Second derivative spectrophotometry for simultaneous determination of iron (II) and copper (II) using 2-ketobutyric acid thiosemicarbazone

A new chromophoric reagent, 2-ketobutyric acid thiosemicarbazone (KBAT) has been used for the simultaneous determination of iron, copper and vanadium. KBAT forms yellowish-green and blue complexes with iron (II) and copper (II) respectively at pH 6.5 and a yellow complex with vanadium (V) at pH 5.5. Calibration graphs for the individual determinations by second derivative spectrophotometry were obtained. The derivative amplitudes obeyed Beer’s law at 387.2 nm for copper (II), 440 nm for iron (II) and 400 nm for vanadium (V), in the concentration ranges 0.30-2.40, 0.202.280 and 0.25-2.56 μg mL respectively. Zero crossing method using the second derivative mode at the selected wavelengths was employed in the simultaneous determinations. The accuracy and reproducibility of the determination methods on known amounts of iron, copper, and vanadium in their binary mixtures were tested. The effects of foreign ions on the determinations of the metals were also studied. The recommended procedure was applied to the analysis of ferrovanadium alloy, phosphor bronze, rice and groundnut.