Highly selective second order derivative spectrophotometry for simultaneous determination of nickel (ii) and cobalt (ii) using 2-ketobutyric acid thiosemicarbazone

A simple and highly selective second order derivative spectrophotometric method is proposed for the simultaneous determination of Ni(II) and Co(II) using 2-ketobutyric acid thiosemicarbazone (KBAT) as a sensitive complexing reagent. KBAT forms green and pink color complexes with nickel and cobalt at pH range of 8-11 and 5-10 respectively. Molar absorptivities of Ni-KBAT (1.55 × 104 L cm-1 mol-1 ) and Co-KBAT (1.03 × 104 L cm-1 mol-1 ) were obtained at 330 nm, under optimum pH of 9.5. Calibration graphs for the individual determination by second order derivative spectrophotometry were obtained. Beer’s law was obeyed at 369.8 nm for Ni(II) and 410 nm for Co (II) in the concentration ranges 0.30-2.34 μg mL-1 Ni and 0.33-2.65 μg mL-1. The zero crossing point at 369.8 nm for nickel and the amplitude measurement at 410 nm for cobalt were employed in the simultaneous determinations. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of nickel and cobalt in various steel alloys and biological sample