Solid-phase extraction of Cu, Co and Pb on oxidized single-walled carbon nanotubes and their determination by inductively coupled plasma mass spectrometry.

A novel method using a microcolumn packed with single-walled carbon nanotubes (SWNTs) as a new adsorption material was developed for the preconcentration of trace Cu, Co and Pb in biological and environmental samples prior to their determination by inductively coupled plasma mass spectrometry (ICP-MS). SWNTs oxidized with concentrated nitric acid have been proved to possess an exceptional adsorption capability for the analytes due to their surface functionalization. The adsorption behaviors of the analytes on SWNTs under dynamic conditions were studied systematically. The main factors influencing the preconcentration and determination of the analytes (pH, sample flow rate and volume, eluent concentration and interfering ions) have been examined in detail. Under the optimum conditions, the detection limits for Cu, Co and Pb were 39, 1.2 and 5.4 pg mL(-1), respectively; the relative standard deviations (RSDs) were found to be less than 6.0% (n=9, c=1.0 ng mL(-1)). This method was validated using a certified reference material of mussel, and has been successfully applied for the determination of trace Cu, Co and Pb in real water sample with the recoveries of 96.0-109%.