ISO 26824:2013

Particle characterization of particulate systems - Vocabulary

ISO 26824:2013 establishes a vocabulary of terms and definitions relevant to the particle characterization of particulate systems. It covers such fields as the representation of results of particle size analysis, the descriptive and quantitative representation of particle shape and morphology, sample preparation, specific surface area and porosity characterization and measurement methods including sedimentation, classification, acoustic methods, laser diffraction, dynamic light scattering, single particle light interaction methods, differential electrical mobility analysis and image analysis, in a size scale from nanometre to millimetre.

Caractérisation des particules dans les systèmes particulaires — Vocabulaire

General Information

• Status: Withdrawn
• Publication Date: 14-Jul-2013
• ICS: 01.040.19 - Testing (Vocabularies)
• ICS: 19.120 - Particle size analysis. Sieving
• Technical Committee: ISO/TC 24/SC 4 - Particle characterization
• Drafting Committee: ISO/TC 24/SC 4/WG 1 - Representation of analysis data
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 08-Aug-2022
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 26824:2022 - Particle characterization of particulate systems - Vocabulary
• Effective Date: 23-Apr-2020

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 26824
First edition
2013-07-15
Particle characterization of particulate
systems — Vocabulary
Caractérisation des particules dans les systèmes particulaires —
Vocabulaire
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
Scope. 1
1 General terms, representation of particle size and classification analysis .1
2 Sedimentation analysis . 5
3 Pore size distribution, porosity and surface area analysis . 6
4 Representation of particle shape analysis .11
5 Electrical sensing methods .13
6 Laser diffraction methods .14
7 Dynamic light scattering .17
8 Image analysis methods .18
9 Single particle light interaction methods .21
10 Small angle X-Ray scattering method .22
11 Sample preparation and reference materials .23
12 Electrical mobility and number concentration analysis for aerosol particles .24
13 Electrical charge conditioning .27
14 Acoustic methods .28
15 Focused beam methods .31
16 Characterization of particle dispersion in liquids .31
17 Methods for zeta potential determination .33
17.2 Electrokinetic phenomena .35
17.3 Electroacoustic phenomena .36
Annex A (informative) Alphabetical index .39
Bibliography .49
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 documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2. 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 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. 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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL:  http://www.iso.org/iso/home/standards_development/
resources-for-technical-work/foreword.htm
The committee responsible for this document is ISO/TC 24, Particle characterization including sieving,
Subcommittee SC 4, Particle characterization.
iv © ISO 2013 – All rights reserved

Introduction
Since 1995, some 20 International Standards have been published by ISO/TC 24/SC 4, and at the time of
publication of this International Standard, about 12 projects were under development, not to mention
revisions of existing standards. Therefore it was not before time that terms defined in standards that
were relevant for others be collected and adjusted into a single, uniform vocabulary.
In particular, the interdisciplinary application fields of particle and particulate systems characterization
— from mining and construction, the pharmaceutical and food industries, medicine and life sciences, the
chemical industry, microelectronics and nanotechnology — need clear and unambiguous terminology.
The development of international trade, not only in measurement devices for particle characterization,
but also of process equipment for the production and treatment of particulate systems, underlines the
need for comparability of quality and performance parameters, as well as in international health, safety
and environmental protection regulations.
The structuring and presentation rules applied to the terminological entries, based on a clause structure,
represents the methods of results presentation and the analysis methods, and starts with general terms
in each clause.
INTERNATIONAL STANDARD ISO 26824:2013(E)
Particle characterization of particulate systems —
Vocabulary
Scope
This International Standard establishes a vocabulary of terms and definitions relevant to the particle
characterization of particulate systems. It covers such fields as the representation of results of particle
size analysis, the descriptive and quantitative representation of particle shape and morphology, sample
preparation, specific surface area and porosity characterization and measurement methods including
sedimentation, classification, acoustic methods, laser diffraction, dynamic light scattering, single
particle light interaction methods, differential electrical mobility analysis and image analysis, in a size
scale from nanometre to millimetre.
1 General terms, representation of particle size and classification analysis
1.1
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 14644-6:2007, 2.102, modified — The subject field “” has been removed and the
notes added.]
1.2
agglomerate
collection of weakly or medium strongly bound particles 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.
[SOURCE: ISO/TS 27687:2008, 3.2, modified.]
1.3
aggregate
particle 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 bonds, or those
resulting from sintering or complex physical entanglement, or otherwise combined former primary particles.
Note 2 to entry: Aggregates are also termed secondary particles and the original source particles are termed
primary particles.
[SOURCE: ISO/TS 27687:2008, 3.3, modified.]
1.4
primary particle
original source particle of agglomerates or aggregates 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.
1.5
particle size
x
d
linear dimension of a particle determined by a specified measurement method and under specified
measurement conditions
Note 1 to entry: Different methods of analysis are based on the measurement of different physical properties.
Independent of the particle property actually measured, the particle size is reported as a linear dimension, e.g. as
the equivalent spherical diameter.
Note 2 to entry: Examples of size descriptors are those based at the opening of a sieve or a statistical diameter, e.g.
the Feret diameter, measured by image analysis.
Note 3 to entry: In ISO 9276-1:1998, the symbol x is used to denote the particle size. However, it is recognized that
the symbol d is also widely used to designate these values. Therefore the symbol x may be replaced by d.
[SOURCE: ISO 9276-1:1998, 4.2, modified.]
1.6
equivalent spherical diameter
x
d
diameter of a sphere having the same physical properties as the particle in the measurement
Note 1 to entry: Physical properties are for instance the same settling velocity or electrolyte solution displacing
volume or projection area under a microscope.
Note 2 to entry: The physical property to which the equivalent diameter refers shall be indicated using a suitable
subscript, for example x for equivalent surface area diameter or x for equivalent volume diameter.
S V
[SOURCE: ISO 9276-1:1998, 4.2, modified.]
1.7
type of quantity
r
specification of the quantity of a distribution, a cumulative or a density measure
Note 1 to entry: The type is indicated by the general subscript, r, or by the appropriate value of r as follows:

— number: r = 0
— length: r = 1
— area: r = 2
— volume or mass: r = 3
[SOURCE: ISO 9276-1:1998, 4.3, modified.]
2 © ISO 2013 – All rights reserved

1.8
cumulative distribution
Q (x)
r
distribution of the fraction of material smaller (undersize) than given particle sizes
Note 1 to entry: If the cumulative distribution, Q (x), is calculated from histogram data, only individual points
r
Q = Q (x ) are obtained. Each individual point of the distribution, Q (x ), defines the relative amount of particles
r,i r i r i
smaller than or equal to x . The continuous curve is calculated by suitable interpolation algorithms. The normalized
i
cumulative distribution extends between 0 and 1, i.e. 0 and 100 %.
i i
QQ==Δ qxΔ with 1≤≤vi≤n
r,iv∑∑r, r,v v
v==11v
where
i (subscript) number of the size class with upper limit x
i
ν (integer, see subscript i)
n total number of size classes
Q relative amount of particles in size class with upper limit x
r,ν ν
Note 2 to entry: When plotted on a graph paper with a logarithmic abscissa the cumulative values, Q , i.e. the
r,i
ordinates of a cumulative distribution, do not change. However, the course of the cumulative distribution curve
changes but the relative amounts smaller than a certain particle size remain the same. Therefore, the following
formula holds:
Qx =QxIn
() ()
rr
Note 3 to entry: The cumulative oversize distribution is given by 1 − Q (x).
r
[SOURCE: ISO 9276-1:1998, 5.2, modified.]
1.9
distribution density
q (x)
r
distribution of the fraction of material in a size class, divided by the width of that class
Note 1 to entry: Under the presupposition that the cumulative distribution, Q (x), is differentiable, the continuous
r
distribution density, q (x), is obtained from
r
dQ ()x
r
qx()=
r
dx
Conversely, the cumulative distribution, Q (x), is obtained from the distribution density, q (x), by integration:
r r
x
i
Qx()= qx()dx
ri r
∫
x
min
Note 2 to entry: Differential distribution is also named in statistics “density of a probability or frequency”.
Note 3 to entry: The term “density distribution” can be misunderstood in the context of sedimentation methods
with different materials and will be not used in standards developed by ISO/TC24/SC 4.
[SOURCE: ISO 9276-1:1998, 5.3, modified — Notes 2 and 3 have been added.]
1.10
distribution density on a logarithmic abscissa
*
qx
()
r
distribution density, transformed for a logarithmic abscissa
**
Note 1 to entry: The density values of a histogram, qq= ()xx,, shall be recalculated using the following
r,ir ii−1
formula which indicates that the corresponding areas underneath the distribution density curve remain constant.
In particular, the total area is equal to 1 or 100 %, independent of any transformation of the abscissa.
∗
qq(,ξξ )(ΔΔξ = xx,) x
ri−−1 ii r i1 ii
where ξ is any function of x.
Thus the following transformation shall be carried out to obtain the distribution density with a logarithmic abscissa:
qxΔ ΔQ
qx(,xx)Δ
∗ * r,ii r,i
ri−1i i
qx()=⋅qx or qx(,In Inx )= = =
ri r,ii ri−1i
Inxx−In In(xx )(In xx )
ii−−1 ii 11 ii−1
Note 2 to entry: This formula also holds if the natural logarithm is replaced by the logarithm to base 10.
[SOURCE: ISO 9276-1:1998, 6.2, modified.]
1.11
histogram
qx()
r
normalized histogram, qx , of a distribution density (1.9), q (x), comprising a successive series of
() r
r
rectangular columns, the area of each of which represents the relative quantity ΔQ (x), where
r,i
ΔQ
ΔQx(,x )
r,i
ri−1i
ΔΔQQ==(,xx )(qx ,xx)Δ or qq==(,xx ) =
r,ir ii−−1 i1 i r,i i1− i
r r
Δx Δx
i i
Note 1 to entry: The sum of all the relative quantities, ΔQ forms the area beneath the histogram q (x), normalized
r,l r
to 100 % or 1 (condition of normalization). Therefore, the following formula holds:
n n
ΔΔQq==x 1=100%
r,i i
∑∑ r,i
i==11i
[SOURCE: ISO 9276-1:1998, 5.1, modified.]
1.12
concentration distribution density
distribution of the concentration of material in a size class, divided by the width of that class
Note 1 to entry: In aerosol measurement, e. g. the distribution density of the particle number concentration, is
represented as a function of the particle size.
Note 2 to entry: The concentration distribution density can be calculated from the distribution density function
of the particle size by multiplication with the overall sizes measured concentration.
1.13
analytical cut size
x
a
cut size with the coarse and the fine material containing equal quantities of misplaced material
Note 1 to entry: Since the relative mass of the fine material as determined by the classification process, is taken
to be equal to the relative mass of the undersize material in the feed, that is Q (x), an analytical cut size x
3,s
corresponding to this definition has to be found.
4 © ISO 2013 – All rights reserved

[SOURCE: ISO 9276-4:2001, 4.3.2, modified.]
1.14
equiprobable cut size
x
e
cut size, which represents the median of the grade efficiency curve T(x ) = 0,5
e
Note 1 to entry: The weighted distribution density curves of the fine and the coarse fraction intersect at the
equiprobable cut size x . Independently from other particle sizes, particles of this size have the equal probability
e
to be classified into the fine and into the coarse fraction.
[SOURCE: ISO 9276-4:2001, 4.3.1, modified.]
1.15
grade efficiency
Tromp’s curve
T(x)
representation, for a certain particle size x, of the ratio of the amount of material present in the coarse
material to the amount of the same size initially present in the feed material
Note 1 to entry: In the dust collection field, this efficiency is called “partial separation efficiency”.
[SOURCE: ISO 9276-4:2001, 4.4, modified — The note has been added.]
2 Sedimentation analysis
2.1
effective particle density
particle mass divided by the volume of liquid it displaces
[SOURCE: ISO 13317-1:2001, 3.1.7, modified.]
2.2
true particle density
particle mass divided by the volume it would occupy excluding all pores, closed or open, and surface fissures
Note 1 to entry: True particle density is sometimes referred to as the absolute particle density.
[SOURCE: ISO 13317-1:2001, 3.1.8.]
2.3
oversize
portion of the charge which has not passed through the apertures of a stated sieve
[SOURCE: ISO 13317-1:2001, 3.1.5.]
2.4
pycnometry
method wherein particle density is obtained from the measured mass of sample with a given
calibrated volume
2.5
Stokes diameter
equivalent spherical diameter of the particle that has the same density and terminal settling velocity as
the real particle in the same liquid under creeping flow conditions
[SOURCE: ISO 13317-1:2001, 3.1.2.]
2.6
terminal settling velocity
velocity of a particle through a still liquid at which the force due to gravity on the particle is balanced
by the drag exerted by the liquid
[SOURCE: ISO 13317-1:2001, 3.1.1.]
2.7
undersize
portion of the charge which has passed through the apertures of a stated sieve
[SOURCE: ISO 13317-1:2001, 3.1.6.]
3 Pore size distribution, porosity and surface area analysis
3.1
molecular cross-sectional area
molecular area of the adsorbate, i.e. the area occupied by an adsorbate molecule in the complete monolayer
[SOURCE: ISO 9277:2010, 3.10.]
3.2
free space
volume of the sample holder not occupied by the sample
Note 1 to entry: Also called head space, dead space, or dead volume.
[SOURCE: ISO 9277:2010, 3.14.]
3.3
specific surface area
absolute surface area of the sample divided by sample mass
[SOURCE: ISO 9277:2010, 3.15.]
3.4
apparent density
mass of a powder divided by the total volume of the sample, including closed and inaccessible pores, as
determined by the stated method
[SOURCE: ISO 15901-1:2005, 3.23.]
3.5
bulk density
powder density under defined conditions
[SOURCE: ISO 15901-1:2005, 3.1.]
3.6
blind pore
dead end pore
open pore having a single connection with an external surface
[SOURCE: ISO 15901-2:2006, 3.6.]
3.7
closed pore
cavity not connected to the external surface
[SOURCE: ISO 15901-1:2005, 3.3.]
6 © ISO 2013 – All rights reserved

3.8
contact angle
angle that a non-wetting liquid makes with a solid material
[SOURCE: ISO 15901-1:2005, 4.4.]
3.9
external surface area
area of external surface including roughness but outside pores
[SOURCE: ISO 15901-1:2005, 3.5.]
3.10
ink bottle pore
narrow necked open pore
[SOURCE: ISO 15901-1:2005, 3.3.]
3.11
interconnected pore
pore which communicates with one or more other pores
[SOURCE: ISO 15901-1:2005, 3.7.]
3.12
internal surface area
area of internal pore walls
[SOURCE: ISO 15901-1:2005, 3.8.]
3.13
intraparticle porosity
ratio of the volume of open pores internal to the particle to the total volume occupied by the solid
[SOURCE: ISO 15901-1:2005, 3.9.]
3.14
interparticle porosity
ratio of the volume of space between particles in a powder to the apparent volume of the particles or powder
[SOURCE: ISO 15901-1:2005, 3.10.]
3.15
macropore
pore of internal width greater than 50 nm
[SOURCE: ISO 15901-1:2005, 3.11.]
3.16
mesopore
pore of internal width between 2 nm and 50 nm
[SOURCE: ISO 15901-1:2005, 3.12.]
3.17
micropore
pore of internal width less than 2 nm which is accessible for a molecule to be adsorbed
[SOURCE: ISO 15901-1:2005, 3.13.]
3.18
open pore
cavity or channel with access to an external surface
[SOURCE: ISO 15901-1:2005, 3.14.]
3.19
open porosity
ratio of the volume of open pores and voids to the total volume occupied by the solid
[SOURCE: ISO 15901-1:2005, 3.15.]
3.20
pore size
pore width, for example, the diameter of a cylindrical pore or the distance between the opposite walls of a slit
Note 1 to entry: One of the methods to determine pore sizes is by mercury porosimetry.
[SOURCE: ISO 15901-1:2005, 3.16.]
3.21
pore volume
volume of pores determined by stated method
[SOURCE: ISO 15901-1:2005, 3.17.]
3.22
porosimeter
instrument for measuring porosity and pore size distribution
[SOURCE: ISO 15901-1:2005, 3.18.]
3.23
porosimetry
methods for the estimation of porosity and pore size distribution
[SOURCE: ISO 15901-1:2005, 3.19.]
3.24
porosity
ratio of total pore volume to apparent volume of particle or powder
[SOURCE: ISO 15901-1:2005, 3.20.]
3.25
porous solid
solid with cavities or channels which are deeper than they are wide
[SOURCE: ISO 15901-1:2005, 3.21.]
3.26
powder density
mass of a powder divided by its apparent volume, which is taken to be the total volume of the solid
material, open and closed pores and interstices
[SOURCE: ISO 15901-1:2005, 3.24.]
3.27
skeleton density
mass of a powder divided by the total volume of the sample, including closed pores but excluding open pores
[SOURCE: ISO 15901-1:2005, 3.22.]
8 © ISO 2013 – All rights reserved

3.28
surface area
extent of available surface area as determined by given method under stated conditions
[SOURCE: ISO 15901-1:2005, 3.25.]
3.29
surface tension
force required to separate a film of liquid from either a solid material or a film of the same liquid
[SOURCE: ISO 15901-1:2005, 3.26.]
3.30
through pore
pore which passes all the way through the sample
[SOURCE: ISO 15901-1:2005, 3.27.]
3.31
total porosity
ratio of the volume of void plus the volume of open and closed pores to the total volume occupied by the
solid and the volume of void plus pores, e.g. apparent solid volume
[SOURCE: ISO 15901-1:2005, 3.28.]
3.32
true density
mass of the particle divided by its volume, excluding open and closed pores
[SOURCE: ISO 15901-1:2005, 3.29.]
3.33
void
space between particles, i.e. an interparticle pore
[SOURCE: ISO 15901-1:2005, 3.30.]
3.34
adsorbate
adsorbed gas
[SOURCE: ISO 15901-2:2006, 3.1.]
3.35
amount adsorbed
na
number of moles of gas adsorbed at a given pressure p and temperature T[SOURCE: ISO 15901-2:2006, 3.2.]
3.36
adsorbent
solid material on which adsorption occurs
[SOURCE: ISO 15901-2:2006, 3.3.]
3.37
adsorption
enrichment of the adsorptive gas at the external and accessible internal surfaces of a solid material
[SOURCE: ISO 15901-2:2006, 3.4.]
3.38
adsorptive
gas or vapour to be adsorbed
[SOURCE: ISO 15901-2:2006, 3.5.]
3.39
equilibrium adsorption pressure
p
pressure of the adsorptive gas in equilibrium with the adsorbate
[SOURCE: ISO 15901-2:2006, 3.7.]
3.40
adsorption isotherm
relationship between the amount of gas adsorbed and the equilibrium pressure of the gas, at
constant temperature
[SOURCE: ISO 15901-3:2007, 3.5.]
3.41
monolayer amount
n’m
number of moles of the adsorbate that form a monomolecular layer over the surface of the adsorbent
[SOURCE: ISO 15901-2:2006, 3.14.]
3.42
monolayer capacity
Vm
volumetric equivalent of monolayer amount expressed as gas at standard conditions of temperature and
pressure (STP)
[SOURCE: ISO 15901-2:2006, 3.15.]
3.43
relative pressure
ratio of the equilibrium adsorption pressure, p, to the saturation vapour pressure, p [SOURCE:
ISO 15901-2:2006, 3.18.]
3.44
right cylindrical pore
cylindrical pore perpendicular to the surface
[SOURCE: ISO 15901-2:2006, 3.19.]
3.45
saturation vapour pressure
vapour pressure of the bulk liquefied adsorptive gas at the temperature of adsorption
[SOURCE: ISO 15901-2:2006, 3.20.]
3.46
volume adsorbed
volumetric equivalent of adsorbed amount expressed as gas at standard conditions of temperature and
pressure (STP)
[SOURCE: ISO 15901-2:2006, 3.22.]
10 © ISO 2013 – All rights reserved

3.47
physisorption
weak bonding of the adsorbate, reversible by small changes in pressure or temperature
[SOURCE: ISO 15901-3:2007, 3.13.]
4 Representation of particle shape analysis
4.1
particle shape
external geometric form of a particle
Note 1 to entry: Macroshape is a description of the overall form of a particle defined in terms of the geometrical
proportions of the particle. In general, simple geometrical descriptors calculated from size measurements made
on the particle silhouette are used.
Note 2 to entry: Mesoshape description provides information about details of the particle shape and/or surface
structure that are in a size range not much smaller than the particle proportions.
Note 3 to entry: Microshape determines the roughness of shape boundaries using fractal dimension or higher-
order Fourier coefficients for surface-textural analysis.
[SOURCE: ISO 3252:1999, 1401.]
4.2
Legendre ellipse of inertia
ellipse with its centre at the particle’s centroid and with the same geometrical moments of inertia, up to
the second order, as the original particle area
Note 1 to entry: The ellipse can be characterized by its major and minor diameters, the position of its centre of
gravity and its orientation.
Note 2 to entry: Macroshape descriptor, geometrical descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.2, modified.]
4.3
geodesic length and thickness
x and x
LG E
approximations for very long and concave particles, such as fibres, calculated from the projection area
A and perimeter P:
Ax=⋅x Px=+2( x )
ELG ELG
Note 1 to entry: Macroshape descriptor, geometrical descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.2, modified.]
4.4
ellipse ratio
ratio of the lengths of the axes of the Legendre ellipse of inertia )
Note 1 to entry: Macroshape descriptor, proportion descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.5
aspect ratio
ratio of the minimum to the maximum Feret diameter
Note 1 to entry: For not very elongated particles.
Note 2 to entry: Macroshape descriptor, proportion descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.6
elongation
ratio of the geodesic thickness to the geodesic length
Note 1 to entry: For very elongated particles, such as fibres.
Note 2 to entry: Macroshape descriptor, proportion descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.7
straightness
ratio of the maximum Feret diameter (8.6) to the geodesic length
Note 1 to entry: For very elongated particles (reciprocal of curl).
Note 2 to entry: Macroshape descriptor, proportion descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.8
irregularity
ratio of the diameter of the maximum inscribed circle d and that of the minimum circumscribed
imax
circle d
cmin
Note 1 to entry: Macroshape descriptor, proportion descriptor, (modification ratio).
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.9
compactness
degree to which the projection area A of the particle is similar to a circle, considering the overall form of
the particle with the maximum Feret diameter x :
Fmax
(/4A π
compactness=
x
Fmax
Note 1 to entry: Macroshape descriptor, proportion descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.10
box ratio
ratio of the Feret box area to the projected area A
Note 1 to entry: Macroshape descriptor, proportion descriptor.
[SOURCE: ISO 9276-6:2008, 8.1.3, modified.]
4.11
sphericity
Ψ
square of the ratio of the volume equivalent diameter x to the surface equivalent diameter x
v s
Ψ ==(/xx )/π⋅xS
VS V
Note 1 to entry: Wadell’s sphericity, Ψ, also derived from surface area, S.
12 © ISO 2013 – All rights reserved

Note 2 to entry: Mesoshape descriptor.
[SOURCE: ISO 9276-6:2008, 8.2, modified.]
4.12
circularity
C
degree to which the projection area of the particle A is similar to a circle, considering the smoothness of
the perimeter P:
4πA x
A
C ==
x
p
P
Note 1 to entry: Mesoshape descriptor, also derived from the area equivalent diameter x to the perimeter
A
equivalent diameter x .
P
[SOURCE: ISO 9276-6:2008, 8.2, modified.]
4.13
solidity
ratio of the projected area A to the area of the convex hull A (envelope)
C
Solidity= AA/
C
Note 1 to entry: Measure of the overall concavity of a particle.
Note 2 to entry: Mesoshape descriptor.
[SOURCE: ISO 9276-6:2008, 8.2, modified.]
5 Electrical sensing methods
5.1
dead time
time during which the electronics are not able to detect particles due to the signal processing of a
previous pulse
[SOURCE: ISO 13319:2007, 3.1.]
5.2
aperture
small-diameter hole through which suspension is drawn
[SOURCE: ISO 13319:2007, 3.2.]
5.3
sampling volume
volume of suspension that is analysed
[SOURCE: ISO 13319:2007, 3.3.]
5.4
sensing zone
volume of electrolyte solution within, and around, the aperture in which a particle is detected
[SOURCE: ISO 13319:2007, 3.3.]
5.5
channel
size interval
[SOURCE: ISO 13319:2007, 3.4.]
5.6
envelope size
external size of a particle as seen in a microscope
[SOURCE: ISO 13319:2007, 3.5.]
5.7
envelope volume
volume of the envelope given by the three-dimensional boundary of the particle to the surrounding medium
[SOURCE: ISO 13319:2007, 3.6.]
6 Laser diffraction methods
6.1
light absorption
reduction of intensity of a light beam not due to scattering
[SOURCE: ISO 13320:2009, definition 3.1.1.]
6.2
coefficient of variation
CV
standard deviation divided by the mean
Note 1 to entry: The coefficient of variation is commonly reported as a percentage.
[SOURCE: ISO 3534-1:2006, 2.38.]
6.3
complex refractive index
refractive index of a particle, consisting of a real and an imaginary (absorption) part
Note 1 to entry: The complex refractive index of a particle can be expressed mathematically as
nn=−ik
p pp
where
i is the square root of –1;
k is the positive imaginary (absorption) part of the refractive index of a particle;
p
n is the positive real part of the refractive index of a particle.
p
Note 2 to entry: In contrast to ISO 80000-7:2008, item 7–5, this International Standard follows the convention of
adding a minus sign to the imaginary part of the refractive index.
[SOURCE: ISO 13320:2009, 3.1.3.]
14 © ISO 2013 – All rights reserved

6.4
relative refractive index
m
rel
ratio of the complex refractive index of a particle to the real part of the dispersion medium
Note 1 to entry: Adapted from ISO 24235:2007.
Note 2 to entry: In most applications, the medium is transparent and, thus, its refractive index has a negligible
imaginary part.
Note 3 to entry: The relative refractive index can be expressed mathematically as
mn= /n
rel p m
where
n is the real part of the refractive index of the medium;
m
n
is the complex refractive index of a particle.
p
[SOURCE: ISO 13320:2009, 3.1.4.]
6.5
deconvolution
mathematical procedure whereby the size distribution of an ensemble of particles is inferred from
measurements of their scattering pattern
[SOURCE: ISO 13320:2009, 3.1.5.]
6.6
diffraction
scattering of light around the contour of a particle, observed at a substantial distance (in the ‘far field’)
[SOURCE: ISO 13320:2009, 3.1.6.]
6.7
light extinction
attenuation of a light beam traversing a medium through absorption and scattering
[SOURCE: ISO 13320:2009, 3.1.7.]
6.8
model matrix
matrix containing vectors of the scattered light signals for unit volumes of different size classes, scaled
to the detector’s geometry, as derived from model computation
[SOURCE: ISO 13320:2009, 3.1.8.]
6.9
multiple scattering
consecutive scattering of light by more than one particle, causing a scattering pattern that is no longer
the sum of the patterns from all individual particles
Note 1 to entry: See single scattering (6.20).
[SOURCE: ISO 13320:2009, 3.1.9.]
6.10
obscuration
optical concentration
fraction of incident light that is attenuated due to extinction (scattering and/or absorption) by particles
Note 1 to entry: Adapted from ISO 8130-14:2004, 2.21.
Note 2 to entry: Obscuration can be expressed as a percentage.
Note 3 to entry: When expressed as fractions, obscuration plus transmission equal unity.
[SOURCE: ISO 13320:2009, 3.1.10.]
6.11
optical model
theoretical model used for computing the model matrix for optically homogeneous and isotropic spheres
with, if necessary, a specified complex refractive index
EXAMPLE Fraunhofer diffraction model, Mie scattering model.
[SOURCE: ISO 13320:2009, 3.1.11.]
6.12
light reflection
change of direction of a light wave at a surface without a change in wavelength or frequency
[SOURCE: ISO 13320:2009, 3.1.12.]
6.13
refraction
process by which the direction of a radiation is changed as a result of changes in its velocity of propagation in
passing through an optically non-homogeneous medium, or in crossing a surface separating different media
Note 1 to entry: The process occurs in accordance with Snell’s law: n sinθ = n sinθ
m m p p
[SOURCE: IEC 60050-845:1987.]
6.14
repeatability
closeness of agreement between multiple measurement results of a given property in the
same dispersed sample aliquot, executed by the same operator in the same instrument under identical
conditions within a short period of time
Note 1 to entry: This type of repeatability does not include variability due to sampling and dispersion.
[SOURCE: ISO 13320:2009, 3.1.14.]
6.15
repeatability
closeness of agreement between multiple measurement results of a given property in different
aliquots of a sample, executed by the same operator in the same instrument under identical conditions
within a short period of time
Note 1 to entry: This type of repeatability includes variability due to sampling and dispersion.
[SOURCE: ISO 13320:2009, 3.1.15.]
16 © ISO 2013 – All rights reserved

6.16
reproducibility
closeness of agreement between multiple measurement results of a given property in different
aliquots of a sample, prepared and executed by different operators in similar instruments according to
the same method
[SOURCE: ISO 13320:2009, 3.1.16.]
6.17
light scattering
change in propagation of light at the interface of two media having different optical properties
[SOURCE: ISO 13320:2009, 3.1.17.]
6.18
scattering angle
angle between the principal axis of the incident light beam and the scattered light
[SOURCE: ISO 13320:2009, 3.1.18.]
6.19
scattering pattern
angular pattern of light intensity, I(θ), or spatial pattern of light intensity, I(r), originating from
scattering, or the related energy values taking into account the sensitivity and the geometry of the
detector elements
[SOURCE: ISO 13320:2009, 3.1.19.]
6.20
single scattering
scattering whereby the contribution of a single member of a particle population to the total scattering
pattern remains independent of the other members of the population
[SOURCE: ISO 13320:2009, 3.1.20.]
6.21
single shot analysis
analysis, for which the entire content of a sample container is used
[SOURCE: ISO 13320:2009, 3.1.21.]
6.22
light transmission
fraction of incident light that remains unattenuated by the particles
Note 1 to entry: Transmission can be expressed as a percentage.
Note 2 to entry: When expressed as fractions, obscuration (6.10) plus transmission equal unity.
[SOURCE: ISO 13320:2009, 3.1.22.]
7 Dynamic light scattering
7.1
average particle diameter
x
DLS
harmonic intensity-weighted arithmetic average particle diameter
Note 1 to entry: Average particle diameter is expressed in nanometres. Typical average particle diameters are in
the range 1 nm to about 1 000 nm.
Note 2 to entry: In ISO 13321:1996, the symbol x is used.
PCS
[SOURCE: ISO 22412:2008, 3.1, modified — Note 2 has been added.]
7.2
polydispersity index
PI
dimensionless measure of the broadness of the size distribution
Note 1 to entry: Adapted from ISO 13321:1996, 2.2.
Note 2 to entry: The PI typically has values less than 0,1 for a monodisperse test sample.
[SOURCE: ISO 22412:2008, 3.2.]
7.3
qualification
proof with reference material that an instrument is operating in agreement with its specifications
[SOURCE: ISO 22412:2008, 3.5.]
7.4
scattering volume
V
section of the incident laser beam viewed by the detector optics
Note 1 to entry: Adapted from ISO 13321:1996, 2.3.
[SOURCE: ISO 22412:2008, 3.3.]
7.5
scattered intensity
count rate
photocurrent
I
s
intensity of the light scattered by the particles in the scattering volume; in practice, a number of photon
pulses per unit time or a photodetector current which is proportional to the scattered intensity as
measured by a detector
[SOURCE: ISO 22412:2008, 3.4.]
7.6
validation
proof with reference material that a procedure is acceptable for all elements of its scope
[SOURCE: ISO 22412:2008, 3.6.]
8 Image analysis methods
8.1
binary image
digitized image consisting of an array of pixels, each of which has a value of 0 or 1, whose values are
normally represented by dark and bright regions on the display screen or by the use of two distinct colours
[SOURCE: ISO 13322-1:2004, 3.1.3.]
8.2
connectivity
logical criteria for the connection of a pixel to neighbouring pixels
Note 1 to entry: For rectangular pixels, two neighbouring pixels share the same side, in which case it is called
4-connectivity. If they share the same corner, it is called 8-connectivity.
18 © ISO 2013 – All rights reserved

8.3
edge finding
one of many edge detection methods used to detect transition between objects and background
[SOURCE: ISO 13322-1:2004, 3.1.4.]
8.4
equivalent circular diameter
ecd
diameter of a circle having the same area as the projected image of the particle
Note 1 to entry: It is also known as the Haywood diameter.
[SOURCE: ISO 13322-1:2004, 3.1.7.]
8.5
Euler number
number of objects minus the number of holes inside the objects, which describes the connectedness of
a region, not its shape
Note 1 to entry: A connected region is one in which all pairs of points may be connected by a curve lying entirely in
the region. If a complex two-dimensional object is considered to be a set of connected regions, where each one can
have holes, the Euler number for such an object is defined as; (number of connected regions) - (number of holes).
The number of holes is one less than the connected regions in the set compliment of the object. Euler number
should be reported together with the connectivity applied, i.e. 4-conenctivity or 8-connectivity.
[SOURCE: ISO 13322-1:2004, 3.1.5.]
8.6
Feret diameter
distance between two parallel tangents on opposite sides of the image of a particle
Note 1 to entry: Maximum diameter x corresponding to the “length” of the particle and minimum diameter
Fmax
x corresponding to the “breadth” of the particle.
Fmin
[SOURCE: ISO 13322-1:2004, 3.1.6.]
8.7
grey image
image in which multiple grey level values are permitted for each pixel
[SOURCE: ISO 13322-1:2004, 3.1.8.]
8.8
image analysis
processing and data reduction operation which yields a numerical or logical result from an image
[SOURCE: ISO 13322-1:2004, 3.1.9.]
8.9
measurement frame
field in a view field in which particles are counted for image analysis
Note 1 to entry: The set of measurement frames composes the total measurement field.
[SOURCE: ISO 13322-1:2004, 3.1.2.]
8.10
numerical aperture
NA
product of the refractive index of the object space and the sine of the semi-aperture of the cone of rays
entering the entrance pupil of the objective lens from the object point
[SOURCE: ISO 13322-1:2004, 3.1.10.]
8.11
pixel
picture element
individual sample in a digital image that has been formed by uniform sampling in both the horizontal
and vertical directions
[SOURCE: ISO 13322-1:2004, 3.1.11.]
8.12
raster pattern
scanning order of measurement frames in the total measurement field
8.13
segmentation
part into which something can be divided; subdivision or section
[SOURCE: ISO 13322-1:2004, 3.1.12.]
8.14
threshold
grey level value which is set to discriminate objects of interest from background
[SOURCE: ISO 13322-1:2004, 3.1.14.]
8.15
view field
field which is viewed by a viewing device, e.g. optical microscope or electron scanning microscope
[SOURCE: ISO 13322-1:2004, 3.1.1.]
8.16
depth of field
region where the sharpness of the edges of the images reaches the pre-set optimum
[SOURCE: ISO 13322-2:2006, 3.1.6.]
8.17
flow-cell
measurement cell inside which the fluid-particle mixture flows
[SOURCE: ISO 13322-2:2006, 3.1.1.]
8.18
image capture device
matrix camera or line camera
[SOURCE: ISO 13322-2:2006, 3.1.7.]
8.19
measurement volume
volume in which particles are measure
...