Multi-Angle Dynamic Light Scattering (MADLS)

Dynamic Light Scattering (DLS) also known as photon correlation spectroscopy (PCS) or Quasielastic light scattering (QELS), is a particle and molecule sizing method which measures the diffusion of particles moving under Brownian motion. Using the Stokes-Einstein relationship, the random movement of particles is converted to particle size and particle size distribution.

Non-Invasive Back-Scatter (NIBS) technology incorporated in the Zetasizer series gives the highest sensitivity within the broadest range of sizes and concentrations. The back-scattering mechanism minimises errors due to the presence of dust particles since these are known to scatter light in the forward direction. The position of the measurement point in the sample cuvette can be suitably adjusted to prevent multiple scattering effects and allow measurements of extremely small particles or the ones at a low concentration as well as the large particles or those at a higher concentration. The instrument allows measurement of particle size with little or no sample dilution. In addition to these benefits the Zetasizer DLS series require only very small volumes of sample (just a few microliters) for analysis which is fully recoverable due to the non-destructive nature of the method.

Dynamic light scattering is an ensemble technique meaning all particles in a sample are measured at the same time. The size distribution data is determined from a combined signal for all particles. When size populations are closely spaced, less than a factor of three difference in size, DLS will not precisely characterise a polydisperse sample, making it advisable to apply separation prior to measurement.

The multi-angle dynamic light scattering (MADLS) feature in the Zetasizer Ultra overcomes this limitation and allows for a higher resolution size determination of multimodal samples. MADLS uses three different angles (back, side and forward scattering detection) and combines the information obtained into one size distribution plot. This allows for a better resolved size distribution. MADLS also enables the simple, calibration-free measurement of particle concentration in homogeneous sample types, covering a wide range of materials including viruses and VLPs, which can be very challenging to measure. Zetasizer Ultra can significantly decrease the measurement time and simplify the experimental procedure. It does not require numerous sample filtrations and long data collection times.

At ATA Scientific we sell innovative instruments from leading manufacturers in the particle, surface, life and material sciences. Our suppliers include some of the world’s most well-regarded companies such as Malvern Panalytical, Phenom World, Biolin Scientific, Avestin, Jasco, Precision Nanosystems, Phasefocus and Logos Biosystems.

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