Ion-exchange chromatography as a tool for investigating vanadium speciation in sediments: preliminary studies

Abstract

We conducted this investigation in order to develop a simple method for the determination of bioavailable vanadium and its speciation within sediments. The developed method is based on the determination of acid-extractable vanadium, as this fraction is presumably bioavailable, and its subsequent speciation using IC–UV/Vis (ionic chromatography with an ultraviolet-visible detector). A published procedure for vanadium speciation in pore water was further optimized in order to separate V(IV) and V(V) species using column EDTA derivatization on sediment samples. The analytical approach was applied in order to assess acid-extractable vanadium and its speciation within estuary sediments of the Krka River at the Dalmatian coast of Croatia. The results imply that the majority of vanadium within estuary sediments is in the form of less soluble fraction while the acid-extractable fraction comprises approximately 40% of the total vanadium present. In contrast, open sea sediment (station K4) was completely dominated by the acid-extractable vanadium. The extracted vanadium is in the form of V (IV). Ion-exchange chromatography with an UV/Vis detector is a promising analytical method for vanadium speciation, however, further optimization of the conditions (improvement of the sequential extraction procedure) is needed in order to assess speciation also within other vanadium sedimentary fractions.