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Features at a glance
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.
Rapid, Reliable, and Accurate Analysis
The NanoBrook 90Plus particle size analyzer incorporates all you need for fast, routine, sub-micron measurements. Based on the principles of Dynamic Light Scattering (DLS), most measurements only take a minute or two. Choose the optional avalanche photo diode (BI-APD) for weak scatters. The instrument can be upgraded later on to include zeta potential measurement. Please see the 90Plus Zeta and 90Plus PALS for instruments combining sizing and zeta potential.
Principles of Operation
Dilute suspensions, on the order of 0.0001 to 1.0% v/v 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 are required to make the measurements. Disposable, acrylic 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. 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.
Instrument Nom. 90 Nom. 273 Nom. 111 Nom. 400 A 91±1 276±1 110±1 404±4 B 90±1 279±1 108±1 391±3 C 90±1 276±1 109±1 399±3 D 90±1 277±1 110±1 397±3 E - - 112±1 394±3 Ave. 90.3 277.0 109.8 397.0 Std. Err ±0.3% ±0.3% ±0.6% ±0.6%
Test Results from Brookhaven Instruments Particle Size
Analyzers(diameters, in nm)
Perhaps the most important benefit for users is the reproducibility from sample-to-sample, operator-to-operator, and instrument-to-instrument. The table to the right shows the results obtained for polystyrene latex. Notice the Std. Error of the Effective (or Average) Diameter is less than 1% of the mean of the 10 repeated runs. Such excellent repeatability is typical of the NanoBrook 90Plus particle size analyzer for QC analysis and ensures product quality time-after-time. The table also shows several aspects of the inter-instrument repeatability 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 for examination. The table above shows excellent reproducibility with recognized standard materials and superb internal agreement. You can be confident of the results you get with your NanoBrook 90Plus!
The NanoBrook 90Plus particle size 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. This is illustrated above in Figure 1 for the latex with a narrow size distribution. 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.
Figure 2: Results from Test Bimodal Sample on NanoBrook 90Plus (diameters, in nm)
Figure 2 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.
Sample Type Most nanoparticle and colloidal-sized materials, in any non-absorbing liquid Size Range 0.3 nm to 10 µm, depending on refractive index and concentration Sample Cells 1 to 3 mL disposable plastic, 50 µL disposable, 40 µL quartz flow cell, 10 µL quartz minimum Concentration Range 2 ppm to 50 mg/mL, depending on refractive index and concentration Signal Processing Dynamic Light Scattering, DLS Correlator Brookhaven's TurboCorr, multitau research grade with 510 hardware channels, covering the equivalent of 1010 linearly-spaced channels, 100% efficiency, real-time operation over the entire delay-time range Precision ± 1% typically Temperature Control -5 °C to 110 °C, ± 0.1 °C, active control. No external circulator required. Condensation Control Purge facility using dry air, nitrogen preferred Standard Laser 40 mW red diode laser, nominal 640 nm wavelength Scattering Angle 90° Data Presentation Average & width, lognormal fit, and multimodal size distribution standard Compliance ISO 13321 and ISO 22412 compliant results Power Requirements 100/115/220/240 VAC, 50/60 Hz, 150 Watts Dimensions 23.3 x 42.7 x 48.1 (HWD) Weight 15 kg Environmental Characterisitics
Temperature 10 °C to 75 °C
Humidity 0% to 95%, non-condensing
CE Certificate Class I laser product, EN 60825-1:2001 CDRH
Many everyday industrial processes and products involve dispersions. The dispersed phase is often in a state of fine subdivision. The technology to produce these dispersions, to ensure that they perform according to specifications and to solve problems which may arise in production or use, requires a knowledge of the particle size. The 90Plus can handle virtually any type of submicron sample suspended in, or dissolved in, a liquid. Some examples are
- Polymer latexes
- Pharmaceutical preparations
- Oil/Water and Water/Oil emulsions
- Paints and pigments
- Inks and toners
- Cosmetic Formulation
Avalanche photodiode, up to 3 times the sensitivity of an APD and up to 5 times the sensitivity of a PMT
Absolute molecular weights of polymers in solution. Option includes 40 µL flow cell (90PFC) and Debye plot software. 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. BI-IQOQPQ Qualification for installation, operation and performance. 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 Additional options available; contact us for more information.
BI-SCP Box of 100 plastic cells with caps, 2.2 to 4.5 mL volume. Use with water. 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.
BI-LTX92 Latex refernece 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.
Note: Current users of the 90Plus may upgrade to include zeta potential and backscatter provided their instrument has the necessary mechanics, optics and hardware. Contact the factory for more information.