Optical fiber spectroelectrochemical device for detection of catechol at press-transferred single-walled carbon nanotubes electrodes

Abstract

A new long-optical-pathway spectroelectrochemical cell for absorptometric measurements in the UV-Vis region was developed. This cell consists of two optical fibers brought face to face and fixed on the working electrode support. As a proof of concept, the spectroelectrochemical cell was applied to the determination of catechol using a press-transferred single-walled carbon nanotube film as the working electrode. Voltabsorptometry was demonstrated to be very helpful in understanding the mechanism of catechol oxidation. The experiments showed that the main oxidation product is o-benzoquinone, but other soluble side products are also observed. Multivariate calibration explains the selection of 390 nm as the best wavelength for the univariate absorptometric determination of catechol, avoiding the interference of oxidation side products. Catechol was quantified using both the electrochemical and the spectroscopic signal, demonstrating that this hybrid technique is an autovalidated analytical method. Dual detection of catechol was also carried out using amperometric spectroelectrochemistry. Finally, spectroelectrochemistry was used to quantify catechol in the presence of hydroquinone.

Concluding remarks: there's nowt so queer as carbon electrodes

“…There is evidently much interest in the use of carbon electrodes in batteries, 27,28 and three papers in the session on supercapacitors 5,29,30 generated a huge amount of discussion and debate that could have gone on for much longer had the tea/coffee break not been called! 49,50 However, these types of methodologies did not feature as prominently in this Discussion as I expected, although they were evident. The topic of electrochemical biosensors, likewise, was wide-ranging, from implant electrodes based on diamond microelectrode arrays 31 to the detection of biomolecules in solution, 32 and attempts to understand coupled electron transfer-proton transfer reactions, and the inuence of electrode structure on such processes.…”

Spectroelectrochemical Sensing: Current Trends and Challenges

“…For this reason, the thin‐layer regime was typically used for the development of these cells, as mentioned before. It should be highlighted that, although the generation of a thin and parallel beam is not easy, measurements in long‐optical‐path configuration became much easier with the use of optical fibers , which should absolutely help users to perform parallel arrangement SEC experiments, Figure . Finally, it should be noted the good performance of this configuration to obtain information in the UV region, particularly using optical fibers , due to the high amount of collected light in this spectral region.…”

“…From this point of view, SEC is a really powerful analytical technique. SEC can be used with many different purposes, and excellent examples can be found in literature in different fields such as organic molecules , molecules of biological interest , inorganic complexes , conducting polymers , carbon nanotubes , graphene , fullerenes , metal nanoparticles , quantum dots , etc. A huge variety of information can be obtained using SEC, for example, formal potentials , electron transfer rate constants , diffusion coefficients , number of electrons , molar absorption coefficients , band‐gaps , among many others.…”

“… Development of SEC sensors can be based on the optical response , but also on both responses (optical and electrical) . This last type of sensors provides two independent signals that yield the concentration of the sample with two independent techniques, giving a highest robustness to the analytical method.…”

A Simple Strategy for Easily Assembling 3D Printed Miniaturized Cells Suitable for Simultaneous Electrochemical and Spectrophotometric Analyses

“…The hyphenation of electrochemical methods and optical spectroscopy is expected to be a challenging idea to enhance the information which can be gained on complex chemical systems [45][46][47][48][49]. Moreover, the simultaneous availability of electrochemical and spectrophotometric data can make possible their mutual control, thus providing the autovalidation of the results collected [50][51][52].…”