Modified Carbon Paste Sensor Research Articles

Electroanalysis of an antihistamine drug at nano structured modified electrode

Abstract A nano level voltammetric sensing method has been developed for electrochemical analysis of cetirizine at nano clay modified carbon paste sensor by employing cyclic voltammetry and square wave voltammetry techniques in pH 8.0. The modified carbon particles were characterized by Atomic force microscope. The influence of parameters like pH, accumulation time for cetirizine drug were studied by employing cyclic voltammetry and scan rate, excipients, cetirizine concentration variation were studied by employing SWV technique for quantitative determination in phosphate buffer. The fabricated sensor was employed for the determination of cetirizine in pharmaceutical samples. The linear response was obtained in the range of 0.1 to 0.3 µM with a detection limit of 8.48 nM at nano clay modified carbon paste sensor. A possible mechanism of electrochemical oxidation of cetirizine was proposed.

A Nano-Sepiolite Clay Electrochemical Sensor for the Rapid Electro–Catalytic Detection of Hydroquinone in Cosmetic Products

In this paper, a simple and sensitive electrochemical nano-sensor was developed for the analysis of hydroquinone based on sepiolite clay modified carbon paste sensor by using differential pulse adsorptive stripping voltammetry and square wave adsorptive stripping voltammetry. Surface morphology of sensors was characterized by using scanning electron microscopic technique, electrochemical impedance spectroscopy, and cyclic voltammetry. Electrochemical redox properties of hydroquinone were investigated by cyclic voltammetry. The oxidation peak current of hydroquinone in differential pulse and square wave adsorptive stripping voltammetry changes linearly in the concentration range of 0.01-700 µmolL-1 and 0.01-700 µmolL-1, respectively. Excellent limit of detection (LOD) and limit of quantification (LOQ) values were found as 0.01096 µmolL-1 and 0.03654 µmolL-1 for differential pulse, and 0.01031 µmolL-1 and 0.03438 µmolL-1 for square wave adsorptive stripping voltammetry, respectively. Additionally, the newly proposed sensor was applied to the analysis of hydroquinone in cosmetic cream with satisfying results.

New chemically modified carbon paste sensor for nanomolar concentration measurement of rifampicin in biological and pharmaceutical media

A new carbon paste electrode for rifampicin (RIF) drug was prepared and fully characterized in terms of composition, usable pH range and temperature. The sensor is based on 2-hydroxypropyl β-cyclodextrin as a good ionophore in the carbon paste matrix. The modified electrode showed a Nernstian slope of 59.2 mV/decade over the concentration range of 3.2 × 10−8 to 2.2 × 10−4 M with a limit of detection 2.3 × 10−8 M. The electrode has a short and stable response time of 4 s. The sensor manifested advantages of simple design, low cost, wide concentration range, excellent selectivity to rifampicin, applicable as an indicator electrode and renewability. The sensor was successfully used for determination of rifampicin in tablet and blood serum samples. Temperature dependence of the sensor potential response was examined in the temperature range of 15–55 °C. The sensor showed a very low thermal coefficient within the studied temperature range.

Potentiometric sensors based on hydroxychloroquine-phosphotungstate ion-pair and β-cyclodextrin ionophore for improved determination of hydroxychloroquine sulfate

In this approach, two modified carbon paste sensors were constructed for determination of hydroxychloroquine sulfate (HCQS). One sensor is based on hydroxychloroquine-phosphotungstate ion-pair (HCQ-PTA) called sensor I and the second sensor based on β-cyclodextrin ionophore (β-CD) called sensor II. The investigated sensors exhibited a Nernstian response for HCQS within the concentration range of 1.0 × 10−6 to 1.0 × 10−2 mol L−1, with detection limits of 7.8 × 10−7 and 4.6 × 10−7 mol L−1, and slope values of 30.8 and 31.5 for sensor I and sensor II, respectively. The potentiometric response was not affected by pH in the ranges 3–8 and 2.5–8.5 for the two sensors. The results showed fast dynamic response time 6 and 5 s and long lifetime 58 and 65 days. The investigated sensors showed adequate selectivity for HCQS compared with some common foreign interfering species. The results were compared with previously published data for determination of HCQS.

Novel Potentiometric Sensors Based on Multiwalled Carbon Nanotubes and <inline-formula> <tex-math notation="LaTeX">$\beta$ </tex-math> </inline-formula>-Cyclodextrin for Determination of Antipsychotic Sulpiride: Electrochemical and Surface Morphology Studies

In this approach, two novel modified carbon paste sensors were assembled for potentiometric assay of sulpiride (SLP). One sensor is based on the ion pair of SLP–phosphotungstic acid and incorporation with multiwalled carbon nanotubes (MWCNTs) called MWCPE and the second sensor based on $\beta $ -cyclodextrin ( $\beta $ -CD) ionophore and sodium tetraphenylborate as anionic site additive called $\beta $ -CDCPE. Dibutyl phthalate was added as plasticizer. The characteristics of the suggested sensors showed responses in terms of Nernstian slopes 59 ± 0.7 and 59.5 ± 0.3 mV decade–1 in wide linear ranges from $1\times 10^{-6}$ to $-1 \times 10^{-2}$ mol·L–1 and from $1\times 10^{-5}$ to $- 1\times 10^{-2}$ mol·L–1 with low detection limits $3.5\times 10^{-7}$ and $5\times 10^{-6}$ mol·L–1 with very short response time 5 and 10 s and exhibit adequate operational long lifetime (22 and 17 weeks) for MWCPE and $\beta $ -CDCPE, respectively. Both sensors response were pH independent in the range of 2–8 at 25 °C. For studying the ion-to-electron transducing ability of MWCNTs and $\beta $ -CD on the sensor surface, the electrochemical impedance spectroscopy measurements were done. Scanning electron microscope and transmission electron microscope were used for studying the surface morphology of MWCPE sensor. The sensors showed adequate selectivity for SLP with respect to a large number of interfering species. Moreover, SLP ions were successfully determined in pure state, pharmaceutical preparations, and human urine with high accuracy and precision using these sensors.

Tellurite Carbon Paste Sensors: Microscopic Analysis Provides New Insights on the Nature of the Interaction Between the Ionophore and Analytical Species

AbstractIn this work, scanning electron microscopy (SEM) was used for the characterization of chemically modified carbon paste sensors (CMCPSs), with the aim of understanding their chemical and electrochemical properties. The work also provides a microscopic study on the role of the binder, type of carbon, amount and nature of modifier, composition of the carbon paste and its impact on the electrochemical performance of the sensor. In addition, energy dispersive X‐ray spectroscopy (EDX) was utilized for the direct observation of the interaction between the chemical modifier and the carbon paste. This has enabled the fabrication of new sensitive and selective chemically modified carbon paste sensors that were successfully applied for the detection of tellurite ions in pure solutions, environmental and biological samples. This work provides new insights on the rational design and integration of carbon paste sensors for a variety of applications.

Determination of tramadol in pharmaceutical products and biological samples using a new nanocomposite carbon paste sensor based on decorated nanographene/tramadol-imprinted polymer nanoparticles/ionic liquid

In the present research, design and construction of a development potentiometric sensor based on a newly nanosensing layer for the sensitive determination of tramadol in various real samples were suggested. The proposed nanosensing layer was fabricated with the incorporation of a synthesized tramadol-imprinted polymer nanoparticles “as an efficient sensing agent” into the carbon paste matrix composed of graphite powder, decorated graphene nanosheets with silver nanoparticles, and a typically ionic liquid as the conductive pasting binder. The detection limit and the linear range of this study were found to be 2.04 × 10−9 and 3.50 × 10−9 to 1.00 × 10−2 M with a Nernstian slope of 59.85 ± 0.13 mV decade−1, respectively. The presented modified carbon paste sensor was successfully applied for the determination of tramadol in pharmaceutical and biological samples.

A Study on Voltametric Electro-kinetic Mechanism of Catechol at l-glutamic Acid-Carbon Paste Sensor

Quinones and quinoles, the pervasive components of living organism, perform different biochemical and physiological activities. These compounds have found their widespread applications as life saving drugs in cancer chemotherapy, antioxidant, anti bacterial and antifungal agents. These contribute as components of biological electron transfer chains located indifferent body parts. Electrochemical redox behavior of catechol using cyclic and differential pulse voltammetry at the surface of ℓ-glutamic acid modified carbon paste sensor was observed quite sensitive. There was a remarkable increase in the magnitude of both peak currents of catechol at the surface of modified electrode as compared to that of bare carbon paste electrode. Optimizations of working parameters for both techniques have been performed to perk up the working efficiency during experimentation. The electrochemical process occurs under both the diffusion and adsorption controlled conditions. The kinetic parameters such as heterogeneous electron transfer rate constant for electrode process (K<sub>h</sub>), diffusion coefficient (D), standard rate constant of surface reaction (k°), electron transfer coefficient (α) and the average surface concentrations of electro-active species (χ<sub>1</sub>&χ<sub>2</sub>) at the electro-chemical barriers catechol/o-quinone radical and o-quinone radical/o-quinone were calculated. The calculated value of K<sub>h</sub> lie in close vicinity to limiting value of a complete irreversible process and in far range of quasi-reversible process. In the higher range of applied scan rates at lower potentials of the used potential window, the forward scan revealed the formation of well stable reaction intermediate, at relatively slower rate. This is the rate determining step of the oxidation process but in case of reduction pulse of the same scan rate, there is no indication of any reduction intermediate moieties. The chemical process during electrochemical oxidation of catechol follows pseudo first order kinetics. Furthermore, a two step oxidation, Electronic-Chemical-Electronic-Chemical reactions (ECEC) mechanism has been proposed and single step reduction has been observed for the coupled redox process at the sensor/analyte interface.

Nano Fe<sub>3</sub>O<sub>4</sub>–graphite paste modified electrochemical sensor for phosphatic pesticide -chlorpyrifos

A sensitive, cost effective and selective electrochemical sensor has been developed by exploiting iron oxide nano-particles as modifier in the paste of graphite powder. Cyclic voltammetric (CV) and differential pulse voltammetric (DPV) working parameters have been standardized and used practically for the determination of chlorpyrifos (O, O-diethyl O-3, 5, 6-trichloropyridin-2-yl phosphorothioate) pesticide from its aqueous solutions. Both techniques were deployed to investigate the electro-chemical interactions between chlorpyrifos and modified carbon paste sensor along with the redox characteristics at analyte/ sensor interface. The significant enhancement in peak current signals and the improved magnitude of the redox peak potential indicated the awe-inspiring facilitation of the electron transfer process by the modifier at the sensor/ analyte interface. The difference in the redox -potential (ΔEp) and peak current ratio (Ipc/Ipa) have revealed a notable surface enhancement characteristic of the modifier that responds the higher concentration gradient of pesticide at the interface. In lower analyte’s concentration range i.e. from 1.0 to 100μM, the peak current varies directly to the pesticide concentration with detection limit of 2.8 x10-6 mol/L. The relative stability of the modified sensor is fine and the reproducibility of the results is up to 98%, even after a gap of two months. The proposed analytical method is quite successful when applied for the quantification of chlorpyrifos from its aqueous samples. The electrochemical sensing/ detection of the pesticide chlorpyrifos is confirmed by its two electrons redox behavior and the same have been explained by suitable reaction scheme as:Keywords: Nano-iron oxide, Chlorpyrifos, Modified graphite paste, Voltammetry, Electrochemical method

Novel potentiometric sensors for pyrilamine maleate

The fabrication and electrochemical response characteristics of four novel potentiometric sensors for determination of pyrilamine maleate (PyraH) were described. The sensors include polymeric membrane electrodes (PME1, PME2) and carbon paste electrodes (CPE1, CPE2). The fabricated sensors were based on the ion-pair of pyrilamine with sodium tetraphenylborate (NaTPB) and ammonium reineckate (NH4RN) using dibutyl phthalate (DBP) as plasticizing solvent. The sensors showed linear, stable and near-Nernstian slopes of 56.4 ± 0.4, 54.2 ± 0.2, 58.8 ± 0.3 and 57.9 ± 0.4 mV decade−1 at 25 ± 0.1 °C and detection limits of 2.0 × 10−5, 1.8 × 10−5, 1.0 × 10−5 and 9.5 × 10−6 mol L−1 for PME1, PME2, CPE1 and CPE2 sensors, respectively. The response time was less than 10 and 8 s for polymeric membrane and carbon paste sensors. The proposed sensors displayed good selectivity for pyrilamine with respect to a number of common inorganic and organic species. The thermal temperature coefficients of the investigated sensors were 0.9508, 0.7012, 0.9450 and 0.6497 mV °C−1. Modified carbon paste sensors showed lower detection limits, higher thermal stability and faster response time than those of polymeric membrane sensors. The proposed sensors displayed useful analytical characteristics for determination of pyrilamine in pharmaceutical preparation and biological fluids (Human urine and plasma).

ZrO2-Graphene-Chitosan nanocomposite modified carbon paste sensor for sensitive and selective determination of dopamine

A sensitive and stable electrochemical sensor was developed by modification of carbon paste electrode with ZrO2/graphene/chitosan nanocomposite. The modified sensor served as a potential electrocatalytic platform for dopamine. Electrochemical impedance spectroscopy studies indicated reduction of charge transfer resistance at the modified electrode surface thereby facilitating the electron transfer process which resulted in higher current response to dopamine. The electrochemical behavior of dopamine at the modified electrode was studied using cyclic and square wave voltammetry. The maximum current response for the electro-oxidation of dopamine was observed at pH 7.4 and the process was realized to be diffusion controlled. The modified sensor demonstrated linearity in the range 1000–5000 nM, with high sensitivity (22 nA/nM), detection limit of 11.3 nM and selectivity for dopamine in the presence of ascorbic and uric acid which are found to co-exist with dopamine in physiological media. The method was employed for quantification of dopamine in a pharmaceutical formulation.

Nano molar detection of acyclovir, an antiviral drug at nanoclay modified carbon paste electrode

A nano level voltammetric sensing method has been developed for determination of acyclovir (ACV) at nano clay modified carbon paste sensor by employing cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques in pH5.0. The electro-oxidation current of ACV was enhanced two times greater by the modification of the sensor. The modifier nano clay was characterized by utilizing X-ray diffraction (XRD) and scanning electronic microscope (SEM). The influence of parameters like scan rate, pH, accumulation time, amount of the modifier and concentration on the peak current of the drug were studied. The effect of ACV concentration variation was studied using SWV technique and got lowest detection limit compared to the earlier reported techniques. The fabricated sensor was employed for the determination of acyclovir in pharmaceutical and biological samples.

New Electrochemically-Modified Carbon Paste Inclusion β-Cyclodextrin and Carbon Nanotubes Sensors for Quantification of Dorzolamide Hydrochloride.

The present article introduces a new approach to fabricate carbon paste sensors, including carbon paste, modified carbon paste inclusion β-cyclodextrin, and carbon nanotubes for the quantification of dorzolamide hydrochloride (DRZ). This study is mainly based on the construction of three different carbon paste sensors by the incorporation of DRZ with phosphotungstic acid (PTA) to form dorzolamide-phosphotungstate (DRZ-PT) as an electroactive material in the presence of the solvent mediator ortho-nitrophenyloctyl ether (o-NPOE). The fabricated conventional carbon paste sensor (sensor I), as well as the other modified carbon paste sensors using β-cyclodextrin (sensor II) and carbon nanotubes (sensor III), have been investigated. The sensors displayed Nernstian responses of 55.4 ± 0.6, 56.4 ± 0.4 and 58.1 ± 0.2 mV·decade−1 over concentration ranges of 1.0 × 10−5–1.0 × 10−2, 1.0 × 10−6–1.0 × 10−2, and 5.0 × 10−8–1.0 × 10−2 mol·L−1 with lower detection limits of 5.0 × 10−6, 5.0 × 10−7, and 2.5 × 10−9 mol·L−1 for sensors I, II, and III, respectively. The critical performance of the developed sensors was checked with respect to the effect of various parameters, including pH, selectivity, response time, linear concentration relationship, lifespan, etc. Method validation was applied according to the international conference on harmonisation of technical requirements for registration of pharmaceuticals for human use ICH guidelines. The developed sensors were employed for the determination of DRZ in its bulk and dosage forms, as well as bio-samples. The observed data were statistically analyzed and compared with those obtained from other published methods.

Determination of Samarium(III) by Chemically Modified Carbon Paste Sensor

Determination of Samarium(III) by Chemically Modified Carbon Paste Sensor

Chemically modified carbon paste and membrane sensors for the determination of benzethonium chloride and some anionic surfactants (SLES, SDS, and LABSA): Characterization using SEM and AFM

Chemically modified carbon-paste (CMCP) and membrane- sensors based on incorporating benzothonium-tetraphenylborate (BT-TPB) were constructed for the analysis of benzethonium chloride, and some other surfactants such as sodium lauryl ether sulphate (SLES), sodium dodecyl sulphate (SDS), and linear alkylbenzene sulphonic acid (LABSA). All sensors showed good sensitivity and reverse wide linearity over a concentration range of 5.97×10−7 to 1.00×10−3 and 5.96×10−7 to 3.03×10−3molL−1 with limit of detection of 3.92×10−7and 3.40×10−7molL−1 for membrane and chemically modified carbon paste sensors, respectively, with respect to benzethonium chloride (BT.Cl). They could be used over a wide pH range of 2.0–10.0. The thermal coefficients of membrane and CMCP sensors are 5.40×10−4, 1.17×10−4V/°C, respectively. The sensors indicated a wide selectivity over different inorganic cations. The effect of soaking on the surface morphology of the membrane sensor was studied using EDX-SEM and AFM techniques. The response time was <10s The freshly prepared, exhausted membrane, and CMCP sensors were successfully applied for the potentiometric determination of the pure BT.Cl solution. They were also used for the determination of its pharmaceutical formulation Dermoplast® antibacterial spray (20% benzocaine+0.2% benzethonium chloride) with recovery values ranging from 97.54±1.70 to 101.25±1.12 and from 96.32±2.49 to 101.23±2.15%. The second goal of these sensors is the potentiometric determination of different surfactants such as SLES, SDS, and LABSA with good recovery values using BT.Cl as a titrant in their pure forms, and in samples containing one of them (shampoo, Touri® dishwashing liquid, and waste water). The statistical analysis of the obtained data was studied.

A novel sensor for a food dye erythrosine at glucose modified electrode

A simple and highly sensitive method for the determination of erythrosine using glucose modified carbon paste sensor was presented. The electrochemical measurements were studied using cyclic voltammetry, differential pulse voltammetry and square wave voltammetry. The modified sensor exhibited excellent catalytic activity towards electrochemical oxidation of erythrosine in highly basic phosphate buffer, i.e. pH 11.2. The modified sensor facilitated the determination of erythrosine in the linearity range 1.0×10−4M to 1.0×10−7M with a detection limit of 21.6nM. Good recovery from biological sample such as spiked urine indicates the applicability of the proposed method for clinical trials. The proposed method was successfully employed to detect erythrosine in pharmaceutical as well as food samples. The method exhibits tremendous reproducibility and has proved to be highly reliable for the analysis of erythrosine in biological samples.

TiO2 modified carbon paste sensor for voltammetric analysis and chemometric optimization approach of amlodipine in commercial formulation

A new square wave adsorptive stripping voltammetric (SWAdSV) approach using experimental design and optimization methodology was developed for the quantitative estimation of amlodipine (AMP) in pharmaceutical tablets. To this end, a new carbon paste electrode (CPE) system was fabricated using titanium dioxide (TiO2) nanoparticles to get very well-defined oxidation peak current of AMP under the optimized conditions. Optimal electrochemical conditions for three factor variables, the pH, the accumulation potential, and the accumulation time, were obtained by applying a 33 full factorial design and optimization technique to the oxidation of AMP on the TiO2 modified CPE (TiO2-CPE) system. The numerical values of the optimal voltammetric parameters consisting of the pH, accumulation potential, and accumulation time were found to be 5.69, 562.30 mV, and 64.30 s for the analysis of AMP in samples, respectively. The newly developed voltammetric method for the determination of AMP offers a linear relationship between the peak current and concentration in the range of 1.0 × 10−8 − 1.0 × 10−6 M with the correlation coefficient (r = 0.9990) and the detection limit (LOD = 2.97 × 10−9 M). The lifetime of prepared electrode was also tested, and the current intensity of AMP was nearly stable at least 2 months by using TiO2-CPE. The validity of the method was tested by analyzing standard samples containing the analyzed compound. Under optimized and validated experimental conditions, the proposed method was successfully applied for the quantitative analysis of AMP in commercial tablets.

A combination of β-cyclodextrin functionalized magnetic graphene oxide nanoparticles with β-cyclodextrin-based sensor for highly sensitive and selective voltammetric determination of tetracycline and doxycycline in milk samples

Highly sensitive and selective determination of tetracycline and doxycycline in milk samples using solid phase extraction followed by differential pulse voltammetric determination on a β-cyclodextrin modified carbon paste sensor.

Nano-TiO2 modified carbon paste sensor for electrochemical nicotine detection using anionic surfactant

A newly competitive electrochemical sensor for nicotine (NIC) detection was successfully achieved. Nano-TiO2 with a carbon paste electrode (CPE) were used for the sensor construction, where Nano-TiO2 was considered as one of the richest and highly variable class of materials. The sensor showed electrocatalytic activity in both aqueous and micellar media toward the oxidation of NIC at Britton–Robinson (B–R) buffer solution (4×10−2M) of pH range (2.0–8.0) containing (1.0mM) sodium dodecylsulfate (SDS) using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscope (SEM) and Energy Dispersive X-Ray Analysis (EDX) techniques were also used. The linear range of detection for NIC using the new Nano-TiO2 Modified Carbon Paste sensor (NTMCP) was detected using diffrential pulse voltammetry (DPV) technique and it was found between 2×10−6M and 5.4×10−4M with a detection limit of 1.34×10−8M. The obtained results clarified the simplicity, high sensitivity and selectivity of the new NTMCPE for nicotine determination in real cigarettes and urine samples.

Construction and Performance Characteristics of Modified Screen Printed and Modified Carbon Paste Sensors for Selective Determination of Cu(II) Ion in Different Polluted Water Samples

Four new ion-selective electrodes (ISEs), based on N,N′-bis(salicylaldehyde)-p-phenylene diamine (SPD) as ionophore, are constructed for the determination of copper(II) ion. The modified carbon paste (MCPEs; electrodes I and II) and modified screen-printed sensors (MSPEs; electrodes III and IV) exhibit good potentiometric response for Cu(II) over a wide concentration range of 1.0 × 10−6 – 1.0 × 10−2 mol L−1 for electrodes (I and II) and 4.8 × 10−7–1.0 × 10−2 mol L−1 for electrodes (III and IV) with a detection limit of 1.0 × 10−6 mol L−1 for electrodes (I and II) and 4.8 × 10−7 mol L−1 for electrodes (III and IV), respectively. The slopes of the calibration graphs are 29.62 ± 0.9 and 30.12 ± 0.7 mV decade−1 for electrode (I) (tricresylphosphate (TCP) plasticizer) and electrode (II) (o-nitrophenyloctylether o-NPOE plasticizer), respectively. Also, the MSPEs showed good potentiometric slopes of 29.91 ± 0.5 and 30.70 ± 0.3 mV decade−1 for electrode (III) (TCP plasticizer) and electrode (IV) (o-NPOE plasticizer), respectively. The electrodes showed stable and reproducible potentials over a period of 60, 88, 120, and 145 days at the pH range from 3 to 7 for electrodes (II), (III), and (IV) and pH range from 3 to 6 for electrode (I). This method was successfully applied for potentiometric determination of Cu(II) in tap water, river, and formation water samples in addition to pharmaceutical preparation. The results obtained agree with those obtained with the atomic absorption spectrometry (AAS).