Ruthenium spectrophotometric determination

Dalzin (bis(allylthiocarbamido)hydrazine) forms sparingly soluble complexes (29) in which it is bonded through sulfur and nitrogen atoms (Section 10.2.7) but the bright orange-red bismuth complex can be extracted into chloroform for a spectrophotometric determination provided cyanide is present to mask copper. 1,4-Diphenylthiosemicarbazide PhNHNC(SH)NHPh can be used for the spectrophotometric determination of ruthenium after extraction of its violet-red complex into chloroform. 

Diphenylthiosemicarbazide (formula 42.1) has been used by Hara and Sandell [37] for the spectrophotometric determination of Ru. Heating a solution of the reagent and ruthenium in the presence of SnCb as reductant results in the formation of a red-violet CH3Cl-soluble complex in which the ruthenium is probably tervalent. 

Kiba et al. [93] has described a method for determining this element in marine sediments. The sample is heated with a mixture of potassium dichromate and condensed phosphoric acid (prepared by dehydrating phosphoric acid at 300 °C). The ruthenium is distilled off as RuC>4, collected in 6 M hydrochloric acid-ethanol and determined spectrophotometrically (with thiourea) or radiometrically. Osmium is separated by prior distillation with a mixture of condensed phosphoric acid and Ce(S04)2. In the separation of ruthenium-osmium mixtures recovery of each element ranged from 96.8 to 105.0%. 

Ruthenium can be determined by spectrophotometric methods, based on its catalytic effect on various redox reactions, e.g., ferrozine with KIO4 [74], Ce(IV) with As(lll) [75,76], haematoxylin with H2O2 [77], or Thymol Blue with BrO [78]. 

The method for the determination of ruthenium in the presence of Pt using the complexes with tin(II) chloride and second derivative spectrophotometry has been developed [1]. The determination of Ru in Pt-Ru catalysts with carbon support was described. Ruthenium in carbon-supported Pt-Ru-Ge catalyst was determined by simple selective spectrophotometric method using the complex with thiourea [2]. A 18-fold excess of Pd or Rh did not interfere with the determination of Ru. 

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