Spectrophotometric Determination of Trace Amount of Niobium with 2,3,7-Trihydroxy-9-Sulicylfluoronc as Chromgenic Reagent

In a CH3COOH-CH3COONa buffer solution of pH 5.5, and in the presence of cetylpyridinium bromide, with tartaric acid as assisting complexant, a stable coordination complex between 2,3,7-trihydroxy-9-sulicylfluoronc and niobium(Ⅴ) was formed, with its absorption maximum at the wavelength of 560 nm. Based on these facts, a method of spectrophotometry for the determination of niobium in the extract of Ni-Ta ore was proposed. Beer′s law was kept in the range of 4-240 μg·L-1, with value of apparent molar absorptivity of 1.44×106L·mol-1·cm-1. The proposed method was applied to the determination of niobium in the extract of Ni-Ta ore, giving results in consistency with the results obtained by GB method.