Particle Size:

Particulates dispersed in a solution are normally subjecto Brownian motion. The motion is slower with larger particles and faster with smaller particles. When laser light illuminates particles under the influence of Brownian motion, scattered light from the particles shows fluctuation corresponding to individual particles. The fluctuation is observed according to the pinhole type photon detection method so that particle size and particle size distributions are calculated.

• Measure particle size of samples suspended in liquids in the range of 0.1 nm to 12.3 µm with sample suspension concentrations from 0.00001% to 40%
• Well-established photon correlation spectroscopy technique conforms to ISO 13321 and ISO 22412
• Combination of linear and log-scale correlators covers diverse sample characteristics
• Variety of sample cells available

Evaluation of Dispersion Stability by Zeta Potential/Particle Size

As the absolute value of zeta potential increases, colloidal systems give generally stable dispersion due to electrostatic repulsion between particles. However, as the zeta potential approaches zeos, the stability of the dispersion reduces and aggregation becomes likely.

Zeta Potential

In most cases, colloidal particles possess a positive or negative electrostatic charge. As electrical fields are applied to the particle dispersion, the particles migrate in oppositely charged directions. As particles are irradiated in migration, scattering light causes Doppler shift depending on electrophoretic mobility. ELSZ-2000 software calculates the amount of Doppler shift followed by electrophoretic mobility and zeta potential by combining a herodyne system and photon correlation method to perform Fourier transform of obtained correlation function.

• Measure zeta potential of sample suspension in the range of -1000 mV to +1000 mV (*no practical limit) with concentrations from 0.001% to 40%
• Reliable measurements based on electrophoretic light scattering technology conforms to ISO 13099-2
• Accurately characterizes both dilute and concentrated suspensions
• Capable of measuring the surface on solid surfaces, film, etc based on probing particles

Determination of True Elecotrphoretic 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 on 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 centre moves in the opposite direction (toward the positive electrode) to compensate for the flow by the cell walls. Therefore, an electroosmotic flow is created uring the electrophoresis. The ELSZ-2000 is designed to measure electrophoretic mobility at several points in the cell to obtain a postion (i.e. stationary point) 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 on the cell walls. The multi-point determination allows for exceptional repeatability and reproducibility.

The ELSZ-2000 is capable of obtaining high resolution zeta potential analyses even with multi-component samples. In the example, a mixture of five polystyrene latexes of different particles were measured. Five spectrums corresponding to each latex component was detected. The zeta potential of these components was in the range of -45 mV to -107 mV.

Evaluation of the Surface Charge of a Solid Sample by Zeta Potential
Novel method to measure the zeta potential of solid surfaces using probing particles.

• Surface charge of solid sample can be evaluated. Determination of electrostatic interactions between particles and flat surfaces
• Easy to use. Large sample size, min: 14 x 33 mm, max 16 x 37 mm up to 5 mm thickness
• Solid surface modification analysis. Additive effect and particle adhesion. Zeta potential vs pH/additive volume also available
• Wide sample application. Soft sample-like fibres can be measured.

Concept of FST Method

By conventional methods, scattered light from a concentrated suspension cannot be measured correctly due to multiple scatering (A) or in very concentrated solutions due to its ability to transmit light. The FST method detects the scattered light from particles through a transparent electrode.

The optical path length is minized 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).

FST: Electrophoretic mobility measurements of concentrated suspension using Forward Scattering Transparent electrode.

Molecular Weight Determination of Macromolecules with ELSZ-2000:

There are two modes of MW determination of macromolecules provided by ELSZ-2000. 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 (SLS) techniques.

The first method uses the diffusion constant obtained from the DLS analysis and by providing two emprical 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 Scatterining 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.

Easy to Use Instrument Control, Data Acquisition, and Suprior Analysis Results

The ELSZ-2000 provides intuitive and powerful instrument control, data acquisition, and data analysis. Our software is designed to enable the user to easily understand instrument control and method development to ensure that your productivity is always fully optimized.

SOP Designer – Intelligent and automatic creation of standard operating procedures

Ensure that you get the best results, regardless of the operator or instrument utilized in an analysis. Our intelligent SOP designer permits you to establish fixed SOPs that generate reproducibile and repeatable results time after time. Simply input in the color-coded conditions for measurement, analysis, cell, and diluent conditions. Name and save your SOP, load your sample, and start your analysis.

Configurable Security Levels

Easily and quickly set up four levels of security for accessing software, data collection, and report generation. Complies with 21 CFR Part 11 requirements.

Easy Data file Back-up

Data back-up is automated. Simply choose the directory, network drive, or wireless data storage device directly from the ELSZ-2000 software. A copy of all data files and SOP parameter files will automatically be backed up at the selected location as soon as it is generated, giving the researcher peace of mind.

Real-Time Analysis Monitoring

Data is presented in real time during analysis. The screen can be customized to present as many graphs and tables as needed to fully characterize the material in real time. Post analysis data files are easy to find, organize and review.

Pre-loaded, Dispersion Liquid Properties

There is no need to research dispersion liquid properties such as refractive index, viscosity and dielectric constants. The ELSZ-2000 Software comes pre-loaded with all common dispersion liquids and required properties for size and zeta potential analysis, including different temperature variations.

Features:

• Automatic unattended operation
• Automatic determination of isoelectric point
• Software control of the titration and measurement provides automatic control through standard operation procedures
• Automatically generated reports and graphs; plot size and zeta potential versus pH value and additive volume

Accessories

The ELSZ-PT is used to titrate sample suspension in a pH range from 1 to 13. The instrument automatically controls the pH of these suspensions and conducts titrations during both zeta potential or nano particle size analysis instruments.