Rapid method for the spectrophotometric determination of iridium(IV)

Abstract

lridium(1V) forms, instantaneously, a red radical cation with perazine dimalonate, at room temperature in a phosphoric acid medium. The radical cation exhibits an absorption maximum at 515 nm and Beer's law is obeyed for up to 24 pg ml-1 of iridium. Sandell's sensitivity of the reaction is 0.019 pg cm-2 and the molar absorptivity is 9.93 x lo3 I mol-1 cm-1. The tolerance limits to platinum metals, base metals and common anions are reported. The method is applied to the determination of the iridium content in the synthetic mixtures corresponding to the iridiumrhodium fraction separated from platinum metal concentrates.

Spectrophotometric determination of iridium after complexation and membrane filtration

“…Some methods are time-consuming because reactions develop at higher temperature [35,36,38] and are not selective in the presence of rhodium(III), which is generally found to be associated with iridium [22,35,38]. Compared with other spectrophotometric methods, the present approach is considerably less complicated, because the reaction takes place at room temperature.…”

“…Iridium can be determined spectrophotometrically at trace concentrations with a variety of reagents (Table 1) [21,22,[35][36][37][38][39][40][41]. Some methods are time-consuming because reactions develop at higher temperature [35,36,38] and are not selective in the presence of rhodium(III), which is generally found to be associated with iridium [22,35,38].…”

“…Neutron activation analysis (NAA) [11], atomic absorption spectrometer (AAS) [12], graphite furnace AAS [13], individual catalytic [14], imprinted polymer-based [15], sequential voltammetric [16] and flow injection analysis [17] may be used for the trace determination of iridium in complex materials, however, these instruments are highly expensive, day to day maintenance is high and not free from various types of interferences [18][19][20]. A survey of the literature reveals that iridium may be determined by zero order spectrophotometry using phenanthrenequinone monoxime [21] (e = 2.3 Â 10 4 L mol À1 cm À1 ) perazine dimalonate [22] (e = 9.93 Â l0 3 L mol À1 cm À1 ), tetrahydrofurfuryl xanthate [23] (e = 5.02 Â l0 3 L mol À1 cm À1 ), 1-phenyl-4,4-6-trimethyl-(1H,4H)-pyrimidine-2-thiol [24].…”

Differential Pulse Polarographic Determination of Rhodium(III) and Ruthenium(III) in Synthetic Samples after Preconcentration of Their Quinolin-8-olate Complexes onto Microcrystalline Naphthalene

“…The metals are usually present along with other metals in various osmiridium alloys, rhodium-iridium fraction separated from platinum metal concentrates (native platinum contains 4% iridium, 3% rhodium, 2% osmium, and 1% ruthenium) (24), and also in platinum-bearing sands found in North and South America and the Urals. The composition of these samples is not fixed; it depends mainly on the source from which the sample was taken.…”

Simultaneous Determination of Rhodium and Iridium Using Derivative Spectrophotometry after Preconcentration of Their 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol Chelates onto Microcrystalline Naphthalene

“…Therefore, synthetic mixtures were prepared whose composition corresponding to the Rh-Ir fraction separated from platinum metal concentrates. 19 more samples were prepared in the presence of a large number of common metal ions, so that the developed procedure may be applied to any geological samples. Necessary aliquots of sample solutions (2 -20 ml) were withdrawn from each sample, and the general procedure was followed.…”