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

Vanadium is quantitatively retained on 2-nitroso-1-naphthol-4-sulfonic acid tetradecyldimethylbenzylammonium chloride onto microcrystallinenaphthalene in the pH range of 3.0-4.0 from a large volume of aqueous solutionsof various alloys and synthetic samples. After filtration, the solid mass consistingof the vanadium complex and naphthalene was dissolved with 5.0 mL of dimethyl-formamide and the metal was determined by scond derivative spectrophotometry.The detection limit is 40 ppb (signal to noise ratio= 2) and the calibration curveis linear over the concentration range of 0.08-20 ppm in dimethylformamide solu-tion by measuring the distance d2A/dl2 between l1 (575 nm) and l2 (510 nm) witha 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 ofmetal ions on the determination of vanadium was studied and the developedmethod is found to be highly selective and sensitive.