Reactions of o,o′-Dihydroxy Azo Dyes with the Third Group M(III) Ions: A Spectroscopic and Electrochemical Study

Figure 3

Absorption spectra of 4⋅10⁻⁵ M Calc 1 in 1 M NaOH; 2 at pH 4.4; 3 at pH 9.5, and 4 with 4⋅10⁻⁵ M of Ga(III) at pH 4.4.