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

Andriy M. Tupys, Oleksandr S. Tymoshuk


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 (λmax = 595 nm) which can be extracted into toluene from the alkaline aqueous solution. The complex compound has a molar absorptivity of 1.9∙104 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 Cd2+-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.


cadmium(II); thiazolylazonaphthol dies; spectrophotometry; extraction; chelate


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