An Electrochemically Polymerized Glycine-Modified Carbon Paste Sensor for the Analysis of Carmoisine in the Presence of Environmentally Significant Dyes

In the present work, we have conducted a sensitive and selective analysis of carmoisine (CMS) using a newly developed electrochemically polymerized glycine-modified carbon paste electrode (EPGMCPE). The EPGMCPE shows maximum current responses of CMS as compared to an unmodified carbon paste electrode (UMCPE) in 0.2 M phosphate-buffered saline (PBS) at pH 6.5, using a scan rate of 0.1 V/s. The evaluation and characterization of both the EPGMCPE and UMCPE were carried out using cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Compared to the UMCPE, the EPGMCPE showed an outstanding peak current and parameters such as pH study, active surface area, concentration variations. In DPV, the EPGMCPE showed a limit of detection (LOD) of 0.23 µM and limit of quantification (LOQ) of 0.79 µM, respectively. In CV, the LOD and LOQ were 0.16 µM and 0.55 µM, respectively. Furthermore, the modified electrode exhibited excellent sensitivity for detecting CMS, even in the simultaneous presence of indigo carmine (IC), methyl orange (MO), and methyl red (MR). In addition, the EPGMCPE shows good stability, reproducibility, and repeatability. Analytical applicability of the electrode was confirmed through the detection of CMS in real soft drink and tap water samples.

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