Department of Chemistry, Shahid Bahonar University, Kerman, I.R. IRAN
Lead 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 4.0-6.0 from a large volume of aqueous solutions of various samples with preconcentration factor of 60. After filtration, the solid mass consisting of the lead complex and naphthalene was dissolved with 5 mL of dimethylformamide and the metal was determined by atomic absorption spectrometry. The calibration curve is linear in the range of 1.9-180 mg/mL in DMF with a relative standard deviation 1.7&. The interference of a large number of anions and cations has been studied.