Differential pulse polarographic determination of lead in standard alloys and biological samples after separation and preconcentration with PAN.

A highly selective, sensitive, rapid and economical differential pulse polarographic method has been developed for the determination of trace amount of lead in various samples after adsorption of its 1-(2-pyridylazo)-2-naphthol (PAN) on naphthalene in the pH range of 8.4 - 11.5. After filtration, the solid mass is shaken with 9.0 ml of 1 M hydrochloric acid and lead is determined by differential pulse polarography (DPP). Lead can alternatively be quantitatively adsorbed on [1-(2-pyridylazo)-2-naphthol]-naphthalene adsorbent packed in a column and determined similarly. The detection limit is 0.1 microg/ml (signal to noise ratio = 2) and the linearity is maintained in the concentration range 0.3 - 300 microg/ml with a correlation coefficient of 0.9996 and relative standard deviation of +/- 1.1%. Characterization of the electroactive process included an examination of the degree of reversibility. Various parameters such as the effect of pH, volume of aqueous phase and interference of a number of metal ions on the determination of lead has been studied in detail to optimize the conditions for determination in alloys and biological samples.