Mobius Size and Zeta Potential Detector

The Mobius® uses phase-analysis light scattering (PALS) to make reliable, reproducible, and non-destructive electrophoretic mobility measurements of macromolecules and nanoparticles as small as 2 nm in radius, in addition to dynamic light scattering (DLS) for size. Thanks to an innovative, electro-optical design incorporating 31 parallel detectors, the Möbius characterizes the charge of fragile biomolecules non-destructively at low applied voltage.

Size and zeta potential are measured simultaneously in order to monitor potential sample degradation, to calculate zeta potential or surface charge, and to make these measurements on-line following separation by size-exclusion chromatography (SEC) or asymmetric-flow field-flow fractionation (AF4). The Möbius interfaces with a standard autosampler for high productivity and unattended overnight, multi-sample analyses.

The Atlas™ flow cell pressurization system extends the range of accurate, repeatable mobility measurements to difficult samples such as proteins in high-salt buffers.


  • Measurement configurations: flow cell (required for pressurized measurements, automation with an autosampler or online measurements); 45 µL quartz cuvette with dip electrodes; 100 µL disposable plastic cuvette
  • Hydrodynamic size range (Rh): 0.2 – 5000 nm (flow cell); 0.2 – 200 nm (dip cell, quartz cuvette); 0.2 – 250 nm (disposable cuvette)
  • Sensitivity for size measurements: 0.1 mg/mL of 14.4 kDa lysozyme
  • Conductivity range for mobility: 0 – 7 mS/cm; 0 – 100 mS/cm with the Atlas™ cell pressurization system
  • Sensitivity for zeta potential measurements: 1 mg/mL of 14.4 kDa lysozyme (flow cell) or 5 mg/mL of 66.7 kDa BSA (dip cell)
  • Temperature control: 4 – 70 °C
  • Optional narrow-band fluorescence-blocking filter for measuring the size of fluorescent particles (no filter required to measure zeta potential of fluorescent particles)
  • Optional Atlas pressurization system to measure zeta potential of proteins and other nanometer-sized particles in PBS and high-salt buffers
  • Software: DYNAMICS® analysis software offers comprehensive analysis of size and size distributions, diffusion interaction parameter kD, thermal behavior Tagg/Tm/Tonset, DLS-based viscosity; full export of all results; optional 21CFR11 support for GMP. DYNAMICS can control an Agilent autosampler for automated DLS/PALS measurements.


  • Size, aggregation, charge and stability of proteins and biotherapeutics
  • Polymer and particle size and zeta potential
  • Flow PALS following separation by SEC or AF4 for detailed size-zeta potential distributions of drug-delivery, gene vector and theranostic nanoparticles

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