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A low-cost pre-anodized 6B-pencil graphite (6B-PGE*) is shown as a fouling-free and renewable electrochemical sensor for mono-phenols and can be used for the detection of mono-phenolic preservatives in pharmaceutical insulin formulations.

Multiwalled carbon nanotubes containing an iron impurity (2.1 wt %) (MWCNT‐Fe*) were used to modify a glassy carbon electrode (GCE/MWCNT‐Fe*), which was subsequently exploited for the electrochemical oxidation of benzene (BZ) to redox‐active and surface‐confined quinones (BZO) in H2O2 containing pH 2 HCl–KCl. Physicochemical and electrochemical characterization methods, such as transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, UV/Vis spectroscopy, liquid chromatography coupled mass spectroscopy, and cyclic voltammetry studies with naked Fe3+/2+, catechol (CA), and hydroquinone (HQ), evidenced that, in the presence of H2O2, the intrinsic iron impurity in MWCNT‐Fe* follows the electro‐Fenton reaction to oxidize BZ to BZO (CA+HQ) on the surface of MWCNT‐Fe* (i.e. GCE/MWCNT‐Fe*@BZO). Electro‐catalytic oxidation of hydrazine was demonstrated as a model system for the application of the GCE/MWCNT‐Fe*@BZO catalyst.

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Unusual electropolymerization of aniline to polyaniline (PANI) in a neutral pH solution has been successfully demonstrated using a multiwalled carbon nanotube (MWCNT) modified gold electrode (Au-MWCNT@PANIpH7). The modified electrode showed highly redox active surface confined peaks corresponding to the molecular transitions of leucoemeraldine-emeraldine and emeraldine-pernigraniline in pH 7 phosphate buffered solution (PBS), along with a low capacitance behavior, in contrast to the conventional acidic solution PANI systems. Control experiments in the absence of MWCNTs (i.e., Au/PANIpH7) and in an acidic medium, pH 2 (i.e., Au-MWCNT@PANIpH2), resulted in nil and poor redox features respectively. The physicochemical characterization of the MWCNT@PANIpH7 film by TEM, Raman spectroscopy, FTIR and UV-Vis revealed the presence of polaron type PANI structures on the MWCNT surface. More interestingly, MWCNT@PANIpH7 showed a highly selective electrocatalytic signal to ascorbic acid (AA) at a low oxidation potential, -15 mV vs. Ag/AgCl, without interference from nitrite, uric acid, dopamine, glucose, cysteine and citric acid in pH 7 PBS. Extended flow injection analysis yielded an excellent AA sensing response with a detection limit (signal-to-noise ratio = 3) of 42 nM, which is better than that of the conventional acid assisted MWCNT@PANIpH2 and MWCNT systems.

Isomers of dihydroxy benzene (DHB) such as 1,2-DHB, 1,3-DHB and 1,2,3-trihydroxy benzene (1,2,3-THB) are the functional electro-active constituents of tea polyphenols.