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 /

%

0

2

4

6

8

10

The particle size distribution

› Laser diffraction measurements produce volume based particle size distributions

INTRODUCTION TO LASER DIFFRACTION

The diffraction pattern

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: Predicted scattering

Refracted light

Mie Theory: Optical properties

Absorption

“….. the Mie theory offers the best general solution.”

ISO 13320: 2009

How do we get the size distribution?

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]

EVOLUTION OF LASER DIFFRACTION SYSTEMS

› 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

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 red light

Size range: 0.1 to 2000um

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

Agglomerated Dispersed

Method transfer: dispersion conditions

0

10

20

30

40

50

60

70

80

90

100

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

1

10

100

1000

10000MS2000 Dv90 MS3000 Dv90

Method transfer: stirrer speed

› MS3000 dispersion units have a combined pump and stir

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

20

40

60

80

100

120

140

160

180

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

2

4

6

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

Dry dispersion unitsMastersizer S Mastersizer 2000

Mastersizer 3000

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

Dry powder dispersion: Disperser geometries

Standard Venturi High-Energy Venturi

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

405060708090

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

40

50

60

70

80

90

100

110

120

130

140

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

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

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

/ %

0

2

4

6

8

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

0

5

10

15

20

25

30

Ligh

t Ene

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

0

5

10

15

20

25

30

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

ume

frequ

ency

/ %

0

2

4

6

8

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

Analysis: Models

Analysis: Particle shape

Analysis: MS2000 emulated analysis

CASE STUDIES

Size / m

0.01 0.1 1 10 100 1000

Vol

ume

frequ

necy

/ %

0

2

4

6

8

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

› Pigment sample› Wet dispersion, Hydro S, Hydro MV (2100rpm)

Case studies across the size range

› Calcium carbonate› Wet dispersion, Hydro MU, Hydro EV

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)

0

2

4

6

8

10

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