DLS Analysis

Dynamic light scattering (DLS) is used to characterize particle size distributions and hydrodynamic sizes of particles and molecules ranging from 0.3 nm to 10 µm. Particle size is determined by measuring random changes in the intensity of light scattered from liquid dispersions. DLS is a nondestructive method.

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What is DLS analysis and how does it work?

Dynamic light scattering (DLS) is also called photon correlation spectroscopy (PCS) or quasi-elastic light scattering (QELS). DLS is a spectroscopy method that is used to determine the size distribution of particles in solution or suspension. Size distribution information is obtained from the Brownian motion of particles. The theory of Brownian motion states that small particles move faster than larger particles in a liquid or gas medium.

The scattered light intensity is affected by the physical properties of the particle, such as size and molecular weight. The scattered light intensity is not a constant value because the scattering intensity fluctuates over time as the result of the random movement of particles called the Brownian motion. It is due to the collisions between the particles and the medium molecules. Therefore, the distance between the scatterers in the solution is constantly changing with time. By measuring the random motion changes in the intensity of light scattering, DLS allows for the particle size and particle size distribution to be determined.

In DLS analysis the sample suspension is illuminated by a laser beam, after which the laser light scatters in all directions. The light scattering is observed at a certain angle over time. Signal variation is due to the random Brownian motion of the particles. The angular intensity distribution is used to determine the particle size by the Stokes-Einstein equation.

Suitable sample matrices

  • Liquids and suspensions
  • Inks and pigments
  • Microemulsions
  • Protein and polymer samples

Ideal uses of DLS analysis

  • Analyzing the hydrodynamic size and the size distribution of nanoparticles and molecules
  • Determining the size of proteins, polymers, micelles, carbohydrates and nanoparticles

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Frequently asked questions

What is DLS analysis commonly used for?

Dynamic light scattering is used to analyze hydrodynamic particle size and size distributions. DLS is suitable for particles smaller than 1 micrometer. 

What are the limitations of DLS?

The sample used in DLS must be a liquid suspension. 

What kind of samples can be analyzed with DLS?

DLS samples can be liquids or samples can be suspended to liquid.

What is Measurlabs?

Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.

How does the service work?

When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.

How do I send my samples?

Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.