Preconcentration of trace vanadium with the ion pair of 2-nitroso-1-naphthol-4-sulfonic acid and tetradecyldimethylbenzylammonium chloride onto microcrystalline naphthalene and determination by derivative spectrophotometry

Abstract

Vanadium is quantitatively retained on 2-nitroso-1-naphthol-4-sulfonic acid tetradecyldimethylbenzylammonium chloride onto microcrystalline naphthalene in the pH range of 3.0-4.0 from a large volume of aqueous solutions of various alloys and synthetic samples. After filtration, the solid mass consisting of the vanadium complex and naphthalene was dissolved with 5.0 mL of dimethylformamide and the metal was determined by scond derivative spectrophotometry. The detection limit is 40 ppb (signal to noise ratio= 2) and the calibration curve is linear over the concentration range of 0.08-20 ppm in dimethylformamide solution by measuring the distance d2A/dλ2 between λ1 (575 nm) and λ2 (510 nm) with a correlation coefficient of 0.9995 and relative standard deviation of ±0.98%. The effect of pH, volume of aqueous phase and interference of a large number of metal ions on the determination of vanadium was studied and the developed method is found to be highly selective and sensitive.