Selective Electrochemical Sensor For Determination Research Articles

An ultrasensitive and selective electrochemical sensor for determination of estrone 3-sulfate sodium salt based on molecularly imprinted polymer modified carbon paste electrode.

A highly sensitive and selective electrochemical sensor based on carbon paste electrode (CPE) modified with molecularly imprinted polymers (MIPs) has been developed for the determination of estrone 3-sulfate sodium salt (ESS). MIPs were prepared in polar medium via bulk polymerization and characterized by scanning electron microscopy and infrared spectroscopy. Cyclic voltammetry was performed to the study preparation process and binding behavior of the MIP-modified CPE (MIP/CPE) toward ESS. The conditions for preparing MIPs and MIP/CPE as well as ESS detection were optimized. Under the optimal experimental conditions, the detection linear range for ESS is 4×10-12 to 6×10-9M with a limit of detection of 1.18×10-12M (S/N=3). In addition, the sensor exhibits high binding affinity toward ESS over its structural analogues with excellent repeatability and stability. The fabricated MIP/CPE was then successfully employed to detect ESS in pregnant mare urine (PMU) without any pretreatment, and the average recoveries were from 99.6 to 104.9% with relative standard deviation less than 3.0%. High-performance liquid chromatography was adopted as a reference to validate the established approach in detecting ESS and their results showed good agreement. The as-prepared sensor has high potential to be a decent tool for on-site determination of ESS in PMU in a fast and convenient manner. Graphical Abstract ᅟ.

Bi‐enzyme Electrochemical Sensor for Selective Determination of Organophosphorus Pesticides with Phenolic Leaving Groups

AbstractAn amperometric bi‐enzyme sensor for detection of organophosphorus pesticides (OPs) with phenolic leaving groups, which are not electroactive, is presented in this work. The biosensing platform was created by a simple, controllable, and reproducible one‐step electrodeposition onto the surface of a glassy carbon electrode of a chitosan bionanocomposite with entrapped carboxylated multi walled carbon nanotubes, organophosphorus hydrolase (OPH), and horseradish peroxidase (HRP). The OPs determination involved a sequence of OPH and HRP‐catalyzed reactions resulting in phenolic radicals production, which were quantified by registering the current of their reduction at a potential of −50 mV vs. Ag, AgCl/KClsat.The developed sensor was applied for the determination of prothiofos, as an example. At optimized conditions (pH 7.25 and H2O2 concentration 200 μmol L−1), a LOD as low as 0.8 μmol L−1 was attained, while the linear concentration range was extended from 2.64 μmol L−1 up to 35 μmol L−1. The main advantage of the proposed bi‐enzyme sensor is its selectivity toward the OPs with phenolic leaving groups, excluding the interference of the nitrophenyl‐substituted OPs.

RETRACTED: Electrochemical behavior of polyoxometalates decorated on poly diallyl dimethyl ammonium chloride-MWCNTs: A highly selective electrochemical sensor for determination of guanine and adenine

Abstract In the present study, an efficient electrocatalyst was developed for simultaneous determination of guanine and adenine. The method is based on the synergetic effect of polyoxometalate ([PW11NiO39] 5− ) modified poly diallyl dimethyl ammonium chloride at multiwall carbon nanotube (MWCNTs) on the oxidation of guanine and adenine. The characteristics of the fabricated nanocomposite were studied using different techniques including spectroscopic techniques, Brunauer–Emmett–Teller surface area analysis, and electrochemical methods. The influence of experimental and chemical parameters on the sensitivity was studied. Calibration curves were obtained under the optimum conditions for the determination of adenine and guanine with linear ranges of 0.4–136.0 and 0.4–76.0 µmol L −1 and with detection limits of 0.24 and 0.1 µmol L −1 , respectively. The modified electrode showed excellent repeatability and reproducibility. The designed electrochemical sensor has been used successfully for the determination of these two compounds in ssDNA salmon sperm sample.

Electrochemical sensor based on magnetic molecularly imprinted nanoparticles modified magnetic electrode for determination of Hb

A fast and selective electrochemical sensor for determination of hemoglobin (Hb) was developed based on magnetic molecularly imprinted nanoparticles modified on the magnetic glassy carbon electrode. The nanoparticles Fe3O4@SiO2 with a magnetic core and a molecularly imprinted shell had regular structures and good monodispersity. Hb could be determined directly by electrochemical oxidization with the modified electrode. A magnetic field increased electrochemical response to Hb by two times. Imprinting Hb on the surface of Fe3O4@SiO2 shortened the response time within 7min. Under optimum conditions, the imprinting factor toward the non-imprinted sensor was 2.8, and the separation factor of Hb to horseradish peroxidase was 2.6. The oxidation peak current had a linear relationship with Hb concentration ranged from 0.005mg/ml to 0.1mg/ml with a detection limit (S/N =3) of 0.0010mg/ml. The sensors were successfully applied to analysis of Hb in whole blood samples with recoveries between 95.7% and 105%.

A highly selective electrochemical sensor for 4-chlorophenol determination based on molecularly imprinted polymer and PDDA-functionalized graphene

Molecularly imprinted polymer (MIP) of 4-chlorophenol (4-CP) was synthesized and combined with poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (PDDA-G) to develop an electrochemical sensor for selective determination of 4-CP. The chemical structures of the imprinted films were analyzed using Fourier transform infrared (FTIR) spectroscopy. The morphology and interfacial behavior of MIP and PDDA-G modified glassy carbon electrodes (GCEs) were investigated by scanning electron microscopic (SEM) and electrochemical impedance spectroscopic (EIS) techniques, respectively. The obtained MIP/PDDA-G/GCE showed high sensing performance towards 4-CP. Under optimized conditions, the sensor showed a linear response to the concentration of 4-CP in a wide range from 0.8 to 100μmolL−1 with a detection limit (3S/N) of 0.3μmolL−1. Moreover, the imprinted sensor exhibited excellent specific recognition ability to 4-CP which could avoid the interference of other structurally similar phenolic compounds. The developed sensor was successfully applied to the detection of 4-CP in real-life water samples.

An electrochemical sensor for rizatriptan benzoate determination using Fe3O4 nanoparticle/multiwall carbon nanotube-modified glassy carbon electrode in real samples

In this paper a sensitive and selective electrochemical sensor for determination of rizatriptan benzoate (RZB) was proposed. A glassy carbon electrode was modified with nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles (Fe3O4/MWCNTs/GCE). The results obtained clearly show that the combination of MWCNTs and Fe3O4 nanoparticles definitely improves the sensitivity of modified electrode to RZB determination. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), square wave voltammetry (SWV) and cyclic voltammetry (CV). Also, the effect of experimental and instrumental parameters on the sensor response was evaluated. The square wave voltammetric response of the electrode to RZB was linear in the range 0.5–100.0μmolL−1 with a detection limit of 0.09μmolL−1 under the optimum conditions. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied for real life samples of blood serum and RZB determination in pharmaceutical.

A novel electrochemical sensor for selective determination of uranyl ion based on imprinted polymer sol–gel modified carbon paste electrode

In this work, an electrochemical sensor by combining sol–gel processing and paste electrode was developed. Functional precursor was first synthesized and reacted with tetramethoxysilane to obtain polymer sol–gel and then used as a receptor for selective binding and sensing of uranyl ion in aqueous solution. Ion-imprinted polymer sol–gel synthesized in the presence of uranyl ion was characterized by Fourier transform-infrared spectroscopy, scanning electron microscopy and N2 adsorption–desorption analysis by comparing with non-imprinted sol–gel obtained in the absence of uranyl ion. Surface area, pore volume and diameter were analyzed from the profile of nitrogen adsorption. Uranyl ion imprinted network was employed to achieve a suitable conformation for electrochemical reduction of uranyl ion and also to improve the selectivity of the sensor. The results showed that the ion imprinted polymer sol–gel modified carbon paste electrode exhibited selectivity toward uranyl ion compared to electrode containing non-imprinted polymer sol–gel. The ion-imprinted sensor was also successfully employed to detect uranyl ion in real samples and exhibited distinctive change in current upon interaction with uranyl ion. The corresponding selectivity factors of the sensor toward uranyl ion against the other analogues were evaluated.

A Simple but Highly Sensitive and Selective Electrochemical Sensor for Determination of Dopamine Based on Langmuir-Blodgett Film of Calix[4]resorcinarene

In this work, a new electrochemical sensor was structured based on calix[4]resorcinarene LB film modified glassy carbon electrode (GCE) and used for sensitive determination of dopamine (DA). This new sensor displayed a significant response to DA from the synergetic effect of calix[4]resorcinarene LB film (high supramolecular recognition and enrichment capability) and electrochemically pretreated GCE (large surface area and high active sites). Moreover, the response of DA at this sensor was not interfered by the coexistence of ascorbic acid (AA) and uric acid (UA). Under the selective conditions, the response currents were linear relationship with DA concentrations in range of 5.0 × 10−8 – 1.0 × 10−5 mol L−1 with a limit of detection of 1.5 × 10−8 mol L−1 and a limit of Quantity of 5.0 × 10−8 mol L−1. At the same time, the new sensor showed good stability, selectivity and reproducibility.

Electrografting of 4‐tert‐Butylcatechol on GC Electrode. Selective Electrochemical Determination of Homocysteine

AbstractA new sensor based on the grafting of 4‐tert‐butylcatechol on the surface of a glassy carbon electrode (GC) was developed for the catalytic oxidation of homocysteine (Hcy). The GC‐modified electrode exhibited a reversible redox response at neutral pH. Under the optimum conditions cyclic voltammetric results indicated the excellent electrocatalytic activity of modified electrode toward the oxidation of Hcy at reduced over‐potential about 350 mV. A linear dynamic range of 0.01–3.0 mM and a detection limit of 1.0 µM were obtained for Hcy. The modified electrode was used as an electrochemical sensor for selective determination of Hcy in human blood.

Development of Simple Electrochemical Sensor for Selective Determination of Methadone in Biological Samples Using Multi‐walled Carbon Nanotubes Modified Pencil Graphite Electrode

AbstractThe electrochemical sensor was developed for determination of methadone (MTD) using multi‐walled carbon nanotubes (MWCNT) modified pencil graphite electrode (MWCNT‐PGE). It was found that the oxidation peak current of MTD at the MWCNT‐PGE was greatly improved compared with that of the bare‐PGE. At the MWCNT‐PGE, well‐defined anodic peak of MTD was observed at about 0.7 V (in pH 7 solution). The influence of several parameters on the determination of MTD was investigated. At optimum experimental conditions, differential pulse voltammetry (DPV) was used for determination of MTD, which exhibited a linear calibration graph of Ip versus MTD concentration in the range of 0.1–15 µM with a correlation coefficient of 0.9992. The calculated detection limit for S/N = 3 was 87 nM. It has been shown that the peaks obtained for oxidation of ascorbic acid (AA), uric acid (UA) and MTD in their mixture could be well resolved by differential pulse voltammetry, permitting us to develop a sensitive and selective electrochemical sensor for determination of MTD in the presence of AA and UA. Finally, MWCNT‐PGE was used for determination of MTD in biological samples, such as human serum and urine, using the standard addition procedure and the results were quite promising.

Molecularly imprinted electrochemical sensor for selective determination of oxidized glutathione

A molecularly imprinted sensor was prepared for the selective determination of oxidized glutathione with a detection limit of 1.8 × 10−9 mol L−1, which was lower than most of the other methods.

An electrochemical sensor for selective determination of sulfamethoxazole in surface water using a molecularly imprinted polymer modified BDD electrode

A new electrochemical sensor based on a MIP/BDD electrode is presented for the quantitative determination of sulfamethoxazole and performs a satisfactory recovery for the detection of SMX in surface water samples.

A highly sensitive and selective electrochemical sensor for determination of Cr(VI) in the presence of Cr(III) using modified multi-walled carbon nanotubes/quercetin screen-printed electrode

A novel screen-printed carbon electrode modified with quercetin/multi-walled carbon nanotubes was fabricated for determination of Cr(VI) in the presence of excess of Cr(III) without any pretreatment. The method is based on accumulation of the quercetin–Cr(III) complex generated in situ from Cr(VI) at the modified electrode surface in an open circuit followed by differential pulse voltammetry detection. The new method allowed selective determination of Cr(VI) in the presence of Cr(III). The influence of various parameters affecting the adsorptive stripping voltammetry performance was investigated. Under the optimum conditions, the calibration plot was found to be linear in the Cr(VI) concentration range from 1.0 to 200μmol−1 with a limit of detection(S/N=3) of 0.3μmolL–1. The relative standard deviation (RSD%) of seven replicates of the current measurements for a 50μmol−1 of Cr(VI) solution was 3.0%. The developed electrode displayed a very low or no sensitivity to alkali, alkali-earth and transition metal cations and was successfully applied for the determination of Cr(VI) in drinking water samples.

Electrochemical sensor for selective determination of N-acetylcysteine in the presence of folic acid using a modified carbon nanotube paste electrode

In the present paper, a novel benzoylferrocene (BF) modified carbon nanotube paste electrode (BFCNPE) was prepared. The modified electrode was further used for the successful determination of N-acetylcysteine (NAC), and it showed an excellent electrocatalytic oxidation activity toward NAC with a lower overvoltage, pronounced current response, and good sensitivity. Under the optimized experimental conditions, the proposed electrochemical NAC sensor exhibited a linear calibration plot that ranged from 3.0×10−7 to 7.0×10−4M with a detection limit of 9.0×10−8M. Also, Square wave voltammetry (SWV) was used for simultaneous determination of NAC and folic acid (FA) at the modified electrode. Finally, the proposed method was applied to the determination of NAC in NAC tablets.

Highly sensitive and selective dopamine biosensor based on 3,4,9,10-perylene tetracarboxylic acid functionalized graphene sheets/multi-wall carbon nanotubes/ionic liquid composite film modified electrode

A sensitive and selective electrochemical sensor for determination of dopamine (DA) was fabricated based on 3,4,9,10-perylene tetracarboxylic acid functionalized graphene sheets, multi-wall carbon nanotubes and ionic liquid modified glass carbon electrode and the properties of modified electrode were characterized by scanning electron microscopy, transmission electron microscope and electrochemical impedance spectroscopy. The modified electrode showed excellent electrocatalytic activity toward the oxidation of DA. Meanwhile, a possible reaction mechanism related to the oxidation of DA was proposed. The differential pulse voltammetry was used for the determination of DA in the presence of 500μM ascorbic acid and 330μM uric acid under the optimum conditions and a good linear relationship between peak current and the concentration of DA was obtained in the concentration range from 0.03μM to 3.82mM with a detection limit of 1.2×10−9M (S/N=3). Moreover, the proposed method was successfully applied to determine DA in real sample and satisfactory results were obtained. The results showed that the modified electrode exhibits an excellent catalytic activity, good sensitivity, reproducibility and long-term stability.

A carbon paste electrode impregnated with Cd 2+ imprinted polymer as a new and high selective electrochemical sensor for determination of ultra-trace Cd 2+ in water samples

A carbon paste electrode (CP) impregnated with Cd 2+ ion imprinted polymer (IIP) was prepared and used for differential pulse voltammetry determination of Cd 2+ in real samples. The IIP was prepared by using vinyl pyridine and quinaldic acid as functional monomer and complexing agent, respectively. Voltammetric response of the IIP–CP was considerably higher than that of the electrode modified with the non-imprinted polymer (NIP–CP), indicating properly functioning of the recognition sites of the IIP. Compared to the previously developed cadmium sensors, this sensor showed considerably better resistance against potential interfering agents such as Cu 2+, Hg 2+ and Pb 2+. This sensor showed linear range of 1.0 × 10 −9–5.0 × 10 −7 M and detection limit of 5.2 × 10 −10 M ( S/ N = 3).