Spectrophotometric Determination of Cu2+ Metal Ions via Complex Formation with Carboxylated Tris(2-aminoethyl)amine

Abstract

An aminopolycarboxylic acid chelating agent; tris(2-aminoethyl)aminehexaacetic acid (TAHA) was prepared and characterized. TAHA formed stable complexes with Cu(II) ions and other metal ions at pH 10. The complexation behavior was studied by spectrophotometry at the complex maximum wavelength. Mixtures of Cu(II) and other metal ions (M²⁺; Ca²⁺, Co²⁺, Ni²⁺, Cd²⁺)were titrated with TAHA at pH 10. The stoichiometry of ligand - to - metal was found to be 1:1. The stability constant of Cu(II)–TAHA complex was determined to be 1.86×10⁵ by using the continuous variation method. Beer’s law was obeyed over the concentration range 3.0×10^–4 M – 1.2×10^–2 M for Cu(II) solution. The results of the quantitative determination of Cu(II) gave LOD and LOQ values of 7.285×10^–6 M and 2.428×10^–5 M respectively. The percent relative standard deviation (%RSD) for five replicate samples was found to be 1.088% and 4.804% for Cu(II) concentrations of 1.2×10^–2 M and 3.0×10^–4 M respectively.