Simultaneous derivative spectrophotometric determination of Co(H), Cu(II) and Fe(H) using di-2-pyridylketone thiosemicarbazone (DPKT) without extraction

Abstract

A simple, sensitive and rapid derivative spectrophotometric method using di-2-pyridylketone thiosemicarbazone (DPKT) has been devoloped for the simultaneous determination of Co(II), Cu(II) and Fe(II) ions. Complex formation was completed for three metals in EtOH-H2O (1/9) containing 0. 1 M pH:6 acetate buffer within 5 min at room temperature and the chelates were stable for at least 2 days. Using zero-crossing first and second order derivative spectrophotometry, three metals were determined without any separation and background correction techniques. First derivative absorbance values ('D) at 489. 0 nm (zero-crossing wavelength of Fe(ll) and Cu(ll)) and 649. 4nm (zero-crossing wavelengt of Co(ll) and Cu(11)) were proportional to Co(ll) and Fe(ll) concentrations respectively. Second derivative absorbance value (2 D) at 406. 2 nm(zero-crossing wavelength of Co(ll) and Fe(ll))was proportional to Cu(ll) concentration. Linear correlations between derivative absorbance values and metal concentrations over the ranges of 1 -5 ppm for Co(ll) (r:O. 9996) and Cu(ll) (r:O. 9995) and 1-3 ppm for Fe(ll)(r:0. 9998) were obtained. A systematic study was made for the investigation of the effect of the presence of diverse ions on the determination.