Determination of titanium(IV) and chromium(VI) with 2,7-dichlorochromotropic acid and 1,5-diphenylcarbazide on the solid phase

Possibility of the selective determination of Ti(IV) and Cr(VI) by diffuse reflection spectroscopy after their simultaneous adsorption from one sample on a two-layer substrate is studied. Titanium(IV) is adsorbed on a fiber filled with a cation exchanger (PANV-KU-2) and determined with 2,7-dichlorochromo-tropic acid; chromium(VI) is adsorbed on a fiber filled with an anion exchanger (PANV-AV-17) and determined with 1,5-diphenylcarbazide. Conditions are selected for the simultaneous adsorption of titanium and chromium in the batch and dynamic modes. Conditions are optimized for the determination of titanium with 2,7-dichlorochromotropic acid on PANV-KU-2. The selectivity of titanium and chromium determination in the presence of foreign ions is studied. Calibration graphs are linear in the ranges 5-40 and 2-20 ng/mL for Ti(IV) and Cr(VI), respectively; the detection limits are 4 and 2 ng/mL. The possibility of determining Ti(IV) and Cr(VI) in one sample at their ratios from 5: 1 to 1: 4 is shown.