Extraction-spectrophotometric determination of tantalum(V) with 2-(2-thiazolylazo)-5-dimethylaminophenol and 1, 3-diphenylguanidine

Abstract

Tantalum (V)-2-(2-thiazolylazo)-5-dimethylaminophenol (TAM) chelate anion is extracted quantitatively into benzyl alcohol with 1, 3-diphenylguanidine (DPG) to form a ternary complex. In the organic phase, the complex has an absorption maximum at 605 nm. The optimum pH range for the extraction is 4.1–4.9 and the ternary complex is stable for at least 50 min. Beer's law is obeyed over a concentration range of 2–18 µg of tantalum(V) in 10 ml of the organic phase. The molar absorptivity of the ternary complex is 4.1 × 10⁴ l mol^–1 cm^–1 at 605 nm. The composition of the ternary complex is considered to be (TaO₂)₂(TAM)₃(DPG⁺).