Extraction-photometric determination of cadmium(II) using 1-(5-benzylthiazol-2-yl)azonaphthalen-2-ol

For the first time, the absorption spectra of 1-(5-benzylthiazol-2-yl)azonaphthalen-2-ol were investigated in such solvents as ethanol, toluene, chloroform and carbon tetrachloride. Cadmium(II) ion interacts with 1-(5-benzylthiazol-2-yl)azonaphthalen-2-ol forming a violet chelate complex ( λ max = 595 nm) which can be extracted into toluene from the alkaline aqueous solution. The complex compound has a molar absorptivity of 1.9∙10 4 L∙mol –1 ∙cm –1 . The stoichiometric ratio of reagent to Cd(II) in complex is equal 2:1 that was established using spectrophotometric (mole-ratio method and method of continuous variations) and voltammetric methods. Optimum reaction conditions for complexation were found, an extraction-photometric method for the determination of Cd 2+ -ions has been proposed with determination limit of 0.3 μg∙ml –1 . Zn(II), Mn(II), Ti(III) and Fe(III) ions do not have an influence on the Cd(II) determination. Interference from such ions as Co(II), Cu(II), Ag(I) and Ni(II) was shown.