4. Conclusions
Two nanosubstrates were used and compared for Sb(III)
preconcentration. The on-line combination of NPC or pro-MWCNTs in
a SPE-FI-HG-AAS system resulted fully able to determine Sb at ng L−1
levels. Themixture of each substratewith a lowmolecular weight polyethylene
wax (with no need for substrate immobilisation) avoided agglomerations
and overpressures in the on-line system. NPC and pro-MWCNTs microcolumns featured excellent chemical stability and retention
efficiency without noticeable Sb(III) breakthrough for sample
volumes of 50mL, andwith a long lifetime of up to 600 sorption/elution
cycles.
The excellent dynamic sorption capacity of both substrates and the
enrichment factors obtained render NPC and pro-MWCNTs ideal sorbents
for the determination of Sb(III) and other elements at the very
low concentrations usually expected in natural waters.
Research work in our lab is underway to expanding the proposed
preconcentration method to the use of other nanomaterials for the determination
of key pollutants in environmental matrices. Efforts will
be addressed to the speciation analysis of elements of ecotoxicological
interest.