The objective is to selectively quantify the above mentioned functional groups created by plasma on carbon nanotube buckypapers, without disintegrating or dissolving the buckypapers. The techniques I'm looking at are fluorescence labelling and UV-Vis. Can anyone advise further on this? Or suggest alternative techniques? If XPS, then what peaks to look for in the C1s, N1s and O1s spectra, as the literature available on that is quite confusing.
Just simply titration method can be use to determine COOH and NH2 groups. Furthermore, by considering protein structure, these COOH and NH2 groups just like terminals of protein molecule. Therefore, we can use those colorimetric methods, that use for protein here too. Just try with simple methods for study rather than advanced methods. Good researcher will change some slandered methods depend on his requirements. Best of luck
Thank you Lakmal for taking time to reply. I have titration in mind for COOH (possibly with NaOH or NaHCO3). But what would be a good reagent for titration of NH2.
And can you recommend any particular dyes suitable for detecting COOH and NH2 separately? Thanks
You may try to use silylating agents used in gas chromatogrpahic derivatization. The excess can be titated bacl by low moelcular amines. You may also try to use Schiff base forming reagents for amine detection. Using the substrate itself you may use inverse gas chromatography but that needs calibration.
XPS? Elemental analysis will give information on N an O addatoms, Analysis/fitting of N and O peaks may provide additional information on type of addatoms chemical bonds.
Thank you Gyorgy. Unfortunately, I don't have access to gas chromatography here. Can you send me any literature on the silylation approach? or share a link for the same?
Oleg, I am using XPS, but since I'm using atmospheric pressure plasma, there is bound to be some adsorption of water on the surface. Plus, I am currently reviewing literature on XPS analysis of functionalized CNTs but I am having a difficult time getting consistent binding energy values for the functional groups I am interested in.
Adsorption of water should not be a problem since XPS spectra are measured under UHV conditions.However, you can make control measurements on non-functionalized CNTs and subtract control values from samples of interest results. On most of XPS machines you can do surface pre-cleaning with Ar ion sputtering.
For COOH you can use modified Boehms titration, however I think it wont be accurate in case of buckypaper due to number of stacked CNT layers. For NH2 you can use TGA with mass spectroscopy. It will work for COOH too. Temperature of decomposition is rather low ~ 180oC for COOH and for NH2 up to 350oC ~ like amorphous carbon. Therefore it should be safe and efficient.
Dear Rachit, I "developed" the surface titration technology for NH2 group. its in Burtman and Vardeny Synthetic Metals 2005, 154, 329-332, my Research Gate page have the pdf. In brief I borrowed the NH2 tag from biochemistry, and its working very well for tracking of surface Amines. Remember to store the tag molecule in the fridge and let me know if you will need more assistance. good luck VB
Thank you Oleg, Blazej, Vladimir, Ana and Omid. I am currently using XPS with Ar-ion sputtering prior and have also carried out titration (however data is not consistent).
Thank you Omid. Electrochemistry is certainly an approach that I can try out. Thanks for a good suggestion.
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