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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 m 2 /V·s. The NanoBrook ZetaPALS covers this full range, of course, and extends it by a factor of 1000 in sensitivity!
Surface Zeta Potential - Principles of Operation
The Surface Zeta Potential feature allows the user to measure the electrical charge on materials like coated glass, plastic, tape, or other flexible surfaces. A series of measurements are taken on probe particles at different distances from a surface and the Surface Zeta Potential is calculated as shown:
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.
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.
Electrophoretic Mobilities Determined with the NanoBrook ZetaPALS
(units 10-8 m2 /V·s)
Sample PALS Result Lit. 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 N.A. Dispersed in dodecane TiO2 0.255 ± 0.010 N.A. Dispersed in toluene - not dried TiO2 0.155 ± 0.011 N.A. Dispersed in toluene - dried TiO2 -0.503 ± 0.015 N.A. Dispersed in ethanol Casein -0.025 ± 0.002 N.A. Dispersed in PEG - viscous SiO2 -0.73 ± 0.04 N.A. Dispersed in 2.0 M KCl - High salt
The software can be easily customized to display the columns needed for a quick review of the important parameters as shown below
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.
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 1 nm to 100 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 40 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
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-SZP Surface Zeta Potential
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 Or 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.