I have metallic nanoparticles in solution form. Can any one suggest best method to find the concentration?
Dear Alagu Thirumurugan,
Au or Ag nanoparticles absorb light in the visible range for example. I guess that particles from other metals will show a similar behavior. Maybe the particular wavelengths of absorption are shifted.
For me it seems to be the easiest way when you use UV-Vis absorption spectroscopy and measure a calibration curve.
Atomic absorption spectroscopy (AAS) can be used to quantify the metallic nanoparticles.... u can carry out this .... if i am rite
Dear Alagu Thirumurugan,
Au or Ag nanoparticles absorb light in the visible range for example. I guess that particles from other metals will show a similar behavior. Maybe the particular wavelengths of absorption are shifted.
For me it seems to be the easiest way when you use UV-Vis absorption spectroscopy and measure a calibration curve.
As Mr. Arthur suggested, the easiest way is by procuring similar commercially available metallic nanoparticles (eg. Silver nanoparticles from Sigma) and plotting a calibration curve with your solvent by measuring its absorbance. However these nanoparticles are available in different sizes eg 10 nm, 40 nm, etc. Different sized particles will have different plasmon resonance and absorbance. So make sure you use the right size. If you can however get a AAS done, that would be more accurate. Hope this helps.
Dear Mr. Alagu Thirumurugan,
I agree with other suggestions. You can use Atomic Absorption Spectrocope (AAS) and UV-Vis. For specific method, I have references for using UV-Vis to identify the concentration of metallic nanoparticles.
We compared UV/vis and AAS/ICPMS+TEM methods a couple of years ago. The results in a nutshell: forget about UV/vis. Much too inaccurate. The enclosed paper is on QDs, but the same applies for metal nanoparticles.
Article Quantitative Analysis of Cadmium Selenide Nanocrystal Concen...
The best and accurate method of testing the concentration is AAS. To check the concentration of metallic nanoparticles using AAS, you need to digest your sample carefully in Aqua Regia which can be obtained by freshly mixing concentrated nitric acid and hydrochloric acid, optimally in a volume ratio of 1:3)
AAS will work great for a consistent and narrow size distribution of highly stable nanoparticles ONLY if the concentration is low or diluted with high accuracy.
The answer is dependent on size and concentration. You can also directly measure it on a Si wafer using SEM. But this requires a highly pure suspension medium (acetone, methanol, ethanol, etc) and a mono-distribution.
I agree with others...if possible, use AAS.
know, it is a fight against wind mills. Particles including nano particles in solution is something which does not exists, like innocent guilty. If particles are dissolved (in solution) they do not have an interface and end to be particles.
Try UV/VIS with standard nanparticle beads (i,e, of known concentration) and then also SEM (or TEM) of a small (known) volume and simply count the particles you see int eh image. Hope this helps & good luck :) :)
If you have enough volume to dispense with, dry and weigh on a micro balance. If you have organics, capping agent or so TGA can clear that.
using AAS or ICPMS can help you to find out the concentration of atomic concentration. But in-case of leaching conditions ICPMS is the preferred.
UV/vis spectroscopy is routinely used to determine the absolute concentration of nanoparticles.
SP-ICPMS simultaneously quantifies the concentration of nanoparticles as well.
If the solution is a stable colloid, you can easily use visible absorption to determine the molar concentration. The extinction coefficients for these metal particles generally size dependent; if you have a relatively monodisperse sample, it should be simple. See figure 2 in the attached manuscript.
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