Liquid chromatographic behaviour of chelates of vanadium(V), copper(II), cobalt(III) and chromium(III) with 2-(3,5-dibromo-2-pyridylazo)diethylaminophenol

Abstract

The reversed-phase liquid chromatographic behaviour of the chelates of V^V, Cu^II, Co^III and Cr^III with 2-(3,5-dibromo-2-pyridylazo)diethylaminophenol(3,5-diBr-PADAP) was studied using a C₁₈ column, and a method for the simultaneous determination of V^V, Cu^II, Co^III and Cr^III was developed. A mobile phase of methanol-acetonitrile-water (84 + 12 + 4) containing 0.11 mmol dm^–3 cetyltrimethylammonium bromide and 0.1 mmol dm^–3 NaOAc–HCOOH(pH 3.5) was found to be the best. The chelates were detected at 590 nm. The calibration graphs were linear for 0.20–6.40 µg ml^–1 of V^V, 0.40–12.80 µg ml^–1 of Cu^II, 0.08–2.56 µg ml^–1 of Co^III and 0.40–6.40 µg ml^–1 of Cr^III. The detection limits were 0.2, 0.4, 0.04 and 0.2 ng for V^V, Cu^II, Co^III and Cr^III, respectively. The method was applied to the determination of V^V, Cu^II, Co^III and Cr^III in electroplating waste water samples.