Highly Accurate Zeta Potential Measurements of Concentrated Solutions

Patented FST technology utilizes a transparent electrode to minimize path length and reduce multiple scattering effects. This technology permits accurate zeta potential measurement in a wide concentration range of 0.00001 to 40% (w/v) unique to the ELSZ-2000, eliminating the need to dilute samples.

True Determination of Electrophoretic Mobility

The ELSZ-2000 negates the effects of electroosmosis by measuring zeta potential at five different locations within the cell. As a result, the instrument can calculate and accurately measure true electrophoretic mobility, resulting in a highly accurate determination of zeta potential. This also provides the ability to determine multi-modal distributions of zeta potential mixtures.

Broad Particle Sizing Range with Increased Sensitivity

The ELSZ-2000 has a dynamic sizing range of 0.1 nm to 12.30 µm in a concentration range of up to 40% w/v, and a sensitivity for molecular weight to as low as 250 Da. Dual correlators, log-scale for larger particles prone to time decay and linear scale for small particles, provide high sensitivity measurements in multicomponent samples.

Wide Range of Measuring Cells

The ELSZ-2000 features a wide range of measuring cells available for both zeta and nano particle size measurements. Included is a unique solid sample cell for zeta potential measurement of coated surfaces, films or treated glass slides.

ELSZ-2000 Sample Cells

The ELSZ-2000 has an array of compatible sample cells for both zeta potential and nano particle size measurements. Each sample cell provides additional measurement capabilities of samples in liquid suspensions

Concept of FST Method

FST – Electrophoretic mobility measurement of concentrated suspension using orward cattering through ransparent electrode. By conventional methods, scattered light from a concentrated suspension cannot be measured correctly due to multiple scattering (A). The FST method detects the scattered light from particles through a transparent electrode. The optical path length is minimized to reduce the effects of multiple scattering. Thus, the ELSZ-2000 can perform a zeta potential measurement of a concentrated suspension with a high degree of accuracy (B).

Determination of True Electrophoretic Mobility

When the measurement of electrophoresis is actually taken, an electroosmotic current is generated in the cell due to an electric charge on the cell wall. With a negatively charged cell wall, the electroosmotic flow phenomenon causes the positively charged ions and particles to gather together by the cell walls. The solution located by the cell walls migrates toward the negative electrode during electrophoresis. The solution located in the cell center moves in the opposite direction (toward the positive electrode) to compensate for the flow by the cell walls.

Therefore, an electroosmotic flow is created during electrophoresis. The ELSZ-2000 is designed to measure electrophoretic mobility at several points in the cell to obtain a position (i.e. static) not influenced by electroosmotic flow. As a result, the instrument can calculate and accurately measure electrophoretic mobility, even if the electroosmotic profile of the system is asymmetrical due to adsorption or sedimentation of the sample.

Evaluation of the Surface charge of Solid Sample by Zeta Potential

Novel method to measure the zeta potential of solid surfaces using probong particles.

• Surface charge of the solid sample can be evaluated. Determination of electrostatic interactions between particles and flat surfaces
• Easy to use. Large sample size, min: 14 x33mm, Max: 16 x37mm up to 5mm thickness.
• Solid surface modifications analysis, addictive effect studies and particle adhesion. Zeta potential vs. Ph/additives volume also available
• Wide sample application. Soft sample like fibres can also be measured.

Molecular Weight Determination of Macromolecules with ELSZ-2000:

There are two modes of MW determination of  macromolecules provided by the ELSZ200. The first method is by using dynamic light scattering (DLS) size information with the use of Mark Houwink Sakurada equation and the second method is by using Static Light Scattering techniques (SLS)

The first method uses the diffusion constant obtained from the DLS analysis and by providing two empirical constants associated with the macromolecules–solution under analysis; the molecular weight can be calculated from the Mark Houwink Sakurada equation.

The second method is using Static Light Scattering information in the determination of the Molecular weight of any macromolecules in solution. The scattering intensity is a function of the molecular weight and the concentration of the macromolecule solution as described by Rayleigh equation.

The Scattering intensity of a series of macromolecules solution with known concentrations is being measured. Using a Debye plot, Molecular weight can be calculated by a linear extrapolation line from the Debye Plot.