Spectrophotometric Studies on the Stability Constant of Al3+, In3+ and Ga3+ Chelates with Erichrome Cyanin-R

Abstract

The interaction of metal ion (AI³⁺, In³⁺ and Ga³⁺) with Erichrome
Cyanin-R (ECR) has been investigated by spectrophotometric technique.
Light purple and purple coloured chelate having 1 : 2 metal to ligand ratio
are formed over the pH range of 3.5 to 5.5 with λ_max 515 nm for ECR,
540 for Al³⁺, In³⁺ and 530 nm for Ga³⁺. Their stability constants have
been determined by applying mole ratio method, Job's method of continuous
variation and Dey and Coworkerrs' method. The values of log K for
AI³⁺; ln³⁺ and Ga³⁺ were found to be 10.05, 7.77 and 8.5 respectively. The
analytical applications of the colour reaction have also been investigated.