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 |
Specifications
| . |
. |
| 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 |