- 作者: 孫炳榕; 劉春櫻
- 作者服務機構: Department of Chemistry, National Taiwan University
- 中文摘要:
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 (MR2) may be predominant. The 1:1 complex has maximum absorption at 510 mμ 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..=4.46 or K..=2.9×10.. at pH 1.2. - 英文摘要: --
- 中文關鍵字: --
- 英文關鍵字: --