Date recorded: June 02 2020

Duration: 01 hours 13 minutes 34 seconds

Dynamic light scattering (DLS), also known as photon correlation spectroscopy (PCS) and quasi-elastic light scattering (QELS), is a technique used to measure the Brownian motion (diffusion) and subsequent size distribution of an ensemble collection of particles in solution. For a collection of solution particles illuminated by a monochromatic light source, the scattering intensity measured by a detector will be dependent upon the relative positions of the particles within the scattering volume. For particles moving under the influence of Brownian motion, the measured scattering intensity will fluctuate with time. Correlation is a statistical method for measuring the degree of non-randomness in an apparently random data set.

When establishing the level of confidence in the size distribution results derived from a dynamic light scattering measurement, DLS users should always first consider the repeatability of the measurement, i.e. how repeatable is the result derived from sequential measurements of the same sample aliquot. Given good repeatability and reasonable results, one rarely needs to examine the quality of the raw data collected during the measurement.

The quality of data obtained from a dynamic light scattering (DLS) measurement is paramount to the reliability of the result obtained. However, in dynamic light scattering, there is no single parameter that can be used to gauge the quality or “goodness” of a measurement data set, but rather a collection of measurement parameters that need to be examined prior to attaching a large degree of confidence to a DLS derived size distribution.

The instruments measuring DLS are operated by analysis software common to the systems. The main function of the analysis is to transform the measured raw data (auto correlation function) into a size result.
To simplify the interpretation of the data from a dynamic light scattering measurement, a series of tests are performed on the data and results of the selected measurement record. A good instrumentation approach would be to check if any of the tests fall outside specified limits. If they do then a warning message is to be displayed, together with advice of possible reasons for the warning and possible actions that could be take to address the issue. If none of the tests fail, a “Result Meets Quality Criteria” message can be displayed in the Size Quality Report.

This webinar would discuss on the criteria/tests that are performed on the measured data and based on which the data quality is interpreted to be ‘good’ or ‘needs improvement’. Look out for latest advancements in technology involving Multi-angle Dynamic Light Scattering (MaDLS) for particle concentration analysis too; all possible on the new Zetasizer Ultra.

Join our free series of DLS related webinars

- Webinar 1: Intro to Dynamic Light Scattering and its applications towards vaccine research, formulation and development. More info
- Webinar 2: Better particle size analysis and interpretation of dynamic light scattering data: recognising good vs bad data and practical tips on sample preparation and analysis.   
- Webinar 3: Nanomedicine involving complex composition and the criteria for using nanoparticle tracking analysis. More info 
- Webinar 4: Research applications on gene therapy and virus research using NTA. More info 
- Webinar 5: Focus on Vaccine Development 1: Value of DSC as a Complimentary and Insightful Technique for Structural Characterization of a Multi-Domain Protein Antigen. More info 
- Webinar 6: Focus on Vaccine Development 2: How Stable is Stable? Combining biophysical techniques and advanced kinetics to support formulation development. More info 
- Webinar 7: Strengthening the analytical workflow for rAAV viral vector development. More info
Table of contents
1. Theory of dynamic light scattering
2. What is DLS measuring
3. Factors influencing DLS measurements
4. Data interpretation
5. Tech advancements with multi-angle DLS (MADLS)
6. Question & answer