Gas chromatography on self-assembled, single-walled carbon nanotubes

High-performance stationary phases, which provide high resolutions and are stable at high temperatures, are of significant importance in gas chromatographic analysis. Carbon nanotubes are nanosized carbon-based sorbents that have a high surface area and a large aspect ratio and are known to be stable at high temperatures. It is, therefore, conceivable that gas chromatography can benefit from their unique properties. This paper reports gas chromatography separations in an open tubular format on self-assembled, single-walled carbon nanotubes (SWNTs) inside silica-lined steel capillary tubing. A SWNT film with an average thickness of 300 nm was self-assembled by a unique, single-step, catalytic chemical vapor deposition (CVD) process consisting of dissolved cobalt and molybdenum salts in ethanol. A variety of organic compounds with varying polarity were separated at high resolution, and the column efficiency demonstrated ∼1000 theoretical plates/m. Comparison of capacity factors' and isosteric heats of adsorption with a packed column containing a commercial sorbent (Carbopack C) showed comparable results. This demonstrated high capacity and strong sorbate-sorbent interactions on the SWNT phase. Evaluation of the McReynolds constants suggested that the SWNT was a nonpolar phase.