In a paper published in the Journal of Nanoparticle Research (Volume 10, number
5, May 2008), scientists working at Malvern
Instruments presented experimental protocols for measuring hydrodynamic
particle diameters of less than 1 nm, with a precision of 0.1 nm.
The work was carried out using a Malvern Zetasizer particle characterization
system, which uses dynamic light scattering (DLS) for particle size measurement.
Its optical configuration, comprising a highly sensitive detector in combination
with an optimised fibre optic configuration, was a critical factor in the exceptional
The results, which took sucrose as the model material, clearly demonstrate that
very precise, verifiable sub-nanometre measurements are now possible. The paper
‘Measuring sub nanometre sizes using dynamic light scattering’,
Kaszuba, M. et al., is currently available online with open access, and there
is a related application note that can be freely downloaded from the Malvern
Particle size is a crucial measure of quality in many applications, and scientific
advances have generated a requirement to control increasingly small particles,
and molecules. In drug development, for example, proteins are often used as
active pharmaceutical ingredients and there is a growing need for techniques
sensitive enough to characterise particles in the nanometre size range. Sucrose
was chosen as an extreme example, to give confidence in the capability of the
system and technology at the limits of the specification.
DLS analyzes time-dependent fluctuations in the intensity of scattered laser
light to measure the diffusion coefficient and size of particles. This study
research shows that, with careful sample preparation and an appropriate optical
configuration, the Zetasizer Nano S accurately measures particle sizes at the
sub nanometre scale. These results are highly significant for current and future
applications requiring quality control of small molecules.
To download the application note visit: http://www.malvern.com/sucrose
To download the published paper go to: http://www.springerlink.com/content/4222wpl027319861/?p=9f9d3498756141dba9f6d89ed5be64ac&pi=10