Voltammetric determination of iridium(IV) using 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one after thermal activation of the interaction

Abstract

5-Hydroxyimino-4-imino-1,3-thiazolidin-2-one was proposed as the organic reagent for the voltammetric determination of iridium(IV). The complex compound of iridium(IV) and 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one is the analytical form in the proposed voltammetric method. However, due to the significant kinetic inertness of aqua-hydroxo-chloride complexes of iridium(IV), the complexation with 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one is too slow. To ensure the maximum yield of the complex compound of iridium(IV) with 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one, one of the classic methods of analytical chemistry of platinum group elements was utilized, viz. the thermal activation of analyte’s interaction with . This approach made it possible to improve the validation parameters of the voltammetric technique comparing with the adding of an excess of organic analytical reagent, but without additional thermal activation of the interaction. The optimal conditions of Ir(IV) voltammetric determination using 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one were established, viz. 0.3 M acetate buffer solution (pH 4.0) is a background electrolyte, a concentration of the organic reagent is 1.0×10 -4 М, a duration of heating of solutions on boiling water bath is 30 min, a potential of hydrogen catalytic currents peak is Е c p = −1.177 V. The sensitive method for the voltammetric determination of iridium(IV) was developed (LOD = 8.5×10 -8 M). The concentration intervals for Ir(IV) quantification consist of two linearity ranges of the analytical signal and cover more than two concentration orders (6.0×10 -8 –1.2×10 -6 M and 1.2×10 -6 –1.2×10 -5 M). Significant concentration excesses of concomitant metals ions, in particular, palladium(II) and osmium(IV), do not interfere with iridium(IV) voltammetric determination using 5-hydroxyimino-4-imino-1,3-thiazolidin-2-one after thermal activation of the interaction. The accuracy of the elaborated method was tested on the analysis of real samples, viz. three-component intermetallic alloys Tb 2 Ir 3 Al 9 and Gd 2 Ir 3 Al 9 . Keywords : iridium, hydrogen catalytic currents, azolidone, thermal activation.