Reversed-phase high-performance liquid chromatographic separation and determination of titanium, vanadium, niobium and tantalum ternary complexes with hydrogen peroxide and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol

Abstract

The simultaneous separation of ternary complexes of TiIV, NbV and TaV with hydrogen peroxide and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) was evaluated using reversed-phase high-performance liquid chromatography with a C18 column. Moreover, simultaneous separation of a VV—H2O2—5-Br-PADAP ternary complex and a VV– 5-Br-PADAP binary complex was carried out using the C18 column. The chelates were detected at 590 nm and the calibration graphs (20 µl of sample was injected) were linear for 0.015–0.4 µg ml–1 of TiIV, 0.001–0.08 µg ml–1 of VV, 0.004–0.1 µg ml–1 of NbV and 0.01–0.3 µg ml–1 of TaV. When the S/N ratio is 3, the detection limits for V, Nb, Ta and Ti were 0.15, 0.5, 2.0 and 2.5 ppb, respectively. The method was applied to the direct determination of vanadium in water samples and the simultaneous determination of titanium, niobium and tantalum in human hair.