| The most prevalent oxidation states of vanadium in nature are V(IV) and V(V). Toxicity of vanadium increases with increasing oxidation state. A high-performance-liquid-chromatography inductively-coupled-plasma mass-spectrometry method was optimized for the speciation of V(IV) and V(V). It was applied to the investigation of vanadium leaching from petroleum coke into oil sands process water. Both V(IV) and V(V) leached from the coke into the water but the V(IV) rapidly oxidized to V(V) in the absence of ethylenediaminetetraacetic acid (EDTA). A species preservation method using EDTA was developed that stabilized the species distribution and concentration for 56 days. The method was applied to a 7-day exposure study of V(IV) and V(V) on Hyalella azteca. Tissue extract contained V(IV), V(V), and an unknown vanadium species. V(IV) oxidized in the test water, so the animals were mostly exposed to V(V). Speciation provides essential insight and information on vanadium present in samples. |
