Authors: D. Griffiths, W. Bernt, P. Hole
Affilation: NanoSight USA, United States
Pages: 31 - 33
Keywords: colloids, nanoparticle, characterization, sizing, DLS
Nanoparticle Tracking Analysis (NTA) is a method that has gained increasing popularity for the study of nanoparticle dispersions, providing high-resolution particle size analysis as well as a direct measure of particle count or concentration. By adding the measurement of scattered light intensity to the measurement of each particle, a powerful combination of information allows the differentiation of sub-populations within a heterogeneous mixture to be isolated and analyzed. NTA employs a novel illumination method, allowing direct observation of particles in suspension within the size range of approximately 10 - 1000nm to be individually imaged and sized by tracking their Brownian motion. Particle-by-particle analysis allows high-resolution number-based size distributions to be generated, as well as a direct count and concentration result. The technique offers significant advantages over existing light scattering techniques for the characterization of polydispersed populations. The technique described is extended to allow not just the characterization of size, but also light scattering intensity on an individual particle-by-particle basis. This multi-parameter measurement capability allows sub-populations of nanoparticles of varying characteristics to be resolved in a complex mixture. Examples will be shown of size dependence of scattering intensity and several examples of heterogeneous mixtures showing the ability to differentiate sub-populations.