Self-assembled carbon nanotubes in a microtrap for chemical sensing and chromatography

The first application of self-assembled carbon nanotubes (CNT) inside a steel capillary to fabricate a microtrap for the nanoscale adsorption/desorption of organic molecules is presented. The CNT-coated microtrap functions as a nanoconcentrator that can be used for sensing and analytical-scale separation, e.g., GC. The CNT deposit as a thin-film on the walls of the capillary from either CO or C₂H₄ carbon precursors. Trace level small organic molecules, e.g., hexane and toluene, are adsorbed and then rapidly desorbed from the CNT film inside the capillary. The desorption pulse provides a concentrated injection for the detector, and also for GC separation. Sorption of toluene is much stronger than that of hexane, which is attributed to the p-p interaction between the CNT sidewall and the aromatic ring of toluene. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).