Preconcentration and Electroanalysis of Copper Species at Electrochemically Activated Glassy Carbon Electrodes

Abstract

Electrochemically activated glassy carbon electrodes were applied to the preconcentration and electroanalysis of metal species. Activated glassy carbon electrodes were obtained by potentiostatic oxidation at þ2.0 V in 0.5 M sulfuric acid. Copper species were readily extracted onto the modified electrode and were determined electrochemically. Voltammetric peak currents showed linear response for copper concentrations in the range between 1 to 20 mM with a large slope of 2.11 A M ¹1 and a correlation coefficient of 0.997. The reproducibility of the voltammetric measurements was found to be within 7 % RSD for five replicate measurements on copper concentration of 10 mM. The modified electrodes could be applied for repeated copper determinations without appreciable deterioration in electrode response. Results suggest that the preconcentration of copper species onto activated electrodes involved primarily cation-exchange interactions with the surface graphite oxide film.

Preparation and General Properties of Chemically Modified Electrodes Based on Electrosynthesized Thin Polymeric Films Derived from Eugenol

“…It is well established that oxidative pretreatment of the carbonbased electrode results in an enhancement of its capabilities to adsorb (preconcentrate) metal cations [33]. The effect has been attributed to the generation of different oxygen-containing functionalities on the electrode surface which are able to coordinate adsorbing species.…”

Modified carbon-containing electrodes in stripping voltammetry of metals

“…These factors account for the low sensitivity of unmodified glassy-carbon electrodes in analysis [29][30][31][32][33][34]. The detection limit of elements is reduced by increasing the electrochemical accumulation time (up to 40 min) [35][36][37][38][39][40][41][42], using additional accumulation operations, e.g., the ultrasonic extraction [43] or modifying the GCE surface. Table 1 shows some applications of modified GCE for voltammetric measurements of inorganic ions .…”

“…Different combinations of the modifiers-a metal and OS [70-80, 97-105, 106], a polymer and a metal [86, 132-147, 160- [107][108][109][110][111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126] or the first modifying layer of mercury [70][71][72][73][74][75][76][77][78][79][80], bismuth [97][98][99][100][101][102][103][104][105] or lead-copper [106]. For a more profound immobilization of the compounds, GCE is pre-polarized at a constant potential of (1.2÷2.0) V [36,39,41] or undergoes multiple (up to 100) polarization cycles between 0 and +1.2 V in 0.1 M NaOH [40]. Some investigators think that, in this case, new...…”

“…For a more profound immobilization of the compounds, GCE is pre-polarized at a constant potential of (1.2÷2.0) V [36,39,41] or undergoes multiple (up to 100) polarization cycles between 0 and +1.2 V in 0.1 M NaOH [40]. Some investigators think that, in this case, new functional groups appear on the surface [39][40][41], whereas others are inclined to consider the formation of an oxidized GC film [36]. Still, they are agreed that the anodic polarization radically changes the structure and the composition of the electrode surface, making it possible to fix the modifier or the measured ions on the surface through the ion exchange, the covalent bonding or the electrostatic interaction.…”

“…To make the GCE surface reproducible, it is prepared and cleaned by a great variety of methods such as mechanical polishing [108], treatment with reagents [76], electrochemical treatment by polarization at high anode potentials [36,186], and exposure to microwaves or ultrasound [29,40,131]. Mechanical polishing of the surface with abrasive diamond or Al 2 O 3 powders or special polish cloths is in most common use.…”