Modified carbon paste electrode

Plain electrode surfaces for electrochemical analyses, as well as for syntheses, offer only limited applicability due to the fact that their main purpose is to act as an electron source or sink depending upon the depolarizer present in the bulk solution. Concomitant adsorption, which is rather frequent with CPEs particularly with organic aromatic compounds, is - apart from stripping analysis - rather unwanted because it complicates handling and practical setups due to a necessary control of the exposure time of the electrode to the solution. 

The goals of modification are straightforward (i) improvement of detection ability by accumulation of the target species (ii) generation of electrochemical signals and their characteristics (signal shape, signal separation, decrease of 

Apart from this variety and the individual nuances, chemical modification of CPEs leads to qualitatively new configurations termed chemically modified carbon paste electrodes (CMCPEs [4, 5,8,9]). 

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FIGURE 4-15 Cyclic voltanmiograms for 1.5 x 10 3 M ribose (a), glucose (b), galactose (c), and fructose (d) recorded at a Ru02-modified carbon-paste electrode. Dotted lines were obtained in carbohydrate-free solutions. (Reproduced with permission from reference 50.)... 

In recent years, the electrodes of similar structure have also found application in the electroanalytical chemistry, for purposes of researching the electrochemical behavior of solid substances, etc. These electrodes are known as the modified carbon paste electrodes or carbon paste electroactive electrodes [2]. 

A.A. Ciucu, C. Negulescu, and R.P. Baldwin, Detection of pesticides using an amperometric biosensor based on ferophthalocyanine chemically modified carbon paste electrode and immobilized bienzymatic system. Biosens. Bioelectron. 18, 303-310 (2003). 

V.G. Bonifacio, L.H. Marcolino, M.F.S. Teixeira, and O. Fatibello-Filho, Voltammetric determination of isoprenaline in pharmaceutical preparations using a copper(II) hexacyanoferrate(III) modified carbon paste electrode. Microchem. J. 78, 55-59 (2004). 

S.Q. Liu and H.X. Ju, Reagentless glucose biosensor based on direct electron transfer of glucose oxidase immobilized on colloidal gold modified carbon paste electrode. Biosens. Bioelectron. 19, 177-183 (2003). 

Lorenzo E, Alda E, Hernandez P, et al. 1988. Voltammetric determination of nitrobenzene with a chemically modified carbon-paste electrode Application to wines, beers, and cider. Fresenius Z Anal Chem 330 139-142. 

Parra, V., Hernando, T., Rodriguez-Mendez, M. L., and de Saja, J. A. (2004). Electrochemical sensor array made from bisphthalocyanine modified carbon paste electrodes for discrimination of red wines. Electrochim. Acta 49(28), 5177-5185. 

Roa et al. reported [408] the determination of Pb(II) and Cd(II) ions concentration using a polycyclodextrin-modified carbon paste electrode with anodic stripping voltammetry. 

Also, sodium montmorillonite-modified carbon paste electrode has been used for the determination of trace concentrations of mercury [80]. Hg + was preconcentrated at the electrode, reduced, and then stripped from the electrode surface in the positive potential scan. At a glassy carbon electrode modified with dithizone, mercury has been determined, applying anodic stripping voltammetry [81]. 

Wei, S., Dandan, W., Ruifang, G., and Kui, J., Direct electrochemistry and electrocatalysis of hemoglobin in sodium alginate film on a bmim PF modified carbon paste electrode, Electrochem. Commun., 9,1159-1164, 2007. 

The reduction of Ti4+ to Ti3+ in TS-1 has also been observed with cyclic voltammetry using zeolite-modified carbon paste electrodes. With silicalite, neither anodic nor cathodic processes can be observed. However, TS-1 is electrochemically active, with a reduction process at +0.56 V versus a saturated calomel electrode (SCE) and an oxidation process at +0.65 versus SCE. These observations must be attributed to the redox system Ti4+/Ti3 +. The electrochemical process involves the Ti cations of the inner part of the zeolite crystals, provided that a suitable electrolyte cation can diffuse inside the channels to compensate for the electrical imbalance caused by the redox process in the solid ... 

Alvarez-Crespo et al. [69] L-Glutamate Chicken bouillon cubes L-Glutamate dehydrogenase/ entrapped in carbon paste NAD+ modified carbon paste electrode/+0.15 V vs. Ag/ AgCl o-Phenylenediamine polymerised on the electrode surface... 

M.J. Lobo-Castanon, A.J. Miranda-Ordieres and P. Tunon-Blanco, A bienzyme-poly-(o-phenylenediamine)-modified carbon paste electrode for the amperometric detection of L-lactate, Anal. Chim. Acta, 346(2) (1997) 165-174. 

S. Hu, C. Xu, J. Luo, J. Luo and D. Cui, Biosensor for detection of hypoxanthine based on xanthine oxidase immobilized on chemically modified carbon paste electrode, Anal. Chim. Acta, 412(1-2) (2000) 55-61. 

K.M. Millan, A. Saraullo and S.K. Mikkelsen, Voltammetric DNA biosensor for cystic fibrosis based on a modified carbon paste electrode, Anal. Chem., 66 (1994) 2943-2948. 

S. J. Setford, S.F. White and J.A. Bolbot, Measurement of protein using an electrochemical bi-enzyme sensor, Biosens. Bioelectron., 17 (2002) 79-86. P. Sarkar and A.P.F. Turner, Application of dual-step potential on single screen-printed modified carbon paste electrodes for detection of amino acids and proteins, Fresenius J. Anal. Chem., 364 (1999) 154-159. 

Svancara, I., Baldrianova, L., Tesarova, E., Hocevar, S. B., Elsuccary, S. A. A., Economou, A., Sotiropoulos, S., Ogorevc, B. and Vytras, K. (2006), Recent advances in anodic stripping voltammetry with bismuth-modified carbon paste electrodes. Electroanalysis, 18(2) 177-185. 

Paste electrodes - electrodes prepared by making a paste from an electron-nconducting material and a binder. The binder may be an electrolyte solution or inert oils like - Nujol. Paste electrodes can be part of batteries [i], where the electroactive material is used to prepare the paste, often with the addition of an inert electron conductor. In - electroanalytical chemistry, unmodified and modified - carbon paste electrodes are used. 

Bioelectrocatalytic properties were obtained for FDH at carbon and gold and platinum electrodes [111,113]. The catalytic oxidation current of FDH-modified carbon paste electrodes approached a maximum value at 4-0.5 V vs. Ag/AgCl. At this potential and under optimum conditions, i.e., pH 4.5, fi uctose can be measured between 0.2 and 20 mM in fi uit juices. Most importantly the fructose sensor was insensitive to ambient oxygen. 

Wang, J., and Walcarius, A. 1996. Zeolite-modified carbon paste electrode for selective monitoring of dopamine. Journal of Electroanalytical Chemistry 407, 183-187. 

Ortiz-Viana, M. M., da Salva, M. P., Agraz, R., Procopio, J. R., Sevilla, M. T., and Hernandez. L. (1999). Comparison of two kinetic approaches for copper speciation using ion-exchange modified carbon paste electrodes. Anal. Chim. Acta 382, 179-188. 

T. Ikeda, F. Matushita and M. Senda, D-Fructose dehydrogenase-modified carbon paste electrode containing p-benzoquinone as a mediated amperometric fructose sensor, Agric. Biol. Chem. 54(11), 2919-24 (1990). (fructose in fruits). 

H. Okuma, et. al.. Mediated amperometric biosensor for hypoxanthine based on a hydroxymethyl ferrocene-modified carbon paste electrode. Anal. Chim. Acta., 244 (2), 161-4 (1991). (determination in tuna). 

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