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Paracetamol Sensitive Cellulose-Based Electrochemical Sensors

Journal of Renewable Materials 2018年第3期6卷 242-250页

作者： Maxime Pontie Serge Foukmeniok Mbokou Jean-Philippe Bouchara Bienvenue Razafimandimby Sylvie Egloff Ornella Dzilingomo Pierre-Yves Pontalier ignas kenfack tonle Host-Pathogen Interaction Study Group(GEIHP EA 3142)UNIV AngersUNIV BrestBretagne Loire UniversityInstitute of Health Biology-IRISCHU4 rue Larrey49933 AngersFrance Electrochemistry and Chemistry of Materials Department of ChemistryUniversity of DschangP.O.Box 67 DschangCameroon Toulouse University INP-ENSIACETLCA(Laboratory of Agro-industrial Chemistry)31030 Toulouse France

Electrochemical determination of paracetamol(PCT)was successfully performed using carbon paste electrodes(CPEs)modified with treated coffee husks(CHt)or cellulose powder(Ce).Scanning electron microscopy was used to characterize unmodified or modified CPEs prior to their use.The electrochemical oxidation of PCT was investigated using square wave voltammetry(SWV)and cyclic voltammetry(CV).The oxidation current density of PCT was two-fold higher with the CPE-CHt sensor and 30%higher with CPE-Ce in comparison with the unmodified CPE,and this correlated with the higher hydrophilicity of the modified electrodes.Using SWV for the electrochemical analysis of PCT,carbon paste electrode modified with raw coffee husks(CPE-CHr)showed the presence of impurities at+0.27 V/SCE,showing the interest in using pure cellulose for the present analytical application.Furthermore,CPE-Ce presented a higher real area compared to CPE-CHr,which explains the increase in the limit of saturation from 400 mg/L to 950 mg/L.The better saturation limit exhibited by CPE-Ce justifies its choice for electroanalysis of PCT in commercialized tablets.The proposed method was successfully applied in the determination of PCT in commercialized tablets(DolipraneR 500)with a recovery rate close to 100%,and no interference with the excipients contained in the tablets analyzed was observed.This novel sensor opens the way for sustainable development of electroanalytical control of drugs sold individually in developing countries.

关键词： Paracetamol carbon paste electrode coffee husks cellulose fibers square wave voltammetry electroanalysis

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Fullerene/MWCNT/Nafion Modified Glassy Carbon Electrode for the Electrochemical Determination of Caffeine

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American Journal of Analytical Chemistry 2020年第2期11卷 114-127页

作者： Kevin Yemele Tajeu Liliane Medonbou Dongmo ignas kenfack tonle Electrochemistry and Chemistry of Materials Department of Chemistry University of Dschang Dschang Cameroon

Herein, a convenient method based on a fullerene/multiwalled carbon nanotube/Nafion modified glassy carbon electrode (fullerene/MWCNT/Naf/GCE) for the electrochemical determination of caffeine (CAF) is reported. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study ionic exchange properties and conductivity the proposed electrode using [Fe(CN)6]3-/4- redox couple. Caffeine gave an irreversible oxidation peak around +1.33 V (vs. Ag/AgCl reference electrode) in HClO4 (pH 1). The linear dependence of the peak current with the square root of the scan rate showed that the electron transfer process is controlled by diffusion. After optimization of key analytical parameters involved in differential pulse voltammetry (DPV), the oxidation peak current varied linearly with CAF concentration in the range of 10 to 1000 μM. A detection limit of 7.289 × 10-8 M (S/N = 3) was found. Kinetic and chronocoulometric studies were also performed to characterize the diffusion of CAF. The developed electrode exhibited good stability and was easily regenerated. The influence of some potential interfering compounds such as dopamine, uric acid, glucose and sulfite ions on the anodic peak current of CAF was also examined. The proposed method was successfully employed in the determination of CAF in some commercial drugs.

关键词： Caffeine Fullerene/MWCNT Nafion Film Modified Electrode Electroanalysis

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Adsorptive Stripping Voltammetric Determination of Mangiferin Using an Activated Chitosan Modified Carbon Paste Electrode

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American Journal of Analytical Chemistry 2014年第7期5卷 424-432页

作者： Francis Merlin Melataguia Tchieno Evangeline Njanja Léon Azefack Tapondjou ignas kenfack tonle Electrochemistry and Chemistry of Materials Department of Chemistry University of Dschang Dschang Cameroon Laboratory of Applied and Environmental Chemistry Department of Chemistry University of Dschang Dschang Cameroon

A medium molecular weight powdered chitosan modified carbon paste electrode was used to investigate the electrochemical behaviour by cyclic voltammetry of the pharmacologically-active ingredient mangiferin (MG). An irreversible system was observed, with a peak at ﹢0.55 V (vs Ag/AgCl). The peak current increases about fourfold, at the modified electrode in comparison with that recorded at the chitosan free carbon paste electrode. This allowed the use of adsorptive stripping voltammetry to develop a simple and sensitive electroanalytical method for the determination of MG. The influence of key parameters was investigated, including the electrolysis potential, the preconcentration time, the pH of supporting electrolyte and MG concentration. Upon optimisation of these parameters, the electrode response was found to be directly proportional to the concentration of MG in the range from 2.06 × 10﹣6 M to 6.74 × 10﹣5 M, leading to a detection limit of 1.84 μM for 240 s preconcentration at ﹣0.1 V. A mechanism was also proposed for the electrochemical oxidation of MG.

关键词： Mangiferin (Mangifera indica L.) Xanthones Carbon Paste Electrode Chitosan Stripping Voltammetry

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Biosorption Isotherms and Kinetics Studies for the Removal of 2,6-Dichlorophenolindophenol Using Palm Tree Trunk (<em>Elaeis guineensis</em>)

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Journal of Encapsulation and Adsorption Sciences 2018年第3期8卷 156-177页

作者： Marcel Cédric Deussi Ngaha Lydiane Ghislaine Djemmoe Evangéline Njanja ignas tonle kenfack Electrochemistry and Chemistry of Materials Department of Chemistry Faculty of Science University of Dschang Dschang Cameroon

In this work, the potential of natural and pretreated palm tree trunk (PTT) as agents for adsorption of an organic dye, 2,6-dichlorophenolindophenol (2,6-DCPIP) from aqueous solutions was probed. Natural and acetic acid treated PTT were characterized by Fourier transform infrared (FT-IR) spectroscopy and by the point of zero charge (pzc). The biosorption of 2,6-DCPIP was investigated in batch mode using natural and treated PTT. This study was achieved by highlighting several parameters such as the contact time, biosorbents dosage, the initial concentration of 2,6-DCPIP, the pH of the solution, the ionic strength and the interfering ions. The results showed that 2,6-DCPIP was successfully adsorbed from aqueous solutions by natural and treated PTT. The equilibrium was attained after 40 minutes for treated PTT and 20 minutes for natural PTT. The maximum capacity of adsorption was obtained at pH = 2. The adsorption isotherms were investigated and it was found that the experimental data were best described by the Dubinin-Radushkevich isotherm for the natural PTT (R2 = 0.979) and by the Temkin isotherm for the treated PTT (R2 = 0.976). The maximum adsorption capacities determined by Langmuir isotherm were found as 108.932 and 157.233 μmol·g–1 for natural and treated PTT, respectively. The adsorption kinetics was analyzed and was best described by the pseudo-second order model (R2 ≥ 0.998). The diffusion mechanism was studied and the result showed that external mass transfer is the main rate controlling step. The desorption of 2,6-DCPIP is favorable in alkaline medium.

关键词： Biosorption Palm Tree Trunk 2 6-Dichlorophenolindophenol Isotherms Kinetics Desorption

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Simultaneous Voltammetric Determination of Cd^(2+), Pb^(2+), and Hg^(2+) Ions Using Aminosepiolite-Coated Glassy Carbon Electrode: Optimization of Detection Parameters via Response Surface Methodology

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Journal of Analysis and Testing 2019年第4期3卷 295-305页

作者： Ervice Ymélé Sherman Lesly Zambou Jiokeng Divine Bup Nde Théophile Kamgaing ignas kenfack Tonlé Electrochemistry and Chemistry of Materials Department of ChemistryFaculty of ScienceUniversity of DschangP.O.Box 67DschangCameroon Higher Institute of the Sahel University of MarouaP.O.Box 46MarouaCameroon

Adsorptive stripping voltammetry using a glassy carbon electrode modified by a film of aminosepiolite was utilized for simultaneous pre-concentration and trace detection of cadmium,lead,and mercury ions in aqueous solution.The modified sepiolite exploited as electrode material was obtained by grafting on its surface of[(3-(2-aminoethylamino)propyl)]trimethoxysilane(AEPTMS).The results demonstrated that the amine groups on sepiolite efficiently affected the voltammetric detection of heavy metals.The full factorial design matrix and response surface methodology were applied in designing experiments,to determine the optimal conditions and to evaluate their mutual interactions.The high values of adjusted R2 obtained of the fitted model show that the experiments data were well explained by the model,which then allowed to acquire optimum parameters for the electroanalysis and detection of the analytes by differential pulse voltammetry.At pH 6.5 of accumulating medium,with an electrolysis potential of-0.9 V and in the concentration range of 10^(−8) M to 10^(−9) M,calibration plots were obtained.The limits of detection(3Sd/m)were 8.689×10^(−10) M,8.197×10^(−10) M,and 8.099×10^(−10) M,respectively,for Cd^(2+),Pb^(2+),and Hg^(2+)ions.The interference effect of several cations and anions on the response of the analytes was also evaluated,and finally,the sensor was applied to the simultaneous detection of metal ions in tap water with satisfactory recovery rates.

关键词： Aminosepiolite Surface response methodology Factorial design Differential pulse voltammetry Heavy metals

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