Zetasizer Nano ZS

Performance, simplicity, versatility.

The world’s most widely used system. It is used for the measurement of protein size, electrophoretic mobility of proteins, zeta potential of colloids and nanoparticles, and optionally the measurement of protein mobility and microrheology of protein and polymer solutions. The high performance of the Zetasizer Nano ZS also enables the measurement of the molecular weight and second virial coefficient, A2, of macromolecules and kD, the DLS interaction parameter.

The system can also be used in a flow configuration to operate as a size detector for SEC or FFF.


The Zetasizer Nano ZS is a high performance two angle particle and molecular size analyzer for the enhanced detection of aggregates and measurement of small or dilute samples, and samples at very low or high concentration using dynamic light scattering with ‘NIBS’ optics. The ZSP also incorporates a zeta potential analyzer that uses electrophoretic light scattering for particles, molecules and surfaces, and a molecular weight analyzer using static light scattering.

Using Non-Invasive Backscatter optics (NIBS) it has significantly better performance than systems using 90 degree scattering optics.

In addition, a microrheology option is available for measuring sample viscosity and viscoelastic properties, as well as a Protein Measurement option for protein mobility measurements.

The flow mode option enables the system to be connected to an SEC or an FFF system to use as a detector for the size of proteins or nanoparticles.

A choice of cuvettes are available, from disposable single-use to specific cells for viscous or high concentration samples or measuring the zeta potential of surfaces.

Parameters measured:
Particle and molecule size, translational diffusion, electrophoretic mobility, zeta potential of particles at high and low concentrations, viscosity and viscoelasticity of protein and polymer solutions, concentration, MW, A2, kD.


  • Size measurement from 0.3nm (diameter) to 10 microns using patented NIBS (Non-Invasive Back Scatter) technology.
  • The Expert advice report gives help to improve sample preparation or the measurement procedure.
  • Research software option gives access to further features and analysis algorithms for the light scattering specialist.
  • Alternative laser, 50mW at 532nm for samples incompatible with the standard 633nm laser fitted.
  • Molecular weight measurement down to 980Da.
  • Second virial coefficient measurement for solubility.
  • Automated temperature trend measurements.
  • Sample concentrations from 0.1ppm to 40%w/v.
  • Protein size measurement as dilute as 0.1mg/mL (Lysozyme).
  • A Quality Factor gives confidence in the data.
  • 21CFR part 11 software option enables compliance with ER/ES.
  • Automation of measurements using an autotitrator option.
  • Flow mode capability to enable use as a GPC / SEC detector.
  • Optical filter option to improve measurements with fluorescent sample.
  • Temperature range extension option to 120ºC.
  • Systems can be upgraded to add zeta potential at a later date.

How it Works:

The Zetasizer Nano S incorporates 2 techniques in a single compact unit, and has a range of options and accessories to optimize and simplify the measurement of different sample types.

Dynamic Light Scattering is used to measure particle size and molecule size. This technique measures the diffusion of particles moving under Brownian motion, and converts this to size and a size distribution using the Stokes-Einstein relationship. Non-Invasive Back Scatter technology (NIBS) is incorporated to give the highest sensitivity simultaneously with the highest dynamic size and concentration range.

Static Light Scattering is used to determine the molecular weight of proteins and polymers. In this technique, the scattering intensity of a number of concentrations of the sample is measured, and used to construct a Debye plot. From this the average molecular weight and second virial coefficient can be calculated.
This measurement is very demanding on the sensitivity and stability of the whole system, and means that every element of the design has been optimised to ensure accuracy and repeatability

The software is designed to be versatile and rich in features without compromising ease of use. Standard Operating Procedures (SOP) simplify routine measurements, a quality factor gives a single place to look for the success of a measurement, and expert advice is given to assist with data interpretation.

The MPT-2 Autotitrator enables the study the effect of changes in pH, conductivity, or any additive to be automated.
A range of disposable and reusable cells are available to optimise the measurement in terms of sample volume, concentration and for flow measurement.

Other options include filters to improve the measurement of fluorescent samples, a temperature range extension to 120ºC and a viscometer to determine the sample viscosity to the accuracy required for the techniques used.



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