An exfoliated graphite-based Bisphenol A electrochemical sensor

The use of an exfoliated graphite (EG) electrode in the square wave voltammetric detection of bisphenol A (a model phenolic pollutant) in water, whereby the phenolic electrode fouling challenge is mitigated, is described. The oxidation peak of BPA was observed at about 0.45 V in phosphate buffer solution at pH 10. The current response exhibited a linear relationship with the concentration over a range from 1.56 μM–50 μM. The detection limit was calculated to be 0.76 μM. The EG electrode surface was renewed after each measurement with excellent reproducibility. A real sample application was also investigated

A direct and sensitive electrochemical sensing platform based on ionic liquid functionalized graphene nanoplatelets for the detection of bisphenol A

A simple electrochemical sensor for bisphenol A (BPA) was developed based on a composite of graphene nanoplatelets (GNPs) and 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate (ionic liquid, IL) as a modifier for glassy carbon paste electrodes (GCPEs). Scanning electron (SEM) and atomic force microscopy (AFM) were employed to characterize the morphology and surface modification. The electrochemical behavior of BPA on IL-GNP/GCPEs was investigated and the results showed that IL-GNP composites enhance the electrochemical signal toward BPA due to the synergetic effect of GNPs and IL. The experimental parameters including the amount of IL and GNPs, pH of solution, pulse potential, step potential, and scan rate were optimized. Under optimal conditions, the proposed sensor exhibited a linear relationship between signal and BPA concentrations ranging from 0.02–5.0 μM, with detection and quantification limits of 6.4 nM and 0.02 μM respectively. Moreover, the electrochemical sensor showed good repeatability (RSD = 3.3%, n = 5 measurements), good reproducibility (RSD = 3.8%, n = 5 sensors), high accuracy of 95.3–104.5% recovery, acceptable selectivity, and stability. The sensor was successfully applied to the determination of BPA in water samples in contact with plastic materials. The results were satisfactory and in agreement with reference values from a standard HPLC method.This is the peer-reviewed version of the following article: Butmee, P.; Tumcharern, G.; Saejueng, P.; Stanković, D.; Ortner, A.; Jitcharoen, J.; Kalcher, K.; Samphao, A. A Direct and Sensitive Electrochemical Sensing Platform Based on Ionic Liquid Functionalized Graphene Nanoplatelets for the Detection of Bisphenol A. Journal of Electroanalytical Chemistry 2019, 833, 370–379. [https://doi.org/10.1016/j.jelechem.2018.12.014

A direct and sensitive electrochemical sensing platform based on ionic liquid functionalized graphene nanoplatelets for the detection of bisphenol A

A simple electrochemical sensor for bisphenol A (BPA) was developed based on a composite of graphene nanoplatelets (GNPs) and 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate (ionic liquid, IL) as a modifier for glassy carbon paste electrodes (GCPEs). Scanning electron (SEM) and atomic force microscopy (AFM) were employed to characterize the morphology and surface modification. The electrochemical behavior of BPA on IL-GNP/GCPEs was investigated and the results showed that IL-GNP composites enhance the electrochemical signal toward BPA due to the synergetic effect of GNPs and IL. The experimental parameters including the amount of IL and GNPs, pH of solution, pulse potential, step potential, and scan rate were optimized. Under optimal conditions, the proposed sensor exhibited a linear relationship between signal and BPA concentrations ranging from 0.02–5.0 μM, with detection and quantification limits of 6.4 nM and 0.02 μM respectively. Moreover, the electrochemical sensor showed good repeatability (RSD = 3.3%, n = 5 measurements), good reproducibility (RSD = 3.8%, n = 5 sensors), high accuracy of 95.3–104.5% recovery, acceptable selectivity, and stability. The sensor was successfully applied to the determination of BPA in water samples in contact with plastic materials. The results were satisfactory and in agreement with reference values from a standard HPLC method. © 201

The development of electrochemical (APTA) sensors based on carbon nanofiber composite and silver nanocomposite platforms and their applications on the detection of endocrine disrupting Bisphenol A

Abstract: The primary focus of this research was on the development of three electrochemical sensing systems for the detection of Bisphenol A (BPA) - an endocrine disrupting compound. Studies of health effects on humans associated with BPA exposures reported increased risks of heart diseases, coronary diseases, diabetes and cancer. In recent years, the concern over the effects of BPA on humans has been highlighted by the fact that infants and children are estimated to have the highest daily intake of BPA. Electrochemical methods of detection for BPA have proven to be the most effective and practical ones, when compared conventional techniques such as chromatography. However, the electro-oxidation of BPA is an irreversible process with products that cause surface fouling of electrodes, which always limits the electro-detection of BPA. This surface fouling of electrode surfaces is considered a major challenge on electro-analytical based techniques for determining not only BPA molecule but also other phenolic molecules. To mitigate this major issue, this dissertation reports the use of a regenerable exfoliated graphite (EG) electrode. Regeneration was achieved by mechanical polishing of the robust electrode on emery paper...M.Sc. (Chemistry

Electrochemical deposition of Graphene Oxide- metal nano-composite on Pencil-Graphite Electrode for the high sensitivity detection of Bisphenol A by Adsorptive Stripping Differential Pulse Voltammetry

Magister Scientiae - MSc (Chemistry)Electrochemical platforms were developed based on pencil graphite electrodes (PGEs) modified electrochemically with reduced graphene oxide metal nanoparticles (ERGO–metalNPs) composite and used for the high-sensitivity determination of Bisphenol A (BPA) in water samples. Synergistic effects of both reduced Graphene Oxide sheets and metal nanoparticles on the performance of the pencil graphite electrode (PGE) were demonstrated in the oxidation of BPA by differential pulse voltammetry (DPV). A solution of graphene oxide (GO) 1 mg mL-1 and 15 ppm of metal stock solutions (1,000 mg L-1, atomic absorption standard solution) (Antimony or Gold) was prepared and after sonication deposited onto pencil graphite electrodes by cyclic voltammetry reduction. Different characterization techniques such as FT-IR, HR-SEM, XRD and Raman spectroscopy were used to characterize the GO and ERGO–metalNPs. Parameters that influence the electroanalytical response of the ERGO–SbNPs and ERGO–AuNPs such as, pH, deposition time, deposition potential, purging time were investigated and optimized. Well-defined, reproducible peaks with detection limits of 0.0125 μM and 0.062 μM were obtained for BPA using ERGO–SbNPs and ERGO–AuNPs respectively. The rGO-metalNPs–PGE was used for the quantification of BPA in tap water sample and proved to be suitable for the detection of BPA below USEPA prescribed drinking water standards of 0.087 μM

Development of graphite based nanomaterials for green chemistry applications

Graphite is a valuable natural resource and useful carbon allotrope that has been explored for various applications. Graphene is a two-dimensional (2D) transparent material, which is the strongest, thinnest, and most conductive substance known. Graphene-based materials are strategic nanomaterials that have been investigated for various applications, encompassing water contaminant remediation, energy conversion and storage, and electrochemical biosensors, and graphite is its primary source. This MSc thesis focuses mainly on: (a) the characterization of graphite and the study of its properties, both of which influence the quality of graphene based materials; (b) the development of a novel and simple strategy toward the generation of high quality graphenoids; and (c) the exploration of green chemistry applications such as environmental contaminant remediation and energy conversion and storage. [...

Electrochemical poly(ProDOT) dendritic DNA aptamer biosensor for signalling interferon gamma (IFN-ɣ) TB biomarker

Philosophiae Doctor - PhDTuberculosis (TB) is an infectious disease that, despite all efforts devoted towards its eradication, remains a threat to many countries including South Africa. Current diagnostic assays do offer better performance than the conventional sputum smear microscopy and tuberculin skin tests. However, these assays have been proven to be affected by various factors including the condition of an individual's immune system and vaccination history. By far, electrochemical biosensors are amongst the currently investigated techniques to address the shortcomings associated with these diagnostics