Brookhaven - NanoBrook 90Plus Zeta Particle Size Analyzer

NanoBrook 90Plus Zeta

90plus l6 140x140

Particle Size & Particle Size Analyzer

Features at a glance


Rapid and accurate particle size distributions

Multimodal & unimodal size distribution software

ISO 13321 and ISO 22412 compliant results

Range > 0.3 nm to 6 µm

Customizable reports

Ideal for fast, routine sizing applications in research or quality control

High power 35 mW diode laser

Dynamic light scattering at 90°

Temperature control, -5 °C to 110 °C

Compact bench top unit, USB connection


Zeta potential in low salt aqueous solutions/suspensions

Accurate, rapid, easy to make zeta potential determination

One piece, easy-fill disposable sample cells

No cell alignment or calibration

Zeta potential at 15°

Temperature control, -5 °C to 110 °C

Customizable reports, two parameter plots, graphical overlays

Can resolve multi-modals

Built in automatic procedures and parameters SOP

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Brookhaven's NanoBrook 90Plus Zeta instrument combines our NanoBrook 90Plus and NanoBrook ZetaPlus instruments into one versatile package for routine sizing and zeta potential analysis. It employs Dynamic Light Scattering (DLS) for particles/molecules size and Electrophoretic Light Scattering (ELS) for particles/molecules surface charge evaluation. This package not only allows rapid measurements of the effective size and zeta potential of samples, but also provides further information on multimode distribution in size and surface charge in polydisperse samples. Based on the proven technologies of Brookhaven, the NanoBrook 90Plus Zeta guarantees excellent mobility measurement performance in aqueous suspensions and low salt environments.


Simple fluids like water (low viscosity), glycerin (high viscosity) are Newtonian and exhibit viscosity effects, the dissipation of energy when particles move in such fluids. But dissolve macromolecules in these liquids –synthetic or biopolymers—and networks can form. In addition to viscosity effects, there are now elasticity effects, the storage of energy when embedded particle move. By following the mean square displacement (MSD) of tracer (probe) particles in such fluid and microrheological properties such as η*, the complex viscosity, G″, the viscous loss modulus, and G′, the elastic storage modulus, can be determined as a function of frequency.

Measurement of the autocorrelation function (ACF) using DLS techniques yields the MSD of tracer particles, which, under the right conditions, can be used to determine η*, G″, and G′ over a range of frequencies much higher than mechanical rheometers can attain. Much smaller sample volumes, in the microliters, are possible compared to mechanical instruments. Finally, since strains result from the thermally driven motion of tracer particles, these much smaller strains allow the study of fragile samples. The study of viscoelasticity in aggregating dilute protein solutions is a prime example of the benefits of DLS microrheology.

Reliable, Accurate, and Accurate Analysis

The new NanoBrook 90Plus Zeta particle analyzer incorporates all you need for fast, routine, sub-micron measurements of size and zeta potential. Based on the principles of Dynamic Light Scattering (DLS) for particle sizing and distribution, and based on electrophoretic light scattering (ELS) for zeta potential measurements, most measurements only take a minute or two. Please see the 90Plus PALS for instruments combining sizing and PALS zeta potential.

Two Scattering Angles:

Size measurements will be made at the 90° scattering angle. Zeta potential measurements are always done using the 15° detection angle to minimize diffusion broadening.

Principles of Operation - Particle Sizing using DLS

Dilute suspensions, on the order of 2 ppm to 50 mg/mL are prepared, using suitable wetting and/or dispersing agents. A small ultrasonicator is sometimes useful in breaking up loosely-held agglomerates. Two or three mL of suspension is required to make the measurements. Disposable, polystyrene square cells are used for aqueous and simple alcohol suspensions. Disposable, glass round cells with reusable Teflon stoppers are used for aggressive solvent suspensions. Just a few minutes are required for the sample and cell to equilibrate with the actively controlled temperature environment inside the NanoBrook 90Plus Zeta.A square glass cell is available if desired and special small-volume cells may be used to reduce the volume of material needed to just 50 µL or 10 µL. For aqueous samples the 50 µL is a disposable cuvette. In all cases the sample is recoverable. For very small particles the high-sensitivity BI-APD detector is invaluable.

90Plus reproducability graph

Figure 1


Perhaps the most important benefit for users is the reproducibility from sample-to-sample, operator-to-operator, and instrument-to-instrument. The figure above shows the repeatability of the results obtained by one instrument for a silica (LUDOX) sample. Notice the Std. Error of the Effective Diameter is less than ½% of the mean of the six repeated runs. Such excellent repeatability is typical of the NanoBrook 90Plus Zeta for even routine QC analysis and ensures product quality time-after-time.

The table to the right shows several aspects of the inter-instrument reproducibility found with routine Brookhaven dynamic light scattering equipment. To test the reliability of the information obtained with Brookhaven Instruments a customer subjected five instruments in five locations with different operators and using four different samples to examination. This table shows excellent reproducibility with recognized standard materials and superb internal agreement. You can be confident of the results you get with your NanoBrook 90Plus Zeta!

Data Presentation

The NanoBrook 90Plus Zeta particle size and zeta potential analyzer offers three choices. For routine determinations an average diameter (Eff. Dia.) and a measure of the distribution width (Polydispersity) are sufficient for many applications. The second choice is to fit these values to a lognormal distribution, allowing the user to visualize the size distribution and to interpolate cumulative and differential results at 5% intervals.

92 and 269 bimodal

Results from Test Bimodal Sample on NanoBrook 90Plus Zeta (diameters, in nm)

The figure above shows an example of the third choice, suitable for more complicated, multimodal size distributions. Here, a numerical algorithm, including Mie theory, is used. These results are for a mixture of known latex particles. Positions of the measured particle sizes on the accompanying graph are in excellent agreement with the known sizes of 92 and 269 nm.

During a measurement, the display can be switched interactively between any one of these -- correlation function, lognormal, or multimodal -- each shown "live" as data are accumulated. The live display is particularly useful in determining the end-point of a measurement where multimodal distribution shape may be important.

Reliable, Accurate, Easy to Use

The NanoBrook 90Plus Zeta is the simplest and most accurate particle electrophoresis system available. This revolutionary instrument has been designed to eliminate the shortomcing inherent in other zeta potential instruments. The 90Plus Zeta software is simple and intuitive to operate but yet offers flexibility and a full range of means for those that whish to tune their experiments to specific circumstances.

The screen image shown below indicates the clear and concise presentation. Information obtained from the sample is updated in real time and the use rcan select from several display formats. A literature of physical constants for many usual suspending fluids is provided but the user may provide their own values if desired. Printed reports are fully customizable.

zetaplus ps graph

Comprehensive Information

The NanoBrook 90Plus Zeta measures complete electrophoretic mobility distributions in seconds including multimodals (an example of bimodal zeta potential sample can be seen on the result screen from analyzing a created mixture of charged particles.)

In the example below the results of analyzing a mixture of alpha and gamma Aluminas in 1 mMolar KCI at pH10 is displayed. The left peak is identified with the green curosr and shown to have a zeta potential of -75 mV. If the other peak is chosen the value given is -5.00 mV. The ability of the NanoBrook 90Plus Zeta to provide this informatino distinguishes it from other methods which provide only an ensemble average.

ELS Biomdal zeta

Derive Extended Information

The user can tabulate or graph any appropriate pair of parameters allowing, for example, the determination of the iso-electric point (IEP) as in the example below. The NanoBrook 90Plus Zeta is provided with a pH probe that can be used to measure this value.

ps zeta potential graph

Unique Cell Design

The unique cell configuration eliminates the electroosmotic effect: No stationary levels, no alignment, and no calibration are required; as evidenced by the excellent agreement with NIST1980, a standard reference material. The NanoBrook 90Plus Zeta uses low cost, disposable sample cells. There is no assembly or maintenance required: Cross contamination is eliminated. Glass and quartz cells are available optionally. The same basic cell design is used with the NanoBrook 90Plus Zeta, ZetaPALS, 90Plus PALS, and Omni.

Sample Type: Sizing: nanoparticle and colloidal-sized materials, in any non-absorbing liquid., Zeta potential: nanoparticle, polymer and colloidal-sized materials, suspended in any non-absorbing liquid, with relative mermittivity (dielectric constant) > 20 and viscosity < 5 cP.

Size Range: Sizing:  > 0.3 nm to 6 µm, dependinjg on refractive index and concentration., Zeta potential: 1 nm to 100 µm, sample dependent.

Mobility range: 10-9 to 10-7 m2 / V * s

Zeta potential range: -220 mV to 220 mV, sample dependent

Maximum sample conductivity: Sizing: Unlimited, Zeta potential: 7.5 mS/cm

Sample Cells: Sizing:1 to 3 mL disposable plastic, 50 µL disposable, 40 µL quartz flow cell, 10 µL quartz minimum, Zeta potential: 180 µL, 600 µL, 1250 µL

Concentration range: Sizing: 2 ppm to 50 mg/mL, depending on refractive index and concentration, Zeta potential: 40% v/v, sample dependent

Signal processing: Sizing: Dynamic Light Scattering, DLS, Zeta potential: Electrophoretic Light Scattering, ELS

Correlator: Brookhaven's TurboCorr, multitau, research grade with 510 hardware channels, covering the equivalent of the 1010 linearly-spaced channels, 100% efficiency, real-time oepration over the entire delay-time range.

Precision: Sizing: ± 1% typical, Zeta potential: ± 3% typical

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° & 90°

Data Presentation: Average & wdith, lognormal fit, and multimodal size distribution for sizing. Doppler Frequency Shift, electrophoretic mobility, zeta potential using Smoluchowski, Hückel, or Henry.

Compliance: ISO 13321 and ISO 22412 compliant results for sizing

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

Dimensions: 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

Notes: (*) Sample type dependant

A policy of continual improvement may lead to specification changes.

Options for particle sizing at 90°

BI-APD: Avalanche photo diode, up to 10 times the sensitivity

90PDP: Absolute molecular weights of polymers in solution. Option includes µL flow cell (90PFC) and Debye plot software, requires BI-APD. Relative molecular weight calculated from the DLS determination of the diffusion coefficient is standard.

BI-PSD21: 21 CFR Part 11 software to assist ERES compliance sizing only.

BI-IQOQPQ: Qualification for installation, operation and performance for sizing and zeta.

BI-SFS: Sample filtration system provides fast and convenient way to clean your light scattering samples, a necessity for samples smaller than 20 nm. Utilizing Teflon® tubing and nonreactive components, the BI-SFS is compatible with most sample filtration needs provided there is at least 5 mL of liquid. For protein and other rare samples, use 20 nm BI-DF20AQ Anatop filters instead.

Lasers: 5 or 10 mW, HeNe laser at 632.8 nm wavelength, 50 mW and higher powered, frequency-doubled solid state lasers at 532 nm wavelength

Accessories for particle sizing at 90°


BI-SCP: Box of 100 plastic cells with caps, 2.2 to 4.5 mL volume. Use with water, for sizing and zeta.

BI-RCG: Box of 250 round glass cells with 25 reusable Teflon caps, 1.9 to 4 mL volume. Use with solvents, requires BI-RCH.

BI-RCH: One round cell holder for use with BI-RCH

BI-SM50: Box of 80 plastic cells, disposable, 50 µL volume, sample retrievable, requires Bi-SM50A. Use with water.

BI-SM50A: One sample cell adaptor for use with BI-SM50.

BI-SM10: One 10 µL quartz cell for sizing of small and rare samples, sample is retrievable.

90PFC: Additional 40 µL quartz flow cell for use with 90PDP

Reference Materials: 

BI-LTX92: Latex reference material for validation of sizing, 15 mL, 92 ± 3 nm

BI-SVK92: Starters validation kit for sizing, 2 mL, 92 ± 3 nm

BI-CC: Nitrogen-purge facility for condensation control

Options for zeta potential

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.

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

BI-ZELF-P/B: Box of 2 plastic flow cells for use with BI-ZELF-P

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

Accessories for zeta potential

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-SCP: Box of 100 plastic cells, use with BI-ZEL electrode assembly and aqueous samples.


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

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.

Note: Current users of the 90Plus Zeta may upgrade to include PALS and backscatter provided their instrument has the necessary mechanics, optics and hardware. Contact the factory for more information.


Polymer latexes

Pharmaceutical preparations

Micelles, Liposomes, Exosomes

Oil/Water and Water/Oil emulsions

Paints and pigments



Pigments, inks and toners

Cosmetic Formulations

Liposomes and biocolloids

Ceramics and refractories

Emulsions (foodstuffs, cosmetics)

Wastewater treatment monitoring

Carbon blacks

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