Part 1: Core vocabulary
ISO/TS 80004-6, Nanotechnologies — Vocabulary — Part 6: Nano-object characterization
ISO/TS 80004-8, Nanotechnologies — Vocabulary — Part 8: Nanomanufacturing processes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 80004-1, ISO/TS 80004-6,
ISO/TS 80004-8 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
particle
minute piece of matter with defined physical boundaries
Note 1 to entry: A physical boundary can also be described as an interface.
Note 2 to entry: A particle can move as a unit.
Note 3 to entry: This general particle definition applies to nano-objects.
[SOURCE: ISO 26824:2022, 3.1]
ISO/TS 24672:2023(E)
3.2
nanoparticle
nano-object with all external dimensions in the nanoscale
Note 1 to entry: If the dimensions differ significantly (typically by more than three times), terms such as
nanofibre or nanoplate are preferred to the term nanoparticle.
[SOURCE: ISO 80004-1:2023, 3.3.4]
3.3
primary particle
original source particle (3.1) of agglomerates (3.4) or aggregates (3.5), or mixtures of the two
Note 1 to entry: Constituent particles of agglomerates or aggregates at a certain actual state may be primary
particles, but often the constituents are aggregates.
Note 2 to entry: Agglomerates and aggregates are also termed secondary particles.
[SOURCE: ISO 26824:2022, 3.1.4]
3.4
agglomerate
collection of weakly or medium strongly bound particles (3.1) where the resulting external surface area
is similar to the sum of the surface areas of the individual components
Note 1 to entry: The forces holding an agglomerate together are weak forces, for example, van der Waals forces,
or simple physical entanglement.
Note 2 to entry: Agglomerates are also termed secondary particles and the original source particles are termed
primary particles (3.3).
[SOURCE: ISO 80004-1:2023, 3.2.4]
3.5
aggregate
particle (3.1) comprising strongly bonded or fused particles where the resulting external surface area
is significantly smaller than the sum of surface areas of the individual components
Note 1 to entry: The forces holding an aggregate together are strong forces, for example, covalent or ionic bonds,
or those resulting from sintering or complex physical entanglement.
Note 2 to entry: Aggregates are also termed secondary particles and the original source particles are termed
primary particles.
[SOURCE: ISO 80004-1:2023, 3.2.5]
3.6
differential centrifugal sedimentation
DCS
analytical centrifugation in which the sample is introduced at a defined position in a rotating disc
partially filled with a fluid
Note 1 to entry: Normally the fluid has a density gradient to ensure uniform sedimentation.
Note 2 to entry: Normally there is one detector at a pre-determined position and the times taken for the particles
(3.1) to reach this detector are recorded.
Note 3 to entry: Depending on the effective density of the particles, the technique can measure particle size and
particle size distribution between 2 nm and 10 µm, and can resolve particles differing in size by less than 2 %.
[SOURCE: ISO/TS 80004-6:2021, 4.4.5, modified — the term “line-start incremental disc-type
centrifugal liquid sedimentation” has been removed.]
ISO/TS 24672:2023(E)
3.7
condensation particle counter
CPC
instrument that measures the particle (3.1) number concentration of an aerosol using a condensation
effect to increase the size of the aerosolized particles
Note 1 to entry: The sizes of particles detected are usually smaller than several hundred nanometres and larger
than a few nanometres.
Note 2 to entry: A CPC is one possible detector suitable for use with a differential electrical mobility classifier
(DEMC).
Note 3 to entry: In some cases, a condensation particle counter may be called a “condensation nucleus counter
(CNC)”.
[SOURCE: ISO/TS 80004-6:2021, 4.3.1]
3.8
differential mobility analysing system
DMAS
system to measure the size distribution of sub-micrometre aerosol particles (3.1) consisting of a
differential electrical mobility classifier (DEMC), flow meters, a particle detector, interconnecting
plumbing, a computer and suitable software
[SOURCE: ISO/TS 80004-6:2021, 4.3.3]
3.9
dynamic light scattering
DLS
method in which particles (3.1) in a liquid suspension are illuminated by a laser and the time dependant
change in intensity of the scattered light due to Brownian motion is used to determine particle size
Note 1 to entry: Analysis of the time-dependent intensity of the scattered light can yield the translational diffusion
coefficient and hence the particle size as the hydrodynamic diameter via the Stokes–Einstein relationship.
Note 2 to entry: The analysis is applicable to nanoparticles (3.2) as the size of particles detected is typically in the
range 1 nm to 6 000 nm. The upper limit is due to limited Brownian motion and sedimentation.
Note 3 to entry: DLS is typically used in dilute suspensions where the particles do not interact amongst
themselves.
[SOURCE: ISO/TS 80004-6:2021, 4.2.7, modified — the term “photon correlation spectroscopy” has
been removed.]
3.10
nanoparticle tracking analysis
NTA
particle tracking analysis
PTA
method in which particles (3.1) undergoing Brownian and/or gravitational motion in a suspension are
illuminated by a laser and the change in position of individual particles is used to determine particle
size
Note 1 to entry: Analysis of the time-dependent particle position yields the translational diffusion coefficient and
hence the particle size as the hydrodynamic diameter using the Stokes-Einstein relationship.
Note 2 to entry: The analysis is applicable to nanoparticles (3.2) as the size of particles detected is typically in the
range 10 nm to 2 000 nm. The lower limit requires particles with high refractive index and the upper limit is due
to limited Brownian motion and sedimentation.
Note 3 to entry: NTA is often used to describe PTA. NTA is a subset of PTA since PTA covers larger range of
particle sizes than nanoscale.
ISO/TS 24672:2023(E)
[SOURCE: ISO/TS 80004-6:2021, 4.2.8]
3.11
resistive pulse sensing
RPS
method for counting and size measurement of particles (3.1) in electrolytes by measuring a drop in
electrical current or voltage as a particle passes through an aperture between two chambers
Note 1 to entry: The drop in current or voltage is proportional to the particle volume (Coulter principle).
Note 2 to entry: The particles are driven through the aperture by pressure or an electric field.
Note 3 to entry: The aperture can be nanoscale in size allowing the size measurement of individual nano-objects.
[SOURCE: ISO/TS 80004-6:2021, 4.4.7, modified — the terms “electrical sensing zone method” and
“Coulter counter” have been removed.]
3.12
single particle inductively coupled plasma mass spectrometry
spICP-MS
method using inductively coupled plasma mass spectrometry whereby a dilute suspension of nano-
objects is analysed and the ICP-MS signals collected at high time resolution, allowing particle-by-
particle detection at specific mass peaks and number concentration, size and size distribution to be
determined
[SOURCE: ISO/TS 80004-6:2021, 4.4.8]
3.13
small-angle X-ray scattering
SAXS
method in which the elastically scattered intensity of X-rays is measured for small-angle deflections
Note 1 to entry: The scattering is typically measured in the angular range up to 5°. This provides structural
information about inhomogeneities in materials with characteristic lengths typically ranging from 1 nm to
100 nm. Under certain conditions the limit of 100 nm can be significantly extended.
[SOURCE: ISO/TS 80004-6:2021, 4.24, modified — Note 1 to entry has been replaced.]
3.14
ultraviolet-visible spectroscopy
UV-Vis spectroscopy
spectroscopy of radiation that consists of electromagnetic radiation with wavelengths in the ultraviolet
and/or visible regions
[SOURCE: ISO/TS 80004-6:2021, 5.6]
4 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
BIPM-CCQM bureau international des poids et mesures consultative committee for amount of sub-
stance: metrology in chemistry and biology
CLS centrifugal liquid sedimentation
CPC condensation particle counter
DCS differential centrifugal sedimentation
DLS dynamic light scattering
ISO/TS 24672:2023(E)
DMA differential mobility analyser
DMAS differential mobility analysing system
ES electrospray
MDLS multi-angle dynamic light scattering
PTA particle tracking analysis
RPS resistive pulse sensing
SAXS small-angle X-ray scattering
spICP-MS single particle inductively coupled plasma mass spectrometry
TRPS tunable resistive pulse sensing
UV-vis ultraviolet-visible spectroscopy
VAMAS Versailles project on advanced materials and standards
5 Overview
5.1 General
The number concentration of nanoparticles can be measured by techniques that average the number
of particles measured over a specific sample volume (henceforth referred to as “ensemble techniques”)
or count individual nanoparticles (henceforth referred to as “particle counting” or “particle-by-particle
techniques”). The ensemble techniques described in this document are DCS, MDLS, SAXS and UV-vis
spectroscopy. In these ensemble techniques, the measured sample volume can have some fractionation,
for example in the case of DCS, but an ensemble of particles rather than individual particles are measured
at the detector. The particle counting methods described are PTA, RPS, spICP-MS, CPC and DMAS. All
the techniques discussed in this document are used for measuring nanoparticles in suspensions except
for CPC and for DMAS, which are used to determine the particle number concentration in aerosols,
which includes aerosolised suspensions.
The selection of the method of choice is ultimately dictated by the nature of the sample. The measurement
of the number concentration of a particle population intrinsically depends on the limits of detection,
sensitivity and resolution of the applied technique in terms of particle size. Depending on particle size,
some techniques are capable of measuring the relative concentration of particle populations within
the same sample. Some techniques measure aggregates or agglomerates as one particle, giving no
information on primary particles unless separated by other means. Ensemble techniques generally
require the knowledge of other particle characteristics, such as size and refractive index, in order to
measure the number concentration.
A summary of VAMAS and BIPM-CCQM P194 international interlaboratory studies on the measurement
of the number concentration of colloidal gold nanoparticles with selected techniques is described in
Annex A and a guide on sample preparation for nanoparticles in suspension is described in Annex B.
5.2 Comparison of different techniques
The techniques described in this document are outlined in Table 1. This is not an exhaustive list of
methods to measure nanoparticle number concentration measurements; other methods include
electron microscopy and asymmetrical flow-field flow fractionation (AF4) coupled to PTA or ICP-MS,
but are not discussed in this document. The techniques in Table 1 and Clauses 6 and 7 are grouped
by ensemble and particle counting, and then listed in alphabetical order. Methods for particles in
suspensions (liquid dispersions) are listed first followed by those for aerosols (i.e. CPC and DMAS).
Here, instrument footprint refers to the area that the instrument takes up in the laboratory.
ISO/TS 24672:2023(E)
Table 1 — Comparison of techniques for measuring nanoparticle number concentration in
suspensions (ensemble and particle counting) and airborne
Technique Particle type Critical input parameters Advantages Limitations
Effective density and Multiple information (e.g. size Longer sedimentation times
complex refractive index and concentration). for smaller nanoparticles or
of the particles, refractive High resolution of the size lower density materials.
index, average density and distribution. Calibration of particle losses
viscosity of the density Concentration per size popu- required.
Organic and gradient (medium), and lation. Spherical model assumption
inorganic some instrument-related Minimal sample preparation. applied.
materials parameters. The viscosity Spherical calibrant of known
DCS
which absorb of the gradient, as well as size and density required.
and/or scatter the instrument-related Data post processing re-
light or X-rays parameters, can be replaced quired.
by a single method constant
based on calibration with
spherical reference particles
of known effective density
and size.
Ensemble
Complex refractive index Multiple information (e.g. size Spherical model assumption
Organic and
and temperature of the and concentration). applied.
inorganic
a
medium and the particles, Rapid measurements. Lower performance for heter-
MDLS materials
viscosity of the medium Concentration per size popu- ogeneous samples.
which scatter
lation.
light
Minimal sample preparation.
Organic and Density of the materials Multiple information (e.g. Spherical model assumption
inorganic ma- (more specifically: effective size, internal structure and applied.
SAXS
terials which electron density) concentration).
scatter X-rays Minimal sample preparation.
Organic and Average particle size and Widely available. Material dependent, particle
a
inorganic extinction cross-section Rapid measurements. extinction cross-section is not
UV-vis material which Minimal sample preparation. known for many materials
absorb and/or and is also size dependent
scatter light which limits its applicability.
Effective sensing volume of Multiple information (e.g. size Sample dilution to optimal
the instrument and concentration). concentration.
Organic and Concentration per size popu- Expert setting of signal
inorganic ma- lation. thresholds.
PTA
terials, which High resolution of the size Calibration of sampling vol-
scatter light distribution. ume required. Dependencies
a
Rapid measurements. on tracking algorithms.
Low analyte volume.
Size of the aperture selected Multiple information (e.g. size Concentration calibrant can
and concentration). be required.
High resolution of the size Stable analyte dispersion in
Organic and
distribution. electrolyte solution required.
RPS inorganic
Concentration per size popu- Sample dilution to optimal
materials
lation. concentration.
a
Particle Rapid measurements. Expert setting of signal
counting Low analyte volume. thresholds.
a
Transport efficiency of Rapid measurement. Expert selection of optimal
particles Multiple information [e.g. ele- particle concentration
ment mass per particle (from Expert setting of signal
which size can be calculated thresholds.
by taking into account den- Calculation of transport
Particles with
sity and shape) and number efficiency required. Limits
an element/
concentration]. Low analyte of detection for sizing lim-
spICP-MS tag suitable
volume. ited by procedural blanks,
for ICP-MS
Very diluted matrix thus instrumental background
detection
minimizing matrix effects. and contribution of dissolved
Minimal sample preparation. fraction.
Information on the dissolved
and nanoparticulate fractions
simultaneously.
a
Rapid measurements refer to those that take approximately 60 s or less per measurement.
b
Liquid dispersion.
ISO/TS 24672:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Technique Particle type Critical input parameters Advantages Limitations
Flow rates of air or gas Rapid measurement (one Sample dilution to optimal
a
Airborne parti- mixture (aerosol flow and second resolution). concentration. Calibration of
cles, including sheath flow) transport efficiency required.
CPC aerosolised For dispersions: artefacts
particles from derived from solutes in liquid
b
a suspension dispersions (electrospray or
nebulisation).
Airborne
The flow rates of air or gas Multiple information (e.g. size Sample dilution to optimal
particles
mixture (aerosol flow and distribution and concentra- concentration. Calibration of
Airborne parti- sheath flow). tion) transport efficiency required.
cles, including Voltage for DMA size dis- High resolution of the size Less direct than CPC for
DMAS aerosolised crimination. distribution. aerosols.
a
particles from Efficiency and size distri- Rapid measurement. For dispersions: artefacts
b
a suspension bution preservation of the derived from solutes in liquid
aerosolization method. dispersions (electrospray or
nebulisation).
a
Rapid measurements refer to those that take approximately 60 s or less per measurement.
b
Liquid dispersion.
a) Silica b) Gold
c) Polystyrene
ISO/TS 24672:2023(E)
Key
−1
X particle diameter (nm) Y particle number concentration (kg )
Figure 1 — Comparison of techniques and estimates of related number concentration
measurement ranges as a function of particle diameter for various materials types in
suspension
Figure 1 shows a summary of the estimated silica, gold and polystyrene particle diameter and number
concentration ranges for the different techniques that analyse samples in suspensions and outlined
in this document. This includes DMAS with an electrospray (DMAS-ES) for analysis of suspensions.
The ranges are different for different types of materials. The technical notes given in Table 2 provide
a general description on how the estimated values for various techniques were obtained. For the
measurement of aerosol samples using CPC or DMAS, the concentration range for the CPC or DMAS is
detailed in 7.4.2.
Table 2 — Technical notes on the calculation of Figure 1
Techniques Technical notes
The data was obtained from unpublished experimental work on gold nanoparticles and inferred
DCS
for the other materials and sizes based on mass equivalence considerations.
[2]
MDLS The data are based on literature values .
[1],[3]
PTA The data are based on literature values .
RPS The data are based on unpublished experimental work using typical TRPS measurement parameters.
The data are based on experimental measurements. The size range depends on the available
q-range and thus the used instrument. For high density particles like gold, large particles will tend
SAXS to sediment and would need a constant flow-through or a vertical setup for accurate measurement.
For low density particles like polystyrene, the concentration determination can be facilitated by
increasing the contrast between particles and suspending medium, e.g. by dilution 1:5 in ethanol.
[4],[5],[6]
The data are based on the literature values. The stated diamet
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