Reusable Doped Sol-Gel Graphite Electrodes for Metal Ions Determination

Abstract

A reusable sol-gel graphite composite electrode for the determination of Fe(II) in aqueous solutions is presented. This sensor was prepared by mixing a sol-gel precursor (e.g., methyltrimethoxysilane) and graphite powder, previously modi®ed with 4,7-dimethyl-1,10-phenanthroline. Fe(II) uptake was done by immersing the electrode in Fe(II) solutions at pH 2, TFAaNaOH, for 5 min. The complexation of Fe(II) was followed by Osteryoung square wave voltammetry. Variables affecting the electrode response such as the chemical nature of the ligand and sol-gel precursor, the HCl and ethanol concentrations, added organics and pretreating and renewing of the electrode surface were investigated. This sensor can measure Fe(II) with a linear range from 1.0610 À5 M to 5.0610 À4 M, a sensitivity of 4.80 AaM cm 2 and a detection limit of 7.0610 À6 M. These results were not affected by the presence of a 100-fold amount times of Co(II), Ni(II), Mn(II), Cu(I), Cu(II) and Ag(I). Determination of Fe(II) in peach leaves with this electrode gave a value of 210 AE 11 mgag compared to an accepted value of 218 AE 14 mgag and with a 3.7% relative error. The generality of this approach to the measurement of other metal ions like Ni(II) and Cu(I) is also demonstrated. Important advantages of this electrode are its simple fabrication, easy renewability, reproducible analytical results and good stability.

Modified carbon-containing electrodes in stripping voltammetry of metals. Part II. Composite and microelectrodes

“…Specific features of the last material are its strength, chemical inertness, absence of impurities, nonswelling in water solutions, stability in organic solvents for prolonged periods, ease and simplicity of fabrication, and secure fixing of water-soluble reagents. Table 1 gives examples of the use of modified composite electrodes in stripping voltammetry with the composite materials made under industrial and laboratory conditions using simple sol-gel, sono-gel, spin-casting, and molding technologies [73,[74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92]. The electrodes shown in the table can be divided into two groups: those made of carbon-(soot, amorphous carbon) [73][74][75][76][77][78][79] and those made of graphite-containing [80][81][82][83][84][85][86][87][88][89][90][91][92] materials.…”

“…Silicon-carbon electrodes were proposed for determination of Cu (II), Pb (II), and Zn (II) after modification by mercury [76]; Ni (II) after modification by dimethyl glyoxime [77]; Os (IV) after modification by 9-phenyl-3-fluorone [78]; and Cu (I), Fe (II), and Ni (II) after modification by neocupferron, phenanthroline derivatives, and dimethylglyoxime, respectively [79]. A satisfactory reproducibility of responses of elements to be determined, a high selectivity, and the time stability of sol-gel electrodes can be noted.…”

Electroanalysis with Pure, Chemically Modified and Sol-Gel-Derived Silica-Based Materials

“…However, as common for materials prepared according to the solgel chemistry, they are subject to shrinkage which often results in cracks in the ceramic part of the composite and therefore leads to pore operational stability of the electrode. To overcome this problem, Ji and Guadalupe [164] have recently proposed to use polyethylene glycol as an additive to the starting sol which acted to delay the sol-gel shrinkage and further allowed one to control the gel porosity.…”

Sol-Gel Derived Composite Ceramic Carbon Electrodes

“…Wang and co-workers [34] used dimethylglyoxime doped CCEs to determine trace nickel ions achieving a minimum detection limit of 15 mgaL after only 15 s accumulation period. Ji and Guadalupe demonstrated Fe(II) stripping by several 1,10-phenanthroline derivative ligands, Cu(I) stripping by neocuproine, and Ni(II) by dimethylglyoxime [32].…”