A comparative study of some phenoxazine and phenothiazine modified carbon paste electrodes for ethanol determination

Abstract

An amperometric ethanol electrode is described based on carbon paste modified with alcohol dehydrogenase (ADH) and a mediator. The possibility of coupling this enzymatic system with some commercially available phenoxazines [Meldola Blue (MB), Nile Blue (NB) and Brilliant Cresyl Blue (BCB)] and phenothiazines [Toluidine Blue 0 (TBO)], that allows the electrocatalytic oxidation of NADH, was investigated. Different strategies of mediator immobilization in the carbon paste were compared. The most suitable immobilization technique was the coverage of the modified carbon paste surface with a dialysis membrane and the best electrocatalytic structure was the phenothiazine TBO. The TBO(lO%)-ADH(S%)-modified carbon paste electrode shows steady state signals for ethanol within 30 s. The influence of various experimental conditions was explored for optimum analytical performance. Amperometric detection of ethanol at an applied potential of 50mV (Ag/AgCl) gives linear responses over the concentration range of 10-lOOpM, with a detection limit of 5 x 10-6M. The modified electrode was applied to the determination of ethanol in wine.

Phenoxazine Functionalized, Exfoliated Graphite Based Electrodes for NADH Oxidation and Ethanol Biosensing

“…Surface renewable carbon paste electrodes modified with phenoxazine and phenothiazine have been reported to overcome the overpotential requirements [11,12]. However, the carbon paste electrodes suffer from instability arising due to the presence of binder [13,14].…”

Fabrication of poly(toluidine blue O)/carbon nanotube composite nanowires and its stable low-potential detection of NADH

“…Here selected TBO to noncovalently functionalize the MWNTs is possible because TBO possesses good electrochemical properties and has been widely used for the construction of electrochemical NADH sensors [28,32,35,36]. The purification of carbon nanotubes is mainly to remove any metal catalyst and amorphous carbon, although this yields small amounts of oxygen-containing functional groups, such as carboxylic groups [41].…”

“…But the detection based on carbon nanotubes modified electrodes still needs a relatively high potential. The other conventional approach was to use phenothiazine dyes [27][28][29][30][31][32][33][34], because those dyes are chemically reactive and display negative formal potentials (vs. SCE) at neutral pH. The NADH detectors were developed based on phenothiazine dyes have been either adsorbed [27,28] or covalently attached [29,30] to the electrode surface.…”

Amperometric Sensor for Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide Using a Poly(pyronin B) Film Modified Electrode

“…The phenothiazine dyes easily also adsorb directly onto a wide range of substrates including graphite [24,25], titanium phosphate [26], carbon nanotubes [27], zinc oxide [28,29] and these dyes have been covalently attached on silica gel [30] and gold electrodes through a cysteamine linkage [31]. All these modified electrodes have been used for detection of NADH at lower potential.…”