This frequency shift can be converted into a value of electrophoretic mobility. The particles are illuminated by a laser which indirectly measures the particle speed via a Doppler frequency shift of the scattered light. Particles with a higher-magnitude zeta will move at a fast rate, while particles with low zeta potential will move more slowly. The cells have two conductive electrodes that make contact with the instrument’s applied voltage on the outside, and fold in to make contact with the liquid sample on the inside.Ĭharged particles inside the cell will move through the medium at a rate that is proportional to their zeta potential. In a zeta potential measurement, a sample is loaded into a disposable folded capillary cell. Measurement MechanicsĪt nanoComposix, we perform zeta potential measurements using a Malvern Zetasizer Nano ZS instrument equipped with a 632 nm HeNe laser operating at a 173 degree detector angle. In many cases, Zeta potential is the primary mechanism for obtaining nanoparticle stability in aqueous environments. However, coating nanoparticles with a surface that allows for steric hindrance can change the properties or function of the nanoparticle and is often not desirable. Nanoparticles can have naturally occurring or engineered ligands or surface groups that physically prevent the nanoparticles from contacting and agglomerating. If two adjacent particles have sufficiently high zeta potentials of the same sign, they will not agglomerate due to repulsive electrostatic forces between particles with like charges.Īnother way to make particles stable is through steric hindrance. The zeta potential is defined as the voltage at the edge of the slipping (shear) plane with respect to the bulk dispersing medium, where ions, molecules and other agents are no longer associated with a particle’s surface. Further from the surface is an additional layer of more loosely-associated ions of opposite charge to the surface that move with the particle as it travels through a medium due to Brownian motion or sedimentation this is called the double layer. Surrounding the surface of all dispersed particles is a thin layer of ions that have the opposite charge of the particle’s surface called the Stern layer. Zeta potential is a physical property exhibited by all solid-liquid and liquid-liquid colloidal systems. Submit a sample for zeta potential analysis Zeta Theory
How does malvern zetasizer work series#
You can also see our zeta potential video series above for more information regarding sample preparation and results interpretation. It’s crucial for determining the colloidal stability of charged particles and understanding the performance of your system in a variety of conditions.įor more information on zeta potential testing and other analytical techniques, please visit our Characterization Services landing page. The zeta potential is related to the net surface charge that nanoparticles have. Last Call (discontinued & one-off products).
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