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A Spectrophotometric Study OE Zirconium Complexes of 4,5‐Dihydroxyfluorescein
Author(s) -
Sun PengJoung,
Liu ChuenYing
Publication year - 1972
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.197200004
Subject(s) - chemistry , zirconium , complex formation , metal , metal ions in aqueous solution , gravimetric analysis , reagent , titration , stability constants of complexes , inorganic chemistry , solubility , ion , absorption (acoustics) , ligand (biochemistry) , analytical chemistry (journal) , nuclear chemistry , chromatography , organic chemistry , biochemistry , physics , receptor , acoustics
Zirconium (IV) ions form violet red complex with 4,5‐dihydroxyfluorescein in fairly strong mineral acid medium. The reagent has been successfully applied as a metal indicator in the direct EDTA titration of zirconium. The complex formed by 4,5‐dihydroxyfluorescein and zirconium ions has been studied spectrophotometrically in 0.1 M HCl solution. It is found that when an excess of metal ion is present, a violet red colored complex with metal‐ligand ratio of 1:1, (MR) is formed and when an excess of 4,5‐dihydroxyfluorescein is present a 1:2 complex (MR 2 ) may be predominant. The 1:1 complex has maximum absorption at 510 m μ and the 1:2 complex has very low solubility and tends to precipitate out from the solution. Job's method, log‐ratio method and gravimetric method were used to establish the composition of complexes. The apparent stability constant of the 1:1 complex is found to be log K h = 4.46 or K h = 2.9×10 1 at pH 1.2.