Determination of vanadium species in water, vegetables, and fruit samples using supramolecular solvent microextraction combined with electrothermal atomic absorption spectrometry

A simple supramolecular solvent microextraction followed by solidification of floating coacervates has been developed for the preconcentration and speciation of vanadium prior to its determination by electrothermal atomic absorption spectroscopy. The speciation is based on the extraction of the hydrophobic complex of V(V) with N-benzoyl-N-phenylhydroxylamine in the coacervates of decanoic acid reverse micelles in the water–tetrahydrofuran mixture. Total vanadium was determined after oxidation of V(IV) to V(V) by hydrogen peroxide. The concentration of V(IV) was calculated from the difference in the amounts of total vanadium and V(V). Under the optimized conditions, the linear range and the enhancement factor of 5.0–1400.0 ng L (with a determination coefficient of 0.9998) and 147 were achieved, respectively. A detection limit (based on 3S/m) of 1.2 ng L and a relative standard deviation of 4.2% (at 100.0 ng L for six replicates) were obtained. The method was successfully applied to the determination of vanadium species in water and total vanadium in vegetable and fruit samples.