2026-02-23
Huynh Thanh Danh, Nguyen Chi Bao, Pham Thi Huyen Thoa, Nguyen Quang Man, Pham Dinh Du, Dinh Quang Khieu
In this study, we developed an electrochemical sensor based on an Fe/MCM-41 modified electrode for the simultaneous analysis of acetaminophen (AT) and theophylline (TP). The Fe/MCM-41 material was produced from diatomite silica and ferric chloride salts via a hydrothermal method. The synthesized material was characterized by XRD, SEM, TEM, EDX mapping, and nitrogen adsorption-desorption isotherms. Results showed that the Fe/MCM-41 maintained its mesoporous structure, high surface area, and uniform dispersion of Fe ions. Electrochemical tests revealed that the Fe/MCM-41 electrode exhibits superior electrocatalytic activity and higher current responses for both analytes than the bare electrode. The two oxidation peaks of AT and TP were distinctly separated, enabling simultaneous quantification of drugs with high selectivity. The peak current increased linearly with AT and TP concentrations from 0.50 to 14.15 µM, with detection limits of 0.430 and 0.350 µM, respectively. Notably, the sensor was successfully used to analyze pharmaceutical formulations containing one or both active substances, with satisfactory recoveries. The results confirm that the Fe/MCM-41 electrode is a promising sensing platform for the simultaneous analysis of AT and TP, opening new possibilities for pharmaceutical testing.
2026-02-23
Shashanka Rajendrachari, Hareesha Nagarajappa, Varun Donnakatte Neelalochana, Rakshitha Gattavadipura Shivaraju, Ersin Demir, Santhy Antherjanam, Kazim Erden Karaoglanli
Dopamine (DA) is a vital neurotransmitter used in clinical diagnostics and neurochemical studies. In this article, a robust, accurate, and highly sensitive method for determining DA using a duplex stainless steel (DSS)-modified carbon paste electrode (MCPE) and cyclic voltammetry is reported. To improve the sensitivity of the DSS-MCPE, the electrode was polymerized via 10 potential cycles using asparagine, a non-essential amino acid, thereby forming poly(asparagine) on the electrode surface. This polymerized electrode surface acts as a selective barrier to DA and enables the DSS-MCPE to detect DA accurately, even in the presence of interfering molecules such as ascorbic and uric acids, which have overlapping oxidation potentials. Compared with the bare carbon paste electrode (BCPE) and DSS-MCPE, poly(asp)-DSS-MCPE exhibits excellent electrochemical behaviour, a higher oxidation peak current, and improved electron transfer kinetics. The effects of variations in scan rate, pH, and DA concentration on the electrocatalytic behaviour of poly(asp)-DSS-MCPE were investigated. Also, the electrode active surface area was calculated, and the limit of detection, limit of quantification, and number of electrons and protons involved in electrochemical reactions were determined. The ease of fabrication, cost-effectiveness, and robust performance of poly(asp)-DSS-MCPE make it a promising electrocatalyst for detecting DA and other bioactive molecules, without interference from interfering molecules.
2026-02-06
Nebojša D. Nikolić, Jelena Lović, Nikola Vuković, Predrag Živković
Influence of parallel hydrogen evolution reaction (HER) on morphology of zinc electrodeposits has been investigated. Zn was electrodeposited potentiostatically from the alkaline electrolyte at overpotentials both inside and outside the plateau of the limiting diffusion current density, and scanning electron microscopy (SEM) was used to characterize the resulting deposits. Holes originating from detached hydrogen bubbles were formed among the branchy, fern-like dendrites at overpotentials outside the plateau of the limiting diffusion current density, while HER was not detected at the overpotential inside the plateau. The overpotential of electrodeposition had no significant effect on the amount of hydrogen produced (the HER current efficiency was in the 17.7-19.1 % range), but it did affect the hole size. Depending on the overpotential of the electrodeposition, the size of holes was from several to about 100 mm, including those obtained by a coalescence of neighbouring hydrogen bubbles, and decreased with the increasing overpotential. The absence of inhibition of dendritic growth in spite of a high value of evolved hydrogen was attributed to Zn, which belongs to the group of normal metals characterized by high values of both the exchange current density and the overpotential for hydrogen evolution.
2025-09-30
Harold Ames, Karen Tufinio, Karin Paucar, Jesus M. Falcón, Abel Vergara
Currently, inhibitors represent an economical option for protecting metals against corrosion. However, most inhibitors are synthetic and harmful to the environment. The present study focuses on estimating the anticorrosive effect of Oreocallis grandiflora extract (OGE) on ASTM A1011 steel immersed in a 3.5 wt.% NaCl solution. The investigation was carried out using open circuit potential (OCP) and potentiodynamic polarization curves to different concentrations of OGE in saline solution using a dynamic system. The results of potentiodynamic polarization curves indicated that the corrosion rate of ASTM A1011 steel decreased as the OGE concentration was increased. This inhibitor demonstrated an efficiency of 64 to 88 % in enhancing the corrosion resistance of the steel substrates. The value of the free energy of adsorption was -23.59 kJ mol -1 , indicating that the OGE molecules are spontaneously adsorbed onto the surface of the substrate. The results of this study showed that Oreocallis grandiflora extract has high potential as a green corrosion inhibitor, as it forms a barrier between the substrate and the corrosive solution.
2025-09-22
Sami A. Ajeel, Zamen Karm, Basheer A. Abdulhussein
Low-carbon steel is susceptible to corrosion in various technical applications, particularly in the petroleum industry. Typically, classic approaches like coatings have downsides, includeing toxicity and environmental issues. Plant-based corrosion inhibitors are emerging as new, green, and affordable corrosion preventatives. In this study, an inhibitor of Portulaca oleracea roots was extracted and added in different concentrations of 200, 400, 600, 800 and 1000 ppm to study the adsorption mechanism at low carbon steel in 3.5 % NaCl. The effectiveness of inhibition and the rate of corrosion were assessed by using the potentiometric polarization method. Corrosion rate measurements showed a decrease from 0.149 to 0.021 mm year -1 , respectively, and the maximum efficiency of 85.7 % was obtained at 1000 ppm of Portulaca oleracea extract. The data were tested for Langmuir, Flory-Huggins, El-Awady and Freundlich isotherms, and the Langmuir isotherm provided the best fit, indicating that the layer of inhibitor formed on the metal surface is a monolayer. According to the findings, the extract of Portulaca oleracea is very effective for suppressing corrosion of low-carbon steel in a 3.5 % NaCl solution.
2025-09-18
Khalid A. Mohammed
A systematic approach was adopted to independently assess erosion, corrosion, and their combined effects under controlled flow conditions that closely mimic real drilling environments. This study offers in-depth insight into how increasing flow velocities alter the prevailing degradation mechanism, transitioning from corrosion-dominated behaviour at lower speeds to erosion-driven processes at higher speeds. The effect of particle velocity on the erosion-corrosion behaviour of AISI 1020 carbon steel was investigated in a CO₂-saturated, water-based drilling mud containing 3.5 wt.% NaCl and 500 mg L -1 of sand particles (400 to 500 μm in size). Experiments were conducted using a custom jet impingement flow loop at velocities ranging from 5 to 20 m s -1 . Degradation rates and surface deterioration were evaluated through total weight loss measurements and detailed analysis using scanning electron microscopy. The results demonstrate a substantial increase in material loss as flow velocity rises, with degradation rates exceeding 20 mm year -1 at 20 m s -1 . The synergistic interaction between erosion and corrosion was most evident at lower velocities, whereas erosion alone became predominant at higher velocities. Independent erosion and corrosion tests confirmed that the material loss was caused by the combined influence of mechanical impact and electrochemical reactions. These findings emphasize that synergy decreases with increasing velocity, highlighting the transition from corrosion-assisted erosion to erosion-dominated degradation. The results provide critical insight into the velocity-dependent mechanisms of erosion–corrosion and reinforce the need for velocity management strategies to extend the service life of steel components in drilling operations.
2025-08-25
Huynh Van Chung, Nguyen Hai Phong, Dao Thi Cam Minh, Ho Xuan Anh Vu, Pham Khac Lieu, Nguyen Thi Thanh Huyen, Trinh Ngoc Dat, Doan Manh Dung, Do Thi Duyen, Dinh Quang Khieu
One of the significant durability challenges is the corrosion of reinforced concrete. A gold nanoparticle/reduced graphene oxide modified glassy carbon electrode (AuNPs-rGO-GCE) was fabricated using an electrochemical reduction method for the simultaneous determination of paracetamol (PAR) and chlorpheniramine maleate (CPM). AuNPs-rGO modified GC electrodes were prepared through direct electrochemical reduction of GO to rGO, followed by direct reduction of Au ions to Au on the rGO matrix. X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectra, Raman spectroscopy, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy characterized the resulting AuNPs-rGO. It was found that AuNPs around 15.4 nm were highly dispersed on the rGO. The modification of GCE by AuNPs-rGO accelerates the electron transfer process and increases the conductivity of the electrode. The AuNPs-rGO modified electrode was used to simultaneously determine PAR and CPM using the square-wave anodic stripping voltammetry (SQW-ASV) method. Under suitable experimental conditions, the SQW-ASV method using AuNPs-rGO-GCE showed a wide linear range from 23.7 to 140.0 µM for PAR and from 7.5 to 54.0 µM for CPM. The limit of detection of PAR and CPM was 7.12 and 2.54 µM, respectively. The proposed SQW-ASV method was applied to analyze PAR and CPM in samples of herbal medicine simultaneously, and the results were compared with those of high-performance liquid chromatography, with no statistical difference.
2025-07-31
Nadanasabapathi Sivashankar, Kadhiresan Santhanam, Shikandar Prasad, Mamidala Jawahar, Rajasekaran Thanigaivelan
Electrochemical micromachining (ECMM) is a promising non-traditional technique for fabricating micro-features on conductive materials with high precision and minimal thermal effects. This study focuses on the ECMM of galvanized iron (GI) sheets using sodium nitrate (NaNO 3 ) as the electrolyte. Key process parameters such as voltage, duty cycle, and electrolyte concentration were optimized to improve machining performance in terms of material removal rate (MRR) and overcut (OC). An L9 orthogonal array was used to design the experiments, and signal-to-noise ratio, along with analysis of variance (ANOVA), was employed to identify the most influential parameters. Results showed that voltage significantly influenced both MRR and OC, with optimal MRR observed at 12 V, 70 % duty cycle, and 20 g l -1 NaNO 3 concentration. Conversely, the minimum OC was achieved at 6 V, 50 % duty cycle and 10 g l -1 NaNO 3 electrolyte concentration. SEM analysis confirmed over-etched boundaries at higher voltage and well-defined micro-holes at lower voltage. This research demonstrates the critical role of parameter tuning in enhancing the quality and precision of ECMM on GI sheets.
2025-07-25
Marijo Buzuk, Ivana Škugor Rončević, Nives Vladislavić, Josipa Dugeč
Adrenaline, also known as epinephrine, is a hormone and neurotransmitter produced by the adrenal glands. In the bloodstream, adrenaline affects vital physiological functions such as heart rate, blood pressure and glycogen breakdown. Abnormal adrenaline levels can indicate underlying health disorders, with increases often seen in emotional or physical stress and diseases such as cancer and Parkinson's disease. Electrochemical methods are effective for detecting neurotransmitters, as they are fast-responding, easy to use, and highly sensitive. In this context, a novel electrochemical sensor has been developed for the precise and selective detection of adrenaline. The sensor, based on a glassy carbon electrode modified with a cobalt(II) coordination complex, showed improved electrochemical performance for adrenaline detection, with a linear response range of 0.1 to 2.0 μM, a detection limit of 0.09 μM, and a sensitivity of 26.92 nA μM -1 . When analysing real samples, the modified electrode showed favourable electroanalytical properties for the oxidation of adrenaline and demonstrated stability, reproducibility and suitability for use in pharmaceutical formulations. The selectivity of the sensor was confirmed by interference studies, which showed negligible response changes in the presence of common interferents, except for ascorbic acid (vitamin C).
2025-07-23
Ahmad Amer Al-Salman, Rafah Mohammed Thyab, Muhammad Abdel Hasan Shallal
A new electrochemical sensor based on a CuS-modified carbon paste electrode (CPE) was fabricated for the determination of hydrazine. In comparison with the bare CPE, the CuS-modified electrode significantly enhanced the electrooxidation performance of hydrazine by reducing the oxidation overpotential and increasing the oxidation peak current. Differential pulse voltammetry was used as the analytical method for the quantitative determination of hydrazine. The anode peak current was linearly related to hydrazine concentrations between 0.06 and 270.0 μM with a detection limit of as little as 0.02 μM. The sensor modification also showed good stability, reproducibility, and sensitivity. In addition, experimental results demonstrated the reliability and effectiveness of the sensor in determining hydrazine in various types of water samples.
2025-06-09
Irkham Irkham, Fadli Taufik Abdillah, Muhammad Ihda H. L. Zein, Adisyahputra, Nazwa Alya Zahra, Salma Nur Zakiyyah, Yeni Wahyuni Hartati
Porcine gelatin is widely used in the food and pharmaceutical industries due to its favorable functional properties and low cost. However, its presence in consumer products raises serious concerns for individuals with dietary restrictions based on religious, ethical, or health considerations. In this study, a label-free electrochemical immunosensor was developed using a boron-doped diamond electrode modified with aryl diazonium salt for the selective and sensitive detection of porcine gelatin. The diazonium electrografting enabled stable covalent immobilization of anti-porcine gelatin antibodies via protein A, preserving antibody orientation and activity. Experimental parameters were optimized using the Box-Behnken design, yielding ideal conditions of 500× antibody concentration, 60 min antibody incubation, and 15 min gelatin incubation. Detection was performed using differential pulse voltammetry with [Fe(CN)₆] 3-/4- as a redox probe, allowing label-free monitoring of antibody-antigen interactions based on changes in current. The immunosensor demonstrated excellent analytical performance, with a detection limit of 142.15 pg mL -1 . Specificity testing confirmed that the sensor responds exclusively to porcine gelatin, showing no cross-reactivity with bovine gelatin. These results demonstrate that the proposed immunosensor provides a rapid, highly sensitive, and specific platform for porcine gelatin detection, offering great potential for food authentication and halal verification.
2025-04-01
Puneeth, B. E. Kumara Swamy, S. C. Sharma
In this study, we developed a sensor utilizing a pencil graphite electrode combined with triton X-100 surfactant prepared by immobilization technique. This modified electrode can concurrently detect sunset yellow (SY) and tartrazine (TZ) in a binary mixture. Both com¬pounds are synthetic azo dyes known to have hazardous effects on human health, including the potential for malignant growth at prolonged exposure. The modified electrode shows remarkable sensitivity toward SY and TZ individually and in combination. We conducted pH studies, scan rate analysis, reproducibility tests, and simultaneous detection studies using cyclic voltammetry. Differential pulse voltammetry technique was used to investigate concentration and mutual interference effects. Our pH study found that the maximum anodic peak current for SY occurs at pH 7.4, while TZ shows a higher current at pH 7.0. The scan rate analysis indicated that anodic reactions of both dyes are adsorption process controlled. The limit of detection (LOD) and limit of quantification (LOQ) for SY are 0.17 and 0.59 µM, respectively, while for TZ, the LOD and LOQ are 0.67 and 2.26 µM, respectively. The surfactant-modified pencil electrode demonstrates excellent peak separation between SY and TZ in a binary mixture, exhibiting stability of 86.3 % for sunset yellow and 65 % for tartrazine over 25 cycles.