Voltammetric Determination Research Articles

Electrochemical and microscopic study of a rotating disk Gold-Film electrode for voltammetric determination of arsenic (III)

This article is dedicated to the fabrication and thorough examination of the properties of a gold-film electrode (AuFE) intended for arsenic (III) determination using square-wave anodic stripping voltammetry (SWASV). The gold-film electrode was prepared ex-situ by potentiostatic electrodeposition of a gold layer onto a rotating glassy carbon electrode (GCE). Various deposition parameters were investigated and optimized, including the concentration of HAuCl4 solution (0.25 – 4 mM), deposition potential (0 – −600 mV), deposition time (120 – 1200 s), and electrode rotation speed (600 – 1500 rpm). Gold films prepared under different conditions were characterized using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). The influence of AuFE characteristics on the parameters of the As(III) stripping peak was studied. Using the optimized AuFE, sensitivity and detection limit for As(III) of 0.468 μA/μg·L−1 and 1 μg/L, respectively, were achieved. The effects of interfering ions (Fe(III), Mn(II), Pb(II), Cu(II), Sn(IV), Tl(I)) on the As(III) response were investigated. The analytical utility of the optimized AuFE was validated for the quantitative determination of arsenic in tap water and seafood. The proposed procedure provides optimal conditions for the electrochemical preparation of gold-film electrodes aimed at routine arsenic monitoring.

Deep eutectic solvent-mediated synthesis of ZnCo2O4/MWCNT-COOH: Investigation of electrocatalytic activity for gatifloxacin detection

The overuse of gatifloxacin seriously pollutes the environment and cause potential harm to our health. Hence, it is imperative to develop a rapid and sensitive method for gatifloxacin determination. Herein, an efficient electrocatalyst was designed for the voltammetric determination of gatifloxacin based on carboxylated multiwalled carbon nanotubes warped ZnCo2O4 nanoparticles (ZnCo2O4/MWCNT-COOH). The ZnCo2O4 nanoparticles were synthesized by a green deep eutectic solvent-mediated ion-thermal route, and further composited with MWCNTs-COOH. The ZnCo2O4/ MWCNT-COOH combined the catalytic activity of ZnCo2O4 with the high electrical conductivity of MWCNT-COOH, aiming to improve the electrochemical sensing performance toward gatifloxacin. The synergistic interactions between ZnCo2O4 and MWCNT-COOH endowed the ZnCo2O4/MWCNT-COOH with extraordinary catalytic activity for gatifloxacin oxidation. Consequently, the ZnCo2O4/MWCNT-COOH displayed a wide linear response range (0.01–10 μM) for detecting gatifloxacin, with a high sensitivity (29.64 μA μM−1 cm−2) and low detection limit (2.0 nM). The ZnCo2O4/MWCNT-COOH showed robust voltammetric responses against potential interfering species, and maintained highly stable responses for at least two weeks. Moreover, the ZnCo2O4/MWCNT-COOH/GCE was successfully used to detect gatifloxacin in water samples with satisfactory recoveries (97.22 − 104.5 %). Together with its low cost, environment friendly and rapid response, the ZnCo2O4/MWCNT-COOH shows promising prospects in trace detection of gatifloxacin.

Voltammetric Determination of Heavy Metals in Soil and Vegetable Produce

Voltammetric Determination of Heavy Metals in Soil and Vegetable Produce

Synthesis of ultrasmall cerium oxide nanoparticles in deep eutectic solvent and their application in an electrochemical sensor to detect dopamine in biological fluid.

Asolvothermal synthesis of ultrasmall cerium oxide nanoparticles (USCeOxNPs) with an average size of 0.73 ± 0.07 nm using deep eutectic solvent (DES) as a stabilizing medium at a temperature of 90 ºCis reported. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were used to morphologically characterize the USCeOxNPs. These revealed approximately spherical shapes with emission lines characteristic of cerium. Selected area electron diffraction (SAED) was used to determine the crystalline structure of the cerium oxide nanoparticles (CeO2NPs), revealing the presence of crystalline cubic structures. The USCeOxNPs-DES/CB film was characterized by scanning electron microscopy (SEM), which demonstrated the spherical characteristic of CB with layers slightly covered by DES residues. DES was characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR), indicating its formation through hydrogen bonds between the precursors. An electrochemical sensor for dopamine (DA) determination in biological fluids was developed using the USCeOxNPs together with carbon black (CB). An enhanced current response was observed on DA voltammetric determination, and this can be attributed to the USCeOxNPs. This sensor displayed linear responses for DA in the range 5.0 × 10-7 mol L-1 to 3.2 × 10-4 mol L-1, with a limit of detection of 80 nmol L-1. Besides detectability, excellent performances were verified for repeatability and anti-interference. The sensor based on USCeOxNPs synthesized in DES in a simpler and environmentally friendly way was successfully applied to determine DA in biological matrix.

Voltammetric determination of the antifungal drug posaconazole in the presence of an anionic surfactant on a boron-doped diamond electrode

This study describes a new, fast and simple procedure of electrochemical assay of posaconazole (PCZ), which is currently regarded as one of the most important antifungal agents, recommended in the treatment of systemic infections, effective even against rare and atypical kinds of fungi. PCZ is very effective and safe, displaying much lower toxicity than other traditional antifungal drugs. A new, attractive procedure of assaying the compound on boron-doped diamond (BDD) electrode after cathodic pretreatment in the presence of sodium dodecyl sulfate (SDS) is presented in the work. The anionic surfactant SDS was selected after the comparative analysis of various cationic surfactants. PCZ gave a single irreversible oxidation peak at the potential of 0.59 V. The addition of SDS resulted in an almost 5-fold growth in the value of recorded currents as compared to those observed in the absence of the surfactant. The highest peak was obtained in Britton-Robinson buffer at pH 3.78. The calibration curve of PCZ plotted using the SWV technique was linear in the concentration range from 1.34·10−8 mol/L to 1.44·10−6 mol/L. The limit of detection and limit of quantification were 3.78·10−9 mol/L and 1.14·10−8 mol/L, respectively. The value of relative standard deviation of the measurements did not exceed 4.42 %, which proves good precision of the proposed method. The proposed procedure was successfully used in assaying PCZ in simulated gastric juice.

Electrochemical study and simultaneous square‐wave voltammetric determination of tyramine and spermidine in wines

Electrochemical study and simultaneous square‐wave voltammetric determination of tyramine and spermidine in wines

A novel composite electrode based on graphene oxide/MnO2:h‐MoO3 particles for square wave voltammetric determination of acetaminophen

AbstractA novel composite electrode was developed based on graphene oxide (GO)/MnO2:h‐MoO3 nanocomposite for sensitive and selective voltammetric detection of acetaminophen (ACP). The composite electrode materials were characterized using X‐Ray photoelectron spectroscopy (XPS), X‐Ray Diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetric (CV) techniques. In the optimum conditions, the oxidation peak current (Ipa) of ACP was increased linearly with its concentration over two linear ranges from 0.06 to 10.0 μmol L−1 and 20.0 to 80.0 μmol L−1 with a detection limit of 0.0133 μmol L−1. Due to its higher selectivity and long term stability, the composite electrode was applied to the detection of ACP in pharmaceutical formulations.

Spark-Discharge-Activated 3D-Printed Electrochemical Sensors.

3D printing technology is a tremendously powerful technology to fabricate electrochemical sensing devices. However, current conductive filaments are not aimed at electrochemical applications and therefore require intense activation protocols to unleash a suitable electrochemical performance. Current activation methods based on (electro)chemical activation (using strong alkaline solutions and organic solvents and/or electrochemical treatments) or combined approaches are time-consuming and require hazardous chemicals and dedicated operator intervention. Here, pioneering spark-discharge-activated 3D-printed electrodes were developed and characterized, and it was demonstrated that their electrochemical performance was greatly improved by the effective removal of the thermoplastic support polylactic acid (PLA) as well as the formation of sponge-like and low-dimensional carbon nanostructures. This reagent-free approach consists of a direct, fast, and automatized spark discharge between the 3D-electrode and the respective graphite pencil electrode tip using a high-voltage power supply. Activated electrodes were challenged toward the simultaneous voltammetric determination of dopamine (DP) and serotonin (5-HT) in cell culture media. Spark discharge has been demonstrated as a promising approach for conductive filament activation as it is a fast, green (0.94 GREEnness Metric Approach), and automatized procedure that can be integrated into the 3D printing pipeline.

Digital fabrication of 3D printed bismuth sparked sensors for electrochemical sensing

The fast and in-house fabrication of high-performance metal-based sensors is highly desirable in modern electrochemistry. Compared with plain carbon electrodes, metal-modified sensors offer wider applicability and higher sensitivity to electroanalytical methods. Herein, we introduce the entirely digital fabrication of biodegradable 3D printed thermoplastic sensors, in-situ modified with "green" spark discharge generated bismuth particles (BiPs). The hybrid fabrication process of these metal/plastic sensors employs two different printing methodologies, including fused deposition modeling for the 3D printing of the plastic electrode and printing via sparking for the deposition of BiPs on the electrode surface. More specifically, the sensors are 3D printed from a carbon black/polylactic acid filament by a 3D printer and then are modified with BiPs through repetitive sparking spots, applying an electrical discharge at 1.2 kV between a Bi-tip and the 3D printed electrode. The sparking process is performed using a desktop device equipped with a Bi-sparking head and a high voltage power supply. Full control of the sparking head movements by custom g-code software allows for the toposelective application of a predetermined number of sparking spots over the electrode surface. These ready-to-use 3D printed metal/plastic sensors are tested for the anodic voltammetric determination of lead and cadmium and the cathodic voltammetric determination of riboflavin in real samples, offering low limits of detection. These features highlight the potential of the 3D printed sparked sensor as a new generation candidate for the development of printed-at-point and sensitive metal-based sensors.

Preparation of graphene oxide and multi-walled carbon nanotubes, and they are used to modify the glassy carbon electrode for sensing Enalapril Maleate

In this study, the graphene oxide and multi-walled carbon nanotubes fabrication was evaluated using (SEM), (FTIR), Raman spectroscopy and (XRD). The results showed promising accuracy for the graphene oxide and multi-walled carbon nanotubes voltammetric sensor. The direct voltammetric determination of Enalapril Maleate in pharmaceutical samples, urine, and serum is detailed using a straightforward and extremely sensitive technique. Graphene oxide-multiwall carbon nanotubes are added to glassy carbon electrodes in an efficient manner to activate the GO-MWNT structures, which then electrocatalyzes the reduction of Enalapril Maleate. The results of the cyclic voltammetric (CV) experiment showed that the electrocatalytic activity of GO-MWNTs to reduce Enalapril Maleate was significantly improved, leading to a much higher cathodic peak current for EM. This finding opens the door to the possibility of creating a very sensitive voltammetric sensor to detect EM in biological and pharmaceutical fluid samples. A linear calibration curve in the 2.5–12.5 ppm concentration range, a detection limit of 0.2 ppm, and a relative standard deviation (R.S.D.%) lower than 1.0 % (n = 5) were all indicative of ideal conditions. Lastly, EM is a diffusion-controlled process that proceeds through a two-electron-two-proton change, which provides a mechanism for the reduction of EM.. The GO-MWCNTs/GCE sensor had a good repeatability and excellent reproducibility, R.S.D.% =1.77 and 1.82.

Nanoparticles based on carbon dots and reduced graphene oxide as electrochemical sensor for voltammetric determination of hydroxychloroquine

AbstractThe hybrid material was obtained from the synthesis of graphene oxide (GO) followed by GO chemical reduction with L‐ascorbic acid. Then hydrothermal synthesis was carried out to form and grow carbon dots (CDs) on the surface of reduced graphene oxide (rGO). The material obtained, CD@rGO, was characterized by transmission electron microscopy (TEM), the infrared (FTIR), Raman and UV‐visible (UV‐Vis) spectroscopy, in addition to X‐ray diffractometry (XRD), spectroscopy and electrochemical methods. The results indicated the formation of carbon dots on the surface of rGO. The study of the voltammetric determination of hydroxychloroquine (HCQ) was performed using adsorptive stripping voltammetry (AdSV) and employing a modified electrode with CD@rGO (ECR). Optimizations were kept in the electrolytic environment and AdSV technique parameters, making it possible to obtain a LOD and LOQ of 2.40 and 7.99 pmol L−1, respectively. The evaluation of the ECR electrochemical stability, repeatability and reproducibility tests were performed with maximum variations of up to 2.79 and 2.03 %, respectively. Determinations in commercial samples of HCQ (tablets) and synthetic urine, recovery in the range of 101.55–106.83 % were obtained.

Propranolol chiral analysis using voltammetric sensor based on triterpenoid-graphene oxide hybrid material

Enantioselective sensors are potentially in demand at all stages of the production, storage and use of drugs, including identifying impurities of undesirable isomers and improving stereoselective synthesis methods. A key aspect for enantioselective sensors design is the development of appropriate molecular architectures that make it possible to create recognition sites with different affinities for enantiomers. This experimental work proposes a new chiral sensor based on glassy carbon electrode (GCE) modified by graphene oxide (GO) covalent functionalized with pentacyclic triterpenoid betulonic acid (BetA) for voltammetric recognition and determination of propranolol (Prop) enantiomers. Characterization of the materials was carried out using FTIR spectroscopy, scanning electron microscopy and cyclic voltammetry. Differential pulse voltammetry was used for Prop enantiomers recognition and quantification. The potential difference reached 30 mV along with enanitoselectivity coefficient ipS/ipR equal to 1.30. The calculated binding energy for S-Prop/GO-BetA complex is higher by 4.801 kcal moll−1 compared to R-Prop/GO-BetA indicating a more favorable mutual arrangement of molecules. The linear determination range was established as 5.0 × 10-6 ∼ 1.0 × 10-4 mol·L-1 and 1.0 × 10-4 ∼ 4.0 × 10-4 mol·L-1 for both enantiomers. The detection limits were determined to be 3.9⋅10-7 mol·L-1 and 5.0⋅10-7 mol·L-1 for S-Prop and R-Prop, respectively. The standard spike-recovery tests were carried out in human biological fluids with recoveries 97.3 % − 106.9 % for both enantiomers. The proposed sensor was used to determine the ratio of Prop enantiomers in mixture by regression analysis with projection to latent structures (PLS). The purpose was to build a PLS-model based on a calibration set containing a known number of Prop enantiomers and recognize a test set prepared independently. All samples of test set are correctly identified and the RSD did not exceed 8.7 %. GCE modified by covalent functionalized GO with BetA showed better stability compared with noncovalent functionalization in terms of electrode degradation.

An Affordable and Efficient Graphite‐Coated Electrode for the Voltammetric Determination of Catechol

AbstractAn affordable and highly efficient graphite‐coated electrode was developed and applied in this work as a compelling alternative to other modified electrodes in catechol determination. Electrode modification involved a simple deposition process using a commercial graphite dispersion, Aquadag®Acheson. Morphological and electrochemical studies revealed the formation of a uniform layer with enhanced surface area and significant conductivity. Catechol quantification was successfully achieved in the linear concentration range extended up to 80 μmol L−1 with a detection limit of 0.5 μmol L−1 under optimized conditions (pH 7 and an accumulation time of 2 min). Spike‐and‐recovery experiments validated the accuracy of the determination. Unlike hydroquinone, structurally similar compounds such as phenol and resorcinol did not interfere with catechol analysis. The interference posed by hydroquinone was addressed by derivative treatment of the voltammograms allowing peaks resolution.

A micro-electrochemical sensor based on a nanostructured carbon paste electrode as an original tool for selective detection of ultra-traces of 17α –ethinylestradiol in environmental water samples and in biologic fluids

A new electrochemical micro-sensor has been designed for the sensitive detection of ultra-traces of 17α – ethinylestradiol (EE2). A carbon paste cavity micro-electrode modified by carbon black nanoparticles (GC-nCB)-µCPE was used with an electrochemical preconcentration (EP) step of EE2 on (GC-nCB)-µCPE at 0.0 V during 300 s in a 0.01 mol.L-1 phosphate buffer solution (pH = 7.4) before voltammetric determination. The results demonstrate that two line calibrations were obtained in the concentration ranges of 0.005 to 0.2 μmol.L-1 and 0.2 to 1 μmol.L-1. The detection and quantification limits are estimated at 1.4 nmol.L-1 and 4.9 nmol.L-1, respectively. Moreover, a high sensitivity of 4.16 µA.mol−1.L and good selectivity for the quantification of EE2 in the presence of different interfering organic and inorganic compounds were observed. Based on the results (satisfactory recovery (less than 3.5 %) and relationship standard deviation (less than 2.5 %)),the designed micro-sensor can be successfully applied to the analysis of EE2 in environmental water samples and in biologic fluids.The modified microsensor presented an efficient and inexpensive tool for the quantification of EE2.

Solid Bismuth Drop Electrode – A New Tool for Voltammetric Determination of Electrochemically Reducible Organic Compounds

Solid bismuth drop electrode (SBiDE) is a new working electrode commercially available on the Czech market from 2020 by the company Metrohm. The aim of this work was to verify the applicability of the SBiDE in the voltammetric determination of a model organic substance. According to the available information, this is the very first published work on this topic. Metronidazole (an antibiotic used to treat diseases caused by both Gram-positive and Gram-negative anaerobic bacteria) was chosen in this study as a model drug representing electrochemically reducible biologically active compounds. Under optimum conditions (Britton-Robinson buffer of pH 12.0 used as the supporting electrolyte and no electrochemical regeneration of the working electrode surface), a linear calibration dependence of metronidazole was recorded in the concentration range from 1 to 600 μmol L–1, with the limits of detection (LOD) and quantification (LOQ) of 0.41 μmol L–1 and 1.4 μmol L–1, respectively. The newly developed differential pulse voltammetric (DPV) method has also been successfully applied in the determination of metronidazole in various dosage forms.

Novel disposable screen-printed sensors based on copper oxide nanoparticles for sensitive voltammetric assay of antazoline

The fabrication and electroanalytical validation of a novel homemade screen-printed carbon electrode enriched with copper oxide nanoparticles (CuONPs/SPCEs) were demonstrated for sensitive and selective voltammetric determination antazoline (ANT) in eye drop solution and spiked serum samples. With a reported electrocatalytic activity, CuONPs catalyzed the oxidation of ANT at the electrode surface showing an irreversible anodic oxidation peak at 0.9 V under a diffusion-controlled electrode reaction. Based on the electroanalytical and molecular orbital calculation studies, oxidation of ANT molecule undergoes via oxidation of the aliphatic nitrogen atom within the ANT moiety. Linear calibration curves were illustrated covering the ANT concentration ranged from 0.01 to 3.819 µg mL−1 with and limit of detection 3 ng mL−1. The fabricated sensors enriched with CuONPs exhibited high fabrication and measurement reproducibility with a prolonged shelf lifetime (6 months). The electroanalytical approach presented adequate sensitivity and selectivity with a short analysis time, applying low-cost instrumentation and simple pretreatment protocol avoiding handling hazardous organic solvents. Trace ANT was monitored in the presence of different interfering species, degradation products, and xylometazoline hydrochloride (ZYL) in the co-formulated ophthalmic pharmaceutical samples. The CuONPs based voltammetric sensors were introduced as a reliable eco-friendly analytical tool for monitoring ANT in ophthalmic solutions and biological fluids with acceptable recovery values.

Fabrication of Highly Sensitive Electrochemical Sensor Based on Chromium-Doped Ferrite Nanoparticles: Hybrid Graphene Nanosheets for the First Voltammetric Determination of Asenapine Maleate in Formulations and Human Plasma

Ferrite nanoparticles are interesting materials given their unique physical and chemical properties and wide applications. A novel electrochemical sensor based on a series of chromium-nano-ferrites {Fe3+[Fe2+Fe3+ (1-x)Cr3+ x ]O4; x (0.0–1.0} was fabricated for determination of Asenapine maleate (ASE.M). X-ray diffraction revealed the formation of crystallite nano-particles of lattice constant of (8.299–8.345 Å) with a single phase of cubic inverse spinel structures. Particle size and specific surface area were (9.10–27.60 nm) and (60–175 m2g−1) using Transmission electron microscopy and Brunnauer-Emmett-Teller (BET) analysis, respectively. Among this Cr x Fe(3−x)O4 series, (CrFe2O4; x = 1) was appeared to get the smallest particles size and highest BET surface area. The charge transfer resistance (RCT) of (2220, 1680, 765, and 490 Ω) were achieved for Cr x Fe(3−x)O4 NPs/CPE (x = 0.0, 0.4, 0.8, and 1.0), respectively. CrFe2O4 performance was then improved via incorporation of 2D-graphene atomic crystals in a new ferrite-graphene nanocomposite of [0.25%(w/w) CrFe2O4 NPs: 7%(w/w) graphene nanosheets]. The feasibility of this sensor is achieved for determination of ASE.M in brand Saphris® and local Asenapine pharmaceutical products. In addition, a wide linear concentration range of (6.5 × 10−9–1.0 × 10−6 M) with LOD value of 8.88 × 10−10 M were achieved in human plasma.

Fabrication of mechanically alloyed high entropy alloys (20-Fe-20Cr-20Ni-20Mn-20Ti) modified carbon paste electrode sensor for the cyclic voltammetric determination of methyl orange

We have successfully fabricated high entropy alloys (HEA) of composition 20-Fe-20Cr-20Ni-20Mn-20Ti by ball milling method for 20 h after optimizing the milling parameters. Generally, the HEAs are very popular for their multi-elemental cocktail effect and exhibit excellent high temperature oxidation resistance, high strength, electromagnetic, wear and corrosion resistance properties. But, HEAs also exhibit significant electrocatalytic properties due to their unique morphology, composition, and structure. Therefore, we have used planetary ball milled HEA powders for the electrochemical determination of methyl orange (MO). MO is recalcitrant and very difficult to degrade and can affect the humans as well as the environment. Therefore, we must determine the presence of MO. We have investigated the effect of scan rate, modifier and analyte concentration, and the pH variation on the anodic peak current (Ipa) of MO. The calculated active syrface area of bare carbon paste electrode (BCPE) and HEA-modified carbon paste electrode (HEA-MCPE) were found to be 0.041 cm2 and 0.137 cm2 respectively. We have obtained the maximum oxidation peak current for the 8 mg HEA-MCPE at a pH of 7.2 during the electrochemical oxidation of MO. The increased Ipa in basic medium is due to structural transformation of MO from quinoid form (in acidic medium) to azo structure (in basic medium). We have also calculated the number of electrons and the protons involved in the electrochemical reaction. The calculated values of detection limit (DL) and quantification limit (QL) of 8 mg HEA-MCPE was found to be 0.114 × 10−8 M and 0.38 × 10−8 M respectively.

Cobalt(II) bis-(1,10-phenanthroline) complex electropolymerized glassy carbon electrode and its electrocatalytic sensing of diclofenac in pharmaceuticals and biological samples

Diclofenac (DCF) is a nonsteroidal anti-inflammatory drug (NSAID) that is used to treat acute and chronic inflammatory diseases. High consumption and indiscriminate use of DCF pose serious health issues, prompting the consideration of electroanalytical methods for detecting and controlling DCF levels in various samples. A sensitive and highly selective sensor was established for voltammetric determination of diclofenac (DCF) based on poly[cobalt(II) bis-(1,10-phenanthroline) complex] modified glassy carbon electrode (poly(Co(Phen)2)/GCE). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the performance of a poly(Co(Phen)2)/GCE sensor, revealing a negative oxidation potential shift and higher DCF peaks of current. CV and adsorptive stripping square wave voltammetry (AdSSWV) were used to evaluate the electrochemical behavior of DCF at poly(Co(Phen)2)/GCE. Under the optimized experimental conditions, AdSSWV current signal of DCF at poly(Co(Phen)2)/GCE provided linearity over the range of 1–250 μM with a limit of detection (LOD) and limit of quantification (LOQ) of 6.40 ×10−2 and 2.13 ×10−1, and 5.60×10−2 and 2.27×10−1 µM for Ip I and Ip II, respectively. The sensor for determining DCF was tested in pharmaceuticals, milk, serum, and urine samples, demonstrating excellent selectivity despite potential interferences like atorvastatin (ATS), chloroquine (CQ), and sulfamethoxazole (SMX). The detected DCF amounts ranged between 92.3% and 106.6%. The established sensor demonstrated excellent performance in determining DCF in real samples, with spiked recoveries exceeding 95.6%, demonstrating low LOD, high sensitivity, selectivity, repeatability, and long-term stability. These results confirm that the established method displays outstanding applicability for electrochemical determination of DCF in numerous real samples.

Biochar from sugarcane bagasse: Synthesis, characterization, and application in an electrochemical sensor for copper (II) determination

Biochar (BC) is a carbonaceous material obtained from the thermal decomposition of organic matter under limited oxygen supply that plays an attractive role in waste management. In this study, biochar was prepared from sugarcane bagasse, using pyrolysis temperatures from 300 to 700 °C, and chemically activated with HNO3. Structural characterizations showed that degradation increased as pyrolysis temperature increased. Furthermore, a higher number of functional groups were observed for the materials produced under the lowest temperatures. Chemical activation resulted in oxidation and nitration of carbonaceous structure, increasing the number of functional groups on the materials. All materials were evaluated for the construction of electrochemical sensors towards Cu2+ ions voltammetric determination. The material produced at 400 °C pyrolysis temperature and activated (BCA400) provided the most intense response, which can be related to the presence of one of the highest numbers of surface groups, such as oxygen groups, on it. A method for Cu2+ determination was successfully developed based on differential pulse adsorptive stripping voltammetry (DPAdSV). A linear dynamic range (LDR) from 1.0 to 15.0 μmol L−1 was achieved, with limit of detection (LOD) of 0.36 μmol L−1, and limit of quantification (LOQ) of 1.09 μmol L−1. The method was also adequate in terms of accuracy and precision, as well as selective against most cationic species commonly found in tap water. The analyte was determined in tap water samples, in natura and spiked with the maximum concentration allowed by Brazilian legislation, and successful recovery values were obtained. Therefore, biochar from sugarcane bagasse, an environmentally-friendly material, was successfully used to construct an electrochemical sensor and determining an environmental and health interest analyte.