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 Ti^IV, Nb^V and Ta^V 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 V^V—H₂O₂—5-Br-PADAP ternary complex and a V^V– 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 Ti^IV, 0.001–0.08 µg ml^–1 of V^V, 0.004–0.1 µg ml^–1 of Nb^V and 0.01–0.3 µg ml^–1 of Ta^V. 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.