A simple and sensitive electrochemical sensor by using a glassy carbon electrode modified by iridium oxide nanoparticles (GCE/IrOxNPs) was constructed and utilized to determine isoprenaline (IP). This sensor was used successfully for IP determination in human urine samples. IrOxNPs are grown on a GCE by electrodepositing method. Various experimental parameters influencing the electrochemical behavior of the modified electrode were optimized by varying the scan rates and pH. Compared with a bare GCE, the GCE/IrOxNPs exhibits a distinct shift of the oxidation potential of IP in the cathodic direction and a marked enhancement of the current response. The results showed that GCE/IrOxNPs exhibited excellent electrochemical activity towards IP in pH 7.0 phosphate buffer solution (PBS). The detection limit, sensitivity and catalytic rate constant (kcat) of the modified electrode toward IP were 90 nmol L-1, 17.3 nA µmol-1 L and 1.6 × 104 mol-1 L s-1, respectively, at linear concentration rang up to 2500 µmol L-1. The modified electrode displayed linear responses to IP in amperometry assays in real urine, with a detection limit of 120 nmol L-1.

In this study, a procedure is developed for cloud point extraction of Pd(II) and Rh(III) ions in aqueous solution using Span 80 (non-ionic surfactant) prior to their determination by flame atomic absorption spectroscopy. This method is based on the extraction of Pd(II) and Rh(III) ions at a pH of 10 using Span 80 with no chelating agent. We investigated the effect of various parameters on the recovery of the analyte ions, including pH, equilibration temperature and time, concentration of Span 80, and ionic strength. Under the best experimental conditions, the limits of detection based on 3Sb for Pd(II) and Rh(III) ions were 1.3 and 1.2 ng mL-1, respectively. Seven replicate determinations of a mixture of 0.5 µg mL-1 palladium and rhodium ions gave a mean absorbance of 0.058 and 0.053 with relative standard deviations of 1.8 and 1.6%, respectively. The developed method was successfully applied to the extraction and determination of the palladium and rhodium ions in road dust and standard samples and satisfactory results were obtained.