Histidine functionalized multi-walled carbon nanotubes as sorbent for flow injection-electrothermal atomic absorption spectrometric ultrasensitive determination of trace vanadium (V) in biological and environmental samples

Histidine functionalized multi-walled carbon nanotubes (MWCNTs-His) were synthesized for selective preconcentration of V(V). Using flow injection coupled with electrothermal atomic absorption spectrometric strategy, an on-line ultrasensitive determination of V(V) in biological and environmental samples was achieved. Statical and dynamical adsorption of V(V) with MWCNTs-His was carefully evaluated. Isotherm and kinetics of adsorption were studied and fitted in the Langmuir model. The MWCNTs-His sorbent was demonstrated to be good column packings for on-line preconcentration. All of the experimental conditions with MWCNT-His packed microcolumn for the preconcentration and determination of V(V) were investigated in detail. Including the optimal sample's pH, sample's flow rate, loading time, eluting solution and interfering ions were performed on-line, to ensure automatic determination with a high precision. With a consumption of 5.0 mL sample solution and a preconcentration time of 1 min, an enhancement factor of 35 with a detection limit (3s) of 9 ng L-1 or 0.2 nM is achieved. The sample throughput and the precision (RSD) for 11 replicate measurements of 400 ng L-1 level was 28 h(-1) and 1.5%, respectively. The method was applied to the determination of trace V(V) in a variety of biological and environmental samples. (C) 2012 Elsevier B.V. All rights reserved.