Mastersizer S, Mastersizer 2000 and Mastersizer 3000 ... · ›A particle can be described as a...
Transcript of Mastersizer S, Mastersizer 2000 and Mastersizer 3000 ... · ›A particle can be described as a...
Mastersizer S, Mastersizer 2000 and Mastersizer 3000:Method transfer – how to get the same results on all three systems
Overview
› Introduction to particle sizing› Introduction to laser diffraction› Evolution of laser diffraction systems› Method transfer
Dispersion Analysis
› Case studies
Introduction to particle sizing
› A particle can be described as a discrete sub-portion of a substance, e.g. solid particles liquid droplets or gas bubbles
› Laser diffraction measures particles in the size range from nanometres to millimetres
How do we describe the size of particles
› Equivalent spheres Maximum length Minimum length
Max. length
Min. length
Max. lengthMin. length
How do we describe the size of particles
› Equivalent spheres Maximum length Minimum length Sedimentation rate
Max. lengthMin. length
Sedimentation rate
Sedimentation rate
How do we describe the size of particles
› Equivalent spheres Maximum length Minimum length Sedimentation rate Sieve aperture
Max. lengthMin. length Sedimentation rate
Sieve aperture
Sieve aperture
How do we describe the size of particles
› Equivalent spheres Maximum length Minimum length Sedimentation rate Sieve aperture Surface area
Max. lengthMin. length Sedimentation rate Sieve aperture
Surface area
Surface area
How do we describe the size of particles
› Equivalent spheres Maximum length Minimum length Sedimentation rate Sieve aperture Surface area Volume
Max. lengthMin. length Sedimentation rate Sieve aperture
Surface area
Volume
Size classes / m
0.01 0.1 1 10 100 1000 10000
Volu
me
dens
ity /
%
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The particle size distribution
› Laser diffraction measurements produce volume based particle size distributions
Dependence of diffraction pattern on particle size
Dr Kevin Powers, PERC, University of Florida5 microns 800 nanometres
Incident lightSmall angle scattering
Incident light Large angle scattering
Scattering models: Mie Theory
› Models the interaction of light with matter Assuming that the particles are spherical Assuming that it is a two phase system
› Valid for all wavelengths of light and all particle sizes› Predicts the dependence of scattering intensity on
particle size› Predicts that secondary scattering is observed for small
particles
‘For particles smaller than about 50μm Mie theory offers the best general solution’
ISO13320
Mie Theory: Optical properties
Absorption
“….. the Mie theory offers the best general solution.”
ISO 13320: 2009
Diameter
% V
olum
e
Reporting and interpreting the results
› Particle size distribution Volume based
› Percentiles› Averages, weighted by surface area or volume
Dv10 Dv50 Dv90D[3,2] D[4,3]
› Extremely successful - 10,000’s users worldwide Routine tool in many industries – versatility and ease of
use are key Mastersizer 3000 is the latest generation
Evolution of Laser Diffraction Particle Sizing
1988 1994 1998 2011
A basic laser diffraction system
The optics are arranged so that particles of the same size scatter light to the same part of the detector array
Optical systems: Mastersizer S
Lens Size range300RF 0.05 to 880um300mm 0.5 to 880um1000mm (long bench) 4.2 to 3480um
Optical systems: Mastersizer 2000 blue light
› The scattering intensity observed for sub-micron particles is increased by using 466nm blue light source
Size range: 0.02 to 2000um
Measurement cell Focal plane detectors
Side scatter detectors
Back scatter detectors
633nm red laser
Precision folded optics
Optical systems: Mastersizer 3000 red light
Size range: 0.1 to 3500um
Optical systems: Mastersizer 3000 blue light
470nm blue light source
Side scatter detectors
Measurement cell
Back scatter detectors
Size range: 0.01 to 3500um
SAMPLE DISPERSION
Wet dispersion unitsDispersion conditionsUltrasoundStirrer speedConcentrationDry dispersion
Method development and method transfer
› A laser diffraction measurement requires
‘a representative sample, dispersed at an adequate concentration in a suitable liquid or gas’
<USP429>
› Method development must define appropriate Sampling Dispersion Measurement conditions
Wet dispersion unitsLarge volumes: 600ml to 1000ml
Medium volumes: 80ml to 120ml
Small volumes: 6 to 18ml
Method transfer: dispersion conditions
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0 2 4 6 8 10 12 14 16 18 20
Size
/ um
Measurement no.
Dx (10) (μm) Dx (50) (μm) Dx (90) (μm)
After Ultrasound
Stirring
Ultrasound
Method transfer: ultrasound
› Ultrasound titration – ground glass› In-line sonication can reduce required ultrasound duration
Ultrasound duration / s
-100 0 100 200 300
Dv9
0 / µ
m
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1000
10000MS2000 Dv90 MS3000 Dv90
Method transfer: stir speed titration
› For coarse or dense materials particle size will increase with stir speed until all particles are suspended A stable particle size is obtained above 2500rpm
0
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500 1000 1500 2000 2500 3000 3500
Part
icle
siz
e / μ
m
Stir speed / rpm
d10 dv50 d90
› Obscuration is a measure of concentration› The low limit is defined by signal to noise ratio
and measurement reproducibility
› The high limit is defined by multiple scattering
Method transfer: concentration
Multiple scattering
› If we add too much sample the results may be affected by multiple scattering This generally affects samples smaller than 10μm
Measurement cell
Det
ecto
r
Low angle detectors
High angledetectors
Multiple scattering
› If we add too much sample the results may be affected by multiple scattering This generally affects samples smaller than 10μm
Measurement cell
Det
ecto
r
Low angle detectors
High angledetectors
Increase in scattering angle
Achieving comparable results: concentration Particle Size Distribution
0.01 0.1 1 10 100 1000 3000 Particle Size (µm)
0
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8 Vo
lum
e (%
)
Averaged 3%, 18 March 2011 15:32:25 Averaged 5%, 18 March 2011 15:35:46Averaged 9%, 18 March 2011 15:42:01 Averaged 13%, 18 March 2011 15:49:02Averaged 17%, 18 March 2011 15:53:59
Achieving comparable results: obscuration titration
Obscuration / %
0 2 4 6 8 10 12 14 16 18 20 22
Dv1
0 / µ
m
0.05
0.10
0.15
0.20
0.25
0.30
0.35MS3000MS2000
› Comparison of MS2000 and MS3000 results vs. obscuration
Wet dispersion method transfer summary
› Ultrasound efficiency will vary with: Power and frequency of generator Mechanism: in-line or dip-in probe Volume of dispersion unit
› Concentration Different systems show multiple scattering at effects
different obscurations
› Stirrer speed Stir speed titration may be required to achieve
comparability
The Aero S has a range of different tray designs to aid method transfer
Micro tray
Macro tray General purpose tray with hopper
Large volume tray
Dry powder dispersion: Mechanisms
› Importance of each mechanism depends on: Disperser geometry Flow rate or pressure drop Material type
› Higher impact energies may improve the dispersion effectiveness Needs to be balanced against the risk of particle break-up
Energy/aggressive
Method transfer: pressure titration
› Make measurements at 4, 3, 2, 1, 0.5 and 0.1 bar. Investigate the effect of pressure on the state of
dispersion
Method transfer: comparing dispersers
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100110120130140
0 0.5 1 1.5 2 2.5 3 3.5 4
Dv5
0 / u
m
Air Pressure / bar
Aero Standard Aero High Energy Wet Dispersion
Method transfer: Aero vs Sirocco
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0 0.5 1 1.5 2 2.5 3 3.5 4
Dv5
0 / u
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Air Pressure / bar
Aero Standard
Aero High Energy
Scirocco
Wet Dispersion
Dry dispersion method transfer summary
› Different disperser mechanisms are used Carry out a pressure titration Choose the pressure that gives equivalent and robust
results
› Choose the best tray option for your material Volume of material to be measured Flowability
› Different vibration mechanisms are used Choose the vibration rate that gives a consistent flow
within the obscuration range.
Analysis: Optical properties
› Calcium carbonate sample› Optical properties
Refractive index: 1.52 Absorption: 0.1
Size / m
0.01 0.1 1 10 100 1000
Vol
ume
frequ
ency
/ %
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MS3000MS2000
Dv 10 Dv 50 Dv 90 Residual Weighted residualMS2000 0.92 4.17 10.41 1.13 2.37MS3000 1.04 4.07 10.90 0.79 1.75Average 0.98 4.12 10.66
Standard deviation 0.07 0.06 0.26%RSD 6.73 1.41 2.47
Data Graph - Light Scattering
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 Detector Number
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rgy
Fit data(weighted) calcium carbonate, 27 January 2011 15:31:52
Analysis: Assessing the data fit
Residual Weighted residual
0.79 1.75
Residual Weighted residual
1.13 2.37
Data Graph - Light Scattering
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 Detector Number
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Ligh
t Ene
rgy
Fit data(weighted) calcium carbonate, 27 January 2011 15:31:52
Analysis: Assessing the data fit
Residual Weighted residual0.69 0.81
Residual Weighted residual
0.59 0.59
The optical property optimiser (OPO)
› Offers a quick way to adjust optical properties and assess the fit and result
Size / m
0.01 0.1 1 10 100 1000
Vol
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frequ
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/ %
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MS3000MS2000
Analysis: Correct optical properties
› Calcium carbonate sample› Optical properties
Refractive index : 1.6 Absorption: 0.01 Dv 10 Dv 50 Dv 90 Residual Weighted residual
MS2000 1.87 4.98 11.48 0.69 0.81MS3000 1.84 4.79 11.54 0.59 0.59Average 1.85 4.88 11.51
Standard deviation 0.02 0.11 0.07%RSD 0.85 2.17 0.64
Size / m
0.01 0.1 1 10 100 1000
Vol
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/ %
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10MS3000MS2000MSS
Case study: Calcium carbonate
› Correct optical properties Refractive index between 1.53 and 1.65, absorption 0.01
› No multiple scattering 5% to 10% obscuration
Case studies across the size range
› Silicon carbide sample› Wet dispersion; Hydro G, Hydro LV (3500rpm)
Case studies across the size range
› Emulsion sample, wet dispersion, Hydro S, Hydro MV Particle Size Distribution
0.01 0.1 1 10 100 1000 3000 Particle Size (µm)
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Volu
me
(%)
emulsion, 11 June 2012 13:55:38
Examples at the extremes of the size range
› Coffee› Dry dispersion, Aero S standard venturi, Scirocco
Summary
› The optical systems of diffraction systems have evolved to measure a wider particle size range: measurements at narrower angles due to smaller detector
elements more high angle scattering data due to more sensitive
detector elements Additional lower wavelength light sources
› The dispersion units have evolved to Provide more efficient dispersion Provide dry dispersion mechanisms tailored to the
robustness of the material
› By understanding the materials state of dispersion, excellent comparability can be achieved