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.

The electrochemical behavior of indigo carmine (IC) at poly (glycine) modified carbon paste electrode (PGMCPE) was investigated by cyclic and differential pulse voltammetry. The oxidation peak of IC was observed in phosphate buffer of pH 6.5. The influence of different pH, scan rate, and concentration were analyzed. The probable reaction mechanism involved in the oxidation of IC was also proposed. Results showed that PGMCPE a remarkable electrocatalytic activity for the oxidation of IC under optimal conditions. The electrocatalytic response of the sensor was proportional to the IC concentration in the range of (2 × 10-6-1 × 10-5 M) and (1.5 × 10-5-6 × 10-5 M) with a limit of detection 11 × 10-8 M and limit of quantification 3.6 × 10-7 M. The modified electrode demonstrated many advantages such as simple preparation, high sensitivity, low detection of limit, excellent catalytic activity, short response time, and remarkable antifouling property toward IC and its oxidation product.

In this paper, a poly (glycine) modified carbon paste electrode (PGMCPE) for sensitive determination of Tartrazine (Tz) was developed. The electrochemical behaviors of Tz at the PGMCPE were investigated by cyclic voltammetry, differential voltammetry and the results showed that the polymer film on electrode exhibited excellent electrocatalytic activity for the electrochemical oxidation of Tz in phosphate buffer solution, pH 7 (PBS). The influencing factors containing a supporting electrolyte, pH of the solution, deposition potential, amount of Tz and scan rate were investigated. The sensor exhibited two linear behavior in the range of 1 × 10-6 to 2.7 × 10-5 mol L-1 and 3.5 × 10-5 to 8.7 × 10-5 mol L-1 for Tz (correlation coefficients: 0.991 and 0.995 respectively) with detection limit (LOD) of 2.83 × 10-7 mol L-1, limit of quantification (LOQ) 9.4 × 10-7 mol L-1 and detection sensitivity (2.0452 μA/μM), for Tz. The results show that the biosensor is sensitive and useful for the determination of Tz.

In this work, an electrochemical sensor based on a poly threonine modified graphite-carbon nanotube paste electrode was developed for the investigation of