Carbon nanotubes: purification, functionalization and analytical application as stationary phases for chromatographic separations

Multi-walled carbon nanotubes (MWCNTs) were studied as stationary phases for packed-column gas chromatography (GC). At first, a preservative purification procedure based on HCl washings was developed for removing the metallic impurities from the raw material. CNTs were covalently derivatized with different functionalities and chromatographic separations have been undertaken on pristine, purified and functionalized MWCNTs. Mixtures of analytes of different chemical classes were analyzed with remarkably diverse results on the different stationary phases. On MWCNTs-COOH the best separation of light alkanes has been obtained, whereas MWCNTs-RNH2 were particularly suitable for the analysis of BTX, alcohols, esters and chloroaromatics, with results comparable or even better of those achieved on a commercial sorbent usually employed for such applications. Commercial samples of distillates and paint thinners were successfully analyzed by GC on columns packed with the derivatized CNTs.