We have magnetite spheres that are polystyrene coated and I wish to get analysis that tells me the concentration before and after magnetic recovery.
Can the above mentioned techniques work?
The count-rates (DLS) will give you a qualitative comparison. In any case magnetite has a strong optical absorption at ca. 600 - 650 nm. UV-Vis spectroscopy to get extinction coefficient (at a well selected wavelength) is the most accurate and hassle-free method for you I guess. It is important for both these techniques, to have a stable dispersion both before and after recovery.
For scattering measurements the Rayleigh approximation tells us that Ι α d6 to the power 6.... so the counts of the DLS equipment are related to that... So it is extremely sensitive towards small size variations. So if you are sure your solids variation is the only variation... you may use it as a qualitative comparison.. else not.
Why not do a very simple gravimetric determination? Does the nature of your sample give a problem to do so?
A. it is a very direct method
B. Mostly very accurate.
its for size analysis........mass and density is not involved, hence No.
Zetasizer can also tell number of particles, volume as well as size. Cannot we use these to find concentration?
HI all, thanks very much for your answers, I think the UV/Vis might be a good option
It provides a counting but not the exact concentration. The size doesn't depend on it so it's not an important parameter during the measure.
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