Abstract
Attention has been paid to vanadium because of its antidiabetic action. There are a lot of natural water products whose sales point is to contain vanadium. However, in most cases, existing form of vanadium is not clear. There have been two methods developed for the differential determination of vanadium. One is graphite-furnace atomic absorption spectrometry based on the extraction of vanadium(V) and vanadium(IV) with different solvents. The other is the speciation method by using high performance liquid chromatography and inductively coupled plasma mass spectrometry. The present study demonstrated that an ion chromatography is very effective for the separation of vanadium(IV) and vanadium(V). If vanadium(V) is existed in aqueous samples, it can be reduced by electrolysis, resulting in the appearance of vanadium(IV). In addition, since electron spin resonance (ESR) spectrometry can be used to confirm the existence of vanadium(IV) based on the spectrum with eight signals, ESR spectrometry can detect the electrolysis-induced reduction of vanadium(V) to vanadium(IV). Therefore, we propose that the combination of these three methods is very useful for the determination and speciation of vanadium in water samples.
