A Study on Stripping Voltammetric Determination of Osmium(IV) at a Carbon Paste Electrode Modified In Situ with Cationic Surfactants

Abstract

This article deals with the development of a method for the determination of osmium at a carbon paste electrode (CPE) modified with cationic surfactants of the quaternary ammonium salt type; namely, cetyltrimethylammonium bromide (CTAB) and 1-(ethoxycarbonyl)-pentadecyltrimethyl-ammonium bromide (Septonex); both being added in situ and serving for preconcentration of osmium via its hexachloroosmate(IV) anion. The proper electrochemical detection was performed by cathodic scanning in the differential pulse voltammetric mode. Optimization studies concerning important experimental parameters also included a specially performed potentiometric titration, helping to define the actual stoichiometry for the ion-pairing process, the main principle and driving force of the accumulation step. In a chloride/acetate buffer based supporting medium and with Septonex as the modifier of choice, the reduction signal for osmium was found to be proportional to the Os(IV) concentration in a range from 5 Â 10 À9 to 5 Â 10 À7 mol L À1 with a limit of detection close to 5 Â 10 À9 mol L À1 (with preconcentration for 60 s). The method capable to determine Os(IV) in the presence of both Pt(IV) and Ir(III) was tested on model solutions as well as with real sample of industrial waste water (spiked with the analyte); both yielding the recovery rates within 88 -99%.

Carbon Paste Electrodes in Facts, Numbers, and Notes: A Review on the Occasion of the 50‐Years Jubilee of Carbon Paste in Electrochemistry and Electroanalysis

“…A wide palette of papers concerning inorganic electroanalysis with carbon-paste based electrodes hide some interesting contributions which could also be mentioned; among others: i) The determination of twelve rare-earth metals (Y, Sc, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), identified and quantified as a sum using the same methodical procedure [276]; ii) Simultaneous determination of three heavy platinum metals (Os, Ir, and Pt [263]), with additional studies on stripping analysis of Os(IV) at the trace concetration level [264] or dealing with possible accumulation of the remaining platinum metals (Ru, Rh, and Pd [277]); iii) Indirect amperometric detection of non-electroactive cations (alkali and alkaline earth metal ions) with a zeolite-modified CMCPEs after the separation in a HPLC column [278]; iv) Atypical quantification by means of evaluation of the shift in the peak potential [279] …”

Sequential Voltammetric Determination of Ultratrace Osmium, Ruthenium and Iridium. Application to Superficial Water

“…Really, for the determination of these metals, spectroscopic techniques [6][7][8][9][10][11][12][13][14][15][16] are prevalently used, more rarely neutron activation analysis [17,18] and chromatography [19][20][21][22][23][24][25]. Voltammetric measurements are seldom employed [26][27][28][29][30][31].…”

Carbon paste electrodes in the new millennium

“…Various modifications of carbon paste were applied in potentiometric sensors for copper [286][287][288][289][290][291][292], silver [97, 153,293], mercury [94-296], lead [297], arsenic [97,298], antimony [299], bismuth [300], cobalt [301], osmium [302], aluminium [107], lithium [303], ammonium [304], halides and pseudo-halides [305][306][307][308], and sulphate ions [309]. Some of them [97,302] were applied to monitor titrations based on ion-pair formation principles described and discussed in detail previously [310].…”