Extraction preconcentration of platinum and ruthenium using high molecular weight amines prior to simultaneous determination by derivative spectrophotometry

Abstract

The accurate determination of platinum group metals in various matrices is one of the most difficult analytical problems. Large variety and complexity of examined materials (geological, industrial, biological and environmental), inhomogeneous distribution of metals in the examined samples and wide range of concentrations to be determined (from ppb levels e.g. in biological and environmental materials even up to 99.99 % in some industrial products) make the choice of the analytical procedure to be used a fundamental problem.Direct use of instrumental techniques for the determination of noble metals is considerably restricted owing to numerous interferences caused by various types of matrices. Separation of analytes from base elements as well as particular precious metals from each other usually precedes the final detection [1,2]. Due to exceptional ability of ruthenium and osmium to be converted into the volatile tetroxides, RuO 4 and OsO 4 , which can be isolated from the examined samples by distillation, the majority of separation procedures were developed for mixtures of the other metals: platinum, palladium, rhodium, iridium and gold. It should be noted however, that quantitative isolation of ruthenium and osmium from the mixture of noble metals by distillation, in particular from chloride solutions, is a difficult problem. Chloride complexes of both metals do not easily oxidize to volatile species.Recent applications of two metals, platinum and ruthenium, as effective catalysts in various chemical processes [3] lead to the interest in analytical methods allowing the determination of both metals directly in solutions obtained after digestion of various catalysts. Bimetallic Pt-Ru catalysts are widely applied e.g. in methanol fuel cells capable of changing the chemical energy directly into electrical energy [4][5][6][7]. Ruthenium has been successfully applied to promote the catalytic activity of platinum in electro-oxidation reaction of methanol.Spectrophotometric methods can be employed to the determination of microgram amounts of the metals present in the catalysts. Essential increase in the selectivity of the determination can be achieved by numerical calculation of derivative spectra of the suitable order allowing to isolate the individual signal of particular analytes from their mixtures [8].Simultaneous extraction of platinum and ruthenium from chloride solutions and direct determination of analytes in the presence of each other in the obtained extract by applying derivative spectrophotometry [9] were the aims of this work. 829Extraction preconcentration of platinum and ruthenium using high molecular weight amines prior to simultaneous determination by derivative spectrophotometry M. Balcerzak* and E. Wyrzykowska Department of Analytical Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, PolandAbstract. Platinum and ruthenium can be simultaneously extracted from hydrochloric acid solution by high molecular weight amines (trioctylamine (TOA) or diantipyrylmethane (DAM) in 1,2-dich...

Solubility of Tridodecylamine in Supercritical Carbon Dioxide

“…18 Tertiary amines with long hydrocarbon chains, such as trioctylamine (TOA) and TDA, have been used in the extraction of metals such as platinum and ruthenium. 19 A variety of organic chelating agents, such as crown ethers, dithiocarbamates, β-diketones, and tributylphosphates have been used for the extraction of metal ions from various solvents by using supercritical solvents. [20][21][22] The motivation for this work stems from our interest in the chemical separation of dicarboxylic acids and precious metals using scCO 2 .…”