Amperometric sensor for the flow-injection determination of iridium(IV) ions

The electrochemical behavior of iridium(IV) chloride complexes was studied by cyclic and hydrodynamic voltammetry on carbon composite electrodes manufactured on the basis of a mixture of carbon powder and a hydrophobic silicone support covalently bonded with molecules of thiacrown compounds and their analogues. An amperometric sensor was proposed on the basis of an electrode modified by 1,4-dioxa-7,10-dithiacyclododecane, and its potential use for the flow-injection determination of iridium(IV) ions in chloride solutions was demonstrated. The calibration graph was Linear in the concentration range 0.05-0.50 mM Ir; the detection limit was 10 mu M. For the determination of iridium in model solutions containing Fe(II), Hg(II), Cu(II), Pd(IV), Pt(II), Rh(III), and (Ru(IV) ions, the relative standard deviation did not exceed 5% (n = 6). The throughput was 50-180 h(-1) for a sample volume of 400 mu L.