Brookhaven - NanoBrook 90Plus PALS Zeta Potential Analyzer

NanoBrook 90Plus PALS

90plus pals 140x140

Zeta Potential Analyzer using Phase Analysis Light Scattering

Features at a glance

Zeta potential for the difficult cases

For proteins, peptides, mAb, RNA, and other biological samples

For zeta potential in organic solvents

For oily or viscous media

For high-salt suspensions

For samples near the I.E.P.

1,000 times more sensitive than other techniques

Disposable cuvettes, no contamination or alignment

Built in automatic procedures and parameters (SOP)

Easy to use

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

For measurements of very low mobilities, the NanoBrook ZetaPALS is the answer. The only answer! With concepts developed at Bristol University and Brookhaven Instruments, the NanoBrook 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 NanoBrook ZetaPlus. Such measurements cover the range of typically ± (6 to 100) mV, corresponding to mobilities of ± 0.5-8x10-8 m2 /V·s. The NanoBrook ZetaPALS covers this full range, of course, and extends it by a factor of 1000 in sensitivity!

Principles of Operation

The NanoBrook 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 or denaturation. This is due to the fact that the measurement analyzes the phase shift. The particles need only to move a fraction of their own diameter to yield good results. In salt concentrations up to 2 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.

zetapals ps graph

Figure 1

Simple Clear Presentation

Figure 1 above shows the results of an actual experiment with a NanoBrook 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 expermental curve (red, bold) and it's fitted version (red, thin). As with all Brookhaven instruments the user can simply produce a customized report.

Multiple Sample Types

Table 1 below shows a variety of difficult to measure samples, all of which were easily measured with the NanoBrook ZetaPALS. Some were measured in high salt concentration; some in low dielectric constant non-polar solvents; and one in a viscous liquid.

Custom Columns

The software can be easily customized to display the columns needed for a quick review of the important parameters as shown below

zetapals ps columns

Figure 2

Something More Challenging

Of course the NanoBrook 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:

Biological samples such as proteins, antibodies, peptides, DNA/RNA are easily denatured by electrical fields. The NanoBrook ZetaPALS can successfully measure the mobility of biological samples with typical voltages from 2 to 4 Volts. In Figure 1 above, Lysozyme was measured with 2.5 Volts applied.

Aggressive Solventssuch as DMF, THF, DMSO, MET, etc. are easily accomodated by Brookhaven's NanoBrook 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 NanoBrook ZetaPALS. Some examples of this are shown in Table 1.

High salt concentrations difficult to measure due to the Joule heating and energy dissipated. The power applied in high salt has to be kept low in order to avoid affecting the sample. Only Brookhaven's NanoBrook ZetaPALS can measure in salt conditions up to 2 Molar. An example is shown in Table 1.

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

Typical Applications

Liposomes and biocolloids

Proteins, IgG, peptides, RNA/DNA

Ceramics and refactories

Pigments and inks


Emulsions (foodstuffs, cosmetics)

Wastewater treatment monitoring


Carbon blacks

Sample Type: Most proteins, nanoparticle and colloidal-sized materials, suspended in any non-absorbing liquid, with relative permittivity (dielectric constant) > 1.5 viscosity < 30 cP

Size Range: 0.3 nm to 6 µm diameter, sample dependent

Mobility range: 10-11 to 10-7 m2 / V * s

Zeta potential range: -500 mV to 500 mV, sample dependent

Sample cells: 180 µL, 600 µL, 1250 µL

Maximum sample concentration: 40% v/v, sample dependent

Maximum sample conductivity: 220 mS/cm, covering saline and PBS solutions for proteins, sample dependent

Signal processing: Electrophoretic & true Phase Analysis Light Scattering, ELS & PALS

Precision: ± 3%, depending on salt concentration

Temperature control range: -5 °C to 110 °C ± 0.2 °C

Condensation control: Purge facility using dry air, nitrogen preferred

Standard laser: 35 mW red diode laser, nominal 640 nm wavelength

Scattering angle: 15°

Data Presentation: Doppler Frequency Shift, electrophoretic mobility, zeta potential suing Smoluchowski Hückel, or Henry

Power Requirements: 100/115/220/240 VAC, 50/60 Hz, 150 Watts

Diemensions: 23.3 x 42.7 x 48.1 cm (HWD)

Weight: 15 kg

Environmental Characteristics: 

Temperature 10 °C to 75 °C

Humidity 0% to 95%, non-condensing

CE certification: Class I laser product, EN 60825-1:2001, CDRH


BI-ZTU: Autotitrator, 4-pump, pH, temp, conductance for use with acids, bases, surfactants, dispersing agents, salts and other additives to determine the IEP and trend of zeta potential with concentration of additive. BI-ZTU includes one BI-ZELF-P and one BI-ZELF-P/B for use with aqueous samples or BI-ZELF-G and one BI-ZELF-G/B for use in solvents.

BI-ZELF-P: Plastic electrode assembly for use with BI-ZTU in flow mode, including one BI-ZELF-P/B, for use in water.

BI-ZELF-P/B: Box of 2 plastic flow cells for use with BI-ZELF-P. Use in aqueous environments.

BI-ZELF-G: Solvent resistant electrode assembly for use with BI-ZTU in flow mode, including one BI-ZELF-G/B glass cell, for use in solvents.

BI-ZELF-G/B: Additional glass cell for use with BI-ZELF-G

BI-870: Dielectric constant meter improves accuravy when calculating zeta potential in solvent mixtures and speciality solvents.

BI-PALS21: 21 CFR Part 11 software to assist in ERES compliance.

BI-IQOQPQ: Qualification for installaion, operation and performance.


BI-SREL: Solvent resistant electrode assembly for use with BI-SCGO glass cells, inconvenient for use with BI-SCP cells.

BI-SCGO: Box of 10, open-topped glass cells for use with solvents.

When working in saline and other high salt concentrations use one of these electrodes*:

BI-ZEL: Electrode assembly for aqueous systems, use BI-SCP cell, 1.25 mL sample volume.

BI-ZEL2: Electrode assembly for aqueous systems, use BI-SCP cell, 450 µL sample volume


BI-SVE175: Electrode assembly for aqueous systems, with BI-SCP cell, 175 µL sample volume

BI-CC: Nitrogen-purge facility for condensation control

BI-ELECCK: Electrode cleaning kit including wand and polishing strip, for use with BI-ZEL and BI-SREL

BI-ZR5: Zeta reference material for validation, blue pigment for use in water, -(44 ± 8) mV.

*While it is tempting to buy just the solvent resistant electrode assembly and use it with the glass cells (BI-SCGO) in solvents and the plastic cell (BI-SCP) if measuring in saline or other aqueous environments, it is a mistake on two accounts. First, cross-contamination is a problem with small sample volumes such as those found in zeta potential determinations. Second, the solvent resistant assembly has to be small enough to clear the inside dimensions of the glass cells to prevent cracking. It is less convenient when removing the assembly and cells. But the standard BI-ZEL electrode can fit snugly into the BI-SCP cells and so both are convenient to remove when measuring in aqueous-based samples.

Note: Current users of the ZetaPALS may upgrade to include particle sizing and backscatter provided their instrument has the necessary mechanics, optics and hardware. Contact the factory for more information.

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