1. Iwao Teraoka Polytechnic University
Particle Sizing
Iwao Teraoka
Polytechnic University

2. Outline of the Tutorial
Overview
Static light scattering
Dynamic light scattering
Dynamic structure factor and diffusion
Particle sizing by DLS

3. Outline of Overview Methods of particle sizing Laser diffraction
Hydrodynamic chromatography
Electrical-sensing zone
Single-particle optical sensing

4. Particle Size Distribution: Where Is It Measured?
Powders (wheat, starch, cement, drugs, detergents, etc.)
Suspensions (milk, paints, inks, blood, etc.)
Gels (yogurt, mayonnaise, pastes, etc.)
Aerosols (spray, smoke, Anthrax, etc.)
analytical
online monitoring in process control

5. Instrument Manufacturers
Brookhaven Instruments (NY)
Coulter (FL) — Beckman-Coulter (CA)
Horiba (Japan)
Malvern (UK)
NiComp (CA)
Otsuka (Japan)
Polymer Laboratories (UK)
...

6. Methods of Particle Sizing
Other methods include optical microscopy, sieving, and sedimentation.

7. Range of Measurement OM: optical microscopy
SPOS: single particle optical sensing
LD: laser diffraction
FD: Fraunhofer diffraction
ESZ: electrical-sensing zone
DLS: dynamic light scattering
QELS: quasi-elastic light scattering
PCS: photon correlation spectroscopy
HDC: hydrodynamic chromatography

8. Particle Sizing: Assumption
Assume that the solute consists of independently moving spheres of different radii.

9. Hydrodynamic Chromatography (HDC)
column packed with solid spheres
flow velocity in a narrow channel
larger particles
smaller particles
Larger particles flow ahead of smaller particles.

10. HDC in Size Exclusion Chromatography
HDC mode

11. Single-Particle Optical Sensing (SPOS)
SPOS detects the shadow. Obviously, it cannot measure particles smaller than ~1 µm. To extend the range to less than 1 µm, SPOS has an additional detector for detecting light diffracted (scattered) by the smaller particles.

12. Electro-Zone Sensing (Coulter Principle)
As a particle blocks the orifice, the conductivity drops temporarily.

13. Laser Diffraction (Fraunhofer Diffraction)
Angular dependence of the scattering intensity (diffraction pattern) is different for particles of different sizes.