Carbon Paste Research Articles

Analysis of Brucine using Poly(L-Arginine) modified biosynthesized CuO nanoparticle composite sensor

The study investigated the sensitive and selective electrochemical behavior of Brucine (BC) using electrochemically polymerized L-Arginine (LA) modified with a composite comprising biosynthesized copper oxide (CuO) nanoparticles (NPs) and carbon paste electrode (PAMCuONPs/CPE). PAMCuONPs/CPE showed an optimum reversible redox-peak at 0.2 M phosphate buffer solution (PBS) at pH 2.5, allowing detection of BC. The characterization of PAMCuONPs/CPE and bare CuONPs composite carbon paste electrode (BCuONPs/CPE) was performed using scanning-electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) methods were employed to evaluate the performance of PAMCuONPs/CPE. Experimental parameters, including pH, and variation of concentration, were investigated. PAMCuONPs/CPE exhibited an electrochemical performance with a limit of detection (LOD) of 0.12×10−6 M and a limit of quantification (LOQ) of 0.43×10−6 M. It demonstrated good reproducibility, repeatability, and stability. PAMCuONPs/CPE was successfully validated in determining BC in real samples.

Development of low-cost, fast, and sensitive voltammetric methods for the determination of donepezil using unmodified carbon paste electrode

Development of low-cost, fast, and sensitive voltammetric methods for the determination of donepezil using unmodified carbon paste electrode

Electroanalysis of Statin Drugs: A Review on the Electrochemical Sensor Architectures Ranging from Classical to Modern Systems.

An overview of the latest advances in the design of electrochemical sensor architectures dedicated to the determination of drugs from the statin class is presented in this review. Statins are drugs widely consumed for cholesterol control, and their determination in different matrices through the application of electroanalysis is growing considering advantages such as operational simplicity, lower cost and ease of sample preparation. Within the context of statins, electrochemical sensor architectures can be subdivided into conventional/classical electrodes such as glassy carbon electrodes, carbon paste electrodes, pencil graphite electrodes, boron-doped diamond electrodes and metallic electrodes, and more modern electrode systems, including the screen-printed electrodes and 3D-printed electrodes. Thus, different aspects related to the preparation of these electrochemical sensors and analytical performance are presented, also reflecting advances in terms of designs of new architectures and possible improvements not previously reviewed. Analyzed samples, advantages and disadvantages of different implemented sensor's modification strategies and perspectives for the electroanalysis of statins are also included throughout the work.

Utility of Gold/Multiwalled Carbon Nanocomposite for Electrochemical Determination of Omarigliptin in Tablets and Human Plasma

Abstract An innovative voltammetric sensor was developed to estimate omarigliptin, a novel long-acting anti-diabetic drug. The sensor utilized a carbon paste electrode enhanced with a nanocomposite of carbon nanotubes and electrodeposited gold nanoparticles. The modified electrode was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The modification significantly improved the electrode's sensitivity and electrochemical efficiency and decreased its electron transfer resistance. The surface area of the modified electrode increased by about 2.8-fold compared to the bare electrode. Omarigliptin's oxidation behavior on the modified electrode was pH-dependent and irreversible, resulting in a peak current 4 times higher than the unmodified electrode. The modified electrode revealed good reproducibility, reusability, and stability. It allows for sensitive voltammetric analysis of omarigliptin over a linear range of 0.4–27 µM (LOD=0.12 µM) and good applicability in tablets and plasma. The recovery percentages are 98.47–101.27% in tablets and 95.86–105.02% in plasma. The modified electrode exhibits good selectivity towards OMR without interference from tablet excipients, endogenous plasma components, and co-administered drugs. The comparison with the reported methods reveals the superiority of the proposed method in terms of sensitivity, selectivity, applicability, and eco-friendliness. Finally, the proposed method demonstrates excellent environmental profiles based on recent assessment metrics.

Metal–Organic Framework-Derived CeO2/Gold Nanospheres in a Highly Sensitive Electrochemical Sensor for Uric Acid Quantification in Milk

In this work, CeBTC (a cerium(III) 1,3,5-benzene-tricarboxylate), was used as a precursor for obtaining CeO2 nanoparticles (nanoceria) with better sensor performances than CeO2 nanoparticles synthesized by the solvothermal method. Metal–organic framework-derived nanoceria (MOFdNC) were functionalized with spheric gold nanoparticles (AuNPs) to further improve non-enzymatic electrode material for highly sensitive detection of prominent biocompound uric acid (UA) at this modified carbon paste electrode (MOFdNC/AuNPs&CPE). X-ray powder diffraction (XRPD) and transmission electron microscopy (TEM) analysis were used for morphological structure characterization of the obtained nanostructures. Cyclic voltammetry and electrochemical impedance spectroscopy, both in an [Fe(CN)6]3−/4− redox system and uric acid standard solutions, were used for the characterization of material electrocatalytic performances, the selection of optimal electrode modifier, and the estimation of nature and kinetic parameters of the electrode process. Square-wave voltammetry (SWV) was chosen, and the optimal parameters of technique and experimental conditions were established for determining uric acid over MOFdNC/AuNPs&CPE. Together with the development of the sensor, the detection procedure was optimized with the following analytical parameters: linear operating ranges of 0.05 to 1 µM and 1 to 50 µM and a detection limit of 0.011 µM, with outstanding repeatability, reproducibility, and stability of the sensor surface. Anti-interference experiments yielded a stable and nearly unchanged current response with negligible or no change in peak potential. After minor sample pretreatment, the proposed electrode was successfully applied for the quantification of UA in milk.

Eletrochemical evaluation of a sensor modified with tucumã biochar for analysis of environmental samples

In this study, a carbon paste electrode modified with tucumã biochar (EPCM/TB) was produced for the determination of pyridine in industrial effluents. To develop the methodology, different paste proportions were evaluated, and a proportion of 40:30:30 (m/m/m) of graphite:tucumã biochar:binder was selected. Cyclic voltammetry was used to characterize the charge and mass transfer process of the electrochemical system; the reaction occurred with the transfer of two electrons. The reaction was irreversible and controlled by diffusion. The experimental variables such as the supporting electrolyte, pH and instrumental parameters of the differential pulse voltammetry (DPV) technique were evaluated. After the optimization of these parameters, four analytical curves were constructed using DPV to calculate the matrix effect (ME). The analytical curves in the presence of the matrix showed good linearity for the three effluents, with R2 values of 0.991, 0.997 and 0995. The limits of detection (LODs) for effluents 1, 2 and 3 were 34.9, 5.5 and 36.8 nmol/L, respectively. The limits of quantification (LOQs) for effluents 1, 2 and 3 were 116.6 nmol/L, 18.4 nmol/L and 122.6 nmol/L, respectively. The MEs of the three effluent samples showed values above 50.0 %, indicating strong MEs; therefore, the quantification of pyridine was performed using the matrix curves. The method had recoveries close to 100 % for the three effluents. The repeatability and reproducibility studies of the method provided RSD% values below 5 %; therefore, the method has potential application in the quantification of pyridine in textile effluents.

Multifunctional CeO2:Fe3+ electrodes: Superior uric acid sensing and high-efficiency supercapacitor application

This study investigates the versatile capabilities of iron-doped CeO2-modified carbon paste electrodes (FCO MCPE) for both enhanced uric acid (UA) detection and efficient energy storage applications. Iron-doped CeO2 nanoparticles were synthesized via combustion synthesis. Cyclic voltammetry (CV) showed a 29 % increase in anodic peak current (2.05 µA) with the FCO MCPE compared to bare carbon paste electrodes (BCPE) (1.59 µA), indicating improved catalytic properties. Analysis of scan rates revealed a diffusion-controlled oxidation process. Differential pulse voltammetry (DPV) demonstrated excellent linearity (R2 = 0.999) and low detection limits (LOD: 0.132 µM, LOQ: 0.442 µM). Selectivity tests confirmed the superior ability of the FCO MCPE to differentiate UA from dopamine (DA), with a high linearity (R2 = 0.998). Stability tests showed only an 11 % decrease in performance after 15 cycles. In super capacitor evaluations, FCO materials exhibited a high specific capacitance of 200.43 F g−1 at 2 mV/s and impressive cycling stability with 87.5 % capacitance retention after 5000 cycles. Electrochemical impedance spectroscopy (EIS) revealed efficient charge transfer with a peak specific capacitance of 52.39 F g−1 at 0.01 Hz. These findings underscore the potential of FCO MCPEs for both effective UA detection and efficient super capacitor applications.

Point-of-Care Sensor Using Modified Nickel-doped Zinc Oxide Nanoparticle Carbon Paste Electrode for Homovanillic Acid Cancer Biomarker Detection in Urine

The prevalence of cancer worldwide has prompted efforts to develop and produce a range of electrochemical biosensors for cancer diagnosis. Efficient cancer diagnosis can be enhanced by the sensitive detection of biomarkers, which can also lower the cost of medical diagnostics. Neuroblastoma is an embryonic cancer arising from neural crest stem cells and is considered the most common malignancy in infants and the extracranial solid tumor in children. In this paper, we describe the construction of a nanoparticle-modified electrochemical sensor for detecting and quantifying homovanillic acid (HVA), a biomarker for neuroblastoma. The electrooxidation of HVA was studied at a carbon paste electrode (CPE) modified with nickel-doped zinc oxide nanoparticles (Ni-ZnO NPs). The use of these nanoparticles enhanced electrochemical sensitivity and the electrocatalytic activity. The differential pulse voltammetric response of HVA was found to be linear in the concentration range of (3.96 × 10−6 to 3.83 × 10−5 M) with a lower detection limit of 1.01 × 10−6 M. The electrode demonstrated good stability in the HVA determination process, with a minor decrease in response after 10 weeks. The proposed sensor was successfully applied to determine HVA in a urine sample with a good detection result and a worthwhile biological impact.

A New Modified Carbon Paste Electrode for Selective Determination of Chromium(III) in Pharmaceutical Drugs and Food Samples

Background and Objective: This study presents a novel potentiometric method for the precise, accurate, selective, and rapid determination of Cr(III) ion concentration in different samples. Methods: A new ionophore, namely macrocyclic tetramide ionophore (MCTA), was synthesized through an inexpensive and straightforward approach, yielding a high-quality product. The (MCTA) ionophore was utilized as the active center in the preparation of modified carbon paste electrodes (MCPEs) to quantify the Cr(III) ion. The paste was made by adding graphite, MCTA, and plasticizer and mixing them in varying weight percent ratios. Results: The proposed electrodes, I and II, exhibited a trivalent Nernstian response of 20.029 ±0.57 and 20.3±0.56 mV decade-1 , respectively, with linearity of 1.0x10-7 – 1.0x10-2 and 1.0x10-5 – 1.0x10- 2 mol L-1 . Electrodes I and II were examined for their pH, response time, and thermal stability. In comparison to other mono-, bi-, and trivalent cations, starch, and sugars, the electrodes demonstrated a high degree of selectivity for Cr(III). The modified electrodes were used to determine the concentration of Cr(III) in various real samples, including drug tablets, juice extractions, and tap water, with acceptable recovery values. Conclusion: The results were compared with those obtained using the previously reported method, with no significant difference observed between them, as indicated by the F and t-test values. The data showed good accuracy and precision, as well as a high percentage of recovery. The adsorption capacity of the MCTA ionophore towards Cr(III) ions was also examined.

Efficient electrochemical determination of Sudan I in food samples based on modified electrode by using Ni-Fe layered double hydroxide nanosheets and ionic liquid

Sudan I, is one of the commonly used azo dyes in food samples, which has shown adverse effects on human health. Therefore, determining the level of Sudan I in food samples can be very effective in ensuring food safety and protecting human health. In this study, an electrochemical sensing platform was designed using Ni-Fe layered double hydroxide nanosheets and ionic liquid modified carbon paste electrode (Ni-Fe LDH/ILCPE) which was utilized to determine Sudan I. Comparison of cyclic voltammograms of Sudan I on the unmodified CPE and Ni-Fe LDH/ILCPE showed that, the higher oxidation currents were obtained on the surface of the Ni-Fe LDH/ILCPE, indicating that the modified CPE owns significant surface improvement effects and good electrochemical performance in detecting Sudan I. Under optimized conditions, the developed Ni-Fe LDH/ILCPE sensor demonstrated a linear relationship between the voltammetric response and Sudan I concentrations from 0.03 µM to 510.0 µM with a low detection limit (LOD) of 0.01 µM based on S/N = 3.0. Additionally, the Ni-Fe LDH/ILCPE platform exhibits high accuracy, with a recovery of 96.4 % to 104.1 % for Sudan I determination in food samples including Ketchup and Chilli powder, which implies that it will be a potential detection method for Sudan I detection.

Producing Activated Biochar from the Reuse of Discarded Coffee Grounds with Enhanced Adsorptive Features Explored Towards the Stripping Voltammetric Sensing of Copper (II)

AbstractThis work aims to allocate coffee grounds waste to the production of biochar from pyrolysis under different temperatures (350 °C and 500 °C), to add value to it. The resulting materials were characterized by immediate, elemental, thermogravimetric analysis, SEM, FT‐IR, XRD and Raman spectroscopy. Additionally, the need to activate the biochar produced for the desired use was evaluated. The obtained biochars were applied in electroanalysis in the manufacture of modified carbon paste electrodes. This choice was made due to the possibility of reaching a high sensitivity towards the determination of Cu2+ ions. The differential pulse adsorptive anodic stripping voltammetry technique was applied to perform the Cu2+ determination and, in this case, several parameters were optimized, including biochar’ percentage, pH of pre‐accumulation step and reduction/stripping step, pre‐accumulation time, potential and time of reduction of adsorbed‐Cu2+. From this, the proposed modified electrode showed a linear voltammetric response towards Cu2+ in the range of 66.1 to 3997.3 ppb, with a limit of detection of 31.8 ppb, in addition to having been satisfactorily applied in the analysis of water samples (recoveries close to 100 %). Thus, demonstrating the potential for reuse of discarded coffee grounds for the preparation of activated biochar with outstanding electrochemical performance.

Preparation and application of a new ion-imprinted polymer for nanomolar detection of mercury(II) in environmental waters

This study introduces a novel ion-imprinted polymer for the ultrasensitive detection of mercury(II) in water. The ion-imprinted polymer was synthesized via a simple bulk polymerization process using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, morpholine-4-carbodithioic acid phenyl ester as the chelating agent, and ammonium persulfate as the initiator. The electrochemical mercury(II) sensing capability of the ion-imprinted polymer was studied via the modification of a cost-effective carbon paste electrode. A stripping voltammetric technique was utilized to quantify the analyte ions following open-circuit enrichment. Critical experimental parameters, including the nature and concentration of the eluent, solution pH, preconcentration duration, ion-imprinted polymer dosage, sample solution volume and reduction potential, were systematically studied and optimized. Under optimal conditions, the sensor exhibited a linear response in the range of 1.0 to 240.0 nM, with a low detection limit of 0.2 nM. The sensor demonstrated remarkable selectivity against potential interfering ions, including lead(II), cadmium(II), copper(II), zinc(II), manganese(II), iron(II), magnesium(II), calcium(II), sodium(I) and cobalt(II). The practical applicability of the developed method was successfully validated through the analysis of real water samples, suggesting its potential for environmental monitoring applications.

Electroanalysis with Carbon Paste Electrodes: A Look Behind the Scientific-Research Activities of the Electroanalytical Group in Pardubice

In this article, a retrospective view of the research activities of the electroanalytical group at the University in Pardubice (UPCE) is presented, offering a concise overview on the development, continuing work, and significant achievements in electrochemical measurements with carbon paste electrodes (CPEs). At the very beginning, a brief history of the field is provided and the state-of-the-art in a global view outlined. Second, research activities with CPEs and related configurations in the former Czechoslovakia and the succeeding Czech Republic are also summarised and the respective publications cited. The introductory section ends with a historical survey of the activities of the electroanalytical group at the UPCE, characterising the individual time periods with CPEs from the mid-1980s up until now and highlighting the most important achievements and the corresponding publications. The pivotal part of the text then gathers five various examples representing some of the truly key-themes that have made electroanalysis at UPCE well-known and, at the same, distinctive. Namely, overviewed, commented, and illustrated in selected figures are (i) carbon paste mixtures with atypical binders from liquid esters, (ii) extractive pre-concentration onto the carbon paste bulk and determination of iodine, (iii) method for determination of Ag(I) ions at a CPE with extraordinary analytical performance, (iv) carbon pastes as substrates for mercury, gold, bismuth, and antimony films, and (v) recent applications of CPEs prepared from carbonaceous materials of natural origin.

Nanohybrids of B- and N-codoped reduced graphene oxide/CeO2–Co3O4 nanocomposite for efficient water oxidation

Transition metal oxides are well known as highly active and durable catalysts for the oxygen evolution reaction (OER). In this work, to enhance the electrocatalytic activity of CeO2 nanostructure in the water oxidation reaction, CeO2/Co3O4 and boron-nitrogen co-doped reduced graphene oxide incorporated (B,N-rGO) into CeO2/Co3O4 with a weight ratio of 3:1 of nanoparticles to graphene oxide were synthesized using co-precipitation and hydrothermal methods, respectively. The prepared materials were studied in detail regarding their crystal structure and morphological properties. The as-prepared materials were used as modified carbon paste electrodes for electrochemical water oxidation in an alkaline solution. The results showed that incorporating graphene oxide network into the nanoparticles structure enhances their OER performance. The material based on CeO2/Co3O4@B,N-rGO hybrid nanocomposite showed excellent OER activity with an overpotential of 410@10 mA cm−2, which is 240 and 140 mV less than that of the single CeO2 and CeO2/Co3O4 samples. Also, CeO2/Co3O4@B,N-rGO displayed the lowest Tafel slope and charge transfer resistance among the other catalysts. Moreover, the proposed catalyst displayed high stability and durability during OER. The enhanced OER performance of the CeO2/Co3O4@B,N-rGO is attributed to several catalytically active sites created by B and N doped rGO in the nanocomposite structure. The high performance of this catalyst results from the synergy of combining CeO2/Co3O4 nanoparticles with a three-dimensional co-doped rGO network.

Development of a 1D-WO3 and CuO nanocomposite modified electrode for enhanced detection of 2,4-dichlorophenol

A common chlorinated phenol known as 2,4-dichlorophenol (2,4-DCP) was investigated electrochemically using cyclic voltammetry (CV) and square wave voltammetry (SWV). The electrochemical investigation was carried out at 1D nanostructured tungsten dioxide (WO3) and copper (II) oxide (CuO) nanocomposite-modified carbon paste electrode (CPE). The electrode's sensitivity was improved by the WO3/CuO nanocomposite, enabling investigators to more precisely measure the 2,4-DCP's electrochemical characteristics. The hydrothermal method was utilized to synthesize the WO3 NPs. The XRD, AFM, SEM, and EDS techniques were used to characterize the nanocomposite and WO3 NPs. Numerous parameters have been studied, including pH, concentration variation, scan rate variation, and accumulation time. Samples of soil, fruits, and vegetables were examined using the fabricated WO3/CuO/CPE. In the concentration range of 7.0 × 10−8 M to 2.6 × 10−7 M, a linear relationship was established along with the lower limit of detection of 0.17 × 10−8 M and the limit of quantification of 0.57 × 10−7 M. The 0.2 M phosphate buffer (PB) of pH 10.4 increased the peak current, which contributed to the WO3/CuO/CPE sensor's sensing performance and was highly sensitive with respect to 2,4-DCP detection. Anodic peak current was observed for the WO3/CuO/CPE is at -7.45 µA whereas for unmodified CPE is at -1.31 µA. According to the findings, the nanostructured WO3 and CuO nanocomposite showed exceptional sensitivity in identifying the electrochemical characteristics and reactions of 2,4-DCP.

Flow injection analysis of hydroquinone using amperometric sensor modified with nanomaterials

Modified carbon paste electrodes (CPE) have been widely used in diverse applications, such as environmental, food, and pharmaceutical analysis, among other applications. In this work, the development of an amperometric sensor modified with functionalized multi-walled carbon nanotubes (CNT) and HY-type zeolite (ZEO) is reported for the analysis of hydroquinone (HQ) in pharmaceuticals. Practical and theoretical studies were carried out regarding the modifiers used. No chemical bond was observed between the modifiers and the analyte, such as HQ and CNT. It is likely that dynamic interactions governed by surface adsorption phenomena, rather than covalent bonding, are occurring. Furthermore, the contribution of modifiers to the improvement of the analytical peak current was elucidated through characterization studies, such as electrochemical impedance spectroscopy. These experiments revealed a 147-fold decrease in charge transfer resistance when CPE was modified with ZEO and CNT, which is likely due to an enhancement in electron transfer. A sample rate of 100 injections per hour, and the limit of quantification (LQ) of 8.99 x 10-7 mol/L were achieved during the oxidation of HQ using amperometry in association with flow injection analysis (FIA). The sensitivity of the proposed sensor was of 0.0186 mol/L cm−2. Determinations of pharmaceutical samples were in good agreement with results obtained by High Performance Liquid Chromatography.

Nanoclay composites in electrochemical sensors

Nanoclays are layered structures in the nanoscale range with widespread application due to their unique properties such as swelling, cation exchange capacity, and ease of functionalisation using metals, metal oxides, and organic compounds such as carbon paste, polymers, and other biomolecules that form nanoclay composites. Nanoclay functionalisation with silver (Ag), zinc oxide (ZnO), and bimetallic silver–gold (Ag–Au) using hydrophilic and hydrophobic clays is here evaluated and discussed. The composites’ synthesis and morphological, crystallinity, and electroactive properties in comparison with pure nanoclay are also assessed. The layered structure and crystallinity of all these nanoclay composites were slightly changed. The clumped layered structures on the surface of the nanocomposites had dispersed white spots that indicated possible surface modification. The nano-films of the composites’ electroactivity were comparatively high, as seen from the increase in current in the cyclic voltammetry characterisation voltammograms and the differential pulse voltammograms of the pharmaceutical detection. Efavirenz, nevirapine, and zidovudine detection was improved by modification of the nanocomposite with human serum albumin (HSA), as shown by the higher current, thus indicating improved conductivity of the composites compared to the pure nanoclays. Applying HAS-modified nanocomposites in the analysis of efavirenz, nevirapine, and zidovudine on a glassy carbon electrode (GCE) showed good linearity and acceptable detection limits comparable to those of previous studies. Therefore, it has potential for application in pharmaceutical quality control and environmental monitoring.

Attachment of ρ-aminobenzene sulphonic acid into magnetic Fe3O4 reduced graphene oxide and its application for sensitive determination of L-tryptophan in milk and banana samples

This paper reports the attachment of p-aminobenzene sulfonic acid on the surface of magnetic Fe3O4-reduced graphene oxide. Different techniques including FTIR, UV, EIS, XRD, and SEM imaging were employed for characterization. The finding indicates the successful attachment of the p-aminobenzene sulfonic acid to the surface. The synthesized material was used to make a carbon paste electrode for the determination of the essential amino acid L-tryptophan (L-Try). EIS and CV characterization of the electrode further confirms the attachment of the acid. Of the different electrode materials used, the p-aminobenzene sulfonic acid attached magnetic Fe3O4 reduced graphene oxide showed very good electrocatalytic activity. The scan rate study showed that the electrode process is an adsorption-controlled one. The prepared electrode material gave a linear curve for 0.001 μM to 10 μM L-Try concentrations, and the limit of detection and limit of quantification were 0.26 nM and 0.78 nM, respectively. Furthermore, the electrode material was employed for the determination of L-Try in a milk and banana sample.

Water oxidation through electrocatalytic process using cobalt and nickel complexes of thiazole Schiff-base ligands

Ni(OAc)2.4H2O and CoCl2.6H2O reacted with thiazole ligands, HL and HL' (where HL= (E)-2-(((4-phenylthiazol-2-yl)imino)methyl)phenol and HL'= (Z)-2-(2-benzylidenehydrazinyl)-4-phenylthiazole, in ethanol to create new mononuclear Co(II) and Ni(II) complexes, CoL2, NiL2, CoL'2, and NiL'2 (1-4). X-ray diffraction analysis, spectroscopic, and electrochemical methods were used to study the complexes. A carbon paste electrode that had been modified by complexes 1-4 was used as the working electrode in a three-electrode setup to test the complexes' ability in water oxidation reaction at pH 13. The linear sweep voltammetry (LSV) curves showed that complexes 3 and 2 have much greater activity and only require the overpotential of 570 and 690 mV ʋs. RHE at a current density of 10 mA/cm2 with Tafel slopes of 86.92 and 94.19 mVdec−1 respectively in an alkaline solution. In addition, the amperometry tests exhibited brilliant stability for water oxidation by CPE-complex 3 and CPE-complex 2 under electrochemical conditions at pH 13. Although X-ray diffraction patterns did not display a crystalline structure, the scanning electron microscopy images displayed that cobalt oxide and nickel oxide in an alkaline condition are proper catalysts for water oxidation reaction on the surface of the modified electrode.

A highly sensitive and selective molecularly imprinted sensor for the determination of atorvastatin

In this study, we developed a highly sensitive carbon paste sensor that combines a molecularly imprinted polymer (MIP) with specific recognition capabilities to monitor atorvastatin (ATV). In the MIP synthesis, designed especially for ATV, ethylene glycol dimethacrylate (EGDMA) was utilized as a cross-linking monomer and methacrylic acid (MAA) as a functional monomer. This non-covalent method made use of polymerization by free radicals. After that, this MIP was added to a carbon paste electrode (CPE), which served as both a selective detection element and a preconcentration agent for ATV analysis. The improved CPE was characterized using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). To investigate ATV, the anodic peak signal was assessed using square wave stripping voltammetry (SWSV).The calibration curve exhibited two linear regions encompassing dosages from 0.005 to 1 µM and 1 to 20 µM, with a 1.5 nM calculated detection limit. The designed MIP electrode was successfully utilized to assess ATV in tablet and human blood serum samples, demonstrating its usefulness in practical analysis.