Second-Derivative Spectrophotometric Determination of Trace Copper after Preconcentration with the Ion Pair of 2-Nitroso-1-Naphthol-4-Sulfonic Acid and Tetradecyldimethylbenzylammonium Chloride on Microcrystalline Naphthalene or a Column

Abstract

Copper is quantitatively retained by 2-nitroso-1-naphthol-4-sulfonic acid and tetradecyldimethylbenzylammonium chloride on microcrystalline naphthalene in the pH range 7.1–10.7 from large volumes of aqueous solutions of various samples. After filtration, the solid mass consisting of a copper complex and naphthalene is dissolved with 5 mL of dimethylformamide, and the metal is determined by second-derivative spectrophotometry. The copper complex can alternatively be quantitatively adsorbed on tetradecyldimethylbenzylammonium–naphthalene adsorbent packed in a column and determined similarly. About 1.5 μg of copper can be concentrated in a column from 300 mL of aqueous sample, where its concentration is as low as 5 ng/mL. The effects of pH, the volume of the aqueous phase, and interferences from a number of metal ions on the determination of copper have been studied in detail to optimize the conditions for its determination in standard alloys and biological samples.