We are often asked to perform a calibration on one of our Dynamic Light Scattering (DLS) instruments and, at times, are met with confused looks when we state there is no calibration and that DLS is not a calibrated technique.
Dynamic Light Scattering is considered an uncalibrated technique primarily because it relies on theoretical models from first principles rather than direct calibration against standard reference materials.
DLS is an absolute, first-principles technique that calculates particle sizes directly from the physical laws governing Brownian motion. It does not require calibration curves—like those used in chromatography—because the fundamental relationship between a particle’s size and how fast it diffuses through a liquid is mathematically defined
DLS measures the fluctuations in scattered light intensity caused by particles undergoing Brownian motion. These fluctuations are analyzed using the Stokes-Einstein equation to derive particle size. The accuracy depends on the validity of these models, which assume spherical particles, dilute suspensions, and known refractive indices.
Factors such as instrument alignment, laser wavelength, detector sensitivity, scattering angle and sample optical properties can influence measurements across various manufacturers. Variations in these parameters may not be fully accounted for through calibration, leading to discrepancies.
DLS is more of an analytical technique based on physical principles and models rather than a calibrated measurement system. It provides rapid, useful information about particle size distribution but is not inherently calibrated against standard references, which is why it is considered a non-calibrated or semi-quantitative method.
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Brookhaven Instruments, with a legacy of pioneering in light scattering and zeta potential analysis, is committed to advancing its technology to provide reliable and innovative solutions that support modern scientific breakthroughs in nanotechnology, pharmaceuticals, and materials science.
Contact us today to learn more about our light scattering solutions for particle size and zeta potential analysis.