In these comparisons, a conspicuous difference has generally been found between DLS and other methods.
Several international comparisons have been carried out to investigate the measurement accuracy of various techniques for nanoparticle sizing including DLS. However, the accuracy of this technique has been questioned. Dynamic light scattering (DLS) is widely used as a convenient technique for determining nanoparticle size in liquids. Nanoparticle sizing is critically important in the production of nanomaterials, evaluation of nanostructures, and risk assessment of nanomaterials with respect to human health and environmental regulations. The result of this study clearly demonstrates that consideration for the dependence of measured particle sizes on the scattering angle and particle concentration is crucial in intra-method comparisons of mean particle sizes obtained using DLS. The mean particle sizes obtained at NIST and at NMIJ agreed quite well for all four PSL particle samples after compensating for the angle and concentration differences. The established function was then used to predict the mean particle sizes that would have been obtained if the same scattering angle and particle concentrations as those used at NIST had been selected at NMIJ. These data were used to establish the functional dependence of the measured particle size on the scattering angle and particle concentration through the least-squares fitting method. The mean particle size of the PSL particles was measured using the multi-angle-type instrument at various scattering angles and at various concentrations of particle suspension.
#Malvern zetasizer ns nm series#
A series of nearly monodisperse polystyrene latex (PSL) particles with nominal diameters of 100 nm, 70 nm, 50 nm, and 30 nm were measured using two different types of DLS instruments: one owned by the National Metrology Institute of Japan (NMIJ) of the multi-angle type and the other owned by the National Institute of Standards and Technology (NIST) of the fixed-angle type.
#Malvern zetasizer ns nm how to#
The question of how to relate particle sizes measured using a fixed-angle dynamic light scattering (DLS) instrument with those measured using a multi-angle DLS instrument is addressed.