Dynamic Light Scattering (DLS)

Dynamic Light Scattering  (DLS) is used to measure particle size and is also known as Photon Correlation Spectroscopy (PCS).

By DLS you can evaluate particle size distribution of very small particles in the range of 0.3nm – 1µm which are invisible for Optical Microscopy and Laser Diffraction. This gives you the possibility to resolve such challenging tasks as:

Investigation of secondary structure and stability
Evaluate particle size of micelles and viruses
Studying particle size of organic and inorganic nano-particles and pigments

Typical applications are emulsions, micelles, polymers, proteins, nano-particles, or colloids.

The effect of temperature on particle size and stability can be investigated. The Dynamic Light Scattering instruments at Particle Analytical can measure both particle size and zeta-potential:

Dynamic Light Scattering. This technique measures the diffusion of particles moving under Brownian motion and converts this to size and a size distribution using the Stokes-Einstein relationship.
Laser Doppler Micro-electrophoresis is used to measure zeta potential. An electric field is applied to a solution of molecules or a dispersion of particles, which then move with a velocity related to their zeta potential.

For Material Experts:

Instrument and measuring principles, DLS

The Dynamic Light Scattering instrument applied by Particle Analytical measures the particle size distribution using laser dynamic light scattering and analysis of the Brownian motions of particles in the media. Non-Invasive Back-Scatter technology allows measurement on concentrated samples – no or little dilution necessary.

Instrument	Malvern Nano Zetasizer (DLS) and Zetasizer Ultra Red Label (MADLS)
USP/Ph. Eur.	USP 〈788〉/ Ph.Eur. 2.9.50
Sample amount	Minimum 12µL for DLS, 1 mL for Zetapotential
Temperatures	From 15 to 40 °C.
Result	The result are given as particle size distribution of stable emulsions and suspensions in the size range 0.3 nm to 1 µm (Zetasizer). Diameter: 0.3 nm – 15 μm
Requirements	The viscosity of the emulsion/suspension is required as well as the refractive indices of media and sample.