Fabrication of Efficient and Selective Modified Graphene Paste Sensor for the Determination of Catechol and Hydroquinone

An electrochemical sensor, based on a graphene paste electrode (GPE), was modified with a polymerization method, and the electrochemical behavior of catechol (CC) and hydroquinone (HQ) was investigated using electroanalytical methods like cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The effect of CC at the modified electrode was evidenced by the positive shift of the oxidation peak potential of CC at the poly (rosaniline)-modified graphene paste electrode (PRAMGPE) and the nine-fold enhancement of the peak current, as compared to a bare graphene paste electrode (BGPE). The sensitivity of CC investigated by DPV was more sensitive than CV for the analysis of CC. The DPV method showed the two linear ranges of 2.0 × 10−6–1.0 × 10−5 M and 1.5 × 10−5–5 × 10−5 M. The detection limit and limit of quantification were determined to be 8.2 × 10−7 and 27.6 × 10−7 M, respectively. The obtained results were compared successfully with respect to those obtained using the official method. Moreover, this sensor is applied for the selective determination of CC in the presence of HQ. The high sensitivity, good reproducibility, and wide linear range make the modified electrode suitable for the determination of CC in real samples. The practical application of the sensor was demonstrated by determining the concentration of CC in water samples with acceptable recoveries (97.5–98%).

Electroanalytical Performance of Graphene Paste Electrode Modified Al(III)-TiO2 Nanocomposites in Fipronil Solution

The new composite material Al(III)-TiO2 has been synthesized and applied as a modifier of graphene paste electrode for the determination of fipronil pesticide by cyclic voltammetry. The methods were to synthesis of Aluminum-Titanium dioxide (AT), preparation of graphene paste electrode with mass varied Al(III)-TiO2 (GAT) (0.05 g, 0.1 g, 0.2 g), and fipronil electroanalytic respons. Addition of Al(III)-TiO2 to the graphene paste electrode shows redox properties which are well characterized by a fast electron transfer process. Based on the results of measurements in a solution containing fipronil, it is known that fipronil is oxidized at a potential value of 0.26 V. Furthermore, the fipronil oxidation process on the GAT surface is influenced by diffusion control, this is powered by R2 value 0.91 when plotted between peak oxidation currents (Ip­a) vs. root scan rate. Other results show that measurement linearity is in the range 0.01 to 0.09 µg/L with a limit of detection (LOD) value of 0.0164 μg/L. Moreover, GAT shows good stability in the determination of fipronil with% RSD equal to 5%.

Poly (Adenine) Modified Graphene-Based Voltammetric Sensor for the Electrochemical Determination of Catechol, Hydroquinone and Resorcinol

Objective: This paper presents the application of Poly (Adenine) Modified Graphene Paste Electrode (PAMGPE) for the analysis of Catechol (CC) with Resorcinol (RC) and Hydroquinone (HQ) by a voltammetric technique. Methods: Electropolymerization technique was utilized for the modification of the sensor surface. The electrode surface was characterized by Field Emission Scanning Electron Microscopy (FE-SEM). Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) were used to study the redox behavior of CC, RC and HQ. Results: Oxidation peak current of CC increased linearly with the concentration of CC in the range from 2×10-6- 8×10-6 M and 1×10-5-1.5 ×10-4 M with a detection limit of 2.4×10-7 M. The practical application of the developed sensor was verified as exact for the determination of CC in water sample. Conclusion: The stability, repeatability, and reproducibility of the developed electrode were studied and established good characteristics. Furthermore, the PAMGPE was examined for the simultaneous determination of CC, RC and HQ.

Electrochemical Polymerised Graphene Paste Electrode and Application to Catechol Sensing

Objective: To build up an advantageous strategy for sensitive determination of catechol (CC), a poly (proline) modified graphene paste electrode (PPMGPE) was fabricated and used as a voltammetric sensor for the determination of CC. Methods: The performance of the modified electrode was studied using cyclic voltammetric (CV) and differential pulse voltammetric method (DPV). The modified electrode was characterized by CV and DPV. The surface of the modified electrode was examined by FESEM. The electrochemical behavior of CC in phosphate buffer solution (pH 7.5) was inspected using bare graphene paste electrode (BGPE) and PPMGPE. Results & Conclusion: The PPMGPE shows a lower limit of detection, calculated to be 8.7×10–7mol L−1 (S/N=3). This modified electrode was applied successfully for the determination of CC in water samples without applying any sample pretreatment.