Microtrac MRB’s NANOTRAC Wave II / Zeta is a highly flexible Dynamic Light Scattering (DLS) analyzer which provides information on particle size, zeta potential, concentration, and molecular weight. It allows faster measurements with reliable technology, higher precision, and better accuracy. All of this combined into a compact DLS analyzer with a revolutionary fixed optical probe.

With the unique and flexible probe design and the use of the Laser Amplified Detection method in the NANOTRAC Wave II / Zeta, the user is able to choose from a wide array of measurement cells that satisfy the needs of any application. This design also allows measurements of samples over a wide concentration range, monomodal or multimodal samples, all without prior knowledge of the particle size distribution. This is made possible through the use of the Frequency Power Spectrum (FPS) method instead of classical Photon Correlation Spectroscopy (PCS).



180° backscatter DLS setup
Stable fixed optics sample interface – no adjustments required
Rapid field reversal prevents electro-osmosis
Robust mobility calculation as a function of power spectrum ratio
High concentration zeta potential measurements
Sample concentration and molecular weight determination
Universal solvent compatibility
Frequence Power Spectrum calculation model instead of PCS
Laser Amplified Detection – high signal to noise ratio


Accurate Measurement of Colloidal Systems

All NANOTRAC WAVE series analyzers use the same revolutionary probe technology for DLS measurements. Utilizing our Laser Amplified Detection method, repeatable and stable particle size measurements for all types of materials are provided.

The NANOTRAC WAVE II series can also calculate the sample concentration through the use of the power spectrum and the resulting loading index. Depending on the distribution calculation, concentration will be displayed in appropriate units such as cm3/ml or N/ml. It is also possible to calculate the molecular weight by either the hydrodynamic radius or a Debye plot.

The NANOTRAC WAVE II particle analyzer has multiple reusable samples cells in different sizes. There is a standard and micro volume Teflon cell for a wide range of materials. For more difficult to clean samples, there is a standard volume stainless steel cell, as well as a large volume stainless steel cell.

The NANOTRAC WAVE II Zeta particle analyzer has a special reusable zeta cell with an electrode for running zeta potential measurements. Sample cells listed for the Wave II are also compatible with the zeta model.



Ideal for Nanoparticle & Zeta Potential Analysis

The measurement of zeta potential in the NANOTRAC WAVE II particle size analyzer takes advantage of the same Frequency Power Spectrum methodology used for measuring nanoparticle size distributions. The same stable optics sample interface means no adjustments are required. The backscatter and laser amplified detection signals are collected as in the size measurement, and the rapid sequencing of applied electric fields prevents electroosmosis. The optical probe surface is coated to provide electrical contact with the sample. Two probes are used, one to determine the polarity of the particle charge at the slipping plane and one to measure the mobility of the particles in an electric field. Polarity is measured in a pulsed electric field, while mobility is measured in a high frequency sine wave electric field excitation. The zeta cell has two detection probes, on opposite sides, to detect polarity and mobility.

From the linear frequency power spectrum distribution (PSD), the Loading Index (LI), which is proportional to particle concentration, can be calculated. Loading Index values provide a single number for total scattering that can be used to determine particle mobility in microns / sec / volt / cm and particle polarity as + / -, positive or negative.

Measuring mobility and zeta potential begins by measuring the PSD and determining the LI with the excitation off. Then the PSD is measured with the high frequency sine wave on and a ratio is taken. Polarity is determined by measuring the LI before and after pulsed DC excitation. A ratio of LI after the excitation divided by LI before excitation of less than one is a positive polarity (concentration decreasing) and a ratio greater than one is negative (concentration increasing) for a positively charged probe surface.

Mobility = C x (ratio of [PSD(on) – PSD(off)] / LI(off)
Zeta Potential ∝ Mobility


Typical Applications

Versatility is a great strength of Dynamic Light Scattering (DLS). This makes the method suitable for a variety of applications in both research and industry, such as pharmaceuticals, colloids, macroemulsions, polymers, industrial minerals, inks and many more.