Differential pulse voltammetric determination of cobalt with a perfluorinated sulfonated polymer-2,2-bipyridyl modified carbon paste electrode

Abstract

A highly selective method for the determination of cobalt with a chemically modified carbon paste electrode Is proposed. It Is based on the chemical reactivity of an Immobilized modifier, 2,2-bipyrldyl, toward cobaH(II) Ion to yield the corresponding cation complex ((Bpy)3Co)2+, which Is taken up by another modifier, perfluorinated sulfonated polymer (Nation). Differential pulse voltammetry Is employed, and the oxidation of the complex, at +0.1 V vs SCE, Is observed. For a 5-mln preconcentration period, a linear calibration curve Is obtained for cobalt concentrations ranging from 7 X 10"7 to 1 X 10~5 mol/L, and the detection limit Is 3 X 10'7 mol/L. A lower detection limit can be obtained for longer preconcentration times. For eight preconcentratlon/determlnation/renewal cycles, the differential pulse voltammetric response could be reproduced with 4.3% relative standard deviation. Rapid and convenient acid renewal allows the use of an individual modified electrode surface In multiple analytical quantitations.Many coexisting metal Ions have little or no effect on the determination of cobalt. The procedure was applied to the determination of cobalt for four standard reference materials with relative standard deviation of 4.0-5.2%.

Electrochemistry of Cytochrome c Immobilized on Colloidal Gold Modified Carbon Paste Electrodes and Its Electrocatalytic Activity

“…The cytochrome c colloidal gold modified carbon paste electrodes, however, showed a larger charging current than the abovementioned two electrodes ((6.5 AE 0.7) Â 10 À 7 A). The cyclic voltammogram of K 3 [Fe(CN) 6 ] at this electrode gave a couple of tailed peaks with smaller peak currents than at only colloidal gold modified carbon paste. As comparison we prepared the electrodes without paraffin oil by mixing carbon graphite powder and colloidal gold (1 mg : 2 mL) or cytochrome c colloidal gold (1 mg : 1 mL : 2 mL) solution.…”

“…All other reagents were of analytical grade. K 3 [Fe(CN) 6 ], HAuCl 4 ¥ 3 H 2 O, trisodium citrate dihydrate were purchased from Aldrich (Deisenhofen, Germany). Sodium dihydrogen phosphate, disodium hydrogen phosphate and KCl for preparation of the measuring buffer were from Fluka (Deisenhofen, Germany).…”

“…Thus, the carbon paste electrodes were characterized by means of charging current measurements and cyclic voltammograms of 1. 6 ]. The modification of the paste with colloidal gold improves its conductivity.…”

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

“…The protective layer of choice for a CPE can, e.g., be either thick polycarbonate membrane used in combination with biosensors (e.g., [69]) and gas probes [178], or a thin film of Nafion applied via ethanolic/aqueous solutions to the surface of a CMCPE [179]. ix) Multiple modifications are being the case of methods in which advantageous properties of carbon paste-based substrates are combined with special function of modifier(s) and/or some additional operations.…”

Voltammetric Determination of Dopamine in a Mixture of Dopamine and Ascorbic Acid at a Deactivated Polythiophene Film Modified Electrode

“…They can be solely based on size exclusion 2 , or involve complexation of the probe with a ligand incorporated into the polymer film. 3 Simple ion exchange is also utilized in CMEs. [4][5][6] Ion-exchange films of both anionic and cationic nature have been developed to electrostatically accumulate/trap oppositely charged analyte molecules.…”