I have oleic acid capped iron-oxide nanoparticles which needs to be analyzed using ICP to determine the %mass of iron in the nanoparticle suspension. These nanoparticles being hydrophobic, can be suspended in THF, chloroform, and hexane, but readily precipitate in a mildly polar solvent like acetone. I have tried dissociating these particles based on literature reports which state the use of Aqua regia overnight, but a black oily layer(presumably the nanparticles) remains on the surface. I am presently trying to dissociate the nanoparticles in concentrated nitric acid overnight, but the oily layer seems to be still present. How can these nanoparticles be digested effectively for ICP elemental analysis?
Try the mixture of concentrated nitric acid and H2O2 (volume ratio：5:3)。
Dear Dr. Fazal:
The analysis of major element by ICP emission is requested. Would be interesting verify the type of ICP system that you is operating and its specific configuration item such detector, as well as characteristic detection metallic element/level, see:
http://crustal.usgs.gov/laboratories/icpms/intro.html
Also, would be interesting to know the iron-oxide variety synthesized: FeO, Fe2O3 (alfa-Fe2O3, gama-Fe2O3), Fe3O4 (FeO.Fe2O3).
If you have some Kind of interest in some cationic species in forming a solid-solution in the matrix of iron-oxide is necessary the “opening of the structure of iron-oxide”, see basic procedure via link below:
http://www.inorganicventures.com/advice/iron-oxide-pigment-analysis-icp
In these above sense, some kind of dilution can be typically useful, seems that there is several procedures but some procedures are most frequent being practical to generate excellent samples, see pdf file in the link:
http://www.fao.org/ag/agn/jecfa-additives/specs/monograph5/additive-238-m5.pdf
Also, a good sample standard can be prepared.
In the same way above commented, typically, a procedure adopted for ICP would be the acid method tailored for trace element analysis, that is correlated to a good level dilution factor (close to 100). From this point, there are several routes, based on the strong-acid dissolution and acid digestion.
Dissolution: HCl concentrated via Hot
Dissolution: H2SO4 concentrated via Room temperature/hot
It is possible dissolution in EDTA with formation of chelates, see pdf.
It is possible dissolution in oxalic acid with formation of a kind of chelate, Ironoxalatecharacterization.pdf.
Best regards
Marcos Nobre
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