First derivative spectrophotometric determination of palladium after column preconcentration with 1-(2-pyridylazo)-2-naphthol supported on naphthalene

A solid chelating material, 1-(2-pyridylazo)-2-naphthol (PAN) supported on naphthalene provides a rapid and highly selective means of preconcentrating palladium from a large aqueous volume (similar to 500 mL) of its synthetic samples. Palladium is quantitatively retained on this adsorbent in the pH range 3.1-5.0 when its aqueous solution is passed on it at a flow rate of 1 -8 mL/min. The solid mass consisting of the adsorbent along with the metal complex is dissolved out of the column with 5 mt of dimethylformamide (DMF) and the metal is determined by first derivative spectrophotometry. The cal ibration curve is linear over the concentration range 0.3-200 mu g of palla dium in 5 mt of the final DMF solution by measuring the distance dA/d lambd a between lambda(1) (680) and lambda(2) (650). Eight replicate determinatio ns of a sample solution containing 20 mu g of palladium gave a mean intensi ty (peak to peak signal between lambda(1) and lambda(2)) 0.138 with a relat ive standard deviation of 1.5%. The sensitivity of the method is 0.0318 [(d A/d lambda)/(mu g/mL)] found from the slope of the calibration curve and de tection limit is 0.04 mu g/mL (signal to noise ratio = 2). Various paramete rs such as pH effect, flow rate, volume of aqueous phase and the interferen ce of anions and cations on the estimation of palladium have been evaluated and the developed method is found to be highly selective and sensitive and applied to the determination of trace amounts of palladium in various comp lex samples corresponding to standard samples.