Background: This paper presents the application of polyglycine-modified graphene paste electrode (PGMGPE) for the electrochemical detection of Hg (II) and Pb (II) ions in the water and biological samples. Method: The developed electrode was characterized by field emission scanning electron microscopy. Electrochemical techniques such as cyclic voltammetry and differential pulse voltammetry were used to study the behavior of metal ions. Results: The modification process improves the electrochemical behavior of heavy metal ions. The peak current varied linearly with the increase of the concentration leading to a detection limit of 6.6 μM (Hg (II)) and 0.8 μM (Pb (II)), respectively. Conclusion: The developed electrode exhibits good sensitivity, selectivity, stability, and lower detection limit, and was successfully applied to the determination of heavy metal ions in water and biological samples with a good recovery range.

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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.

Suitable electro-catalytic technique is established for the selective determination of Indigo Carmine (IC) at poly(arginine) modified carbon paste electrode (PAMCPE). The surface morphological study of the electrode is done through Field Emission Scanning Electron Microscopy (FESEM). The different parameters such as concentration, pH and scan rate on the electrode response are studied. The individual and simultaneous performance of IC and Riboflavin (RF) is carried out through differential pulse voltammetry. The electrocatalytic response of the sensor varied with the concentration of IC in the range from 2×10-7 M to 1×10-6 M and 1.5×10-6 M to 3.5×10-6 M is observed. Limit of detection (LOD) and the limit of quantification (LOQ) is found 2.53×10-8 M and 8.43×10-8 M respectively. The developed PAMCPE successfully shows better electrochemical response towards IC when compared with BCPE. Preparation and characterization of both the electrodes is simple and easier. This has derived a standard method for the determination of IC in real samples.

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