Electrophoretic Light Scattering Zeta Potential Analyzer

What is the Electrophoretic Light Scattering Zeta Potential Analyzer?

A laser Doppler electrophoresis instrument that measures particle mobility in an applied field and converts it to zeta potential. It serves dilute aqueous and organic dispersions from about 3 nm to 100 µm and is the standard general-purpose choice for colloid stability work.

Overview

The analyzer directs a laser beam through a dip cell or capillary cell fitted with two electrodes. An alternating or reversing electric field makes charged particles migrate, and the frequency shift of scattered light, measured against a reference beam, gives velocity. Field reversal reduces electro-osmosis errors and electrode polarisation. Mobility is converted to zeta potential using the Smoluchowski or Hückel limits or the Henry function. Typical instruments cover roughly 3 nm to 100 µm, conductivity up to about 200 mS/cm with suitable cells, and temperature from 0 to 90 °C. The measurement needs 0.75 to 1 mL in a disposable folded capillary cell. Basic models report zeta potential and mobility only, while many units combine a dynamic light scattering module for size. This variant is reliable for moderate mobility but can be limited in high-salt media where PALS is superior.

How does it work?

Charged particles in a liquid are surrounded by an electrical double layer. The zeta potential is the potential at the slipping plane of this layer, and cannot be measured directly. Electrophoretic light scattering applies an electric field and measures particle velocity from the Doppler shift of scattered laser light; electrophoretic mobility is then converted to zeta potential by the Smoluchowski or Hückel approximation, or the Henry function for intermediate cases. Phase analysis light scattering improves sensitivity by measuring phase rather than frequency shift. Streaming potential instruments force electrolyte through a capillary or plug and measure the generated potential difference for solids. Electroacoustic methods detect sound waves generated by an applied alternating field in concentrated suspensions. Key components include the laser, electrodes and cell, temperature control and often a titrator.

What are the key features?

• Laser Doppler velocimetry with heterodyne reference beam
• Field reversal to limit electro-osmosis and polarisation
• Disposable folded capillary cell for low cross-contamination
• Peltier temperature control from 0 to 90 °C
• Smoluchowski, Hückel and Henry model selection in software
• Optional combined dynamic light scattering size module

What are the technical specifications?

A typical electrophoretic light scattering zeta potential analyzer configuration offers size range of 3 nm–100 µm, zeta potential range of −500 to +500 mV, mobility range of ±20 µm·cm/V·s, laser of 633 nm, ≥ 4 mW, electric field of Up to 150 V/cm, alternating and conductivity range of 0–200 mS/cm. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Electrophoretic Light Scattering Zeta Potential Analyzer is used in emulsion and suspension stability screening, polymer latex charge characterisation, water treatment coagulant dosing studies, clay and mineral dispersions and pharmaceutical nanosuspensions. Across the wider Zeta Potential Analyzers class, laboratories also deploy it for colloidal stability of emulsions and suspensions, protein and biologic formulation screening and water and wastewater coagulation control.

Which standards and certifications apply?

Relevant standards and methods include ISO 13099-1, ISO 13099-2, ISO 13099-3, ASTM D4187, GB/T 32671 and ISO 13320. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Zeta potential depends on pH, ionic strength, temperature and sample history, so each report should state dispersant, pH, conductivity and temperature. Use low-conductivity, filtered dispersants and avoid bubbles at the electrodes; high salt can cause electrode polarisation and sample heating. Verify performance periodically using a zeta potential transfer standard, typically around −42 mV, and follow the supplier's interval. Clean cells thoroughly, since contamination and electrode degradation alter results. Gold or palladium electrodes and disposable capillary cells simplify maintenance. For regulated use, carry out IQ/OQ/PQ and maintain audit trails. Report the model used to convert mobility to zeta potential.

How do I select the right Electrophoretic Light Scattering Zeta Potential Analyzer?

Choose this variant for dilute aqueous or organic dispersions with moderate mobility and salt content where routine zeta screening is the goal. Specify the size and conductivity range, solvent and dielectric constant, cell type, whether combined DLS sizing or a titrator is wanted, and audit-trail software needs. For high-salt or low-mobility samples, compare with the PALS variant.

How does it compare with other Zeta Potential Analyzers variants?

Begin with the sample type. Dilute colloids and macromolecules suit electrophoretic light scattering; very low-mobility or high-conductivity samples benefit from phase analysis light scattering. Concentrated opaque suspensions, such as slurries, need electroacoustic methods, and flat or fibrous solids need streaming potential. If isoelectric point or pH dependence is required, choose a system with an automatic titrator. Check the required size range, conductivity limits, minimum sample volume and whether non-aqueous solvents are used, since the dielectric constant must be known. Decide if zeta potential alone is enough or whether combined size measurement is needed. Also weigh software validation support, cell durability and cost of disposable cells, and whether ISO 13099 conformity is expected in your methods.