A photometric study of the complexation reaction between Alizarin complexan and zinc(II), nickel(II), lead(II), cobalt(II) and copper(II)

• Published in: Talanta (Oxford) 1982-08, Vol.29 (8), p.707-711
• Main Authors: Xing, Wu, Ingman, Folke
• Format: Article
• Language: English
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/0039-9140(82)80082-9

The complexation reaction between Alizarin complexan ([3- N, N-di(carboxymethyl)aminomethyl]-1,2-dihydroxyanthraquinone; H 4L) and zinc(II), nickel(II), lead(II), cobalt(II) and copper(II) has been studied by a spectrophotometric method. All these metal ions form 1:1 complexes with HL; 2:1 metal:ligand complex were found only for Pb(II) and Cu(II). The stability constants are (ionic strength I = 0.1, 20°C): Zn 2+ + HL 3− ⇌ ZnHL − log K ± 3σ(log K) = 12.19 ± 0.09 ( I = 0.5) Ni 2+ + HL 3− ⇌ NiHL − log K ± 3σ(log K) = 12.23 ± 0.21 Pb 2+ + HL 3− ⇌ PbHL − log K ± 3σ(log K) = 11.69 ± 0.06 PbHL − + Pb 2+ ⇌ Pb 2L + H + log K ≈ −0.8 Co 2+ + HL 3− ⇌ CoHL − log K 3σ(log K) = 12.25 + 0.13 Cu 2+ + HL 3− ⇌ CuHL − log K 3σ(log K) = 14.75 ± 0.07 Cu 2+ + CuHL − ⇌ Cu 2L + H + log K ≈ 3.5 The solubility and stability of both the reagent and the complexes and the closenes of the values of the stability constants make this reagent suitable for the photometric detection of several metal ions in the eluate from an ion-exchange column.