Differential Pulse Voltammetric Techniques Research Articles

Development of electrochemical sensor for adrenaline at poly (allura red) modified carbon paste electrode: A voltammetric study

Abstract Poly (allura red) modified carbon paste electrode (MCPE) sensor is developed for the electrochemical determination of Adrenaline (AD) in the presence of Uric acid (UA), by cyclic voltammetric and differential pulse voltammetric techniques. Developed Poly (allura red) MCPE is more sensitive and selective. The effect of pH, scan rate and concentration on the oxidation of adrenaline were studied, LOD 6.8 µM, LOQ 22 µM for AD and LOD 17 µM, LOQ 54 µM for UA respectively and the poly (allura red) modified carbon paste electrode is applied for the simultaneous determination of adrenaline and Uric acid, the Poly (allura red) MCPE has capable of determining both AD and UA individually with two identical different oxidation peaks for AD and UA. This method can be used for some other bioactive molecules.

A facile electrochemical sensor based on titanium oxide (TiO2)/reduced graphene oxide (RGO) nano composite modified carbon paste electrode for sensitive detection of epinephrine (EP) from ternary mixture

Abstract Titanium Oxide/Reduced Graphene Oxide (TiO2/RGO) nano composite was prepared using hydrothermal method using titanium butoxide and Graphite oxide (GO). GO was synthesised by following modified Hummers method. The prepared materials were characterised by Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetry combined with Differential Scanning Calorimetry (TG-DSC). An electrochemical sensor based on TiO2/RGO nano composite was constructed for sensitive and selective detection of epinephrine (EP). Due to greater surface area, TiO2/RGO nano composite modified carbon paste electrode (TiO2/RGO-MCPE) shows enhanced electrocatalytic activity towards the oxidation of EP by increasing anodic current. The differential pulse voltammetric (DPV) technique shows that EP could be detected independently and simultaneously from a mixture of ascorbic acid (AA) and uric acid (UA) using TiO2/RGO-MCPE. The developed sensor shows good reproducibility, stability and two linear dynamic ranges 0.005–0.1 mM and 0.1–2 mM respectively.

Electrochemical quantification of vitamin B9 on poly tyrosine modified pencil graphite electrode

An electrochemically polymerized tyrosine film on pencil graphite substrate was found to be an affordable electrochemical sensor for vitamin B9 or folic acid. The electrochemical characteristics of the electrode was studied using cyclic and differential pulse voltammetric techniques in phosphate buffer (pH 7). The surface study of the electrode was carried out by scanning electron microscopy. The sensor showed a linear range from 1μM – 85 μM concentration range by means of differential pulse voltammetry. A good repeatability was obtained for the developed sensor and was utilized for the sustainable application in pharmaceutical tablets.

Electrochemical preparation of poly (direct yellow 11) modified pencil graphite electrode sensor for catechol and hydroquinone in presence of resorcinol: A voltammetric study

Present study describes the fabrication of new electrochemical sensor by electropolymerization of direct yellow 11 on the surface of pencil graphite electrode (PGE) for the investigation of catechol (CC) and hydroquinone (HQ) in the presence of resorcinol (RS). The modified electrode surface was further characterized by Transmission electron microscopy (TEM) and Field Emission Scanning Electron Microscope (FESEM). After the modification of PGE, it exhibits an excellent electrochemical response for the analytes using cyclic voltammetry (CV) and differential pulse voltammetric (DPV) technique. Specific parameters including varying concentration of analytes, sweep rate and pH solution were optimized to the electrode. The kinetic property of a modified electrode was got to be both adsorption and diffusion controlled and it give lower detection limit for CC (0.11 µM) and HQ (0.16 µM) respectively. In the simultaneous electroanalysis, bare PGE was failed to depict the oxidation peaks, whereas modified electrode gives well separated three anodic peaks for CC, HQ and RS with superior enhancement in peak current. The proposed modified electrode was applied for the quantification of CC, HQ and RS in a tap water and obtained a consistent recovery in-between 96 and 100 %. The proposed sensor can be fabricated using a simple method with a low cost.

Fabrication of Conductive Polypyrrole Doped Chitosan Thin Film for Sensitive Detection of Sulfite in Real Food and Biological Samples

AbstractIn this study, we reported electrochemical synthesis of conductive polypyrrole‐chitosan (PPY‐CHI) thin film for sensitive detection of sulfite in real samples. The synthesized PPY‐CHI film was characterized in terms of surface morphology, optical property, binding energy, conductivity and electrochemical properties. The synthesized copolymeric PPY‐CHI film displayed good electrocatalytic behaviour towards oxidation of sulfite. The synthesized PPY‐CHI film was used for sulfite detection using differential pulse voltammetric technique with detection limit, sensitivity and linearity of 0.21 μM (S/N=3), 15.28 μA μM cm−2 and 50–1100 μM respectively. In addition, the current responses of PPY‐CHI film towards sulfite were repeatable, reproducible response and unaffected by selected electroactive interferents. Finally, the synthesized PPY‐CHI was successfully and satisfactorily applied for determination of sulfite in real food and biological samples. The results obtained from this study highly placed PPY‐CHI film as a promising sensor for sensitive and accurate detection of sulfite in food and biological samples for human health protection.

Tailoring the electrochemical interface of mesoporous carbon with ubiquinone for detection of parabens in cosmetics

AbstractQuality assessment of paraben in cosmetic products is in need to avoid and control the deadly side effect caused in humans. Though, there are various studies reported on sensing paraben electrochemically, the use of chemical modifiers is restricted to carbon based materials due to its efficiency but, the mesoporous carbon with high surface area and electron transfer property is hitherto unexplored. Here, we have investigated the sensing of paraben and its derivatives by using ubiquinone (Q10) introduced mesoporous carbon (MPC) via cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques. The morphological studies of MPC showed rod shaped structure. The pore size and the pore volume were found to be 3.93 nm and 0.4 cm3/g respectively. The fabricated sensor showed good electrocatalytic activity for detecting methyl, ethyl and propyl paraben with the detection limit of 0.26 μM, 0.3 μM and 1.07 μM, respectively. Real time measurements of the modification were further utilized for commercially available cosmetic samples.

Sensitive and selective voltammetric oxidation and determination of an antiemetic drug using gold electrode and its biomedical applications

In this study, we investigated the voltammetric oxidation and determination of an antiemetic drug, metoclopramide hydrochloride at gold electrode using cyclic, linear sweep and differential pulse voltammetric (DPV) techniques. The anodic peak was characterized and the process was diffusion-controlled. The influence of current on pH, scan rate, concentration was studied to optimize the experimental conditions. The number of electrons transferred was calculated and plausible oxidation mechanism was proposed. The ability of gold electrode to determine trace amount of MCP was studied using DPV. Limit of detection and quantification was calculated under the optimized conditions. For the analytical applications, pharmaceutical formulation and human urine sample analysis were performed. Various excipients were used to investigate their interference in the analytical application and it was found that the proposed method can be adopted for clinical trials, quality control and real sample analysis.

Elevated and rapid voltammetric sensing of riboflavin at poly(helianthin dye) blended carbon paste electrode with heterogeneous rate constant elucidation

The potent, selective, and consistent electrochemically polymerized helianthin dye modified carbon paste electrode (PHLDMCPE) was generated for the assessment of the significant antioxidant riboflavin (RL) with ascorbic acid (AA) and tyrosine (TR) using cyclic voltammetric (CV) and differential pulse voltammetric (DPV) techniques. The PHLDMCPE explicates a superior electrocatalytic resolution for the redox activity of 1 × 10−4 M RL in 0.1 M phosphate buffer solution (PBS) of pH 7.0 than the bare carbon paste electrode (BCPE). The oxidation peak current of RL and concentration of RL were attained linearly in the range of 60 µM to 150 µM with the lower limit of detection (LOD) of 4.02 × 10−8 M and the limit of quantification (LOQ) of 13.42 × 10−8 M, respectively. The heterogeneous rate constant for the equipped sensor was detected for RL at variable scan rates. This work conveys a modest and advisory methodology for the concurrent investigation of RL with AA and TR. The studied CV technique and developed sensor were adopted for the assessment of RL in pharmacological medication as a real sample. Electrochemically polymerized HLD modified carbon paste electrode was exposed for the evaluation of antioxidant riboflavin in both real and commercial samples in optimum circumstances using CV and DPV techniques. The selective resolution and interference study of riboflavin were done with ascorbic acid and tyrosine. The surface morphology of modified and unmodified carbon sensors was studied using FE-SEM and CV methods. The modified sensor exposes refined stability, reproducibility, and repeatability with a low LOD (4.02 × 10−8 M).

Electrochemical quantification of pyridoxine (VB6) in human blood from other water-soluble vitamins

For the first time reporting a pencil graphite electrode modified with gold nanoparticles and non-conducting polymeric film of o-aminophenol for the selective determination of pyridoxine (VB6) from other water-soluble vitamins in human blood. The fabricated electrode was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and attenuated total reflection infrared spectroscopy. Voltammetric response of VB6 on the fabricated electrode was investigated out using cyclic and differential pulse voltammetric techniques. Under optimized conditions, an irreversible oxidation peak at + 0.632 V was observed which corresponds to the oxidation of VB6. The oxidation peak current and the pyridoxine concentration were found to be linear in the range from 5 to 200 μM with a detection limit of 0.30 μM. The sensitivity of the proposed electrode was calculated to be 3.373 μA/μM/cm2 with excelled reproducibility and stability. The electrode is suitable for the routine analysis of VB6 in human blood samples as it highly selective from other water-soluble vitamins.

Simultaneous electroanalysis of dopamine, paracetamol and folic acid using TiO2-WO3 nanoparticle modified carbon paste electrode

In this study, mixed titanium oxide and tungsten trioxide nanoparticles (TiO2-WO3NPs) were prepared and characterized by different characterization techniques. The prepared materials TiO2-WO3NPs were used as modifiers in carbon paste electrode (TiO2-WO3NPs/MCPE) to study the electrochemical behaviour of dopamine (DA) in phosphate buffer solution (PBS) at pH 7.4 by using cyclic voltammetric (CV) technique. The TiO2-WO3NPs/MCPE shows enhanced electrocatalytic activity compared to bare CPE. As a result, the TiO2-WO3NPs/MCPE was used for further electrochemical studies. The effect of pH proposed that an equal number of electron and proton are involved in the electrochemical reaction of DA. The DA concentration determination was in the range 2 × 10−6 M to 18 × 10−6 M and the limit of detection (LOD) and limit of quantification were found to be 10.18 nM and 34.32 nM. From the scan rate study the oxidation of DA was found to be adsorption controlled and simultaneous detection of DA, PA and FA were well separated in CV and differential pulse voltammetric (DPV) technique. Moreover the stability and reproducibility of TiO2-WO3NPs/MCPE at DA was studied and furthermore successfully demonstrated for the detection of DA in blood serum and injection samples.

Electrochemical sensing performance of citicoline sodium modified carbon paste electrode for determination of dopamine and serotonin

In this work, the execution of an electrochemical sensor was investigated by a carbon paste electrode modified with citicoline sodium for the co-detection of dopamine (DA) and serotonin (5-HT) by using voltammetric techniques. The citicoline sodium modified carbon paste electrode (CDP-Choline/MCPE) has been used to increase the characteristics in terms of electro-conductivity, sensitivity, surface area, availability of active absorption sites and reduce fouling property for peak resolution of DA and 5-HT. After the peak resolution studies, we turned to explore the other electrochemical characteristics like scan rate, pH, and concentration, interference study. The overall electrode process of DA was controlled by adsorption and 5-HT was controlled by diffusion. Using CDP-Choline/MCPE, DA and 5-HT were determined by concentration in the range of 10 µM to 100 µM and 10 µM to 30 µM respectively, where as the detection limits are 3.96 µM and 5.81 µM respectively. The separation of the oxidation peak potential for DA and 5-HT was about 0.176 V by cyclic voltammetric (CV) technique. Sensitive electrooxidation peak potential at 0.112 V and 0.302 V from the differential pulse voltammetric (DPV) technique was observed for DA and 5-HT respectively. The proposed sensor was successfully applied for the detection of DA in the injection sample and obatined good results.

Green synthesis of silver nanoparticles (SNPs)-modified electrode for electrochemical detection of nitrobenzene

Nitrobenzene (NB) is a highly toxic and hazardous compound that needs to be detected at the low level. The current work describes an eco-friendly synthesis of silver nanoparticles (SNPs) using a Eucalyptus extract as reducing and stabilizing agent and its use for electrochemical detection of NB. The synthesized SNPs were characterized by following techniques UV–visible spectroscopy, powder X-ray diffraction, FESEM, HRTEM and TEM, FTIR spectroscopy. Further electrochemical investigation of SNPs-modified glassy carbon electrode (SNPs/GCE) is carried out by cyclic voltammetric and differential pulse voltammetric techniques. The prepared NPs exhibit excellent electrochemical behaviour towards reduction of NB and show a linear response in the range 5–40 µM, sensitivity of 2.262 µA µM−1 cm−2 and limit of detection of 0.027 µM. SNPs/GCE shows good selectivity towards NB detection. Also, the system exhibits a considerable recovery towards NB detection in of water and waste samples.

Preparation of GCE modified with ZnO@CoFe2O4magnetic nanoparticles and its application in electrocatalytic determination of Acetaminophen

In this work, a nanocomposite of zinc oxide (ZnO) and cobalt ferrite (CoFe 2 O 4 ) was synthesised with a facile preparation method in order to fabricate a nanosensor for acetaminophen (AC) sensing. The ZnO nanoparticles were electrochemically deposited onto glassy carbon electrode (GCE) coated with magnetic nanoparticles CoFe 2 O 4 . The morphology and structure of ZnO@CoFe 2 O 4 nanocomposite were investigated by scanning electron microscopy and energy dispersive X-ray. The performance of the proposed sensor was characterised with cyclic voltammetry and differential pulse-voltammetry techniques. The ZnO@CoFe 2 O 4 /GCE nanosensor shows excellent electrocatalytic activity for AC oxidation in phosphate buffer (pH = 7) solution and it exhibits a good linear relationship and the low limit of detection (LOD). The ZnO@CoFe 2 O 4 /GCE showed good sensitivity, selectivity, stability, reproducibility, larger specific area and fast response in comparison with other reported sensors. The result calibration diagram of using the differential pulse-voltammetric technique has two linear ranges of 0.495-9.53 and 9.53-47.00 μm, and the LOD for AC by this method obtained 0.36 μm. The performance of this modified electrode was evaluated for measuring AC in some pharmaceutical formulations.

Voltammetric detection of globulin with ionic liquid modified electrodes

In the present study, the ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (IL)) modified pencil graphite electrodes (PGEs) were developed for electrochemical detection of protein, globulin (GLB). The microscopic characterization of PGE and IL modified PGE was performed by scanning electron microscopy (SEM). The electrochemical behaviour of IL modified PGEs was investigated by cyclic voltammetric (CV) technique and electrochemical impedance spectroscopic (EIS) technique. Differential pulse voltammetric (DPV) technique was used for measuring the oxidation signal of globulin. Under the optimum experimental conditions, a linear concentration range of globulin was obtained in the range of 20 to 100 nM and the detection limit was found to be 7.64 nM. The selectivity of our assay to GLB was also tested against to Glutathione, Glucose, l-Cysteine, l-Methionine, l-Tryptophan individually as well as in the mixture sample (1:1) of Globulin:Glutathione, GLB:glucose, GLB:L-Cysteine, GLB:L-Methionine and GLB:L-Tryptophan.

The bi-band silver microelectrode: Fabrication, characterization and analytical study

In this work a new type of working electrode for voltammetry – the bi-band silver microelectrode (b-BAgmE) – is presented for the first time. The sensor consists of two Ag bands 25 μm thick and 4.5 mm long. The bands are arranged symmetrically and contrariwise, along the lateral, cylindrical surface of the Ag guide, coated with a thin layer of epoxy resin. Simple and inexpensive microelectrode construction ensures its reliability of use as well as wide possibilities of application in electroanalysis.Electrochemical properties of the sensor were tested by means of the cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS) in the [Ru(NH3)6]2+/3+ redox system. Comparative experiments, carried out simultaneously on a homemade silver annular band electrode (AgABE), commercially available silver microelectrode (AgmE) and b-BAgmE, confirmed occurrence of the microelectrode effect in case of the AgmE and b-BAgmE. Moreover, the b-BAgmE is characterized by significantly lower value of charge-transfer resistance Rct = 179 ± 6 Ω in comparison to AgmE Rct = 6.0 ± 0.4 MΩ.The practical usefulness of the b-BAgmE was confirmed by determination of Pb2+, Tl+, In3+ and vitamin B2 using the differential pulse (DP) voltammetric technique.

Poly (vanillin) modified carbon paste electrode for the determination of adrenaline: A voltammetric study

The bare carbon paste (BCPE) was modified by electrochemical deposition of vanillin on the surface of carbon paste electrode and applied for the study of electrochemical behavior of Adrenaline (AD) and Uric acid (UA) using cyclic voltammetric and differential pulse voltammetric techniques. Compared to bare carbon paste electrode, a good enhancement in peak current was observed at modified carbon paste electrode. The effect of scan rate and concentration on the oxidation of Adrenaline and uric acid was examined and it was found that the oxidation peak current was proportional to the scan rate and concentration, the LOD and LOQ were found that 5.4 µM and 18 µM. The poly (Vanillin) modified carbon paste electrode showed significantly higher sensitivity and selectivity and used for the simultaneous determination of Adrenaline and uric acid which gives good report.

Voltammetric sensing of minoxidil using a molecularly imprinted polymer (MIP)-modified carbon paste electrode

This study presents voltammetric sensing of minoxidil using a molecularly imprinted polymer (MIP). For fabrication of the electrochemical sensor, the synthesized MIP was incorporated into the carbon paste electrode (CPE). MIP-CPE and non-imprinted polymer carbon paste electrode were compared for the recognition ability toward minoxidil. The most important parameters affecting sensor performance were optimized and a calibration curve was then plotted using differential pulse voltammetric technique. Under optimum conditions, the sensor has a linear response in the 1–400 nM minoxidil concentration range and a 0.3 nM limit of detection (at an S/N ratio of 3). Also, the selectivity of the sensor was investigated. Finally, this sensor was applied successfully for minoxidil determination in real samples with different matrices.

Nanomolar detection of 4-aminophenol using amperometric sensor based on a novel phthalocyanine

Novel cobalt (II) tetra-β-[N(2-(1,3-benzothiazole))carboxamide] phthalocyanine (CoTBTCAPc) has been synthesized for the first time. The dark green colored complex was characterized by different physicochemical and analytical techniques. Cyclic voltammetric studies revealed that the synthesized complex is redox-active nature. The CoTBTCAPc modified glassy carbon electrode (GCE/CoTBTCAPc) showed a stagnant charge transfer behavior for the redox probe whereas, composite hybrid of CoTBTCAPc with carbon nanoparticles (CNP) coated on GCE (GCE/CNP-CoTBTCAPc) showed facile and better charge transfer compared to the bare GCE. The GCE/CoTBTCAPc and GCE/CNP-CoTBTCAPc fabricated electrodes exhibited a decrease in over potential with the increase in oxidation peak current. Electrochemical oxidation of 4-aminophenol (4-AP) at nanomolar concentration was obtained in phosphate buffer pH 7.0 electrolytic media. The modified electrodes showed linear electrochemical response in the concentration range of 40–800 nM and the detection limit (LOD) was found as 13 and 11 nM (S/N = 3) for GCE/CoTBTCAPc and GCE/CNP-CoTBTCAPc electrodes respectively. Differential pulse voltammetric (DPV) technique showed linear response for the 4-AP oxidation in the concentration range of 100–1000 nM with sensitivity of 0.0328 and 0.4179 μA nM−1 cm−2 for the phthalocyanine and CNP-phthalocyanine modified electrodes respectively. In contrast, the amperometric sensor displayed linear response in the concentration range of 100–900 nM with sensitivity values of 0.4008 and 0.8887 μA nM−1 cm−2 and LOD of 40 and 30 nM for GCE/CoTBTCAPc and GCE/CNP-CoTBTCAPc electrodes respectively. The GCE/CNP-CoTBTCAPc showed selectivity for 4-AP even in the presence of interfering organic and inorganic species. This stable and simple sensor offers an opportunity for the electrochemical sensing of 4-aminophenol in real sample analysis like 4-AP in paracetamol tablets.

Electrochemical oxidation of curcuminoids: an experimental and computationalinvestigation

Curcuminoids, reported to have important biological properties, such as antioxidant, anti-Alzheimer, and antidiabetic properties, comprise curcumin (CRM; 1,7-bis [4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) and its derivatives demethoxycurcumin (DMC; (E,6E)-1-(3,4-dimethoxy-cyclohexyl)-7-(3,4-dimethoxyphenyl)hepta-1,6-diene-3,5- dione) and bisdemethoxycurcumin (BDMC; 1,7-bis[4-hydroxyphenyl]-1,6-heptadiene-3,5-dione). Their electrochemical oxidations are thoroughly explored by applying cyclic and differential pulse voltammetric techniques. The dependence of current intensities and potentials on pH, concentration, scan rate, and nature of the buffer was investigated. The outcome is supported by density functional theory computations indicating the transfer of 4-e􀀀 /H+ , 6-e􀀀 /H+ , and 8- e􀀀 /H+ couples involved in the oxidation mechanisms of CRM, DMC, and BDMC, respectively, leading to the formation of the same oxidized product.

Enantioselective biomimetic sensor for discrimination of R and S-Clopidogrel promoted by β-cyclodextrin complexes employing graphene and platinum nanoparticle modified carbon paste electrode

To mimic the enantioselectivity of an enzyme in the field of biosensor for a drug molecule is daunting task for chiral selector. Here, we report beta cyclodextrin (β-CD) as artificial enzyme model for molecular recognition of Clopidogrel (CLP) isomers on chiral carbon paste electrode. The inclusion of CLP enantiomers was initiated by β-CD and stability constants obtained for 1:1 complex of β-CD-R-CLP and β-CD-S-CLP. The stability constants calculated for β-CD-R-CLP and β-CD-S-CLP were 6.109×103M−1 and 5.023×102M−1, respectively at 25°C. The best enantioselectivity was obtained for R-CLP which was found to be 12 times higher to that of S-CLP. The thermodynamic consideration of the complex formation shows negative values of Gibbs free energy (ΔG) -21.602 kJ K−1mol−1 (R-CLP) and−15.411 kJ K−1mol−1 (S-CLP) which indicates inclusion process to be exothermic and spontaneous. The difference in ΔG values indicates effective enantiomeric recognition of the aforementioned electrode systems for CLP. The synergistic effect of graphene, platinum nanoparticle and beta cyclodextrin in the form of modified carbon paste electrode (GNS-PNP-β-CD-CPE) were studied by differential pulse voltammetric techniques. The anodic peak potential difference of 102mV was able to discriminate isomers of CLP at the surface of GNS-PNP-β-CD-CPE. Under optimum conditions, R-CLP and S-CLP exhibited good linear response in the range of 2.0×10−6 to 2.0×10−4M with low detection limit of 4.87×10−7M and 2.10×10−7M, respectively. The Michaelis-Menten constants (KM) calculated for R-CLP and S-CLP were 44.0μM and 60.0μM employing chronoamperometry. The higher value of KM for S-CLP suggests weak binding of S-CLP to the β-CD confirming catalytically different biotransformation rate of each enantiomer towards oxidation. Although the kinetic parameters do not match the level of enzymatic transformations, this study predicts the Michaelis-Menten constants for CLP using β-CD which may become useful guide for future exploration of enzyme mimics in the area of chiral electrochemical biosensor.