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Particle Size Determination

Particle sizes can be measured using a variety of techniques depending on the size and nature of the material:

Technique Dynamic light scattering Laser diffraction Particle tracking Disc centrifuge
Approximate suitable particle size < 1 µm > 1 µm < 1 µm < 10 µm
Properties

Average size

Fast measurement

Zeta potential

Dry powders

Liquid dispersions

Higher resolution

Good for multi-modal systems

Aqueous dispersions

Higher resolution

Longer preparation time


cogsHow does it work?

Dynamic light scattering is also known as photon correlation spectroscopy, and measures the way photon scattering changes with time, which is a function of the size of the particles (the hydrodynamic diameter). Laser diffraction is an angular technique, in which the angle and intensity of the scattering are used to determine the particle size.

Particle tracking uses a laser beam shone through a sample in a dispersant, and the scattering particles moving under Brownian motion are tracked by software which measures how fast they are moving. This is used to calculate the size of the particles.

In the disc centrifuge, a dispersed sample is spun at very high speeds in a gradient solution. The time that the particles take to settle out is related to their size.

Applications:

Suspensions and emulsions; dry powders; food industry; pharmaceuticals; microcapsules; fine chemicals; polymers; pesticides; water analysis; flocculation; membrane filtration; cosmetics; perfumes; creams; petrochemicals; fuels; pigments; inks; toners; paints; varnishes.

Sample handling requirements:

Powders or dispersions.

Complementary techniques:

Scanning electron microscopy, Transmission electron microscopy, Gel permeation chromatography

Warwick Capability:

Malvern Instruments Zetasizer Nano-ZS , Malvern Instruments Mastersizer 2000, Nanosight LM10, CPS Disc Centrifuge 24000

Contact:

Dr Ian Hancox, 024 76 150380 email i dot hancox at warwick dot ac dot uk

DLS RTP
Typical results:

particle_size_data_cropped.jpg

Status
Availability
green_tick.gif Warwick collect/analyse data
green_tick.gif Warwick collect data
 green_tick.gif Available to user with expertise/ contribution
 green_tick.gif Spare capacity for collaborative research
 

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