Differential Kinetic Determination of Cobalt and Vanadium Using the Thermal-Lens Monitoring
By the example of a model indicator reaction of the oxidation of cobalt(II) and vanadium(IV) ions with the complex of iron(III) with 1,10-phenanthroline resulting in the formation of iron(II) tris- (1,10-phenanthrolinate) it is shown that thermal-lens monitoring can be used in differential kinetic determinations. For differential kinetic determination of mixtures of cobalt(II) and vanadium(IV) with thermal lens monitoring (514.5 nm, 35.5 mW), the limits of detection of 2 ng/ mL for both metals are achieved, which is the same as the limits of detection for individual metals. Contrary to the spectrophotometric measurements, the role of the synergetic effect degrading the sensitivity of determination in this indicator system is almost negligible with thermal-lens monitoring. As a whole, the sensitivity of differential kinetic determination of cobalt(II) and vanadium(IV) with thermal-lens monitoring excels their determination with spectrophotometric determination by a factor of 100.