title: Improvements in the sample preparation for the determination of ruthenium in catalysts by different spectrometric techniques.
abstract: The sample preparation steps of two analytical methods for the determination of ruthenium in carbon supported catalysts with flame atomic absorption spectrometry (FAAS) or UV-vis spectrophotometry, were carefully optimised. As a first step, the carbon support is ignited in air at 450 degrees C then the residue is fused with potassium hydroxide and potassium nitrate to convert ruthenium into ruthenate anion RuO4(2-). The melt is dissolved in water with potassium persulphate and potassium hydroxide as stabilisers. Ruthenium may be directly estimated by measuring the UV-vis molecular absorption of ruthenate at the isosbestic point of the ruthenate-perruthenate mixture or by FAAS. In the latter case, an aliquot of the sample solution is added to the concentrated hydrochloric acid to obtain hexachlororuthenate RuCl6(2-), that is nebulized into the flame after proper dilution. This novel procedure allows to determination of ruthenium without the sensitivity loss (-66%) which occurs in the alkaline media resulting from the fusion. The relative standard deviation is 1.1% for FAAS and 1.3% for UV-vis, at 5% Ru (n = 7). The detection limit (3sB) is 0.07% Ru for FAAS and 0.02% Ru for UV-vis. Both methods were applied to the analysis of a commercial sample and a statistical comparison was carried out.
authors.affiliation: Dipartimento di Chimica G. Ciamician, Università di Bologna, Via F. Selmi 2, I-40126 Bologna. taddia@ciam.unibo.it
authors.forename: M
authors.initials: M
authors.lastname: Taddia
authors.forename: P
authors.initials: P
authors.lastname: Sternini
mesh_terms: D002384:Catalysis; D004784:Environmental Monitoring; D006851:Hydrochloric Acid / Q000737:chemistry; D012428:Ruthenium / Q000032:analysis*; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D013054:Spectrophotometry, Atomic / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*
chemical_list: D012428:Ruthenium; D006851:Hydrochloric Acid