ASTM E2834-12(2022)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2834 − 12 (Reapproved 2022)
Standard Guide for
Measurement of Particle Size Distribution of Nanomaterials
in Suspension by Nanoparticle Tracking Analysis (NTA)
This standard is issued under the fixed designation E2834; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E2490Guide for Measurement of Particle Size Distribution
of Nanomaterials in Suspension by Photon Correlation
1.1 This guide deals with the measurement of particle size
Spectroscopy (PCS)
distributionofsuspendedparticles,from~10nmtotheonsetof
2.2 ISO Standards:
sedimentation,sampledependent,usingthenanoparticletrack-
ISO 13320Particle Size Analysis—Laser Diffraction Meth-
ing analysis (NTA) technique. It does not provide a complete
ods
measurement methodology for any specific nanomaterial, but
ISO 13321 Particle Size Analysis—Photon Correlation
provides a general overview and guide as to the methodology
Spectroscopy
that should be followed for good practice, along with potential
ISO 14488Particulate Materials—Sampling And Sample
pitfalls.
Splitting for the Determination of Particulate Properties
1.2 The values stated in SI units are to be regarded as
ISO 22412Particle Size Analysis—Dynamic Light Scatter-
standard. No other units of measurement are included in this
ing (DLS)
standard.
3. Terminology
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.1 Definitions:
responsibility of the user of this standard to establish appro-
3.1.1 diffusion coeffıcient, n—a measure to characterize the
priate safety, health, and environmental practices and deter-
rate a particular molecule or particle moves in a particular
mine the applicability of regulatory limitations prior to use.
medium when driven by random thermal agitation (Brownian
1.4 This international standard was developed in accor-
motion).
dance with internationally recognized principles on standard-
3.1.1.1 Discussion—After measurement, the value is to be
ization established in the Decision on Principles for the
inputted into the Stokes-Einstein equation (Eq 1, see
Development of International Standards, Guides and Recom-
7.2.1.2(3)). Diffusion coefficient units in nanoparticle tracking
mendations issued by the World Trade Organization Technical
analysis (NTA) measurements are typically cm /s, rather than
Barriers to Trade (TBT) Committee.
the correct SI units of m /s.
3.1.2 repeatability, n—in NTA and other particle sizing
2. Referenced Documents
techniques, this usually refers to a measure of the precision of
2.1 ASTM Standards:
repeated consecutive measurements on the same group of
C322Practice for Sampling Ceramic Whiteware Clays
particles under identical conditions and is normally expressed
E456Terminology Relating to Quality and Statistics
as a relative standard deviation (RSD) or coefficient of varia-
E1617Practice for Reporting Particle Size Characterization
tion (CV).
Data
3.1.2.1 Discussion—The repeatability value reflects the sta-
bility (instrumental, but mainly the sample) of the system over
time. Changes in the sample could include dispersion, aggre-
gation and settling.
1 3.1.3 reproducibility, n—in NTA and particle sizing this
This guide is under the jurisdiction of ASTM Committee E56 on Nanotech-
nology and is the direct responsibility of Subcommittee E56.02 on Physical and usually refers to a measure of the deviation of the results
Chemical Characterization.
obtained from the first aliquot to that obtained for the second
Current edition approved Sept. 1, 2022. Published October 2022. Originally
and further aliquots of the same bulk sample (and therefore is
approved in 2012. Last previous edition approved in 2018 as E2834 – 12 (2018).
subject to the homogeneity or heterogeneity of the starting
DOI: 10.1520/E2834-12R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2834 − 12 (2022)
material and the sampling method employed). Normally ex- 3.2 Acronyms:
pressed as a relative standard deviation (RSD) or coefficient of 3.2.1 CV—coefficient of variation
variation (CV).
3.2.2 CCD—charge-coupled device
3.1.3.1 Discussion—Inaheterogenousandpolydisperse(for
3.2.3 CMOS—complementary metal–oxide–semiconductor
example, slurry) system, it is often the largest error when
3.2.4 DLS—dynamic light scattering
repeatedsamplesaretaken.Otherdefinitionsofreproducibility
also address the variability among single test results gathered
3.2.5 EMCCD—electron-multiplying charge-coupled de-
from different laboratories when inter-laboratory testing is vice
undertaken, or operator-to-operator, instrument-to-instrument,
3.2.6 NTA—nanoparticle tracking analysis
location-to-location, or even day-to-day. It is to be noted that
3.2.7 PCS—photon correlation spectroscopy
the same group of particles can never be measured in such a
3.2.8 RSD—relative standard deviation
system of tests and therefore reproducibility values may
typically be considerably in excess of repeatability values.
4. Summary of Guide
3.1.4 robustness,n—ameasureofthechangeoftherequired
4.1 Nanoparticle tracking analysis (NTA) is a method for
parameter with deliberate and systematic variations in any or
the direct and real-time visualization and analysis of nanopar-
all of the key parameters that influence it.
ticles in liquids. Particles in suspension are illuminated with a
3.1.4.1 Discussion—For example, dispersion energy input
focused laser beam. Light scattered from each particle is
(that is, ultrasound power and duration) almost certainly will
visible through magnifying optics fitted to a digital camera
affectthereportedresults.VariationinpHislikelytoaffectthe
such as a CCD. The software analyzes the video stream from
degree of agglomeration and so forth. A useful discussion of
thecamera,identifyingandtrackingthemotionofeachparticle
robustness experiment considerations is found in the ICH
with time. Because each particle in the field of view is being
Validation of Analytical Procedures Q2(R1) Guideline (1).
simultaneously but separately tracked and analyzed, the par-
3.1.5 rotational diffusion, n—a process by which the equi-
ticle size distribution profile obtained by NTA is a direct
librium statistical distribution of the overall orientation of
number-based distribution.
molecules or particles is maintained or restored.
4.2 The laser beam is focused such that only particles in the
3.1.6 translational diffusion, n—a process by which the
focal plane of the magnifying optics are illuminated. Particles
equilibrium statistical distribution of molecules or particles in
out of the focal plane are not illuminated and at the size range
space is maintained or restored.
under discussion are not visible to the camera. This yields a
3.1.7 visualization, n—as it relates to the NTA technique,
highsignaltonoiseimage,allowingparticlesassmallas10nm
the particles themselves are not imaged, being below the
to be visualized, depending on sample material. While outside
diffractionlimit.Eachparticleactsasapointscatterer,meaning
the scope of this document, the technique is generally able to
that the imaging system only sees the scattered light from the
measure particles as large as approximately 1 µm.
particle. This allows the position of each particle to be
4.3 Theaveragedistanceeachparticlemovesintheimageis
identified and followed with respect to time. See 7.2.
automatically calculated by the software. From this value, the
3.1.7.1 Discussion—Theintensityandshapeofthescattered
particle diffusion coefficient can be obtained and through the
light pattern for each particle may vary, and some additional
use of the Stokes-Einstein equation, particle size can be
information may be obtained from these differences, at least
determined.
qualitatively, but is outside the scope of this guide.
4.4 This guide discusses the scientific basis for the
3.1.8 percentile, n—a statistical measure of the distribution
technique, size limits, concentration ranges, sampling and
of sizes. The size below which a certain percent of the
sample preparation considerations, condition and analysis
distribution falls. For example, the 10th percentile is the size
selection, data interpretation and comparison to other comple-
below which 10 percent of the particles may be found.
mentary techniques.
Expressed in ISO form as x ,x ,x , and also commonly
10 50 90
expressed as D10, D50, D90. The 50th percentile is the
5. Significance and Use
median.
5.1 NTA is one of the very few techniques that are able to
3.1.9 coeffıcient of variation, n—in statistics, a normalized
deal with the measurement of particle size distribution in the
measureofdispersionofadistribution.Definedasthestandard
nano-size region. This guide describes the NTA technique for
deviation divided by the mean value. (Note: CV = SD/Mean)
direct visualization and measurement of Brownian motion,
3.1.10 relative standard deviation, n—in statistics, the ab- generally applicable in the particle size range from several
solute value of the coefficient of variation, expressed as a nanometers until the onset of sedimentation in the sample.The
percentage. (Note: RSD = 100·SD/Mean) NTAtechniqueisusuallyappliedtodilutesuspensionsofsolid
material in a liquid carrier. It is a first principles method (that
NOTE 1—Other common statistical measures are defined in Terminol-
is,calibrationinthestandardunderstandingofthisword,isnot
ogy E456.
involved). The measurement is hydrodynamically based and
therefore provides size information in the suspending medium
(typically water).Thus the hydrodynamic diameter will almost
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. certainly differ from size diameters determined by other
E2834 − 12 (2022)
techniquesandusersoftheNTAtechniqueneedtobeawareof video data can be examined during and after acquisition. Such
the distinction of the various descriptors of particle diameter examination can provide useful qualitative information about
before making comparisons between techniques (see 8.7). the sample condition, particle concentration, and system op-
Notwithstanding the preceding sentence, the technique is eration. During data acquisition one looks for a consistent
routinely applied in industry and academia as both a research number of particles in the field of view, well-separated
and development tool and as a QC method for the character- particles, a low level of random or background noise, and
ization of submicron systems. particle tracking lengths sufficient for accurate measurements
of each particle. Manufacturers also provide other means of
6. Reagents
assuring the reliability of the data and it is recommended that
these protocols are consulted, as appropriate.
6.1 In general, no reagents specific to the technique are
7.1.2 Given the likelihood that the size standard has been
necessary.However,dispersingandstabilizingagentsoftenare
certified by electron microscopy, care needs to be exercised in
requiredforaspecifictestsampleinordertopreservecolloidal
direct comparison of the results. While electron microscopy is
stability during the measurement.Asuitable diluent is used to
carried out under high-vacuum conditions, NTA performs the
achieve a particle concentration appropriate for the measure-
analysis with particles in suspension. NTA measures the
ment. The apparent hydrodynamic size or diffusion coefficient
diffusion coefficient of the particle and the diameter given by
may undergo change on dilution, as the ionic environment,
the Stokes-Einstein relation (Eq 1) is that of the sphere-
within which the particles are dispersed, changes in nature or
equivalent, hydrodynamic diameter (the particle itself plus the
concentration. This is particularly noticeable when diluting a
molecular-scale layer of solvent associated with the particle
monodisperse latex. A latex that is measured as 60 nm in 1 ×
-3
surface). This solvent layer may be significant relative to the
10 M NaCl can have a hydrodynamic diameter of over 70 nm
-6
size of the standard particles being analyzed, increasing the
in1×10 M NaCl (close to deionized water).
apparentsizeoftheparticles.Forlargerparticles,however,the
6.2 In order to minimize any changes in the system on
effect of this hydrodynamic layer is minimal.
dilution, it is common to use the “mother liquor”. This is the
7.1.3 Note that verification of a system only demonstrates
liquid in which the particles exist in stable form and is usually
that the instrument is performing adequately with the pre-
obtained by centrifuging of the suspension or making up the
scribed standard materials. Practical considerations for real-
same ionic composition of the dispersant liquid if knowledge
world materials (especially “dispersion” if utilized in sample
of these components is available. Many biological materials
preparation or if the distribution is relatively polydisperse)
are measured in a buffer (often phosphate buffered saline),
mean that the method used to measure that real-world material
whichconfersthecorrect(rangeof)conditionsofpHandionic
needs to be carefully evaluated for precision (repeatability).
strength to assure stability of the system. Instability (usually
through inadequate zeta potential—see (2)) can promote ag- 7.2 Measurement:
glomeration leading to settling or sedimentation in a solid-
7.2.1 Introduction:
liquidsystemorcreaminginaliquid-liquidsystem(emulsion).
7.2.1.1 The measurement of particle size distribution in the
Such fundamental changes interfere with the stability of the
nano- (sub 100 nm) region by nanoparticle tracking analysis
suspension and need to be minimized as they affect the quality
depends on the interaction of light with matter and the random
(accuracy and repeatability) of the reported measurements.
orBrownianmotionthataparticleexhibitsinliquidmediumin
These should be investigated in a robustness experiment.
free suspension (3). There must be an inhomogeneity in the
refractive indices of a particle and the medium within which it
7. Procedure
exists in order for light scattering to occur. Without such an
inhomogeneity (for example, in so-called index-matched sys-
7.1 Verification:
tems) there is no scattering and the particle is invisible to light
7.1.1 The instrument to be used in the measurement should
and no measurements can be made by the NTA or any other
be verified for correct performance, within pre-defined quality
technique making use of light scattering. A coating or func-
control limits, by following protocols issued by the instrument
tionalization of the primary particle may affect this refractive
manufacturer. These confirmation tests normally involve the
index sufficiently to impact the light scattering properties.
use of one or more NIST-traceable spherical particle size
-6
While some physical phenomena used by the NTA measure-
standards. In the sub-micron (<1×10 m) region, these
ment technique are in common with the dynamic light scatter-
standards (for example, NIST, Duke Scientific - now part of
ing technique (photon correlation spectroscopy), as defined in
ThermoFisher Scientific) tend to be nearly monodisperse (that
Guide E2490 and ISO 22412, NTA is a distinctly different
is, narrow, single mode distribution, CV < 17%) and, while
technique.
confirming the x (size) axis, do not verify the y (or quantity)
axis of the size distribution. Note that NTAis a first principles 7.2.1.2 For particles <100 nm, as considered in this guide,
measurement and thus calibration in the formal sense (adjust- several facts hold true:
ment of the instrument to read a true and known value) need (1)The amount of scattering is weak in relative terms and
notbeundertaken.Intheeventofa“failure”attheverification depends highly on the size of the particle as well as particle
stage, then the issues to check involve quality of the dilution composition.IntheRayleighapproximationregion(typicallyd
water, state of dispersion and stability of the standard under < λ/10 in which d is the diameter of particle and λ is the
dilution plus instrumental issues such as thermal stability, wavelengthoflightemployed),thenthisintensityofscattering
6 2
cleanliness and alignment of optical components. The raw is proportional to d —or (volume) or (relative molecular
E2834 − 12 (2022)
mass) . With a commonly utilized diode laser (638 nm), then (or both), then the derived diameter is not likely to correspond
the upper size limit of this Rayleigh scattering behavior is to any measured axis of the image of the particle (4). The
approximately 64 nm. This means, in practice, that a 60 nm viscosity refers to the medium in which the particle is
particlescatters1milliontimesasmuchlightasa6nmparticle dispersed. In a dilute system it is assumed that the particles do
of the same composition. Thus, for a sample that contains a not interact, so the viscosity can be assumed to be that of the
widerangeofparticlesizesorincludescontaminatingparticles medium or diluent.
(for example dust) that are often present in the local environ- (5)Note the term diffusion coefficient.There are two types
ment and are usually considerably larger than the material that of diffusion to be considered for particles in free suspension:
requires measurement, caution must be exercised in selecting
(a)Translational, where the so-called Stokes-Einstein
theappropriatemeasurementconditionstoproperlyanalyzeall
relationshipgiveninEq1applies.Rewritingwiththediffusion
particles. NTA is able to measure over a wide range of sizes,
coefficient on the left:
but it may be difficult to find a set of instrument settings to
K T
measure all particles in a single analysis. This would mean
B
D 5 (2)
t
3πηd
filteringliquidsusedtocontainordilutetheparticlestoatleast
H
(b)Rotational, where the Stokes-Einstein-Debye relation
the same level as the size of the particles that require
applies:
characterizing unless the user is conscious of the inclusion of
these particles in the final result. Alternatively, two separate
K T
B
D 5 (3)
analyses may be conducted, with the conditions optimized for r
πηd
H
either the smaller or larger particles, then the results from each
(6) Association of particles (or molecules) leads to
added together. Unless the two populations are totally distinct,
changes in the rotational diffusion coefficient, and also affects
caution must be exercised in interpreting this combined result
the translational diffusion coefficient. Hence, interactions be-
particularly in the region where the two analyses overlap.
tween particles can complicate the interpretation of the ob-
(2)The intensity of scattering in the Rayleigh region is
serveddiffusioncoefficient,whichfornonsphericalparticles,is
inverselyproportionaltothefourthpowerofthewavelengthof
a combination of the translational and rotational diffusion
light employed.Thus, if the wavelength of incident light could
coefficients. These particle-particle interactions tend to be
be halved then the intensity of scattering that would be
concentrationratherthansizedependent,andbothtranslational
observed is increased by a factor of 16. It is possible to use
and rotational diffusion coefficients are dependent on the
lasers of a lower wavelength than 638 nm to increase the
viscosity of the surrounding fluid. For the concentrations
amount of scattering and, hence, signal. This is usually
appropriatetoNTAmeasurements,theparticleconcentrationis
preferable to increasing the power of the laser with possible
generally too dilute for these effects to be significant.
undesired effects (for example, heating, convection currents).
(7)Brownian translational motion occurs in three dimen-
However, note that lower wavelengths sometimes overlap an
sions but NTA observes motion only in two dimensions. It is
absorptionedgeforsomemolecularspeciesleadingtoalossof
possible to determine a diffusion coefficient based on the
signal intensity.The detector is a digital video camera (such as
measurement of one, two or three dimensions (and theoreti-
CCD,higher-sensitivityEMCCD,orCMOS)ofanappropriate
cally up to six if rotation could be measured). By measuring a
frame rate and spectral response to the laser wavelength being
higherorderofD amoreaccurateapproximationcanbemade
r,t
used. Sensitivity of the camera varies with manufacturer and
of the particle size for a given number of steps that contribute
together with the other variables discussed such as laser
towards a track. D is derived from measuring the mean
t
wavelength and power, particle and liquid refractive indices,
squared displacement of a particle in one, two or three
and optical configuration will determine the lower detection
dimensions (Eq 4-6 respectively) (5, 6).
limit of the system.
2TK t
B
(3)The measurement of size in the sub-100 nm region ¯
x 5 (4)
~ !
3πηd
relies on the measurement of the amount of Brownian motion
4TK t
(in particular the diffusion coefficient) of the particle as
B
¯ 2
~x,y! 5 (5)
formulated in the Stokes-Einstein equation: 3πηd
K T 2TK t
B B
¯ 2
x,y,z 5 (6)
d 5 (1) ~ !
H
πηd
3πηD
t
Where t is the time between sequential displacement
Where d is the particle hydrodynamic diameter, K is the
H B
measurements, in this case the frame to frame period.
Boltzmann constant, T is absolute temperature in Kelvin, η
is viscosity in centipoise and D the (measured) translational
t
2 (a)In the case where measurement of movement in two
diffusion coefficient in cm /s.
dimensions is made:
(4)Note that, in Eq 1, the density of the particle plays no
role in Brownian motion (although, of course, it does in 2
¯
~x,y! TK
B
5 D 5 (7)
settling; see Point 9 below), even though this appears to be t
4t 3πηd
counterintuitive. Note also that a hydrodynamic diameter is
and results thus obtained by NTA are shown as a function of
derived. This refers to an equivalent size in spherical terms to particle diameter, d.
that of a particle moving with the same diffusion coefficient as (8) The motion of the particles must be random. Nonran-
the observed particle. Thus, for an irregularly shaped particle dom particle motion is the main reason for apparent failure or
oronewithsignificantexternalmorphologyorsurfacecoatings nonapplicabilityofthetechnique.Suchnonrandommotioncan
E2834 − 12 (2022)
occur through convection currents being present in the system, assumes that the reader has access to a well dispersed liquid
through particles (too large or dense for the technique) settling suspension or preparation of nano-size particles for the mea-
during the measurement sequence, or through particles inter- surement or that the measurement of the agglomerates is of
acting due to chemical reaction or electronic charge.While the interest.
system can measure and compensate for this motion, it is (12) Note from Eq 1 the obvious points that:
preferable to reduce this through accurate temperature mea- (a)As the size of particle increases then the amount of
surement and stabilization where possible. If settling/ Brownian motion decreases.
sedimentation occurs in the measurement, other than to a very (b)As the viscosity of the medium increases then the
minor extent, then the result is almost certainly compromised, amount of Brownian motion decreases.
as it will reflect a changing and unstable system. If visible (c)As the temperature is increased then the amount of
settled solid is present at the bottom of a container, then it is Brownian motion increases correspondingly.
verylikelythattheNTAtechniqueisnotrecommended.Inthis
7.3 Measurement and Analysis of Diffusion Coeffıcient:
case conventional laser light scattering (laser diffraction) is
7.3.1 It is necessary to measure the diffusion coefficient to
likely to be the preferred technique. If settling can be observed
input into Eq 1 in order to derive a particle size. The diffusion
either in the sample container or in the measurement chamber,
coefficient for each particle in the field of view is determined
thenitiscertainthattheoriginalmaterialbeingmeasuredisnot
individually and the resulting sizes are summed to produce the
“nano” or is unstable during the measurement time frame.
final particle size distribution. This section deals with the
(9)With respect to size and density, consider the calcula-
measurement of the diffusion coefficient and the objective of
tions in Table 1 using Stokes’Law:
providing a particle size distribution from the measured data.
(10)It can be deduced from Table 1 that if a material is
7.3.2 In viewing the scattered light from a group of sus-
truly < 100 nm, it tends to remain in suspension and exhibits
pended moving particles over a period of time, each particle
little if any settling tendency. In many situations, for example
moves under Brownian motion. Each particle is identified and
a gel, the particle density is significantly lower due to incor-
trackedforthedurationofitspresenceinthesamplingvolume,
poration of water into the particle matrix and thus the settling
which is defined by the field of view of the camera, the
time increased further.
dimensionsoftheilluminationbeam,andthefocalplaneofthe
(11)Sometimes it is thought that placing the particles in a
magnification optics. The mean squared displacement of each
material of higher viscosity reduces or even eliminates any
particle is directly measured from the video file images.
settling tendency.This is true, but the Brownian motion is also
Dimensions of the displacement (in pixels) are translated into
reduced accordingly and no gain is achieved.
actualdisplacementthroughknowledgeofthemagnificationof
(a)Most dry powder materials are difficult to fully the system and dimensions of each pixel. This should be
disperse back to a primary size and thus size measurements calibrated or verified to improve accuracy of the displacement
from diffusion reflect the state of agglomeration of the system measurement. From the mean squared displacement, the diffu-
rather than to a primary “as produced” size. Hence this guide sion coefficient is calculated and entered into Eq 1.
TABLE 1 Settling Calculations Based on Stokes’ Law as a Function of Size and Density (T = 298K)
-2
η (Water)
Timetosettle1cm(1×10 m) in water
Diameter Diameter ρ (Material) ρ (Water)
298K,
3 3
µm nm kg/m kg/m
Minutes Hours Days
Poise
0.01 10 2500 997 0.008955 1815494.39 30258 1261
0.1 100 2500 997 0.008955 18154.94 302.58 12.61
1 1000 2500 997 0.008955 181.55 3.03 0.126
10 10000 2500 997 0.008955 1.82 0.03 0.001
100 100000 2500 997 0.008955 0.02 0.00 0.000
0.01 10 3500 997 0.008955 1089296.64 18154.94 756
0.1 100 3500 997 0.008955 10892.97 181.55 7.56
1 1000 3500 997 0.008955 108.93 1.82 0.076
10 10000 3500 997 0.008955 1.09 0.02 0.001
100 100000 3500 997 0.008955 0.01 0.00 0.000
0.01 10 4200 997 0.008955 851013.00 14183.55 591
0.1 100 4200 997 0.008955 8510.13 141.84 5.91
1 1000 4200 997 0.008955 85.10 1.42 0.059
10 10000 4200 997 0.008955 0.85 0.01 0.001
100 100000 4200 997 0.008955 0.01 0.00 0.000
0.01 10 5500 997 0.008955 605164.80 10086.08 420
0.1 100 5500 997 0.008955 6051.65 100.86 4.20
1 1000 5500 997 0.008955 60.52 1.01 0.042
10 10000 5500 997 0.008955 0.61 0.01 0.000
100 100000 5500 997 0.008955 0.01 0.00 0.000
E2834 − 12 (2022)
7.3.3 Eachparticlemustbetrackedforasufficientlengthof sample cell, while magnifying optics (microscope) equipped
time required to accurately determine the average displace- with a video camera capture the images. Different approaches
ment. The software sizes particles based on analysis of their to beam focusing and alignment may be used. A g
...