Advanced electrochemical sensors based on the functional carbon materials

Editoria

Fe3O4/GO nanocomposite modified glassy carbon electrode as a novel voltammetric sensor for determination of bisphenol A

A new voltammetric sensor is proposed for the determination of bisphenol A, using a glassy carbon electrode (GCE) modified with Fe3O4/graphene oxide (GO) nanocomposite. The modification of the electrode surface was performed by dispersion drop-casting. The electro­chemical behavior of bisphenol A was evaluated by cyclic voltammetry (CV). The oxidation peak was observed during the anodic potential scan at potentials of 0.45 V. Higher anodic peak currents (Ipa) were observed at Fe3O4/GO/GCE modified electrode than at bare GCE. The elec­trochemical determination by differential pulse voltammetry (DPV) revealed a linear response in the concentration range of 1.0×10-7 to 5.0×10-5 M, with a detection limit of 9.0×10-8 M. The proposed method was successfully applied using water samples, with good recoveries

Electrocatalytic response of nitrogen-doped hollow carbon spheres modified glassy carbon electrode for sulphite detection in water

In this work, the glassy carbon electrode (GCE) surface was modified with nitrogen-doped hollow carbon spheres (N-HCSs) to achieve a new electrochemical sulphite sensor (N-HCSs/GCE) in water samples. The N-HCSs were explored for electrocatalytic behavior through voltammetric approaches using a routine three-electrode system. The findings revealed an admirable efficiency for modified electrodes towards sulphite oxidation, highlighting the effectiveness of our as-produced sulphite sensor. The differential pulse voltammetry was utilized under obtained optimal circumstances to study the as-developed sensor, the results of which underlined linear electrochemical current in relation to sulphite concentration, with dynamic range as wide as 1.0-100.0 μM and limit of detection as narrow as 0.35 μM. Moreover, N-HCSs/GCE had commendable practical applicability for sensing sulphite present in real specimens with voltammetric techniques

Voltammetric and amperometric sensors for determination of epinephrine: A short review (2013-2017)

The present review focuses on voltammetric and amperometric methods applied for determination of epinephrine (EP) in last five years (2013-2017). Occurrence, role and biological importance of EP, as well as non-electrochemical methods for its assessment, are firstly reviewed. The electrochemical behavior of EP is then illustrated, followed by a description of the voltammetric and amperometric methods for EP content estimation in various media. Different methods for development of electrochemical sensors are reviewed, starting from unmodified electrodes to different composites incorporating carbon nanotubes, ionic liquids or various mediators. From this perspective, the interaction between functional groups of the sensor material and the analyte molecule is discussed, as it is essential for analytical characteristics obtained. The analytical performances of the voltammetric or amperometric chemical and biochemical sensors (linear range of analytical response, sensitivity, precision, stability, response time, etc.) are highlighted. Numerous applications of EP electrochemical sensors in fields like pharmaceutical or clinical analysis where EP represents a key analyte, are also presented

Electrochemical determination of propranolol by using modified screen-printed electrodes

73-78A simple and sensitive method for the determination of propranolol using modified screen printed carbon electrode (MSPCE) has been presented. The electrochemical measurements of propranolol are studied using differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CHA). The MSPCE exhibite excellent catalytic activity towards electrochemical oxidation of propranolol in phosphate buffer solution (PBS) of pH 7.0. The MSPCE facilitate the determination of propranolol in the concentration range 0.4 – 200.0 μM and a detection limit and sensitivity of 80 nM and 0.052 μA/μM has been achieved

A novel dopamine electrochemical sensor based on La3+/ZnO nanoflower modified graphite screen printed electrode

Flower-like La3+/ZnO nanocomposite was facile synthesized. A simple and ultrasensitive sensor based on graphite screen printed electrode (SPE) modified by La3+/ZnO nanoflower was developed for the electrochemical determination of dopamine. The electrochemical behavior of dopamine was studied in 0.1 M phosphate buffer solution (PBS) using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Compared with the unmodified graphite screen printed electrode, the modified electrode facilitates the electron transfer of dopamine, since it notably increases the oxidation peak current of dopamine. Also, according to CV results the maximum oxidation of dopamine on La3+/ZnO/SPE occurs at 150 mV which is about 140 mV more negative compared with unmodified SPE. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range from 0.15 to 300.0 μM, with a detection limit of 0.08 μM (S/N = 3). The proposed sensor exhibited a high sensitivity, good stability and was successfully applied for dopamine determination in dopamine ampoule, with high recovery

An electrochemical sensor based on a modified glassy carbon electrode for detection of epinephrine in the presence of theophylline

Background and purpose: Neurotransmitters are chemical messengers that enhance and balance signals between cells and target cells in the body. They are vital to the body's ability to function. Epinephrine is one of the most essential catecholamine neurotransmitters with an important biological and pharmacological role in the mammalian central nervous system. Therefore, it is very important to develop sensitive, simple, and fast methods for the determination of this compound. Experimental approach: In the present work, a glassy carbon electrode (GCE) modified with the cerium oxide-zinc oxide (CeO2-ZnO) nanocomposite (CeO2-ZnO/GCE) was developed for the sensitive and quick detection of epinephrine. The CeO2-ZnO nanocom­posite was prepared by hydrothermal method. Electrochemical methods such as voltammetry and chrono­ampero­metry techniques were used to investigate the performance of the developed sensor. Key results: The resulting CeO2-ZnO/GCE showed a remarkable response towards the determination of epinephrine. The electrochemical sensor demonstrated a wide dynamic linear range from 0.1 to 900.0 μM for analysis of epinephrine. The LOD equalled 0.03 μM for epinephrine. In addition, the electrochemical sensor had good feasibility for concurrent detection of epinephrine and theophylline. Furthermore, experimental outputs indicated that the oxidation peaks of epinephrine and theophylline were separated by a 685 mV difference between the two peaks in PBS at a pH of 7.0. Also, an electrochemical sensor has been employed to analyse epinephrine in real samples (urine and epinephrine Injection). Conclusion: The good and acceptable analytical performance of the developed sensor can provide a promising tool for the analysis of epinephrine in real samples

A sensitive Cu(salophen) modified screen-printed electrode for simultaneous determination of dopamine and uric acid

This research applied a nanostructured electrochemical sensor with a screen-printed electrode (SPE) for examining the dopamine (DA) electrocatalytic oxidation when uric acid (UA) was present. Cu(salophen) nanostructured modified SPE (Cu(salophen)/SPE)was employed to investigate the electrochemical behavior of DA. At optimal pH (pH7.0), oxidation of DA at the modified electrode takes place at a potential around 100 mV less positive than at the unmodified SPE. Chronoamperometry was used to determine the diffusion coefficient of DA (D=1.96×10-5cm2s-1). Differential pulse voltammetry (DPV) showed linear response in the range between 0.2-450.0 μM for DA. The limit of detection (LOD) of DA was computed to be 0.05 μM. Moreover, Cu(salophen)/SPE was employed for determining DA in the presence of UA using DPV. The DPV results showed that at the modified electrode, two well-separated oxidation peaks of DA and UA could be obtained at potentials of 180 and 325 mV, respectively. This separation forms the basis for the co-detection of these two materials on the surface of Cu(salophen)/SPE. This sensor was then employed to determine DA and UA in real specimens

Glutathione detection at carbon paste electrode modified with ethyl 2-(4-ferrocenyl-[1,2,3]triazol-1-yl)acetate, ZnFe2O4nano-particles and ionic liquid

The purpose of the present study was to introduce a newly designed approach for deter-mination of glutathione using modified carbon paste electrode with ZnFe2O4nanoparticles, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and ethyl-2-(4-ferrocenyl--[1,2,3]triazol-1-yl)acetate (EFTA/ZFO/IL/CPE). According to the results from the electro-chemical experiments, oxidation current of glutathione on the modified electrode surface was incremented and its oxidation potential was decreased compared to bare CPE. A linear response was observed for the electrode at different glutathioneconcentrations (0.2 to 300.0 μM)

Development of a highly sensitive voltammetric sensor for the detection of folic acid by using MoS2 and ionic liquid-modified carbon paste electrode

Background and purpose: Sensitive analytical determination of folic acid is important in clinical laboratories due to its versatile biological functions. Experimental approach: A simple folic acid sensor was successfully fabricated based on two-dimensional transition metal dichalcogenide MoS2 modified carbon ionic liquid paste electrode (MoS2-CILPE). The electrochemical properties of the fabricated electrode were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry. Key results: The fabricated sensor displayed excellent electroactivity towards folic acid using CV. Under optimal conditions (0.1 M PBS (pH 7.0)), the DPV oxidation peak current was proportional to folic acid concentration in the range from 5.0 μM to 100.0 μM with an estimated limit of detection of 1.0 µM and limit of quantification of 5.0 µM. Conclusion: The ability of the sensor for routine analyses was demonstrated by the detection of folic acid present in folic acid tablets and urine samples with appreciable recovery values.