Spectrofluorimetric determination of iridium(IV) traces using 4-pyridone derivatives.

A new spectrofluorimetric determination of iridium(IV) with 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) or 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) is reported. Iridium(IV) react with HX or HY and chelates were extracted into chloroform or dichloromethane. The organic phase showed fluorescence. The fluorescence measurements to quantify iridium were carried out in its fluorescent band centred at lambda(ex)=373nm and lambda(em)=480nm. Under optimal conditions, the calibration graphs were linear over the concentration range of 0.1-7.6mugml(-1) of iridium for Ir(IV)-HX and 0.1-5.8mugml(-1) for Ir(IV)-HY with a correlation coefficients of 0.999 and 0.992 and relative standard deviation of +/-1.1%. The method is free from interference by Rh(III) and Pt(IV), which normally interfere with other methods. Iridium can be determined in the presence of 300-fold excess of rhodium(III) and 10-fold excess of platinum(IV). The method was applied successfully to the determination of iridium in some synthetic mixtures and mineral sample gave satisfactory results.