SIMULTANEOUS SPECIATION DETERMINATION OF VANADIUM(IV) AND VANADIUM(V) AS EDTA COMPLEXES BY LIQUID-CHROMATOGRAPHY WITH UV-DETECTION

A liquid chromatographic (LC) method for the simultaneous determination of the speciation of vanadium(IV) and vanadium(V) was developed by using reversed-phase ion-pair liquid chromatography. Vanadium(IV) and vanadium(V) were complexed with EDTA in a precolumn, then a C, column was used to separate the vanadium-EDTA complexes from other species with an eluent containing acetonitrile, EDTA and tetrabutylammonium ion. The separated species were monitored at 245 nm with a UV detector. Factors affecting the chromatographic behaviour, complex stability and possible interferences were investigated. The proposed LC-W detection method provides a simple procedure for the determination of vanadium speciation. The detection limits were 1.0 ng for both species with a 20-mu l injection. The relative standard deviations for vanadium(IV) and vanadium(V) were 0.69% and 0.43%, respectively, for a 20 mu g ml(-1) (20-mu l) injection (n = 5).