Differential Pulse Voltammetric Method Research Articles

Electrochemical behavior of theophylline at methylene blue dye modified electrode and its analytical application

Electrochemical oxidation of theophylline was investigated at the surface of carbon paste electrode with methylene blue dye as an electron mediator. The electrode surface was characterized by atomic force microscopy (AFM) and XRD. Methylene blue a cationic dye is an excellent redox mediator. Cyclic voltammetric technique was used to investigate the electrochemical behaviour of modified electrode. There was enormous increase in the peak current as compared with bare electrode. The effect of pH on oxidation behaviour of theophylline in the pH range of 3.0-11.2 was carried out. Electrochemical oxidation of theophylline was predominant in pH 3.0. In addition, the effect of scan rate variation was used to calculate the number of electrons transferred and heterogeneous rate constant. Further, a possible electrode reaction mechanism was proposed. Differential pulse voltammetric method in the linear range 0.2 -10 µM was performed and limit of detection and quantification were calculated 2.25 nM and 7.52 nM respectively. The developed electrode was further successfully employed for the determination of theophylline in pharmaceutical and human urine samples.

Nano-silica modified electrode as a sensor for the determination of mefenamic acid - A voltammetric sensor

Electrochemical oxidation of mefenamic acid was investigated at the surface of carbon paste electrode with silica nanoparticles as an modifier. The electrode surface was characterized by using SEM and TEM. Voltammetric behaviour of mefenamic acid was studied using cyclic voltammetric method. A nano silica modified carbon paste electrode was used to investigate the electrochemical oxidation of mefenamic acid. Comparison of bare carbon paste electrode and silica nanoparticles modified carbon paste electrode, it was observed that the modified electrode has advantage of high sensitivity and selectivity with low detection limit. Effect of supporting electrolyte (phosphate buffer, I = 0.2 M) solution in the range, 3.0 – 11.2 pH was investigated and found that pH 5 is suitable for the investigations. In addition, effect of scan rate variations was studied to calculate some of the physiochemical properties. An electrode reaction mechanism was proposed and differential pulse voltammetric method was developed for the analytical application. Further, the applicability of the proposed method was investigated for pharmaceutical dose form and human urine samples.

Porous Reduced Graphene Oxide β-cyclodextrin Modified Electrode as Enhanced Sensing Platform for the Determination of Dihydrochalcone: Phloretin

A facile and sensitive electrochemical sensor based on glassy carbon electrode (GCE) modified with β cyclodextrin (β-CD) functionalized porous reduced graphene oxide (prGO) was fabricated and used for electrochemical determination of dihydrochalcone, phloretin in biological samples. Low temperature solution combustion method was employed to fabricate prGO from graphene oxide. The product so obtained was mixed with β-CD and treated for ultra sonication in order to get β-CD-prGO. Enhanced electrochemical response for phloretin (PHL) was observed at β-CD-prGO modified GCE. The effect of pH, scan rate, accumulation time and amount of modifier on the electrochemical behavior of PHL was studied. The probable electro-oxidation mechanism was proposed based on obtained experimental results. Linearity between the peak current and concentration of PHL was noticed in the range of 0.1–75.2 μM and 0.5–65.25 μM for square wave and differential pulse voltammetric methods, respectively. The developed methods were successfully applied for the determination of PHL in spiked biological samples. Further, prepared β-CD-prGO modified GCE was used to understand the interaction between HSA and PHL.

Electrochemical behavior of mefenamic acid at zinc oxide nanoparticles modified carbon paste electrode

Electrochemical oxidation of mefenamic acid at zinc oxide nanoparticles modified electrode was performed. Comparison of bare carbon paste electrode and zinc oxide nanoparticles modified carbon paste electrode, it was observed that the modified electrode has advantage of high sensitivity and selectivity with low detection limit. Effect of supporting electrolyte (phosphate buffer, I = 0.2 M) solution in the range, 3.0 – 11.2 pH was investigated and found that pH 5 is suitable for the investigations. In addition, effect of scan rate variations was studied to calculate some of the physiochemical properties. A differential pulse voltammetric method was developed for the analytical application. Low detection limit and quantification of 5.13 x 10 –10 and 1.17 x 10 –9 M respectively in the linearity range 1.0 x 10 –6 to 2.0 x 10 –8 shows that the developed method has a wide advantage over early reported methods. Further, the applicability of the method was investigated for pharmaceutical dose form and human urine samples

Eco-friendly reduced graphene oxide for the determination of mycophenolate mofetil in pharmaceutical formulations

Graphene oxide (GO) was synthesized and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). GO was then electrochemically reduced and used for electrochemical study of mycophenolate mofetil (MMF). The electrochemically reduced graphene oxide (ERGO) film on glassy carbon electrode (GCE) showed enhanced peak current for electrooxidation of MMF. MMF exhibited two irreversible oxidation peaks at 0.84V (peak a1) and 1.1V (peak a2). Effects of accumulation time, pH and scan rate were studied and various electrochemical parameters were calculated. A differential pulse voltammetric method was developed for the determination of MMF in bulk samples and pharmaceutical formulations. Linear relationship was observed between the peak current and concentration of MMF in the range of 40nM–15μM with a limit of detection of 11.3nM. The proposed method is simple, sensitive and inexpensive and, hence, could be readily adopted in clinical and quality control laboratories.

Challenge Approach of an Inexpensive Electrochemical Sensor for Rapid Selective Determination of two Non‐classical β‐Lactams in Presence of Different Degradants and Interference Substances

AbstractAn inexpensive stability−indicating anodic voltammetric method for rapid determination of two non‐classical β‐lactam antibiotics; Meropenem (MP) and Ertapenem (EP) has been developed and validated. The method was based on the enhancement of voltammetric response at a disposable graphite pencil electrode (GPE). Differential pulse voltammetric (DPV) method was developed for quantification of both drugs in B−R buffer solution (pH 2.0) at GPE. The GPE displayed very good voltammetric behavior with significant enhancement of the peak current compared to glassy carbon electrode (GCE). Stress stability studies were performed using 0.5 M of either HCl or NaOH and H2O2. Mass and infrared spectroscopy were used for identification of degradants and their pathways were illustrated. Under optimal conditions, the peak currents showed a linear dependence with drug concentrations. The achieved limits of detection (LOD) were 1.23, 2.07 and 1.50 μM for MP and two waves of EP, respectively. The developed voltammetric method was successfully applied for direct determination of MP and EP in drug substances, pharmaceutical vials and in presence of either their corresponding hydrolytic, oxidative‐degradants or interfering substances with no potential interferences. The differential pulse voltammograms were highly advantageous and applicable in QC laboratories for rapid, selective micro‐determination of MP and EP.

Modification of carbon paste electrode by electrochemical polymerization of neutral red and its catalytic capability towards the simultaneous determination of catechol and hydroquinone: A voltammetric study

In this study, a new electrochemical sensor was developed and fabricated based upon the electrochemical polymerization of neutral red (NR) on the surface of carbon paste electrode (CPE). The newly developed sensor shows electrocatalytic capability towards the simultaneous determination of catechol (CC) and hydroquinone (HQ) in presence of 0.2M phosphate buffer solution (PBS) at pH7.4 with the scan rate of 50mVs−1. Electrochemical measurements were performed using both cyclic voltammetry (CV) and differential pulse voltammetric (DPV) methods at poly (neutral red) modified carbon paste electrode (PNR/MCPE). The effects of scan rate, concentration and pH variation for CC and HQ was investigated at PNR/MCPE. The proposed sensor exhibits adsorption-controlled type of electrode process, moreover it show good detection limit (LOD) (CC=6.46μM and HQ=4.97μM) and limit of quantification (LOQ) (CC=21.5μM and HQ=16.5μM). Hence, the proposed sensor was successfully applied in the simultaneous determination of CC and HQ with satisfied results.

Flexible graphene oxide−wrapped SnO2 hollow spheres with high electrochemical sensing performance in simultaneous determination of 4−aminophenol and 4−chlorophenol

Graphene oxide−wrapped hierarchical hollow structured SnO2 spheres were fabricated by hydrothermal strategy and applied to the sensitive electrochemical sensing of phenolic compounds. The as−prepared new nanocomposite modified electrode characterized by morphology, X−ray diffraction, Raman spectroscopy, electrochemical impedance, and electroactive surface area suggested its efficiency for the individual and simultaneous sensing of 4−aminophenol (4−AP) and 4−chlorophenol (4−CP), exhibiting as the remarkable increase in peak currents compared with SnO2 or graphene oxide modified electrodes. After optimization of electrochemical parameters, the detection limits of 2.2nM for 4−AP and 3.1nM for 4−CP were obtained using differential pulse voltammetric method. Finally, the application of the modified electrode in real water samples was evaluated, indicating that it could be used as an excellent platform for the detection of phenolic pollutants.

Square wave and differential pulse voltammetric methods for the analysis of olivetol at gold electrode

<p class="PaperAbstract"><span lang="EN-US">Few electrochemical techniques have been employed for the determination of the powerful antitumor agent olivetol (OLV) in real samples at gold electrode. An intense and well pronounced oxidation peak was obtained at 1.04 V in the phosphate buffer pH 5.0 as the supporting electrolyte. The effects of pH and scan rate on the oxidation peak were studied. The electrochemical behavior of OLV was investigated using cyclic voltammetric (CV), square wave voltammetric (SWV) and differential pulse voltammetric (DPV) techniques. In DPV and SWV, the gold electrode showed a good sensitivity for OLV in a linear range of 0.1-1.5 µM and 0.1-1.3 µM and detection limits of 1.936×10<sup>-9</sup> M and 4.754</span><span lang="EN-US">×</span><span lang="EN-US">10<sup>-9</sup> M, respectively. A plausible mechanism involving an adsorption controlled oxidation reaction was deduced. The effect of various excipients was also studied and the method was successfully applied for the determination of OLV in human biological samples. </span></p>

A sensitive amplified sensor based on improved carbon paste electrode with 1-methyl-3-octylimidazolium tetrafluoroborate and ZnO/CNTs nanocomposite for differential pulse voltammetric analysis of raloxifene

In this work, we suggested a carbon paste electrode improved with 1-methyl-3-octylimidazolium tetrafluoroborate (1-M-3-OITFB) and ZnO/CNTs nanocomposite (1-M-3-OITFB/ZnO/CNTs/CPE) for electrochemical determination of raloxifene (RXF) as a non-steroidal selective estrogen receptor regulator. The cyclic and differential pulse voltammetric methods were apply for investigation of RXF electrochemical response at a surface of 1-M-3-OITFB/ZnO/CNTs/CPE. Under the best experimental conditions, the 1-M-3-OITFB/ZnO/CNTs/CPE showed a wide linear dynamic range of 0.08 − 400.0μM. We detected a detection limit of 0.04μM for RXF analysis using differential pulse voltammetric method (DPV). The 1-M-3-OITFB/ZnO/CNTs/CPE showed high performance ability to RXF analysis in trace amounts on pharmaceutical and clinical preparations.

Cadmium voltametric quantification in table chocolate produced in Chiquinquira-Boyaca, Colombia

Bioaccumulation of heavy metals such as cadmium has been a major concern in scientific communities and international food organizations, given the great toxicological risk to the consumer, and in many places there is no detailed record of its actual content. In this way, the need arises to carry out a study and registration of the concentration of this metal in products such as table chocolate, of great consumption at regional and national level. Likewise, we seek to have effective quantification tools and a reliable and affordable method to achieve the aim of this research. In this research, Cadmium content in powdered and granulated table chocolate was determined, elaborated and commercialized in the municipality of Chiquinquira, Boyacá-Colombia, using the differential pulse voltammetric method of anodic redisolution (DPVMAR). Previously, the parameters of this method were evaluated, selecting selectivity, linearity, sensitivity, precision and accuracy with satisfactory results as follows: selective at a potential range of 0.54 to 0.64 V, sensitivity in ppb, R2> 0.95, % CV <10% % R> 80%). Analysis of variance showed no significant statistical differences (P <0.05) between the results. Cadmium quantification in samples of granulated and powder chocolate showed values of concentration between 214 and 260 ppb, with the highest concentrations of powder chocolate. Cadmium level did not exceed the tolerable weekly intake limit for this type of food.

Sequential injection differential pulse voltammetric method based on screen printed carbon electrode modified with carbon nanotube/Nafion for sensitive determination of paraquat

The screen-printed carbon electrode (SPCE) modified with various nanoparticles has been studied for using as a working electrode in voltammetric technique. The electrochemical behavior of paraquat on different electrodes was studied by cyclic voltammetry (CV), and then differential pulse voltammetry (DPV) has been employed for trace analysis of paraquat based on redox reaction which the peak current was directly proportional to the concentration of paraquat in the solution. The SPCE modified with carbon nanotube dispersed in Nafion and ethanol (SPCE-CNT/Nafion) gave the best result. Sequential injection-differential pulse voltammetric (SI-DPV) method has been developed for more automated analysis and to reduce chemical consumption. The parameters affecting the SI-DPV system such as step potential, modulation amplitude, flow rate, and concentration of sodium chloride as an electrolyte were studied to improve the sensitivity. Under the optimum condition of the system, i.e., Nafion concentration of 1% (w/v), volume of CNT suspension of 2µL, flow rate of 100µLs−1, step potential of 5mV, modulation amplitude of 100mV and concentration of sodium chloride of 1M, a linear calibration graph in the range of 0.54–4.30µM with a good R2 of 0.9955 and a limit of detection of 0.17µM (0.03mgL−1) were achieved. The proposed system shows high tolerance to some possible interfering ions in natural water, surfactant, and other pesticides. The relative standard deviation (RSD) was 4.2% for 11 replicate measurements with the same electrode. The reproducibility for the preparation of 7 modified electrodes was 2.3% RSD. Recoveries of the analysis were obtained in the range of 82–106%. The developed system can be conveniently applied for analysis without pretreatment of the samples.

A new electrochemical platform for ultrasensitive detection of atrazine based on modified self-ordered Nb2O5 nanotube arrays

In this work, one dimensional self-ordered Nb2O5 nanotube arrays were grown from Nb substrate by anodization method and were modified with optimum amounts of chitosan (CS) and carboxyl-Fe3O4 nanoparticles. These nanocomposites were characterized by SEM, XRD, and XPS and used as electrode materials for the direct detection of atrazine traces in aqueous solution. The test signals were obtained from the interaction between anti-atrazine monoclonal antibody and atrazine and recorded using via differential pulse voltammetric (DPV) method in electrochemical system. These modified one-dimensional Nb2O5 nanotube arrays showed the linear detection ranges of 0.04ng/mL–0.6ng/mL and a detection limit of 0.018ng/mL for atrazine under the optimized conditions. These above results indicate that these Nb2O5 nanotube arrays are promising candidates for electrochemical sensors.

ELECTROCHEMICAL OXIDATION AND DETERMINATION OF AN ANTI-CANCER DRUG PEMETREXED DISODIUM

Abstract-The electrochemical oxidation of an anti-cancer drug Pemetrexed disodium has been investigated at glassy carbon electrode using voltammetric techniques. The dependence of current on potential, pH, concentrartion, scan rate, and excipients were investigated to optimize the experimental conditions. According to the liner relation between peak potential, peak current, scan rate and Pemetrexed disodium concentration, differential pulse voltammetric method for the quantitative determination in phosphate Buffer solution was developed. The linear response was obtained in the range of 10 µM to 0.75 µM with a detection limit of 0.19 µM. The electrochemical oxidation of mechanism of an anti-cancer drug Pemetrexed disodium was proposed. Keywords- Pemetrexed disodium, Cyclic Voltammetry, Electochemical Studies, Glassy carbon electrode

Electrochemical Characteristics and Electrosensing of an Antiviral Drug, Entecavir via Synergic Effect of Graphene Oxide Nanoribbons and Ceria Nanorods

AbstractA sensitive electrochemical sensor was fabricated based on ceria‐graphene oxide nanoribbons composite (CeO2‐GONRs) for an antiviral drug, entecavir (ETV). It was characterized by SEM, EDAX, AFM, IR and Raman spectroscopic techniques. The electrochemical behaviour of ETV was investigated by cyclic voltammetric, differential pulse voltammetric (DPV), linear sweep voltammetric (LSV) and square wave voltammetric (SWV) methods at CeO2‐GONRs modified glassy carbon electrode. Good linearity was observed between the peak current and concentration of ETV in the range of 0.51 ‐ 100 μM with a detection limit of 0.042 μM in DPV method, 2.1 – 61.1 μM with a detection limit of 0.7 μM in LSV method and 0.1 ‐ 80 μM with a detection limit of 68.1 nM in SWV method. The proposed sensitive DPV method was successfully applied for the determination ETV in tablets and biological samples.

An electrochemical nanosensor for simultaneous determination of hydroxylamine and nitrite using oxadiazole self-assembled on silver nanoparticle-modified glassy carbon electrode

Environmental pollutions are causing serious health problems for human, and their quantification is still a big challenge. For determination of hydroxylamine and nitrite as two important environmental pollutants, a novel and highly sensitive electrochemical nanosensor has been developed for the simultaneous determination of hydroxylamine and nitrite in the presence of nine interference moieties using oxadiazole self-assembled on silver nanoparticle-modified glassy carbon electrode (OAgNPs-GCE). The charge transfer coefficient, α, and the charge transfer rate constant, k s, of oxadiazole adsorbed on AgNPs were calculated. The OAgNPs-GCE displayed excellent electrochemical catalytic activities toward the oxidation of hydroxylamine. The detection limit of 0.10 μM and two linear calibration ranges of 0.45–69.4 and 69.4–833.3 μM are obtained for hydroxylamine determination at OAgNPs-GCE surface using a differential pulse voltammetric method. The investigated method showed good stability, reproducibility, and repeatability and high recovery in real samples. Moreover, this modified electrode is found quite effective in simultaneous determination of hydroxylamine and nitrite in the presence of nine moieties. OAgNPs-GCE has been applied to the determination of hydroxylamine and nitrite at water samples with acceptable results.

Electrochemical determination of 5-dodecylsalicylaldoxime and 2′-hydroxy-5′-nonylacetophenone oxime in commercial extractants

A differential pulse voltammetric method using a hanging mercury drop electrode (HMDE) was optimized for the determination of 5-dodecylsalicylaldoxime in hydro-alcoholic solutions using factorial and central composite designs. The Taguchi design methodology was used to extend the formerly optimized method to the determination of 2?-hydroxy-5?-nonylacetophenone oxime. The method was successfully applied to quantify 5-dodecylsalicylaldoxime and 2?-hydroxy-5?-nonylacetophenone oxime in samples of commercial extractants over the concentration range 0.05?2.45 and 0.07?0.82 mg L-1, respectively, with detection limits of 0.034 and 0.019 mg L-1, respectively.

Electrochemical Behaviour of Tinidazole at 1,4-Benzoquinone Modified Carbon Paste Electrode and Its Direct Determination in Pharmaceutical Tablets and Urine by Differential Pulse Voltammetry.

A simple and highly sensitive electrochemical method based on a 1,4-benzoquinone modified carbon paste electrode (1,4-BQMCPE) was described for the determination of tinidazole (TDZ). In Britton Robinson buffer solution, TDZ yields well-defined irreversible reduction peak at −0.344 V on a 1,4-BQMCPE. Compared with that on a bare CPE, the reduction peak of TDZ increased significantly on the modified CPE and the effects of different parameters on the voltammetric responses were also investigated. Differential pulse voltammetric method was proposed and optimized for TDZ determination and its reductive peak current response at 1,4-BQMCPE was found to show linear dependence on the concentration of TDZ in the range of 1.0 × 10−6 to 5.0 × 10−4 M with a linear regression equation, correlation coefficient, limit of detection (LOD), and limit of quantification (LOQ) of IPC (μA) = 0.19958 + 0.02657C (μM), 0.99486, 1.10 × 10−7 M, and 3.77 × 10−7, respectively. Excellent recovery results for spiked TDZ in pharmaceutical tablet samples ranging within 97.44–97.51% and in urine ranging within 95.37–96.91% were observed. The selectivity of the method for TDZ was further studied in the presence of selected potential interferents and confirmed the potential applicability of the developed method for the determination of TDZ.

Electrochemical Sensor Based on Reduced Graphene Oxide Nanoribbons for the Determination of Baicalein in Urine Samples

Electrochemically reduced graphene oxide nanoribbons (ErGONRs) have been prepared, characterized and utilized for sensing of a flavone, baicalein (BAI) by adsorptive stripping differential pulse voltammetric (AdSDPV) and square wave voltammetric (SWV) methods. BAI showed redox peaks (Epa = 0.582 V and Epc = 0.557 V) and an irreversible oxidation peak at 1.402 V on ErGONRs/GCE in phosphate buffer of pH 3. A 50-fold enhanced electrochemical response was observed at ErGONRs/GCE for BAI when compared to that noticed at bare GCE. The parameters concerning the electrochemical behavior of BAI were carefully optimized. Under optimized conditions, SWV and AdSDPV methods showed linearity in the range of 10 nM–87.4 μM and 0.4 μM–50 μM, respectively. Applicability of the proposed electrode was demonstrated by determining BAI in urine samples

Fabrication of the electrochemically reduced graphene oxide-bismuth nanoparticles composite and its analytical application for an anticancer drug gemcitabine

The present study explores an electroreduced graphene oxide-bismuth nanoparticles composite (Er-GOBi) as an electrochemical sensor for the determination of an anticancer drug, gemcitabine hydrochloride (GMB). The Er-GOBi interface was prepared by drop casting of bismuth nitrate-graphene oxide suspension on a glassy carbon electrode (GCE) followed by electro-reduction in the potential range of 0.6V to −1.7V. SEM, FTIR, EDAX and AFM techniques were employed for the characterization of prepared materials. Cyclic voltammetric and electrochemical impedance spectroscopic methods were used to understand the charge transfer properties of stepwise modification of Er-GOBi/GCE. GMB exhibited an irreversible oxidation peak at 1.144V on Er-GOBi/GCE in phosphate buffer of pH 3. A 100-fold enhanced oxidation peak current was observed at Er-GOBi/GCE when compared to that at bare GCE. Sensing performance of ErGO-Bi/GCE was optimized by varying peak current dependent parameters. Linear relationship between the peak current and concentration of GMB was observed in the range of 0.1–51.1μmol/L in differential pulse voltammetric method and 2.1–61.1μmol/L in linear sweep voltammetric method. The practical utility of the proposed sensor, Er-GOBi/GCE was demonstrated by determining GMB in pharmaceutical formulations and spiked urine samples.