Zeta Potential Analysis

Features at a glance

• Zeta potential for the difficult cases...
  • In organic solvents
  • In oily or viscous media
  • In high-salt suspensions
  • Near the I.E.P.
• 1000 times more sensitive than other techniques
• Disposable cuvettes, no contamination or alignment
• Built in automatic procedures and parameters
• Easy to use
• Upgradable to include full particle sizing functionality

A whole new concept.....
Unique to Brookhaven! For the difficult cases

For measurements of very low mobilities, the Brookhaven ZetaPALS is the answer. The only answer! With concepts developed at Bristol University and Brookhaven Instruments, the ZetaPALS determines zeta potential using Phase Analysis Light Scattering: A technique that is up to 1,000 times more sensitive than traditional light scattering methods based on the shifted frequency spectrum.

Electrostatic repulsion of colloidal particles is often the key to understanding the stability of any dispersion. A simple, easy measurement of the electrophoretic mobility "even in nonpolar liquids" yields valuable information. Measurements made in water and other polar liquids are easy and fast with the Brookhaven ZetaPlus. Such measurements cover the range of typically ±6 - 100 mV, corresponding to mobilities of ± 0.5-8x10^-8 m² /V·s. The ZetaPALS covers this full range, of course, and extends it by a factor of 1000 in sensitivity!
Principles of Operation

The ZetaPALS utilizes phase analysis light scattering to determine the electrophoretic mobility of charged, colloidal suspensions. Unlike its cousin, Laser Doppler Velocimetry (LDV) (sometimes called Laser Doppler Electrophoresis (LDE)), the PALS technique does not require the application of large fields which may result in thermal problems. Because in the measurement of phase shift, the particles need only to move a fraction of their own diameter to yield good results. In salt concentrations up to 3 molar and with electric fields as small as 1 or 2 V/cm enough movement is induced to get excellent results. In addition, the Autotracking feature compensates for thermal drift.

Simple clear presentation

The screen image above shows the results of an actual experiment with a ZetaPALS instrument. The important parameters and results are seen at a glance. The excellent agreement of the five runs in this experiment is obvious as is the match of experimental curve (red) and it's parametrized version (black). As with all Brookhaven instruments the user can simply produce a customized report using the supplied color printer.

Something more challenging

Of course the ZetaPALS can quickly and easily yield results from all "regular" samples but its real strength is in the difficult cases and to demonstrate the performance of this premium instrument where others fail we offer the following table.

Aggressive solvents such as DMF, THF, DMSO, MEK etc are easily accommodated by the Brookhaven ZetaPALS system with the use of our special solvent resistant electrodes and glass sample cells. The extension of zeta potential measurements into the realm of such systems is just another standout property of the Brookhaven ZetaPALS.

Unusual solvent? If your solvent is unusual then it's dielectric constant is probably unknown. In this case our BI-870 DielectricConstant Meter will quickly easily and accurately provide the information necessary for a zeta potential measurement.

Additional Capabilities

Of course every ZetaPALS system also contains a complete ZetaPlus system and this has the special ability to characterize multimodal zetapotential distributions if they exist.

The ZetaPALS instrument is also available with the full capability of our 90Plus particle sizer and this combination instrument provides a benchtop particle characterization center of great power.

Typical Applications

• Liposomes and biocolloids
• Ceramics and refractories
• Pigments and inks
• Pharmaceuticals
• Emulsions (foodstuffs, cosmetics)
• Wastewater treatment monitoring
• Latexes
• Carbon blacks

Specifications

Zeta Potential	Size range for measurement	1 nm to 100 µ
	Mobility range	10-11 to 10-7 m2/V*s
	Zeta potential range	-220 mV to 220 mV (*)
	Maximum sample concentration	10% v/v (*)
	Sample volume	180 µL, 600 µL, 1250 µL
	Maximum sample conductivity	30 S/m
	Signal processing	Phase Analysis Light Scattering, PALS
Particle Size	Size range (radius)	< 0.3 nm to > 3 microns (*)
	Sample volume	10 µL, 40 µL, 1 - 3 mL
	Concentration range	0.1 mg/mL to 10% v/v (*)
Molecular Weight	Molecular weight range (estimated from hydrodynamic diameter)	1 KDa to 25 MDa
	Molecular weight range (calculated using Debye plot) requires BI-APD	1 KDa to 25 MDa
	Minimum sample volume	10 µL
General	Temperature control range	-5 °C to 110 °C, ± 0.2 °C
	Measurement angles	Three angles, two for particle sizing one for zeta potential
	Condensation control	Purge facility using dry air, nitrogen preferred
	Standard laser	35 mW red diode laser, nom 660 nm
	Correlator	TurboCorr, 25 ns min, 100% real-time, 100% eff.
System Compliance	CE certification	Class I laser product, EN 60825-1:2001, CDRH
System	Dimensions	23.3 cm x 42.7 cm x 48.1 cm (HWD)
	Weight	15 kg
	Power	100/115/220/240 VAC, 50/60 Hz, 150 W max
Notes: (*) Sample type dependant.

A policy of continual improvement may lead to specification changes.

Options and Accessories

Accessories	BI-ZTU, Autotitrator	4-pump, pH, temp, conductivity, additive
	BI-870, Dielectric constant meter	Improves accuracy for solvent mixtures for enhanced zeta potential determination
	Uzgiris cell	Standard, eliminates electro-osmosis completely
Options	Lasers	HeNe 632.8 nm, Freq. Doubled 532 nm
	BI-MAS	Required for particle size measurements
	BI-APD	Detector required for molecular weight measurements
	90PDP	Required for Debye plot measurements
	Narrow band filters	632.8 nm, 532 nm to block fluorescence
	Flow mode option	90PFC flow cell allows DLS size for GPC/SEC
	21 CFR part 11 software option	Software assists ERES compliance
	Research software option	BI-DLSW/BI-ISDAW allows more fitting algorithms