Electroanalytical Performance of a Carbon Paste Electrode Modified by Coffee Husks for the Quantification of Acetaminophen in Quality Control of Commercialized Pharmaceutical Tablets

Electrochemical determination of acetaminophen (APAP) was successfully performed using a carbon paste electrode (CPE)modified with coffee husks (CH-CPE). Scanning electron microscopy (SEM) and SEM-energy dispersive X-ray spectroscopy (SEM-EDX) were, respectively, used for the morphological and elemental characterization of coffee husks prior to their utilization. Theelectrochemical oxidation of APAP was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and squarewave voltammetry (SWV). SWV technique appeared to be more sensitive since the oxidation current of APAP was twofold higherwith the CH-CPE sensor than with the bare CPE, in relation to the increase in the organophilic character of the electrode surface.Furthermore, on CH-CPE, the current response of APAP varied linearly with its concentration in the range of 6.6????M to 0.5 mM,leading to a detection limit of 0.66????M(????/????=3). Finally, the proposed CH-CPE sensor was successfully used to determine theamount of APAP in commercialized tablets (Doliprane�500 and Doliprane 1000), with a recovery rate ranging from 98% to 103%.This novel sensor opens the way for the development of low-cost and reliable devices for the electroanalysis of pharmaceuticalformulations in developing countries

Electrochemical Determination of Epinephrine in Pharmaceutical Preparation Using Laponite Clay-Modified Graphene Inkjet-Printed Electrode

Epinephrine (EP, also called adrenaline) is a compound belonging to the catecholamine neurotransmitter family. It can cause neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and amyotrophic lateral sclerosis. This work describes an amperometric sensor for the electroanalytical detection of EP by using an inkjet-printed graphene electrode (IPGE) that has been chemically modified by a thin layer of a laponite (La) clay mineral. The ion exchange properties and permeability of the chemically modified electrode (denoted La/IPGE) were evaluated using multi-sweep cyclic voltammetry, while its charge transfer resistance was determined by electrochemical impedance spectroscopy. The results showed that La/IPGE exhibited higher sensitivity to EP compared to the bare IPGE. The developed sensor was directly applied for the determination of EP in aqueous solution using differential pulse voltammetry. Under optimized conditions, a linear calibration graph was obtained in the concentration range between 0.8 μM and 10 μM. The anodic peak current of EP was directly proportional to its concentration, leading to detection limits of 0.34 μM and 0.26 μM with bare IPGE and La/IPGE, respectively. The sensor was successfully applied for the determination of EP in pharmaceutical preparations. Recovery rates and the effects of interfering species on the detection of EP were evaluated to highlight the selectivity of the elaborated sensor

Paracetamol Sensitive Cellulose-Based Electrochemical Sensors

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 (Doliprane® 500) with a recovery rate close to 100%, and no interference with the excipients contained in the tablets analyzed was observed

Lignocellulosic-Based Materials from Bean and Pistachio Pod Wastes for Dye-Contaminated Water Treatment: Optimization and Modeling of Indigo Carmine Sorption

In this work, biomass lignocellulosic materials extracted via chemical and physical treatments from bean and pistachio pod waste were used for the optimized elimination of Indigo Carmine (IC) from aqueous medium, using a design of experiments methodology. The physicochemical properties of the studied materials (raw and treated counterparts) used for the sorption of IC were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with EDX, and thermal analysis. Key variables influencing the adsorption of IC, namely the initial IC concentration, the pH of the solution, the stirring time and the mass of adsorbents, were optimized by the central composite design (CCD) with three center points, the measured response being the amount of IC adsorbed. The optimal conditions obtained from the statistical analysis for the removal of IC were as follows: maximum adsorbed amounts of IC: 1.81 mg/g, 2.05 mg/g, 3.56 mg/g; 7.42 mg/g, 8.95 mg/g, 15.35 mg/g, for raw bean pods (RBS), BST1 and BST2 (bean pods chemically treated), and for raw pistachio pods (RPS), PST1 and PST2 (pistachio pods chemically treated), respectively. The pseudo-second-order nonlinear kinetics model well described the IC adsorption kinetics for RBS, BST1 and BST2, while the Elovich model was properly fitted by RPS, PST1, and PST2 biomaterials data. The results collected in this work highlighted the interesting structural, morphological, and physico-chemical properties of the agro-waste used in the study, which properties allowed an important fixation of the target dye in solution. The research showed that the agro-waste used in the study are possible precursors to locally manufacture adsorbents at low cost, thus allowing the efficient removal of waste and dyes in liquid effluents

An inorganic-organic hybrid material from the co-intercalation of a cationic surfactant and thiourea within montmorillonite layers: application to the sensitive stripping voltammetric detection of Pb2+ and Cd2+ ions

International audienceA smectite-based inorganic-organic hybrid material was prepared by a one-step intercalation of cetyltrimethylammonium ions and thiourea within the interlayer space of montmorillonite (MT). The surface and textural properties of the resulting material were examined using several techniques (X-ray diffraction, elementary analysis and N-2 adsorption-desorption experiments (BET method)) that demonstrated the presence of both modifiers in the clay mineral structure. The presence of thiourea molecules in the modified MT greatly improved its ability towards the fixation of Pb2+ and Cd-2+ ions when the organoclay material was used for sensing purposes as a glassy carbon electrode modifier. The electro-analytical procedure was based on the chemical accumulation of both analytes under open-circuit conditions, followed by the detection of the pre-concentrated species using square wave voltammetry. Upon optimization of different parameters likely to influence the electrode response, linear calibration graphs were obtained in the concentration ranges from 0.1 to 1 mu M and 0.01 to 0.1 mu M for Cd2+ and Pb2+, respectively, leading to low limits of detection (4.2 x 10(-1) M for Pb2+ and 1.2 x 10(-9) M for Cd2+)

Evaluation of the degradation of acetaminophen by the filamentous fungus Scedosporium dehoogii using carbon-based modified electrodes

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Hydroxyapatite/L-Lysine Composite Coating as Glassy Carbon Electrode Modifier for the Analysis and Detection of Nile Blue A

An amperometric sensor was developed by depositing a film coating of hydroxyapatite (HA)/L-lysine (Lys) composite material on a glassy carbon electrode (GCE). It was applied for the detection of Nile blue A (NBA). Hydroxyapatite was obtained from snail shells and its structural properties before and after its combination with Lys were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analyses. The coupling of Lys to HA was attributed to favorable interaction between negatively charged -COO- groups of Lys and divalent ions Ca2+ of HA. Electrochemical investigations pointed out the improvement in sensitivity of the GCE/Lys/HA sensor towards the detection of NBA in solution. The dependence of the peak current and potential on the pH, scan rate, and NBA concentration was also investigated. Under optimal conditions, the GCE/Lys/HA sensor showed a good reproducibility, selectivity, and a NBA low detection limit of 5.07 × 10-8 mol L-1. The developed HA/Lys-modified electrode was successfully applied for the detection of NBA in various water samples

Fabrication of an Organofunctionalized Talc-like Magnesium Phyllosilicate for the Electrochemical Sensing of Lead Ions in Water Samples

A talc-like magnesium phyllosilicate functionalized with amine groups (TalcNH2), useful as sensor material in voltammetry stripping analysis, was synthesized by a sol–gel-based processing method. The characterizations of the resulting synthetic organoclay by scanning electron microscopy (SEM), X-ray diffraction, N2 sorption isotherms (BET method), Fourier transform infrared spectroscopy (FTIR), CHN elemental analysis and UV–Vis diffuse reflectance spectroscopy (UV–Vis-DRS) demonstrated the effectiveness of the process used for grafting of amine functionality in the interlamellar clay. The results indicate the presence of organic moieties covalently bonded to the inorganic lattice of talc-like magnesium phyllosilicate silicon sheet, with interlayer distances of 1568.4 pm. In an effort to use a talc-like material as an electrode material without the addition of a dispersing agent and/or molecular glue, the TalcNH2 material was successfully dispersed in distilled water in contrast to natural talc. Then, it was used to modify a glassy carbon electrode (GCE) by drop coating. The characterization of the resulting modified electrode by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed its charge selectivity ability. In addition, EIS results showed low charge transfer resistance (0.32 Ω) during the electro-oxidation of [Fe(CN)6]3−. Kinetics studies were also performed by EIS, which revealed that the standard heterogeneous electron transfer rate constant was (0.019 ± 0.001) cm.s−1, indicating a fast direct electron transfer rate of [Fe(CN)6]3− to the electrode. Using anodic adsorptive stripping differential pulse voltammetry (DPV), fast and highly sensitive determination of Pb(II) ions was achieved. The peak current of Pb2+ ions on TalcNH2/GCE was about three-fold more important than that obtained on bare GCE. The calculated detection and quantification limits were respectively 7.45 × 10−8 M (S/N = 3) and 24.84 × 10−8 M (S/N 10), for the determination of Pb2+ under optimized conditions. The method was successfully used to tap water with satisfactory results. The results highlight the efficient chelation of Pb2+ ions by the grafted NH2 groups and the potential of talc-like amino-functionalized magnesium phyllosilicate for application in electrochemical sensors