Simultaneous Determination of Niobium and Tantalum in Ore Samples by K-ratio H-point Standard Addition Spectrophotometry

In chloride acid medium salicyl fluorone-cetyl pyridinium could react with niobium (Nb) and tantalum (Ta) respectively to form ternary micelle complexes, but the complexes exhibit serious spectrum overlap and are not used for spectrophotometric determination of Nb and Ta. In this paper, a new method for simultaneous determination of Nb and Ta in ore samples by K-ratio H-point standard addition spectrophotometry (HPSA) without chemical separation was reported. The optimum wavelength pairs were selected by home-made procedure in Origin 7.5 software. The spectrum interference on determination of Nb and Ta could be eliminated using K-ratio HPSA method. Under the optimum conditions, the linear ranges of determination for Nb and Ta were (0.4~5.8)×10^-5g/L and (0.4~11.2)×10^-5g/L with a detected limit of 0.28 μg/L and 0.22 μg/L respectively. The determination precision were 0.54%~0.88% RSD for Nb and 0.88%~1.52% RSD for Ta. The method has been applied to the simultaneous determination of Nb and Ta in ore samples with satisfactory results.