There is no peak in volume and intensity (%) but the Z-average did show that the particles can be detected (DLS). For samples with sizes 0-4 micron, they can be detected very well, but there is no peak appearing in samples with sizes 5-10 micron. I have tried to measure it with different concentration but it still did not work.
What´s is your DLS instrument? If is it the NanoSizer of Malvern, the answer is obvious. The range size of measurement is 6 microns.
the instrument is HPPS (Malvern). But when I suspend the particles into water, it did work. it did not work when the particles were suspended into octane.
have you corrected the refractive index in the software for your solvent and nanoparticles? The data you get from the Malvern software are just "number" from anything it could fit...
The diamond particles with size over some microns sediments in water very fast. The DLS measurements of this object will be not correct. You may try use some high viscosity liquid for DLS measurement.
We use Malvern Mastersizer 2000 (based on Rayle scattering) for this measurements. Continous circulation of liquid uses in this instrument for prevention of particles sedimentation in sample.
Some materials in this topics you may find in
http://www.malvern.com/
Basically, in the DLS measurement, Brownian motion is observed by monitoring the scattering laser beam fluctuation. In your case, Brownian motion of 5-10 micron particle should be too weak to be detected.
You should change the detection method from DLS to Laser Scattering ( Fraunhofer diffraction pattern analysis ) or Coulter Counter technique. The latter is better for quantitative analysis.
Maximum range of measurement for DLS Zetasizer Nano series (Malvern) is 0.6nm to 6µm. Check which series you are using. Good luck.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanoparticle Research