APPLICATIONS OF SOME HYDRAZONES OF PHARMACEUTICAL ORIGIN IN CHEMICAL ANALYSIS. Ⅰ: SPECTROPHOTOMETRIC DETERMINATION OF MICROMOLAR CONCENTRATIONS OF ZIRCONIUM(Ⅳ) USING PYRIDOXAL-4-HYDROXYBENZOYLHYDRAZONE AS CHELATE AGENT

摘要

A simple, rapid and at the same time sensitive and accurately repeatable spectrophotometric method for the determination of Zr(Ⅳ) in micromolar concentration levels, is described. The method is based on the formation of a 1/2(Zr(Ⅳ), ligand) yellow chelate complex using pyridoxal-4-hydroxybenzoylhydrazone (BPLH) as a chelating agent. The optimum pH of the formation of this complex was found to be 3.50±0.05, while its apparent molar absorptivity and Sandell's sensitivity at λ_(max) = 418 nm, were measured as 2.46 x 10~4Lmol~(-1) cm~(-1) and 3.70 ng cm~(-2) respectively. Beer's law was obeyed from 0.1 to 3.5 mg of Zr(Ⅳ)/ml (= 1.1-38.5 μmol of Zr(Ⅳ)/L) and the concentration of the Zr(Ⅳ) in the sample examined was calculated by the regression line equation: A = 2.70 x 10~(-1)C +1.91 x 10~(-3)(r = 0.9999; n=32). The accuracy and the precision of the method proposed could be considered as very satisfactory.