engleski

Determination of Iridium(IV) by Fluorescence Quenching of Esculin

The determination of iridium is not a common analytical problem. Owing to their corrosion- resistant nature, iridium alloys have found a wide range of applications in both the chemical industry and the manufacture. Since iridium is usually present in such materials at low concentrations, methods with reasonably high sensitivity are required. In addition, iridium is usually present in association with other platinum metals. Therefore, successful determination of iridium can be performed only by analytical methods having high selectivity. Fluorescence quenching method was developed for determination of microamounts of iridium(IV) by using esculin as a new fluorescent probe. In 15 % methanol-water mixture esculin showed maximum excitation and emission wavelengths at 335 nm and 455 nm, respectively. The fluorescence of esculin was significantly quenched by iridium(IV). Under optimal conditions, iridium(IV) in the range 58- 960 ng/ml can be determined. Most anions and cations do not interfere, even when present in large excess. Relative standard deviation of five measurements is 2, 5 % for 500 ng/cm3 Ir(IV). The quenching rate constant was determined using the Stern-Volmer equation. The proposed method has been applied successfully for the determination of iridium(IV) in a series of synthetic mixtures.

Iridium ; Fluorescence ; Esculin

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