Extraction and spectrophotometric determination of vanadium with 4-(2-thiazolylazo)resorcinol and tetraphenylarsonium and phosphonium chlorides

Extraction of vanadium-4-(2-thiazolylazo)resorcinol complexes by quaternary salts such as triphenylmethylarsonium iodide, tetraphenylarsonium chloride, and tetraphenylphosphonium chloride has been studied. Quantitative extraction is achieved with tetraphenylarsonium and tetraphenylphosphonium chlorides in the pH region between 3.5 and 5. The optimum conditions for the extraction and spectrophotometric determination of vanadium in the extract are: pH 3.8–4.0, the concentration of vanadium 0.1–0.4 μg/ml. Effective molar absorptivity at λmax = 555 is (2.55 ± 0.05) × 104 liters mol−1 cm−1. Beer's law is obeyed. Relative standard deviation is 2–10% depending on the concentration level. The composition of the extracted complexes was studied in the solution and in the solid state. For their characterization chemical and spectral evidence and comparison with the vanadium-PAR complexes have been combined.