Differential pulse polarographic determination of trace amount of bismuth in various complex samples after preconcentration of its 1-(2-pyridylazo)-2-naphthol complex by column and microcrystalline naphthalene methods

A differential pulse polarographic method has been developed for the determination of trace amount of bismuth in various complex samples after adsorption of its 1-(2-pyridylazo)-2-naphthol on naphthalene in the pH range 8.0-10.0. After filtration, the solid mass is shaken with 8 mL of 1 M hydrochloric acid, mixed with 2.0 mL of 1 M pyridine solution and determined with a differential pulse polarograph. It is reduced reversibly under these conditions. Alternatively, bismuth may be quantitatively adsorbed on [1- (2-pyridylazo)-2-naphthol]-naphthalene adsorbent packed in a column and determined similarly. The detection limit is 20 ppb (signal to noise ratio: 2) and the linearity is maintained in the concentration range 80-16 x 10(4) ppb with a correlation coefficient of 0.9994 and relative standard deviation of +/-0.96%. Various parameters such as the effect of pH, aqueous phase volume and interference of a large number of metal ions on the determination of bismuth have been studied in derail. The method is found to be highly selective, rapid, economical and fairly sensitive and has been used for the determination of trace amount of bismuth in various complex samples.