Electrochemistry of methimazole on fluorine-doped tin oxide electrodes and its square-wave voltammetric determination in pharmaceutical formulations

Electrochemical Behaviour Study and Determination of Guanine, 6‐Thioguanine, Acyclovir and Gancyclovir on Fluorine‐doped SnO2Electrode. Application in Pharmaceutical Preparations

“…Figure shows the voltammetric profiles recorded at optimum pH to 0.1 V s −1 potential scan rate in the absence of guanine and its pharmaceutical derivatives. The FTO electrode possesses as characteristic to exhibit a stable capacitive response within the potential range −0.5 V to 1.6 V (thin line), indicating that under the working conditions, no other competitive reactions occur, e. g. oxygen evolution . In the presence of G, TG, Acy and Gan (thick line) voltammograms recorded at 0.1 V s −1 an oxidation peak was observed at +1.33, +1.35, +1.45 and +1.49 V, respectively.…”

“…When the electrooxidation of the pharmaceutical derivatives was performed on transparent conductive substrates, e. g. ITO and undoped tin oxide showed lower electrochemical activity (not shown). This behaviour has already been observed for other molecules . For ITO this can be explained by the electrochemical instability present in acid medium, when an ITO electrode is subjected to negative potentials in acid medium it undergoes deterioration by losing its electrochemical activity .…”

“…Figure shows the effect of the potential scan rate for each compound. The linear dependence between the current peak Ip (A) and of the square root of the scan rate (ν 1/2 ) (inset Figure ) giving a linear correlation coefficient (R 2 ) close to the unity and the plots logarithm of the peak current (Ip) versus logarithm of the scan rate (ν) with the slope value near to 0.5 (Figure 2S supplementary material), demonstrate the processes are diffusion controlled (Table 1S supplementary material); this has also been observed for other molecules on FTO .…”

“…For this reason, when a working electrode is chosen for these purposes, two factors must be mainly considered, the first is the redox behaviour of the studied analyte and the second is the base residual current obtained within the potential window required for the electrochemical measurements . A material that has satisfactorily fulfilled these requirements is the fluorine‐doped tin oxide electrode (FTO) that in addition to be a very economical material, exhibits optical transparency and high electrical conductivity and has been utilized in the determination of different molecules, e. g. thiols and catecholamines .…”

Inclusion of Glutathione Peroxidase on Polypyrrole Modified Electrode, to Be Assayed as Glutathione Sensor

“…Among these, the use of electrochemical methods is interesting because of its low cost, portability, high sensitivity, being these desirable characteristics for the electrochemical detection of GSH and/or GSSG. Therefore, now is in this discipline where major efforts are made in this respect and, particularly, the modified electrode with electrochemical methods for the determination of substrates have received increasing attention in recent years due to its simplicity, low cost, high detectability and easy miniaturization [12][13][14][15][16][17][18] .…”