Vitreous carbon electrode

The redox properties of a series of heterometal clusters were assessed by electrochemical and FPR measurements. The redox potentials of derivatives formed in D. gigas Fdll were measured by direct square wave voltammetry promoted by Mg(II) at a vitreous carbon electrode, and the following values were determined 495, 420,... 

Kirkpatrick, M.J., Finney, W.C. and Locke, B.R. (2003) Chlorinated organic compound removal by gas phase pulsed streamer corona electrical discharge with reticulated vitreous carbon electrodes, Plasmas and Polymers 8, 165-77. 

Shaw et al. [64] described a (D)-penicillamine detection method in blood samples that had been treated with EDTA, deproteinized with trichloroacetic acid, and analyzed within 1 h. Penicillamine was detected at a vitreous-carbon electrode operated at +800 mV after HPLC separation. A linear calibration graph was obtained, and the method had a limit of detection equal to 5-20 ng. The method was useful in clinical and in pharmacokinetic studies. 

Yoshida has studied anodic oxidations in methanol containing cyanide to elucidate the electrode processes themselves.288 He finds that, under controlled potential ( 1.2 V), 2,5-dimethylfuran gives a methoxynitrile as well as a dimethoxy compound (Scheme 57). Cyanide competes for the primary cation radical but not for the secondary cations so that the product always contains at least one methoxy group. On a platinum electrode the cis-trans ratio in the methoxynitrile fraction is affected by the substrate concentration and by the addition of aromatic substances suggesting that adsorption on the electrode helps determine the stereochemistry. On a vitreous carbon electrode, which does not strongly adsorb aromatic species, the ratio always approaches the equilibrium value. 

Florence [98] carried out anodic stripping voltammetry of bismuth in a weakly acidic medium, with a polished vitreous carbon electrode mercury-... 

A method described by Florence and Farrer [584] separated tin from its associated lead by distillation from an aqueous sulfuric acid medium into which the vapour from boiling 50% hydrobromic acid is passed. The distillate provides an ideal supporting electrolyte for the determination of tin (II) (produced by reduction with hydrazinium hydroxide) by anodic stripping at a rotating vitreous-carbon electrode in the presence of codeposited mercury [585,586]. The tin is deposited at -0.70 V versus the SCE for 5 minutes, and then stripped at -0.50 V during a sweep from -0.70 V to -0.45 V at 5 V per minute. Tin in seawater is coprecipitated on ferric hydroxide, and the precipitate is then dissolved in the aqueous sulfuric acid, and subjected to the above procedure. The average content for Pacific coastal waters was found to be 0.58 xg/l. 

Several approaches have been undertaken to construct redox active polymermodified electrodes containing such rhodium complexes as mediators. Beley [70] and Cosnier [71] used the electropolymerization of pyrrole-linked rhodium complexes for their fixation at the electrode surface. An effective system for the formation of 1,4-NADH from NAD+ applied a poly-Rh(terpy-py)2 + (terpy = terpyridine py = pyrrole) modified reticulated vitreous carbon electrode [70]. In the presence of liver alcohol dehydrogenase as production enzyme, cyclohexanone was transformed to cyclohexanol with a turnover number of 113 in 31 h. However, the current efficiency was rather small. The films which are obtained by electropolymerization of the pyrrole-linked rhodium complexes do not swell. Therefore, the reaction between the substrate, for example NAD+, and the reduced redox catalyst mostly takes place at the film/solution interface. To obtain a water-swellable film, which allows the easy penetration of the substrate into the film and thus renders the reaction layer larger, we used a different approach. Water-soluble copolymers of substituted vinylbipyridine rhodium complexes with N-vinylpyrrolidone, like 11 and 12, were synthesized chemically and then fixed to the surface of a graphite electrode by /-irradiation. The polymer films obtained swell very well in aqueous... 

The direct reduction of haloalkynes using either mercury or vitreous carbon as the cathode has been examined in considerable detail [80-84] one example is portrayed in Eq (77). The influence of reduction potential, current consumption, proton donor, electrode, and substrate concentration on the course of the process has been examined. Vitreous carbon electrodes are preferred, though mercury has been used in many instances. Unfortunately, these reactions suffer from the formation of diorganomercurials. While both alkyl iodides and bromides can be used, the former is generally preferred. Because of their higher reduction potential, alkyl chlorides react via a different mechanism, one involving isomerization to an allene followed by cyclization [83]. 

Takamura et al. have reported an electrochemical method for the determination of chlorpromazine with an anodically pretreated vitreous carbon electrode [164]. Optimal conditions for the pre-treatment were attained by the anodic oxidation of vitreous carbon electrodes in 0.5 mM phosphate buffer (pH 6.7) at 1.6 V V5. S.C.E. for 2 minutes. This was found to enhance the oxidation peak of the cyclic voltammogram for chlorpromazine by a factor of simeq 30. The peak current at +0.75 V was directly proportional to the concentration of chlorpromazine over the range of 0.2-40 pM and the detection limit was 0.1 pM. 

Ebel et al. have used a microliter vessel in the voltammetry and polarographic determination of small sample volumes of chlorpromazine [166]. The concentration of cells in glass or PTFE was described for use with a dropping-mercury electrode (sample volume 180 pL), a rotating disc electrode (sample volume 1 mL), or a stationary vitreous-carbon electrode (sample volume 80 pL). Chlorpromazine was determined using oxidative voltammetry at a 3 mm vitreous-carbon or a rotating electrode. 

Takamura et al. have reported a voltammetric method for the determination of chlorpromazine using an anodically oxidized carbon electrode [167]. A vitreous-carbon electrode was maintained at +1.6 V vi. S.C.E. for 2 minutes (in 0.5 M phosphate buffer at pH 6.8). Under these conditions, chlorpromazine gave an oxidation peak current on cyclic voltammograms that varied linearly with concentration over the range of 50 nM to 1 pM. 

An aluminum electrode modified by a chemically deposited palladium pen-tacyanonitrosylferrate film was reported in [33]. Vitreous carbon electrode modified with cobalt phthalocyanine was used in [34]. Electrocatalytic activity of nanos-tructured polymeric tetraruthenated porphyrin film was studied in [35]. Codeposition of Pt nanoparticles and Fe(III) species on glassy-carbon electrode resulted in significant catalytic activity in nitrite oxidation [36]. It was shown that the pho-tocatalytic oxidation at a Ti02/Ti film electrode can be electrochemically promoted [37]. 

In a series of publications by Gomez etal. [61-63], the electrodeposition of nickel on a vitreous carbon electrode has been investigated. 

Figure 4 Cyclic voltammograms of the complexes cii-[MoY2(CsH1oNO)2) (Y = O and/or S) in a solution of 0.2 mol dm-3 [NBU4HBF4] in DMF at 298 K and at a vitreous carbon electrode, scan rate 0.3 V s-1...

HPLC with ED, vitreous carbon electrode, potential range 0.72-0.85 V. 

HAAs RP-HPLC-ED (0.9 V with vitreous carbon electrode vs. Ag/AgCl). SynChropak SCD-100 column (short alkyl-chain ligand, endcapped). Mobile phase ACN-NH4 (acetate) buffer (pH = 5.5). 80-475 pg Food products 202... 

Current-potential curves of the oxidation of hydrogen peroxide with a vitreous-carbon electrode in an alkaline environment with a hydrogen peroxide concentration of (a) 0.15 mol I-1 and pH = 12.04 and (c) 0.44mol I-1 and pH = 12.80, and their corresponding table graphs with (b) an inclination of 0.50 and (d) an inclination of 0.48. 

Carbon electrodes. The vitreous carbon electrode usually is fabricated by sealing a plug or disk, but from a thick sheet of glassy carbon, into a glass tube with epoxy cement. The surface of the electrode is then polished until it is bright and smooth. No further treatment is necessary. 

The cyclic voltammograms at vitreous carbon electrodes for 2-iodooctane, r-butyl bromide and -butyl iodide show two waves [e.g., -1.6 V and -1.8 V (see) for r-butyl bromide] indicating stepwise generation of alkyl radicals and carbanions. The products of large-scale electrolyses of r-butyl bromide (isobutane, isobutylene, 2,2,3,3-tetramethyl-butane) are indicative of the involvement of both radical and carbanion species214. 

Acetylcholineesterase and choline oxidase Immobilization of horseradish peroxidase in the redox polymer poly (4-vinylpyridine-chlorobis-(2,2 -bipyridyl) osmium cross-linked by means of polyoxyethylene 400 diglycidyl ether on polished vitreous carbon electrodes. Response time of 30 s and maintained its sensitivity for 24 h at low substrate concentration. Responses were rectilinear up to 10 mM H202 for 100 pM choline with detection limit of 10 nM and 1 pM. [78]... 

Diffuse reflectance UV-vis spectroscopy was applied in electrocatalysis by El Mouahid et al. (1998), who followed the electropolymerization of a cobalt porphyrin complex on a vitreous carbon electrode. The thin polymer... 

Xie, Y. -B. and Li, X. -Z. (2006b) Interactive oxidation of photoelectrocatalysis and electro-Fenton for azo dye degradation using Ti02-Ti mesh and reticulated vitreous carbon electrodes. Mater. Chem. Phys. 95,39-50. 

Armalis S, Kriksciuniene I, Kubilene E, Djane N-K, Ndung u K, and Mathiasson L. Stripping analysis of trace metals at a flow-through reticulated vitreous carbon electrode after the preconcentration by supported hquid membrane technique. Intern. J. Environ. Anal. Chem. 1999 74 233-242. 

Djane N-K, Armalis S, Ndung u K, Johansson G, and Mathiasson L. Supported liquid membrane coupled on-line to potentiometric stripping analysis at a mercury-coated reticulated vitreous carbon electrode for trace metal determinations in urine. Analyst 1998 123 393-396. 

The influence of anode materials on the electrodecarboxylation in aqueous solutions has been well documented platinum, iridium, and vitreous carbon electrodes favor the cou-... 

In contrast, a very stable and efficient electrode modification has been obtained by Fletcher and Bartlett [23]. In this case, a high-surface-area reticulated vitreous carbon electrode has been modified by electropolymerization of aniline, thereby further increasing the surface area. Horseradish peroxidase (HRP) was immobilized on this electrode by cross-linking with glutaldehyde and 1,2-diaminobenzene. The immobilization of the enzyme led to a strongly enhanced lifetime of the enzyme. 

Fry has used a similar system for the enzymatic reduction of pyruvate to L-lactate. In this case, the one-electron transfer redox catalyst, methyl viologen, and the lipoamide dehydrogenase are coimmobilized within a Nafion cation-exchange layer on the surface of a reticulated vitreous carbon electrode. As production enzyme, L-lactate dehydrogenase (LDH) was employed [48], which was later stabilized considerably in the form of cross-... 

Electropolymerization based on polymerizable vinyl groups has provided a general procedure for the preparation of a variety of films on electrodes (34). Polymeric films have been deposited on Pt, Au, Sn02 Ti02 and vitreous carbon electrodes, although most of the experiments described here have been carried out on Pt. Films have been prepared by electroreductions based on 4-methyl-dine (vbpy), trans-4 -X-stilbazoles, (trans-... 

The encapsulation of catalytically active species into porous solids is one of the possible strategies of particular interest. Thus, Bessel and Rolison (1997b,c) compared the electrocatalytic effect of zeolite Y-encapsulated Co(salen) (salen = N,N -bis(salicylidene)ethylenediamine) on the reaction between benzyl chloride and carbon dioxide in tetrahydrofuran/hexamethylphosphoramide, with that exerted by the same complex in solution. Using a large surface area reticulated vitreous carbon electrode immersed into suspensions of Co(salen) NaY in solutions of the reagents, the effective electrocatalytic turnover is ca. 3000 times that of homogeneous Co(salen) under comparable conditions. Remarkably, coulometric experiments indicated that only... 

Kovalenko and Tikonova (1980) used inert electrodes and discovered a correlation between the oscillations in the redox potential and the concentration changes in the B-Z reactants. The graphite and vitreous carbon electrodes were used to measure the concentration ratio of the redox forms of the catalyst metal ions while the concentration of bromate reduction products were measured by the inert platinum electrodes. 

PN Bartlett, D Pletcher, J Zeng. Approaches to the integration of electrochemistry and biotechnology. 1. Enzyme-modified reticulated vitreous carbon electrodes. J Electrochem Soc 144 3705-3710, 1997. 

A laser magnetic resonance spectrometer has been used in combination with a discharge-flow system to measure the gas-phase reaction rates of the OH radical with NO, NO2 (and CO) at 296 K and over a pressure range 0.4—5 Torr. A study of the behaviour of a number of oxo-nitrogen species in molten NaCl-AlCls mixtures as solvents has been made. The NO ion undergoes reversible one-electron reduction-oxidation at vitreous carbon electrodes. N07 reacts to produce high yields of NO ion, which is separable from the solvent phase as NOCl. NO2, Not, and NOt are reduced to varying extents, whereas N2O and NO remain unaffected for 24 hours. Possible mechanisms for these processes have been discussed. "... 

---