Development of new procedures for the determination of Pb, Fe, Cd, Zn, Cu, Ni, Hg and uric acid using differential pulse polarography

In this study for the determination of trace elements in real samples using differential pulse polarography (DPP), red and white wine samples have been analyzed as an example. It was possible to determine qualitatively and quantitatively Cd, Pb, Zn, Fe, Cu and Ni ions using acetate buffer and ammonia, ammonium chloride buffer at pH 2, 6 and 9 in the presence or absence of EDTA.One of the aims of this work was to determine uric acid in blood serum. The best medium for the determination of uric acid was found as 0,05 M phosphate, in the presence of 0,1 M KNO3 at pH 10-12. The interference of ascorbic acid and dopamine could be eliminated by the addition of Fe(III). The limit of detection was found as 2x10-7 M (S/N=3) in this medium. Uric acid content in serum could be determined with high accuracy.For the indirect determination of mercury, the reaction between Hg(II) and sulfite and between Sn(II) has been used. The change in sulfite peak can be followed precisely because of its sharp peak at about -0.6 V. The best medium was found as acetate buffer pH 4-7. No remarkable interference was observed from Fe(III), Cu(II), Zn(II) and Pb(II) ions. It was found that when Cd(II) concentration was larger than 1/10 th of sulfite a peak overlap occurred. This method can be applied in the presence of large amounts of chloride ion, which is a very important advantage when compared with other methods. The limit of detection for Hg(II) was found as 5x10-6 M.For the determination of Hg(II) a second indirect method has been established. The reaction between Sn(II) and Hg(II) has been used for this purpose since Sn(II) peak can be followed precisely from its sharp peak at about -0.40 V. It was found that this reaction was taking place at pH values lower than 2. Interference of Fe(III), Cd(II), Zn(II), Cu(II) and Pb(II) has been studied. Fe, Cd(II) and Zn(II) had no reaction with Sn(II), but Cu reacted with Sn(II). It was found that Cu(II) did not react when its concentration was equal or lower than Hg(II). Pb(II) had an overlapping peak with Sn(II).