Derivative spectrophotometry determination of trace amounts of vanadium in standard aluminum alloys, steel and environmental samples after preconcentration with 1-(2-pyridylazo)-2-naphthol-naphthalene adsorbent

A solid chelating material, 1-(2-pyridylazo)-2-naphthol (PAN) supported on naphthalene provides a rapid and highly selective means of preconcentration of vanadium from a large volume of its aqueous solutions(similar to 400 mL). Vanadium is quantitatively retained on this adsorbent in the pH range 3.5 - 4.6 with a flow rate of 1-5 mL min(-1). The solid mass is dissolved out of the column with 5 mL of dimethylformamide (DMF) and the metal determined by third derivative spectrophotometry. The detection limit is 0.1 mu g mL(-1) (signal to noise ratio = 2) and the calibration line is linear over the concentration range 2.0-250 mu g of vanadium in 5 mL of the final DMF solution with a correlation coefficient of 0.9996 and a relative standard deviation of 1.2 %. The various parameters effecting the method have been evaluated and the developed conditions utilized for the trace determination of vanadium in standard alloys, steel, environmental and synthetic samples. The method may also be applied safely for the trace determination of vanadium in various other complex materials like biological samples, rocks and ores.