NIST-NCL Protocol Measuring the Size of Nanoparticles in Aqueous Media Using Batch-Mode Dynamic Light Scattering

This assay protocol outlines procedures for sample preparation and the determination of
mean nanoparticle size (hydrodynamic diameter) using batch-mode dynamic light
scattering (DLS - synonyms include photon correlation spectroscopy, PCS, and quasielastic
light scattering, QELS) in dilute aqueous suspensions. The hydrodynamic
diameter is the diameter of an equivalent hard sphere that diffuses at the same rate as
the analyte. Although particle size is the primary determinant of the measured diffusion
coefficient, other parameters can impact these measurements and influence the
measured size. Therefore, guidelines for making successful size measurements in the
nanosize range are provided, as well as a discussion of relevant standards and data
analysis. This protocol can be applied to any suitable DLS instrument with batch
measurement capability. This is intended to be an evolving document; addenda that
address material-class-specific sample preparation and analysis issues will be appended
in the future.