COLUMN PRECONCENTRATION OF COPPER WITH ION-PAIR OF 2-NITROSO-1-NAPHTHOL-4-SULFONIC ACID AND TETRADECYLDIMETHYLBENZYLAMMONIUM CHLORIDE SUPPORTED ON NAPHTHALENE PRIOR TO DISSOLUTION AND COPPER DETERMINATION BY FLAME ATOMIC-ABSORPTION SPECTROMETRY

A column preconcentration method was established for the determination of trace amounts of copper by preconcentration with 2-nitroso-1-naphthol-4-sulfonic acid(Nitroso-S)/tetradecyldimethylbenzylammonium chloride (TDBA) on microcrystalline naphthalene using simple funnel-tipped glass tube. Copper reacts with Nitroso-S to form a water-soluble brown colored chelate anion. The chalate anion forms a water-insoluble Cu/Nitroso-S/TDBA complex on naphthalene packed in a column. Copper is quantitatively retained on the naphthalene in the pH range 7.0 approximately 10.0 in the presence of ammonium citrate at a flow-rate of 1 mL/min. The solid mass consisting of copper complex and naphthalene is dissolved out from the column with 5 mL of dimethylformamide(DMF) and copper is measured by atomic absorption spectrophotometer at 325 nm. A calibration curve is linear over the concentration of 1 approximately 12-mu-g Cu in 5 mL of final DMF solution. Seven replicate determinations of 6-mu-g of copper gave a mean absorbance of 0.110 with a relative standard deviation of 0.8%. The sensitivity for 1% absorption was 0.048-mu-g/ml (0.070g/ml for direct AAS method from the aqueous medium). The detection limit was 0.0030-mu-g/mL. The effect of foreign ions has been studied and the analysis of copper was carried out in standard magnesium alloys and vehicle exhaust samples.