Differential Pulse Polarographic Determination of Zinc and Manganese in Commercial Sodium Salts and Water Samples after Preconcentration of Their 2-(2-Pyridylazo)-5-diethylaminophenol Chelates Using Ammonium Tetraphenylborate-Naphthalene Adsorbent

A highly sensitive, rapid and economical differential pulse polarographic method was developed for the simultaneous determination of trace amounts of zinc and manganese in commercial sodium salts, mineral water, human hair and environmental waste liquid and solid samples. Ammonium tetraphenylborate-microcrystalline naphthalene coprecipitate, loaded in a plastic syringe-type cartridge (i.d. 10 mm, length 100 mm), was used as a column for the preconcentration of zinc and manganese as their 2-(2-pyridylazo)-5-diethylaminophenolates. The retention was quantitative in the pH range 7.5 - 11.0 and 9.0 - 11.5 for Zn and Mn, respectively. Preconcentration factors of 50 and 75 were obtained at a flow rate of 10 ml/min for zinc and manganese, respectively. The detection limits were 300 ng for Zn and 500 ng for Mn in 10 ml of the final solution at signal-to-noise ratio of 3. Various parameters were studied and the developed analytical methodology was validated by analyzing NIES certified reference materials such as human hair, chlorella and tea leaves.