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Molecular charge and nanoparticle zeta potential are core properties of a solute and a solvent, relevant to colloidal stability, chemical modifications and other key qualities.

Charge & Zeta Potential


Commonly associated with the stability of suspensions, zeta potential / molecular charge is also useful in assessing chemical modifications to biomolecules such as polysaccharides or IgG. In order to be relevant the charge must be measured in the solvent or formulation buffer of interest. That's why the Mobius® offers solutions for all solutions – volatile organics or highly conductive aqueous, as well as the more usual low-conductivity aqueous.

Both molecular charge and zeta potential are calculated from three primary measurements: electrophoretic mobility µ, hydrodynamic radius Rh and solvent conductivity σ. Light scattering determines electrophoretic mobility via Massively Parallel Phase Analysis Light Scattering (MP-PALS), and hydrodynamic radius via Dynamic Light Scattering (DLS). Only the Mobius plus integrated WyattQELS™ DLS module offers simultaneous measurement of µ and Rh. Conductivity is measured in the MP-PALS cell as well. Please see Electrophoretic Light Scattering Theory for more details.

MP-PALS Detectors
MP-PALS utilizes low voltage and multiple low-noise, high-dynamic range detectors in parallel to achieve
the highest sensitivity without damaging fragile samples. Click to enlarge.


  • Optimizing stability of colloidal solutions such as quantum dots, liposomes, and monoclonal antibodies
  • Indication of chemical modifications that add or subtract charged residues (e.g., drug molecules in antibody-drug conjugates or super-sulfated heparin)

Instrumentation for Charge & Zeta Potential

  • MP-PALS Detector


    Mobius™ - Massively Parallel Phase Analysis Light Scattering makes the Mobius the most sensitive electrophoretic light scattering detector available. Determines electrophoretic mobility, surface charge and zeta potential of fragile biomolecules as well as more robust nanoparticles, in native buffer. The Mobius is the only mobility detector to provide connectivity to an autosampler for hands off, multi-sample operation.

    The Mobius incorporates dynamic light scattering (DLS) to provide simultaneous DLS measurements in the same scattering volume as PALS measurements. Hydrodynamic radius (Rh, determined by DLS) combines with electrophoretic mobility to calculate zeta potential and net charge.

  • Accessories

    mobius dip cell

    Atlas - Pressurizes the Mobius flow cell to allow measurements of high conductivity samples.

    Mobius Dip Cell - An alternative to the high-pressure flow cell, the dip cell affords simultaneous mobility and size measurements in order to determine zeta potential or charge while monitoring potential degradation of the sample under an applied electric field. The dip cell requires only 65 µL of solution under typical conditions.

    NanoFilter Kit - Makes it easy to filter, recover and refilter precious sample. This is especially useful when your total sample volumes are below 300 µL.

    MicroBatch Kit - Used to inject samples into the flow cell of a Mobius.

  • Software

    DYNAMICS software

    DYNAMICS® - Software for MP-PALS and DLS measurements in the Mobius. Calculates electrophoretic mobility, size and size distributions, and derives zeta potential, Debye-Hückel-Henry and effective net charge.


Ultimate Guide

Thirteen key questions to ask when buying a Multi-Angle Light Scattering (MALS) or Dynamic Light Scattering (DLS) instrument.

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Wyatt Technology is the recognized leader in light scattering instrumentation and software for determining the absolute molar mass, size, charge and interactions of macromolecules and nanoparticles in solution.

Wyatt's line of multi-angle static light scattering products couple to size exclusion chromatography (SEC-MALS), field-flow fractionation (FFF-MALS), and stop-flow composition-gradient systems (CG-MALS). Our dynamic light scattering (DLS) products operate in traditional cuvette as well as on-line and automated, high-throughput modes. We also offer unique instruments for electrophoretic light scattering (MP-PALS), differential refractometry, and differential viscosity.

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