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Nonenzymatic Electrochemical Superoxide Sensor
Author(s) -
Nissim Rita,
Compton Richard G.
Publication year - 2014
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201300209
Subject(s) - chemistry , aqueous solution , saturated calomel electrode , superoxide , detection limit , glassy carbon , electrochemistry , analytical chemistry (journal) , electrode , graphite , carbon fibers , inorganic chemistry , nuclear chemistry , reference electrode , chromatography , cyclic voltammetry , organic chemistry , materials science , composite material , composite number , enzyme
The electrochemistry of nitroblue tetrazolium chloride (NBTC) was studied in aqueous solutions of pH 6.97 on a glassy carbon macroelectrode and at a carbon fibre microelectrode; values of near unity for the reduction transfer coefficient and 7.2×10 −6 cm 2 s −1 for the diffusion coefficient were generated. The electrochemically produced diformazan was shown to adsorb on the glassy carbon surface if the potential was held at −0.35 V [vs. saturated calomel electrode (SCE)]. A carbon paste electrode, fabricated by using dioctyl phthalate and graphite powder, was used as a nonenzymatic sensor. The sensitivity of the diformazan oxidation signal to the presence of superoxide was exploited to detect superoxide, which is voltammetrically visible at about +0.69 V (vs. SCE). The paste electrode was first immersed in aqueous superoxide solutions. It was subsequently equilibrated with NBTC by immersing it into aqueous NBTC solutions. The reduction of NBTC (by superoxide) thus took place in the paste, which allowed quantification of the superoxide in the aqueous phase by means of the diformazan oxidation signal. Values for the practical limit of detection and the sensor sensitivity, 0.059 n M and 1.79 μA n M −1 respectively, were obtained.