HPLC columns and nanocrystals... or radicals?

[Roxanne42]

Updated question :

Any idea if TEMPO-derivatives can cause havoc on silica-based columns? It's a pretty stable radical, but anyone knows or thinks it might cause problems with residual silanol groups? Is there any way of testing the compatibility of particular compounds with a column without injecting...?

Original post :

I have a student running a reaction involving a nanocrystal (quantum dot). Essentially, he starts off with a CdSe nanocrystal (around 22 nm) to which some trioctylphosphine oxides are attached and reacts it with a TEMPO derivative (stable radical species) for exchange - let's call it "A", thus (hopefully) generating the CdSe-(A)n product and trioctylphosphine oxide as a side-product.

He wishes to follow the reaction by HPLC by following the disappearance of the TEMPO-like reagent A. We currently only have a Zorbax Extend-C18 and Zorbax Eclipse XDB-C8 (RP)

Anyone knows if the nanocrystal is safe to inject on such HPLC columns? I don't think it should be a problem, but since I don't know very much about nanocrystals, I just wanted to see if anyone had any idea...


Thanks,

Roxanne
University of Ottawa
Canada

[Mark Tracy]

I have injected latexes (60-200 nm) onto columns, and the columns held up better than I had expected. A 5µm particle size column will be more resistant to fouling than the smaller sizes, and short columns are more resistant than long ones. Wetting agents also help the nanoparticles to pass. You should even be able to see the nanoparticles in the chromatogram. Also, if you really don't want the nanoparticles on your column, Anotop membrane filters (Whatman) are available in 0.02µm absolute rating; I've tested them against the 60nm latex and they work better than anything else I have tried.

[Uwe Neue]

I don't know what TEMPO is, but if it is stable in say acetic acid solution, I would guess that it will be stable in the presence of silanols.

[moino]

personally I don't have experience with hydrophobic nanocrystals, but here are some references:

* Jimenez, V. L., M. C. Leopold, et al. (2003). "HPLC of Monolayer-Protected Gold Nanoclusters." Analytical Chemistry 75(2): 199-206.

* Recycling Size Exclusion Chromatography for the Analysis and Separation of Nanocrystalline Gold Ali M. Al-Somali, Karl M. Krueger, Joshua C. Falkner, and Vicki L. Colvin Anal. Chem.; 2004; 76(19) pp 5903 - 5910; (Article) DOI: 10.1021/ac049355h

* Characterization of Nanocrystalline CdSe by Size Exclusion Chromatography Karl M. Krueger, Ali M. Al-Somali, Joshua C. Falkner, and Vicki L. Colvin Anal. Chem.; 2005; 77(11) pp 3511 - 3515; (Article) DOI: 10.1021/ac0481912


As far as I remember, they usually have some additives in the mobile phase in order to assure the stability of the particles. Do you have more references?