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Spectrophotometric determination of zirconium (IV) and hafnium (IV) with pyrazolo (1, 5-a) quinazolin-6-one derivative reagent

T.A.Lasheen, G.M.Hussein, Y.M.Khawassek, M.F.Cheira

The present work considers a new reagent 2-amino-3-(4-bromo phenyl azo)-8,9 dihydro-7H-pyrazolo[1,5-a]quinazolin-6-one (BrPhPQ) for the selective determination of zirconium and hafnium ions in aqueous solution. A complete study ismade to ascertain the (BrPh-PQ) for quantitative determination of Hf ions in presence of Zr species. The reagent gave a stable yellow colored complexwith bothmetal ions under the same conditions of pH but the Hf-complex was not formed at pH 3.2-4.7 range. The complex had an absorptionmaximumat 368 nmand followed BeerÂ’s law in the concentration range (0.005-1) µg/ml. The molar absorbitivities of aqueous Zr and Hf complexes were 1.68 x 105 and 2.51 x 105 l.mol-1.cm-1 respectively. The method was applied for direct determination of Hf (IV) and Zr (IV) in zircon mineral. Results of analysis using the suggested procedures were in good agreement with the other similar published data elsewhere.