Zeta Potential Analyzer Using Phase Analysis Light Scattering - NanoBrook ZetaPALS

The NanoBrook ZetaPALS is the answer for measurements of very low mobilities. It literally is the only answer. With theories formulated at Bristol University and Brookhaven Instruments, the NanoBrook ZetaPALS establishes zeta potential using Phase Analysis Light Scattering — a method that is nearly 1,000 times more sensitive than traditional light scattering techniques based on the shifted frequency spectrum.

Electrostatic repulsion of colloidal particles is frequently the key to gaining insight into the stability of any dispersion. A basic, easy measurement of the electrophoretic mobility “even in nonpolar liquids” produces useful information.

Using the NanoBrook ZetaPlus, measurements carried out in water and other polar liquids are easy and quick. Such measurements span the range of usually ± (6 to 100) mV, matching mobilities of ± 0.5-8x10-8 m2 /V·s. The NanoBrook ZetaPALS takes care of this complete range, of course, and spreads it by a factor of 1000 in sensitivity.

  • Zeta potential for the tough cases
    • For proteins, RNA, mAb, peptides, and other biological samples
    • For zeta potential in organic solvents
    • For samples near the I.E.P.
    • For high-salt suspensions
    • For oily or viscous media
  • 1,000 times more sensitive than other methods
  • Integrated automatic procedures and parameters (SOP)
  • Disposable cuvettes, no alignment or contamination

Principles of Operation

The NanoBrook ZetaPALS applies phase analysis light scattering to establish the electrophoretic mobility of charged, colloidal suspensions. In contrast to its cousin, Laser Doppler Velocimetry (LDV) (occasionally referred to as Laser Doppler Electrophoresis (LDE)), the PALS method does not need the application of large fields which may cause thermal issues or denaturation.

In the measurement of phase shift, only the particles need to travel a fraction of their own diameter to produce good results. In salt concentrations up to 2 molar and with electric fields as tiny as 1 or 2 V/cm sufficient movement is induced to obtain outstanding results. Furthermore, the Autotracking feature makes up for the thermal drift.

Simple Clear Presentation

The figure below illustrates the results of a real experiment using a NanoBrook ZetaPALS instrument. The crucial parameters and results can be viewed at a glance. The exceptional agreement of the five runs in this experiment is evident as is the match of experimental curve (red, bold) and its fitted version (red, thin). As with all Brookhaven systems, users can simply generate a tailored report.

Multiple Sample Types

The NanoBrook ZetaPALS was able to easily measure a variety of hard to measure samples mentioned in the table below. A few were measured in low dielectric constant non-polar solvents; some in high salt concentration; and one in a viscous liquid.

Electrophoretic Mobilities Determined with NanoBrook Zeta PALS (units 10-8 m2/v s)

Sample PALS Result Literature Value Comments
NIST 1980 2.51 ± 0.11 2.53 ± 0.12 Electrophoretic mobility standard
Blood Cells -1.081 ± 0.015 -1.08 ± 0.02 Dispersed in physiological saline
Fe2O3 -0.013 ± 0.0015 NA Dispersed in dodecane
TiO2 0.255 ± 0.010 NA Dispersed in toluene - not dried
TiO2 0.155 ± 0.011 NA Dispersed in toluene - dried
TiO2 -0.503 ± 0.015 NA Dispersed in ethanol
Casein -0.025 ± 0.002 NA Dispersed in PEG - viscious
SiO2 -0.73 ± 0.04 NA Dispersed in 2.0 M KCI - High salt



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Sample Type Most proteins, nano particle and colloidal-sized materials, suspended in any non-absorbing liquid, with relative permittivity (dielectric constant) > 1.5 and viscosity < 30 cP.
Size range suitable for zeta measurement 1nm to 100 μm, 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
Signal Processing Electrophoretic & true Phase Analysis Light Scattering, ELS & PALS
Maximum sample conductivity 75 mS/cm, covering saline and PBS solutions for proteins
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
Scattering Angle 15°
Data Presentation Doppler Frequency Shift, electrophoretic mobility, zeta potential using Smoluchowski, Hückel, or Henry
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 Certificate Class I laser product, EN 60825-1:2001, CDRH

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