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Some colourants are hazardous to living organisms. Hence, a powerful and fast methodology is required for the analysis of those colourants in food and water samples. A modest electrochemically polymerised glutamic acid layered multi-walled carbon nanotube paste electrode [P(GA)LMWCNTPE] was functionalised for the sensing of indigo carmine (IC) by the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) approaches. Within the optimised experimental conditions, the P(GA)LMWCNTPE holds an acceptable and high rate of electro-catalytic activity towards the redox behaviour of IC. The projected P(GA)LMWCNTPE shows a decent selectivity for IC in the presence of methyl orange. The modified sensor shows an acceptable linear growth between oxidative peak current and concentration in both CV and DPV methods with fine limit of detection values of 4.2 lM and 0.36 lM, respectively. Additionally, the developed sensor was effectively applied to detect IC in food and water samples. The morphological and surface activities of the modified and unmodified electrodes were determined through field emission scanning electron microscopy, electrochemical impedance spectroscopy, and CV techniques. The P(GA)LMWCNTPE requires a simple preparation procedure and is low-cost, with acceptable storage stability, sensitivity, and reproducibility.

Purpose: The novel sodium dodecyl sulfate modified carbon nanotube paste electrode (SDS/CNTPE) was used as a sensitive sensor for the electrochemical investigation of L-tyrosine (TY).Methods: The electrochemical analysis of TY was displayed through cyclic voltammetry (CV)and differential pulse voltammetry (DPV). The surface morphology of SDS/CNTPE and barecarbon nanotube past electrode (BCNTPE) was reviewed trough field emission scanning electronmicroscopy (FESEM).Results: The functioning SDS/CNTPE shows a voltammetric response with superior sensitivitytowards TY. This study was conducted using a phosphate buffer solution having neutral pH(pH=7.0). The correlation between the oxidation peak current of TY and concentration of TYwas achieved linearly in CV method, in the range 2.0×10-6 to 5 ×10-5 M with the detection limit729 nM and limit of quantification 2.43 μM. The investigated voltammetric study at SDS/CNTPEwas also adopted in the examination of TY concentration in a pharmaceutical medicine as a realsample with the recovery of 97% to 98%.Conclusion: The modified electrode demonstrates optimum sensitivity, constancy, reproducibility,and repeatability during the electrocatalytic activity of TY.

The current study explicates the electro-oxidation behavior of formoterol fumarate (FLFT) in the presence of uric acid (UA) on the surface of poly thiazole yellow-G (TY-G) layered multi-walled carbon nanotube paste electrode (MWCNTPE). The modified (Poly(TY-G)LMWCNTPE) and unmodified (MWCNTPE) electrode materials were characterized through electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), and cyclic voltammetry (CV) approaches. The characterization data confirms the good conducting and electrocatalytic nature with more electrochemical active sites on the Poly(TY-G)LMWCNTPE than MWCNTPE towards the FLFT analysis in the presence of UA. Poly(TY-G)LMWCNTPE easily separates the two drugs (FLFT and UA) even though they both have nearer oxidation peak potential. The electro-catalytic activity of the developed electrode is fast and clear for FLFT electro-oxidation in 0.2 M phosphate buffer (PB) of pH 6.5. The Poly(TY-G)LMWCNTPE offered a well-resolved peak with the highest electro-oxidation peak current at the peak potential of 0.538 V than MWCNTPE. The potential scan rate and oxidation peak growth time studies show the electrode reaction towards FLFT electro-oxidation is continued through a diffusion-controlled step. The variation of concentration of FLFT in the range from 0.2 to 1.5 µM (absence of UA) and 3.0 to 8.0 μM (presence of UA) provides a good linear relationship with increased peak current and a lower limit of detection (LOD) values of 0.0128 µM and 0.0129 µM, respectively. The prepared electrode gives a fine recovery for the detection of FLFT in the medicinal sample with acceptable repeatability, stability, and reproducibility.

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