Application of the Ion Pair of 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol and Ammonium Tetraphenylborate onto Microcrystalline Naphthalene. A Column Method for Preconcentration of Trace Palladium and Determination by Third Derivative Spectrophotometry

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Abstract
Palladium is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 4.4–6.7 from large volumes of aqueous solutions of various synthetic samples. After filtration, the solid mass consisting of the palladium complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by third derivative spectrophotometry. The palladium complex can alternatively be quantitatively adsorbed on an ammonium tetraphenylborate-naphthalene adsorbent packed in a column and determined similarly. The detection limit is 15 ppb (signal to noise ratio=2), and the calibration curve is linear 20–4400 ppb in dimethylformamide solution with a correlation coefficient of 0.9994. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of palladium in various synthetic samples.