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MALVERN ZETASIZER EQUILIBRATION TIME SERIES

While the dispersant phase can sometimes be defined on paper, for many colloidal dispersions, the exact composition of the dispersant phase, e.g. The aim of sample preparation is to preserve the existing state of the surface during the process of dilution. It is difficult not to over emphasize this. A measurement result given with no reference to the medium in which the material is dispersed is meaningless, in that t he zeta potential is as dependent on the composition of the disperse phase as it is on the nature of the particle surface itself. For meaningful measurements the dilution medium is crucially important. Further discussion for the concentration requirements for zeta potential measurements on the Zetasizer Nano is available as a technical note from the Malvern website.įor samples requiring dilution, h ow the dilution is performed is absolutely cr itical in determining the zeta potential value measured.

If the concentration of the sample is too high, the laser beam will become attenuated by the particles reducing the scattered light that is being detected. As a general rule of thumb then, samples for zeta potential measurements need to be optically clear. However, the laser beam has to penetrate the sample for light scattered at a forward angle to be detected. As a consequence, many samples can now be measured directly, with no dilution.

MALVERN ZETASIZER EQUILIBRATION TIME SERIES

The automatic attenuation present in the Nano series facilitates an increased concentration range, in comparison to historical instruments, over which zeta potential measurements can be conducted.

Monitoring structure development in complex fluids with time or temperature, or structure breakdown on dilution.How_do_I_dilute_samples_for_zeta_measurements_ How do I dilute samples for zeta measurements?.

High frequency rheology of dilute systems on process-relevant timescales.

Viscoelastic measurements of protein solutions to assess onset of protein-protein interactions and insoluble aggregate formation.

Rheological characterization of therapeutic proteins and biopolymer solutions.

protein-based formulations.Īpplications of DLS Microrheology include:

Only requires microliter-scale volumes for rheological characterization of materials where sample volume is limited e.g.

Probes very high frequencies necessary for characterizing inherent short timescale, viscoelastic responses (whereas mechanical techniques are fundamentally limited by inertia).

For these types of materials, Microrheology offers significant advantages: DLS Microrheology is a passive microrheology technique, whereby the colloidal probe particles only undergo thermal fluctuations in a system at thermodynamic equilibrium.ĭLS Microrheology is applicable for the rheological characterization of low viscosity and weakly-structured complex fluids, such as dilute solutions of polymers and surfactants through to concentrated protein formulations.

Microrheology involves tracking the motion of dispersed tracer particles of known size by Dynamic Light Scattering (DLS) and determining the rheological properties of the sample using the Generalized Stokes-Einstein Relation. Rheological properties, such as viscosity and viscoelasticity, can be measured from bulk sample deformation using a mechanical rheometer, or on a micro-scale using an optical technique such as Microrheology. Rheology is the study of flow and deformation of materials.