Brookhaven Zetapotential


alt Explanation of the difference between the ZetaPlus (Laser Doppler Frequency Shift and the ZetaPALS (Phase Analysis) (292 Kb)



ZetaPlusThe BI-ZetaPlus is a laboratory system for determination of mobility of particles using the Laser Doppler shift method. This is the traditional method where the modification of frequency of light interacting with moving particles is measured to calculate zeta potential. As a minimum travelling speed of particles is required to get reasonable signals, this method is limited to aqueous samples of moderate ionic strength.


alt BI-ZetaPlus alt ZetaPlus brochure (451 Kb)




The PALS-method does not measure frequency shift but the phase difference of scattered light compared to a reference beam. As the phase difference is much faster to detect, this method is up to 100 times more precise and repdroducible than the traditional method. Only this method permits determinations in non polar liquids (oils, organic solvents) or highly conductive suspensions (high salt concentrations). 

alt BI-ZetaPals alt ZetaPALS brochure (348 Kb)

Measuring Permittivity with the BI-870BI-870

When calculating the zeta potential from the mobility readings, the value of the dielectric constant of the suspension liquid is required. Values of the permittivity of mixtures that cannot be found in the literature can simply and precisely be determined using the BI-870.


BI-870 Permittivity


BI-870 brochure 

(224 Kb)



BI-ZTU Titration Unit

BI-ZTU titration unit is offered as an accessory for the determination of zeta potential dependences. It enables recording of zeta potential values with changing pH values (determining the iso electric point) or of concentration of wetting agents. The ZTU prepares the sample and pumps it into a flow through electrode unit, control of the system is done through the software of the zeta potential analyzer.


alt BI-ZTU Titrator  alt BI-ZTU Titrator  (116 Kb)