USE OF CNT AND MODIFIED-CNT AS SUBSTRATE FOR SOLID PHASE EXTRACTION COUPLED TO USN-ICP OES FOR THE ON-LINE PRECONCENTRATION OF CD?

BELÉN PARODI; MARIANELA SAVIO; LUIS D. MARTINEZ; RAÚL A. GIL; GRISELDA POLLA; PATRICIA SMICHOWSKI

Mar del Plata

Simposio; Eleventh Rio Symposium on Atomic Spectrometry; 2010

A study was performed to ascertain the performance and the potential of carbon nanotubes (CNT) and modified CNT as a sorbent for solid phase extraction, coupled to ICP OES with ultrasonic nebulization (USN) for the on-line preconcentration of trace Cd. The on-line solid phase extraction of the analyte on the different carbon nanotubes, e.g. carbon nanotubes (NTC), oxidized-carbon nanotubes (o-NTC) and alanine-carbon (ala-NTC) nanotubes was studied systematically. The main factors that influence the preconcentration and determination of Cd were examined thoroughly, and they included sample pH, flow rate and volume, and eluent concentration and flow rate. The three types of CNTs evaluated showed dissimilar adsorption behaviors that enabled increasing preconcentration factors when were used in this on-line SPE method set up as follows: CNT < ala-CNT < o-CNT. Oxidized carbon nanotubes have been proved to possess an exceptional adsorption capability due to their surface functionalization with oxygen-containing groups. Cd could be adsorbed quantitatively on o-NTC at pH 9.0, and then eluted completely with 10% of HNO3. The adsorption capacity of o-NTC was found to be 130 µmol g-1. Under the optimal conditions, the detection limit was (3) obtained for the investigated metal was 0.01 g l−1. The precision of the method expressed as the relative standard deviation (RSD) turned to be 2.9%. After optimization, the flow injection analysis that involved the use of o-CNT as sorbent and USN-ICP OES, was successfully applied to the determination of Cd in water samples.