Due to recent legalization of marijuana across many states in the U.S., there is an increased concern of users driving while impaired/intoxicated with Δ9‐tetrahydrocannabinol (Δ9‐THC), the principal ...psychoactive constituent of cannabis/marijuana. Hence, there is a need for a rapid roadside detection of this drug that can be used to accurately screen drivers. Current field sobriety tests rely on a series of physical and mental exercises administered during DUI investigations to help determine a driver's level of impairment. Due to their portability and effectiveness, screen printed carbon electrodes (SPCEs) are ideal to work with when it comes to devising a low‐cost screening device for roadside testing. SPCE's can potentially detect low levels of Δ9‐THC in an individual's saliva via electrochemical oxidation of Δ9‐THC. Herein we report a fast, cheap, and accurate approach to electrochemically detect 1–20 μM Δ9‐THC in a 1 mL sample of artificial oral fluid (AF‐OF) diluted to 50 % with a buffer/electrolyte solution using differential pulse voltammetry (DPV) at the surface of a small SPCE. Implications for the use of this method to screen intoxicated drivers are discussed.
A three-dimensional g-C3N4/MWNTs/GO hybrid modified electrode was constructed as an electrochemical sensor for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). ...Due to the high conductivity of MWCNTs and the strong synergy between g-C3N4 and GO, the combination of the three effectively improved the electrocatalytic activity of the modified electrode for the oxidation of AA, DA, and UA, and solved the problems such as overlapping anodic peaks. The electrochemical performance of the as-constructed sensor was investigated and optimized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linear response range of AA, DA, and UA in the optimal condition was 0.2–7.5 mM, 2–100 μM, and 4–200 μM, respectively. The detection limits (S/N = 3) of AA, DA, and UA were 96, 0.22, and 1.36 μM, respectively. The recoveries of AA, DA and UA in serum samples from three groups were 92.82–106.50%, and the relative standard deviations were less than 2%. The results show that the as-constructed g-C3N4/MWNTs/GO modified electrode has the advantages of simplicity, high sensitivity and good selectivity, and can simultaneously determine AA, DA, and UA.
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•A three-dimensional g-C3N4/MWNTs/GO hybrid electrode was constructed as an electrochemical sensor.•g-C3N4/MWNTs/GO hybrid sensor can simultaneously determine DA, AA, and UA.•The recoveries of DA, AA and UA in serum samples from three groups were 92.82–106.50%.•g-C3N4/MWNTs/GO hybrid sensor has the advantages of simplicity, high sensitivity and good selectivity.
Electrochemical methods have low toxicity, fast response and, easy operation. By modifying electrochemical sensors with a conductive and porous modifier, their sensitivity and selectivity can be ...improved. Nanomaterials with new and extraordinary properties are a new approach in science and especially in electrochemical sensors. In this study, UiO66-NH2/mesoporous carbon nitride (M − C3N4) composite provides a porous structure for decorated Au nanoparticles (AuNPs) to prepare a potent modifier for carbon paste electrode (CPE). Due to environmental toxicity of methotrexate, its sensitive, fast and, low-cost determination in workplace environments is of great interest. So, the modified CPE was applied as a sensitivity analysis approach for methotrexate in plasma samples. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used as techniques to optimize the analysis and measurement of methotrexate. To measure this drug, several effective parameters were optimized and a calibration curve was drawn under optimal conditions. The calibration curve showed a linear range from 0.5 to 150 μM with a detection limit of 0.15 μM for methotrexate. Examining the repeatability of the response of one electrode and multiple electrodes under optimal conditions shows the high precision of the developed method. Finally, this developed method based on UiO66-NH2/M-gC3N4/AuNPs|CPE was used to determine the methotrexate in the plasma sample using the standard addition method.
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•UiO66-NH2/mesoporous carbon nitride composite provides decorated AuNPs.•A sensitive electrochemical sensor is used for analysis of methotrexate.•The ability of the developed method to measure methotrexate and acetaminophen in real plasma samples was investigated.
•An electrochemical sensor was fabricated based on ionic surfactant modified graphene paste electrode.•Ability of surfactant modified graphene paste electrode for the individual and simultaneous ...analysis of vanillin and caffeine.•Developed electrode was characterized by LSV, CV, FESEM, and DPV technique.•The practicality of the developed electrode has been determined.
This paper describes a simple approach for the determination of vanillin (VN) based on the ionic surfactant modified graphene paste electrode. The electrochemical behavior of VN at the modified electrode is investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), suggests the modified electrode exhibits excellent electrochemical activity towards VN compared to the bare electrode. VN shows an irreversible behavior, and the nature of the electrode response was noticed to be adsorption controlled. Under the optimized conditions, the anodic peak current for VN was proportional to VN concentration from 4 × 10−6 to 1.5 × 10−5 M and 2 × 10−5 to 7 × 10−5 M with a limit of detection 1.29 µM. The developed method was effectively applied in the determination of VN in commercial food samples with good recovery.
A nanocomposite is described that consists of TmPO
and graphene oxide (GO) and is used to modify a glassy carbon electrode (GCE) to obtain a sensor for simultaneous determination of ascorbic acid ...(AA), dopamine (DA) and uric acid (UA). GO and TmPO
were synthesized via the Hummers method and by a hydrothermal method, respectively. The nanocomposite was characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical properties of the modified GCE were studied by electrochemical impedance spectroscopy and cyclic voltammetry. The good performance of the modified GCE results from the synergistic effects between GO with its good electrical conductivity and of TmPO
as the electron mediator that accelerates the electron transfer rate. Compared to a bare GCE, a GO/GCE and a TmPO
/GCE, the GO/TmPO
/GCE exhibits three well-defined and separated oxidation peaks (at -0.05, +0.13 and + 0.26 V vs. SCE). Responses to AA, DA and UA are linear in the 0.1-1.0 mM, 2-20 μM and 10-100 μM concentration ranges, respectively. Graphical abstract Schematic presentation of a nanocomposite that consists TmPO
and graphene oxide (GO) and is used to modify a glassy carbon electrode (GCE) to obtain a sensor for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA).
A new alpha-fetoprotein-MIP (AFP-MIP) immunosensor based on glass carbon electrode (GCE) modified with polythionine (PTh) and gold nanoparticles (AuNPs) was successfully prepared for the sensitive ...detection of AFP. The AFP-MIP immunosensor presented a facile preparation, low sample consumption, and good stability, and could become a new promising method for the detection of AFP.
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A new α-fetoprotein-MIP (AFP-MIP) immunosensor based on glass carbon electrode (GCE) modified with polythionine (PTh) and gold nanoparticles (AuNPs) was successfully fabricated for sensitive detection of α-fetoprotein (AFP). Through controlling electropolymerization, A “polydopamine (PDA)-AFP” complex was achieved applying AFP as template and dopamine (DA) as imprinted monomers. After elution, the specific cavities can adsorb the target molecules. Using differential pulse voltammetry (DPV) detection, the peak current decreased with the increase in concentration of AFP, and the linear response range of the AFP-MIP immunosensor was from 0.001 ng/mL to 800 ng/mL with the detection limit as low as 0.8138 pg/mL. The MIP immunosensor could become a new promising method for the detection of AFP. Furthermore, this MIP sensor was demonstrated in testing AFP in human serum samples with satisfactory results.
Tryptophan (TRY) is an essential amino acid associated with neurotransmitters and some particular syndromes. For that reason, the detection of Try levels in the food samples is necessary. In recent ...years electrochemical sensors exhibit inherent effect to detect the amino acids because it has more benefits such as high sensitivity, simplicity, celerity, and economy compared to other traditional methods. Some bimetal oxides have emerged as good candidates for the trace-level detection of amino acids due to their large surface area and high conductivity. As the carbon-based materials, importantly reduced graphene oxide (RGO) have large surface areas to increase the conductivity of the electrodes. In this present work, we demonstrate the detection of TRY by using an electrochemical sensor based on a bimetal oxide with RGO nanocomposite material. We synthesized a manganese tungstate-nanoplates-encapsulated reduced graphene oxide nanocomposite (MnWO4/RGO) using a facile hydrothermal method. Morphological and structural characterization of the nanocomposite MnWO4/RGO was performed using various spectroscopic techniques and analytical methods. The resulting MnWO4/RGO/GCE could be used for the quick and selective determination of TRY in the presence of other interfering bioanalytes. Under optimum conditions, this electrochemical sensor exhibited maximum performance toward TRY determination with good linearity in a broad linear range of 0.001–120 μM with a remarkable lower detection limit of 4.4 nM. The newly proposed sensor was used for the precise determination of TRY in milk samples with satisfactory results.
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•MnWO4/RGO nanocomposite prepared by the facile hydrothermal route without external reducing agent and surfactants.•MnWO4 nanoplates encapsulated on RGO nanosheets modified electrode is an efficient nanocatalyst for the detection of Tryptophan.•MnWO4/RGO sensor exhibit lower detection limit, wide linear range and good recoveries for Tryptophan in Milk samples.
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•Modification of carbon paste electrode with synthesised C-C3N4/Li2CoMn3O8 nanocomposite (C-C3N4/LCMO/CPE).•Characterization of Li2CoMn3O8 and C-C3N4 nanocomposite with FT-IR, FE-SEM ...and XRD.•Electrochemical behavior investigation of C-C3N4/LCMO/CPE to detect the ferulic acid (FA) by CV and DPV methods.•The electron transfer coefficient α = 0.68, detection limit 0.0036 µM in the concentration range of 0.009–3.000 µM and 5.00–100 µM were obtained for FA detection.•The diffusion coefficient (D = 3.45 × 10−6 cm2.s−1) was obtained for FA on the surface of C-C3N4/LCMO/CPE.•The fabricated Li2CoMn3O8/C-C3N4/CPE sensor was used to determine FA in honey samples.
Honey is regarded as a valuable food commodity which has many and varied components, including phenolic compounds. Ferulic acid (FA) is one of these compounds, which possesses activities such as antioxidant, anti-inflammatory, anti-diabetic, haemolytic, antiviral, anti-cancer, etc. In view of these unique characteristics, a quick, sensitive, simple and inexpensive method for FA identification is required. This research developed a novel electrochemical sensor for measuring FA in honey samples. The sensor utilizes a C-C3N4/Li2CoMn3O8 nanocomposite modified carbon paste electrode (C-C3N4/LCMO/CPE) to enhance the sensitivity and detection. The synthesized nanocomposite exhibits remarkable properties, featuring an abundance of electrochemically active sites and enhanced electron transfer rates, making it ideal for developing advanced electrochemical sensors. The XRD, SEM and EDX analysis were used to examine and look like the synthesised nanocomposite structure. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods were used to evaluate the electrochemical behavior of C-C3N4/LCMO/CPE sensor for FA detection and optimized by adjusting pH, and potential scan rate. FA was measured in a phosphate buffered saline (PBS; 0.1 M, pH 4.0) by DPV with the detection limit of 3.6 nM and quantitative limit of 0.009 µM in the linear response ranges of 0.009–3.000 and 5.00–100 µM. Chronoamperometry was utilized to calculate the diffusion coefficient of FA (D = 3.45 (±0.11) × 10−6 cm2.s−1) on the surface of the C-C3N4/LCMO/CPE, as well as the electron transfer coefficient (α = 0.68). The sensor’s high sensitivity for accurately assessing FA in real samples was demonstrated by recovery values ranging from 96.96 to 102.36 %.
In this paper, we demonstrate and compare the synthesis of copper (Cu) and copper(I) oxide on Cu (Cu/Cu2O) nanoparticles via thermal decomposition method using a combination of oleic acid and ...oleylamine and oleic acid alone. Using a combination of oleic acid and oleylamine, involves a single nucleation step and control in growth of nanoparticles produces high monodispersity in shape and protects the copper nanoparticles against oxidation. X-ray diffraction (XRD) confirms the formation of single phase Cu only and X-ray photoelectron spectroscopy (XPS) evidences the formation of Cu without any formation of oxides on surfaces for over a long period of time with good stability. In view of interest in electrochemical sensors, we explore the fabrication of a novel and highly sensitive electrode and compare the electrochemical current responses for simultaneous determination of paracetamol and dopamine using Cu/Cu2O nanoparticles stabilized by oleic acid alone and Cu nanoparticles obtained from a combination of oleic acid and oleylamine. Interestingly, we observe that Cu/Cu2O nanoparticles stabilized by oleic acid alone exhibit excellent electrochemical enhancement in the peak current response towards simultaneous determination of paracetamol and dopamine with an increase in peak-peak separation of 239mV. Differential pulse voltammetry (DPV) studies show a linear response to dopamine within the concentration from 0.02μM to 0.159μM with a detection limit of 3.27nM (S/N=3).
Schematic representation of Cu/Cu2O-OA/MWCNTs/GC and Cu-OA-OM/MWCNTs/GC modified electrode in the presence of paracetamol and dopamine simultaneously. Display omitted
•Compare the structural and electrochemical properties of Cu and Cu/Cu2O nanoparticles•We examine the modified electrode for simultaneous determination of DA and PA.•Cu/Cu2O on MWCNTs modified electrode shows excellent electrochemical sensor.
