Simultaneous kinetic determination of copper, cobalt and nickel by means of -group interchange reactions

The kinetic determination of copper, cobalt and nickel in binary and ternary mixtures without prior separation is described. The methods are based on the difference in the reaction rate of interchange of - groups between thiosemicarbazide and 6-methylpicolinaldehyde azine in the presence of these ions at pH 4.5. Through these reactions the corresponding metal thiosemicarbazone complexes are formed. Various ratios of these ions at the 10(-5)M level can be determined photometrically by either the logarithmic extrapolation method or a combined initial-rate and fixed-time method proposed here for the first time.