Catalytic auto-oxidation of o-hydroxyphenylthiourea by Iridium(III): A photometric sensing platform for Iridium

o -Hydroxyphenylthiourea ( HPTU) undergoes oxidative dimerization to form a yellow-colored disulfide in the presence of Iridium(III), a process significantly enhanced by the activator 1,10-phenanthroline. This catalytic oxidation was monitored spectrophotometrically at 416 ​nm under ambient conditions, employing both tangent and fixed-time methods. The method's performance was optimized by investigating factors like pH, reagent concentration, temperature, and potential interferents. A linear relationship between the rate of reaction and Iridium(III) concentration was observed in the range of 0.001 ​ng–5.0 ​mg of Iridium per mL, enabling the detection of Iridium(III) down to 0.001 ​ng/mL at pH 11.7. The method's simplicity, cost-effectiveness, and sensitivity make it suitable for the determination of Iridium(III) in real-time samples, eliminating the need for additional reagents, complex procedures, or preconcentration steps. • PGEs are crucial for Earth history research. Their unique properties and low abundance demand sensitive analysis. This research presents a spectrophotometric method for iridium(III) using HPTU. • HPTU oxidizes to yellow disulphide in presence of Ir(III). 1,10-phenanthroline enhances this reaction. Spectrophotometric method was used for analysis. • The effects of pH, reagent concentration, activators, temperature and interference of associated ions are investigated in the determination of iridium(III). A linear relationship exists between 0.001 ng/mL and 5.0 mg/mL Ir(III). • The method is advantageous due to auto-oxidation of HPTU, simple reagent synthesis, affordable equipment, and no preconcentration. It can be used for real-time Ir(III) determination in samples.