DETERMINATION OF V(V), NB(V) AND TA(V) AS THEIR 2-(5-NITRO-2-PYRIDYLAZO)-5-DIETHYLAMINOPHENOL COMPLEXES BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A method for the reversed-phase liquid chromatographic separation and determination of V (V), Nb (V) and Ta (V) as 2-(5-nitro-2-pyridylazo)-5 diethylaminophenol (5-NO2-PADAP) complexes is reported. The metal complexes were eluted in 9 min with a mobile phase of methanol-water (54 : 46, v/v) containing 10 mmol L(-1) acetate buffer (pH 3.0) on an ODS column. The detection limits for V, Nb and Ta were 0.09, 0.13 and 1.41 ng mL(-1), respectively, with S/N = 3. The analysis of a reference sample of a mineral is discussed. The results corresponded to the certified values, and recoveries of 98.3-101.4% have been obtained.