Potentiometric Techniques Research Articles

Little-Cost Potentiometric and Spectrophotometric Procedures for Cephalothin Assessment in Pure and Biological Fluids.

Low-cost potentiometric and spectrophotometric procedures for cephalothin (CPI) determination in pure and biological fluids were investigated. The potentiometric technique is created through titration of CPI with an aqueous medium of 0.1 M NaOH at an ionic strength of μ = 0.3 M sodium chloride and room temperature by a combined glass pH electrode. Using the standard addition method, we found that the detection and quantitative limits were 0.042 mg/mL, with the standard deviation SD = 0.011, correlation coefficient R = 0.9880 (n = 5), and linear concentration ranges from 0.042 to 0.82 mg/mL. This technique was utilized to assess CPI in pure solutions, urine, and serum with suitable results. No interference was exposed in the presence of public components of the samples under study. Recovery of CPI for pure and biological fluids is in the range of 98.2-101%. Also, the spectrophotometric method has been performed through the formation of the Prussian Blue (PB) complex. The reaction between the acidic hydrolysis product of CPI (T = 60 °C) and the mixture of Fe3+ with hexacyanoferrate (III) ions (HCF(III)) was detected for the spectrophotometric determination of the drug. The maximum absorbance of the formed complex was measured at λ = 283 nm with 2.0 × 103 L mol-1 cm-1 molar absorptivity. Reaction states have been advanced to acquire the PB complex of great sensitivity and longer stability. In optimal states, the absorbent of the PB compound was attained to grow linearly with the increase in the concentration of CPI, which agrees with the correlation coefficient values. The detection and quantitative limits were 0.000036 and 0.0012 mg/mL, respectively, with the standard deviation, SD = 0.0005, correlation coefficient, R = 0.9955 (n = 5), and the linearity range of the calibration plot 0.0005-0.02 mg/mL CPI. The planned technique was positively utilized for the detection of CPI in both urine and serum models. The results fit well with the data found from the potentiometric method.

A cutting edge potentiometric determination of baricitinib in synthetic wastewater and in tablet dosage form using modified carbon paste ion-selective membrane

After the recent hit of COVID-19, many drugs were successively administered to save patients’ lives and those drugs reached aquatic sources, one of those drugs was Baricitinib. Driven by the current situation, a potentiometric technique using an ion-selective membrane (ISM) recipe drop cast on a modified carbon paste electrode was optimized for the superior determination of Baricitinib (BAR). The molecular docking was customized to optimize the proper ionophores incorporated in the ISM, revealing that beta-cyclodextrin (β-CD) is the most compatible ionophore with the studied drug. A multivariate optimization experimental design was employed to optimize the best experimental condition for the analytical method. To this end; dual nanoparticles (multi-walled carbon nanotubes and copper oxide nanoparticles) were incorporated in the carbon paste electrode, and the ISM recipe was enriched with β-CD and cation-exchanger (phosphotungstic acid) in a polyvinylchloride matrix plasticized with dibutyl phthalate. A Nernstian slope equal to 19.97 mV/decade with a linearity range of 7.99 × 10−7–1.00 × 10−3 M was obtained. The validated sensor exhibited good recovery when used to determine the studied drug in synthetic wastewater and tablet dosage form. The greenness of the method was evaluated using the Complementary Green Analytical Procedure Index and Blue Applicability Grade Index.

A novel approach to study ascorbic acid oxidation using hexavalent chromium species—theoretical and practical perspectives of the use of potentiometric titration technique

AbstractThis paper highlights the advantages of using the potentiometric titration technique as a valuable tool for studying the oxidation reaction of ascorbic acid by hexavalent chromium species in aqueous solutions. Particular attention was paid to the method of determining diagnostic points allowing the quantification of ascorbic acid in the sample under study. Additionally, the influence of experimental conditions, specifically the pH of the system and the concentration of the reactants, on the type of hexavalent chromium species involved in the interaction with ascorbic acid was analyzed. It has been shown that the method presented provides a simple, cost-effective, and rapid tool that can be widely used for the direct determination of ascorbic acid.

Biofluid Fouling Effects on 3D Printed Ion-Selective Electrodes for Diagnostic Sensing

Research for more reliable and cost-effective sensors in healthcare applications is a global priority. This is one of the main reasons that the scientific community is pushed in development of diagnostic tools for use in point-of-care (POC) applications. The combination of electrochemistry and 3D-printing techniques in terms of POC sensor development has many advantages. Utilization of ion selective electrodes (ISEs) in potentiometric techniques has provided fast and reliable analysis as well as high selectivity for analytes in many biofluids. 3D printing, as an additive manufacturing technique, has been used in a variety of applications since it has been shown to be a low-cost and rapid fabrication technique for many sensors that can be applied in diverse POC applications. As a result, 3D-printed electrochemical sensors are used for detection of a wide range of biomarkers associated with many diseases. Several 3D printed ISEs have already been shown to selectively detect analytes in biofluids, however a comprehensive study of the effects of biofluid fouling has yet to be established. Herein, we discuss the fabrication of a novel 3D printed sodium ISE to investigate the effect of biofouling on 3D printed ISEs in comparison to conventional PVC-based ISEs. Using a custom 3D printed microfluidic device, various biofluids were introduced to understand the effects of potential ISE deterioration after prolonged use in biofluids.

Solvation-Property Relationship of Lithium-Sulfur Battery Electrolytes Probed via Potentiometric Measurements

The Li-S battery is a promising next-generation battery chemistry that offers high energy density and low cost. Li-S battery has a unique chemistry with intermediate sulfur species readily solvated in electrolytes, and understanding their implications is important from both practical and fundamental perspectives. However, the nature of the solvated sulfur species, their interactions and their impact on the battery remains elusive, in part due to the paucity of techniques. Recently, our group developed a potentiometric technique to probe the solvation free energy of electrolytes. In this study, we utilize the technique to formulate solvation-property relationships in various electrolytes and investigate its impact on the solvated lithium polysulides (LiPS). We find that solvation free energy impacts Li-S battery voltage profile, LiPS solubility, Li-S battery cyclability and the Li metal anode, which are all critical to the battery's performance. Weaker solvation leads to a lower 1st plateau voltage, higher 2nd plateau voltage, lower LiPS solubility, and superior cyclability of Li-S full cell and Li metal anode. We explore the mechanisms behind these observed phenomena and discuss the implications for the design of high-performance electrolytes for Li-S batteries.

Tungsten oxide‐iodide/poly‐2‐aminobenzenethiol nanocomposite with iodine intercalation as a promising electrode for potentiometric sensing of Pb2+ ions in water

AbstractTungsten oxide‐iodide/poly‐2‐aminobenzenethiol nanocomposite (WO2I2/P2ABT) is created through the introduction of iodine into polymer chains, where iodine serves as an oxidizing agent during the synthesis process. With a highly porous structure, the sensing capabilities of WO2I2/P2ABT for detecting Pb2+ ions are successfully demonstrated, revealing a Nernstian slope of 26.2 mV/decade. This detection is accomplished through a simple potentiometric technique, employing a simple two‐electrode cell setup. To further validate its performance, cyclic voltammetry is conducted using a three‐electrode system, revealing a remarkable sensitivity of 7.2 × 10−5 A M−1 for Pb2+ ions. The nanocomposite sensor's selectivity is rigorously examined by subjecting it to testing in the presence of 0.01 M interfering ions. The results unequivocally demonstrate that the sensor remains unresponsive to these interfering ions, underscoring its remarkable selectivity for Pb2+ ions. Moreover, the sensor's behavior is evaluated under real‐world conditions using natural samples, where, no indications of interference from other ions are observed. This is estimated by the absence of cyclic peaks in the voltammogram, indicating the sensor's unique ability to selectively detect Pb2+ ions without being perturbed by other ions that may be naturally occurring in the samples. These findings emphasize the nanocomposite sensor's potential for a wide array of applications in environmental monitoring and analytical chemistry. Its extraordinary combination of high sensitivity, impeccable selectivity, and robust performance in practical scenarios establishes it as an invaluable tool for detecting Pb2+ ions across various contexts.

Study of the Pectinase Production from Soursop and Cherimoya Pulp for Agro-Industrial Waste Reduction in Colombia

Pectic enzymes are an eco-friendly alternative to improve extraction processes for the food industry. The objective of the research was to obtain pectinase from the pulp of soursop (Annona muricata L.) and cherimoya (Annona cherimola L.), as an alternative to reduce agro-industrial waste in Colombia; involving the study of the factors influencing the protein content of the enzymes extracted from different stages and types of fruits, the conditions for enzymatic activity, and the potential application in the food industry, particularly in extraction processes and juice clarification. A factorial design 23, spectrometric and potentiometric techniques evidenced that the protein content depends on factors such as fruit stage (suitable “s” and unsuitable “u” fruits for consumption) and fruit type (soursop and cherimoya). The higher protein content was obtained by the precipitation method in comparison to ion exchange chromatography. Cherimoya fruit presented a higher protein content of 326 ± 26 mg by precipitation, however, the soursop samples evidenced higher enzymatic activity, 2.2 ± 0.1 U/mL. The pectinase obtained was an acidic enzyme of type pectin methylesterase with an enzymatic activity of 27.0 ± 0.9 U/mL, under the optimal conditions of pH 4 and temperature of 40 °C. The application in blackberry juice evidenced a decrease in the absorbance and pH changes. From the current research, the pulp of soursop and cherimoya was proven as a cheap source to obtain pectinase with enzymatic activity for juice clarification, and this process is an alternative to reduce the negative impact on the environment and an economical source for the local producers.

Enhancement in Anticancer Activity of Chitosan Tailored Imidazole-2-Thiosemicarbazones against MCF-7 Cancer Cell Line by Coordination with Copper(II) Ions

The coordination behavior of new batch synthesized chitosan imidazole-2-thiosemicarbazones tailored from both the low molecular weight commercial chitosan and high molecular weight crab shell chitosan was confirmed by Fourier Transform Infrared (FT-IR) and magnetic susceptibility measurements. Chlorine content in the complexes was estimated by potentiometric titration technique. The study showed the tridentate NNS tridentate coordination with copper (II) ion in a square planar orientation with the remaining valence satisfied by coordination with chloride ion. The MTT assay studies showed an enhancement in the anticancer activity of these chitosan thiosemicarbazone ligands upon their coordination with copper (II) ions against the human breast cancer (MCF-7) cell line in vitro. The minimal cytotoxicity of both the ligands and complexes against the normal mouse embryonic fibroblast (NIH3T3) cells revealed the selective attraction of these biomaterial chitosan derivatives towards the cancer cells with non-toxicity to healthy cells. There was only a marginal effect of molecular weight (Mw) and degree of deacetylation (DDA) of chitosan upon the anticancer activity of these chitosan derivatives.

Functionalized fennel extract-mediated alumina/cerium oxide nanocomposite potentiometric sensor for the determination of diclofenac sodium medication

The current work suggests a new, ultrasensitive green functionalized sensor for the determination of anti-inflammatory medication diclofenac sodium (DCF). Alumina (Al2O3) and cerium oxide (CeO2) nanoparticles (NPs) have attracted great interest for their use as outstanding and electroactive nanocomposite in potentiometric and sensory research due to their ultrafunctional potential. The formed nanoparticles have been confirmed using various spectroscopic and microscopic techniques. The fennel extract-mediated Al2O3/CeO2 nanocomposite (Al2O3/CeO2 NCS) modified coated wire membrane sensor developed in this study was used to quantify DCF in bulk and commercial products. Diclofenac sodium was coupled with phosphomolybdic acid (PMA) to generate diclofenac phosphomolybdate (DCF-PM) as an active ion-pair in the existence of polyvinyl chloride (PVC) and o-nitrophenyl octyl ether (o-NPOE). Clear peaks at 270, and 303 nm with band gaps of 4.59 eV and 4.09 eV were measured using UV–vis spectroscopy of Al2O3 and CeO2, respectively. The crystallite sizes of the formed nanoparticles were XRD-determined to be 30.13 ± 8, 17.72 ± 3, and 35.8 ± 0.5 nm for Al2O3, CeO2, and Al2O3/CeO2 NCS, respectively. The developed sensor showed excellent response for the measurement and assay of DCF, with a linearity between 1.0 × 10−9 and 1.0 × 10−2 mol L−1. EmV = (57.76) log [DCF] +622.69 was derived. On the other hand, the typical type DCF-PM presented a potentiometric response range of 1.0 × 10−5-1.0 × 10−2 mol L−1 and a regression equation of EmV = (56.97) log [DCF]+367.16. The functionalized sensor that was proposed was successful in determining DCF in its commercial tablets with percent recovery 99.95 ± 0.3. Method validation has been used to improve the suitability of the suggested potentiometric technique, by studying various parameters with respect to the international council harmonization requirements for analytical methodologies.

Copper(II), Nickel(II) and Zinc(II) Complexes of Peptide Fragments of Tau Protein.

Copper(II), nickel(II) and zinc(II) complexes of various peptide fragments of tau protein were studied by potentiometric and spectroscopic techniques. All peptides contained one histidyl residue and represented the sequences of tau(91-97) (Ac-AQPHTEI-NH2), tau(385-390) (Ac-KTDHGA-NH2) and tau(404-409) (Ac-SPRHLS-NH2). Imidazole-N donors of histidine were the primary metal binding sites for all peptides and all metal ions, but in the case of copper(II) and nickel(II), the deprotonated amide groups were also involved in metal binding by increasing pH. The most stable complexes were formed with copper(II) ions, but the presence of prolyl residues resulted in significant changes in the thermodynamic stability and speciation of the systems. It was also demonstrated that nickel(II) and especially zinc(II) complexes have relatively low thermodynamic stability with these peptides. The copper(II)-catalyzed oxidation of the peptides was also studied. In the presence of H2O2, the fragmentation of peptides was detected in all cases. In the simultaneous presence of H2O2 and ascorbic acid, the fragmentation of the peptide is less preferred, and the formation of 2-oxo-histidine also occurs.

Construction of Dopamine Hydrochloride Liquid Selective Electrodes

Three liquid selective electrodes were synthesized based on particle pair to selective dopamine chloride. The construction electrodes consist of phosphomolybdicacid (dopamine), di-n-butyl phosphate, Di-n-butyl phthalate, and di-octylphenyl phosphonate as plasticizers materials. The construction of preparing probes was examined potentially with successes Nernstain response around 52.50 and 50. 50 mV/decade for electrodes on both DBPH and DOPH were as plasticizers, respectively. The most direct ranges concentrations of dopamine in drug form were found to be around 2.5×10-5-1.0×10-2 for DBPH and 4.30×10-5 -1.0×10-1 M for DOPH. The detection limits were reached to 2.31×10-6 in DBPH and 5. 63×10-6 M in DOPH electrode type. While third electrode relied on di-n-butyl phosphate (DPH), a non-Nernstain equivalent of around 19.10 mV/decade with a range of concentration about 2.2×10-5 -1.0×10-1 with a detection limit equivalent to 6.35×10-6. The pH values in the experimental application were asses to obtain the best determination of dopamine concentration at 10-3M. The optimisation of both electrodes DBPH and DOPH achieved good agreements to lifetime, selectivity, potentiometric techniques and accuracy of measurements. At the same time the standard expansion, various standard expansions and potentiometric titration result in an immediate strategy for the assurance of dopamine in drug form.

Metrological characteristic of the pipette method (GOST 12536-2014) for determining soil granulometric composition

The aim of the study. To calculate precision indicators (repeatability and reproducibility) and uncertainty in determining the granulometric (grain) composition of soils using the pipette method. Methods. Using the pipette method the content of the following granulometric fractions was determined in soil samples: 0,1–0,05 mm, 0,05–0,01 mm, 0,01–0,005 mm, 0,005–0,002 mm, 0,002–0,001 mm, less than 0,01 mm, less than 0,001 mm. The determination of pH of the salt extract was carried out by potentiometric technique, and organic matter was measured photometrically. For each aliquot of the sample 16 single measurements were obtained for each soil fraction. Based on these data, precision indicators were assessed under conditions of intra-laboratory repeatability and reproducibility, uncertainty indicators were assessed as well. Main results. The following intralaboratory quality indicators were obtained for the method of determining the granulometric (grain) composition of soils using the pipette method: 1) The value of the intralaboratory repeatability indicator of analysis results (σr) ranged 0,4–1,8%. 2) The relative indicator of intralaboratory precision (σR) was within the 0,7–2,9% range. 3) Expanded uncertainty (U) for different soil fractions ranged from 0,9 to 3,9%. Conclusions. The calculated metrological characteristics of determining the granulometric (grain) composition of soils using the pipette method facilitates the internal control of the measurements quality, promoting the quality and confidence in the laboratory work.

EHDTA: a green approach to efficient Ln3+-chelators.

The rich coordination chemistry of lanthanoid ions (Ln3+) is currently exploited in a vast and continuously expanding array of applications. Chelating agents are central in the development of Ln3+-complexes and in tuning their physical and chemical properties. Most chelators for Ln3+-complexation are derived from the macrocyclic DOTA or from linear DTPA platforms, both of which arise from fossil-based starting materials. Herein, we report a green and efficient approach to a chelating agent (EHDTA), derived from cheap and largely available furfurylamine. The oxygenated heterocycle of the latter is converted to a stereochemically defined and rigid heptadentate chelator, which shows good affinity towards Ln3+ ions. A combination of NMR, relaxometric, potentiometric and spectrophotometric techniques allows us to shed light on the interesting coordination chemistry of Ln3+-EHDTA complexes, unveiling a promising ligand for the chelation of this important family of metal ions.

A family of kojic acid derivatives aimed to remediation of Pb2+ and Cd2+

The present work analyzes the complex formation ability towards Pb2+ and Cd2+ of a series of kojic acid derivatives that join the chelating properties of the pyrone molecules and those of polyamines, with the aim of evaluating how the different effects of oxygen and nitrogen coordinating groups act on the stability of metal complexes. Experimental research is carried out using potentiometric and spectrophotometric techniques supported by 1H and 13C NMR spectroscopy and DFT calculations. Actually, a different coordination mechanism toward Pb2+ and Cd2+ was proved: in the case of Pb2+, coordination takes place exclusively via the oxygen atoms, while the contribute of the nitrogen atoms appears relevant in the case of Cd2+. Lead complexes of all the studied ligands are characterized by significantly stronger stability than those of cadmium. Finally, on the basis of the measured complex formation stabilities, some of the proposed molecules seems promising effective ligands for lead and cadmium ion decorporation from polluted soils or waste waters.

High resolution electrochemical monitoring of small pH changes

Usually pH measurements are carried out using potentiometric technique. However, sensitivity of this method is low due to limitation set by Nernst equation – the moderate resolution is a significant problem in today demand for tracking small pH changes in various application areas.We propose a novel approach that allows electrochemical monitoring of pH changes with resolution reaching below 0.01 units in alkaline, acidic or close to neutral media. The proposed method uses all-solid state pH sensitive electrode with syringaldazine (Syr) modified multi-walled carbon nanotubes as the reference electrode modulating amperometric signal of Ag|AgCl electrode used as the working one. Due to high slope of the current vs. potential dependence for low-polarizable silver / silver chloride electrode relatively small changes of reference (pH-sensitive) electrode potential are transformed to pronounced changes of the recorded current. Ultimately, this results in significant increase in resolution of traced pH changes. Moreover, the current recorded is found to be linearly dependent on changes of H+ or OH− ions concentration in a broad pH range, which additionally contributes to increased resolution readout. Advantages of herein proposed approach were fully verified by monitoring minute changes of solution pH resulting from dissolution of carbon dioxide.

(Best Student Presentation) A Calorimetric and Potentiometric Titration Method to Elucidate Ca2+ Solvation Thermodynamics

Calcium metal batteries are a promising long-term sustainable alternative to lithium metal batteries due to calcium’s high natural abundance and low electrochemical redox potential. Learning how to control Ca2+ coordination chemistry is essential in enabling high performance and stable calcium batteries. While several spectroscopic and computational studies of Ca2+ coordination have been conducted, they are limited by their qualitative nature and/or require experimental validation. This work introduces a novel methodology using a combination of calorimetric and potentiometric titration techniques, to quantitatively probe electrolyte coordination shell composition, as well as previously unattainable experimental coordination enthalpy, Gibbs free energy, and entropy. To establish the effectiveness of the method, here we investigate the coordination shell thermodynamics in simpler, highly dissociating LiPF6 electrolytes. Starting with a weakly solvated electrolyte, we titrate in a strong solvent—which preferentially coordinates to Li+—and measure the associated heat release/absorption and Li+ potential change with each injection. Fitting both sets of data to a mathematical binding model allows for the extraction of the change in enthalpy (ΔHi), Gibbs free energy (ΔGi), and entropy (ΔSi) associated with each Li+-solvent complex formation. Several weak solvent and strong solvents are investigated to build a dataset of ΔHi, ΔGi, and ΔSi. These thermodynamic values are used to calculate the average coordination number of each solvent in the Li+ coordination shell which agree well with literature. Raman and NMR spectroscopy confirm salt dissociation and solvent displacement during titration. This method unlocks a precise description of the chemical environment around Li+ and enables prediction of the Li+ coordination shell in new electrolytes by rationalizing the hierarchy of solvent binding. Given that this method extends to relevant calcium electrolytes, it is a powerful tool to engineer effective electrolytes for use with a calcium metal anode.

Molecular imprinted polymer-based potentiometric approach for the assay of the co-formulated tetracycline HCl, metronidazole and bismuth subcitrate in capsules and spiked human plasma

BackgroundAn anti-H-pylori co-formulated mixture of tetracycline HCl (TET), metronidazole (MET), and bismuth subcitrate (BSC) is recently available. Only two chromatographic and spectrophotometric methods are reported for determining those drugs simultaneously where the effect of impurities that could be present as well as the biological fluids matrix influence do not be taken into consideration. There is a need to develop an easy-to-use potentiometric technique for analysis of TET, MET, and BSC in their co-formulated capsules, in presence of some official impurities and in spiked human plasma. ResultsThree carbon paste electrodes (CPEs) were fabricated for this purpose. Being a solid contact ion-selective electrode, CPE suffers from the creation of a water layer affecting its stability and reproducibility. Besides, it has a common problem in differentiation between two drugs carrying the same charge (positively charged TET and MET). Water layer formation was prevented through inserting polyaniline nanoparticles (≈10.0 nm diameter) between solid contact and ion-sensing membrane in the three proposed sensors. TET and MET interference was overcome by synthesizing a corresponding molecular imprinted polymer (MIP) for each drug. The synthesized MIPs were inserted in equivalent sensing membranes and characterized using several techniques. The suggested MIPs have a noticeable enhanced sensitivity in potentiometric determination. The obtained LODs were 5.88 × 10−8, 5.19 × 10−7, and 1.73 × 10−6 M for TET, MET and BSC proposed CPEs, respectively, with corresponding slopes of 57.37, 56.20, and −57.40 mV decade−1. SignificanceThe proposed potentiometric method makes the detection of the three cited drugs simple, fast, and feasible. This approach is the first for determining three drugs potentiometrically in one combined formulation. The obtained results were compared favorably with previously reported potentiometric methods.

A novel potentiometric approach for the sensitive detection of cadmium in real samples using modified carbon paste electrodes

AbstractThe goal of this study was to demonstrate a novel potentiometric technique for the measurement of Cd(II) ion. A new ionophore called [5′‐(ethane‐1,2‐diylbis(sulfanediyl))bis(3‐phenyl‐4H‐1,2,4‐triazol‐4‐amine) (ESPTA)] was prepared and used as an electroactive material in the fabrication of new carbon paste electrode (CPE) for the quantification of Cd(II) ion. The paste was prepared by mixing ESPTA, graphite, graphene, and TCP or o‐NPOE as a plasticizer in different weight percent ratios. The developed electrodes I, II, III, and IV showed divalent Nernstian response of 29.80±0.05, 29.80±0.08, 29.86±±0.04 and 29.75±0.33 mV decade−1 over the concentration ranges of 1.0×10−5–1.0×10−1, 1.0×10−8–1.0×10−1, 1.0×10−6–1.0×10−1 and 1.0×10−7–1.0×10−1 mol L−1 with percentage of (2.65 ESPTA: 66.32 graphite: 31.03 TCP), (2.65 ESPTA: 13.27 graphite : 53.05 graphene : 31.03 TCP), (2.75 ESPTA: 68.68 graphite: 28.57 o‐NPOE) and (2.75 ESPTA: 13.74 graphite : 54.94 graphene : 28.57 o‐NPOE), for electrodes I, II, III, and IV, respectively. In order to improve the performance characteristics of electrodes I, II, III, and IV, response time, the effect of temperature, and pH were examined. The electrodes showed high selectivity for Cd(II) over different mono‐, di‐ or trivalent cations. These modified electrodes were applied for the determination of the concentration of Cd(II) in different real samples like Nido Milk, juice extractions and tap water samples with high percentage recovery. The F‐ and t‐test values showed that there is no statistically significant difference between the results obtained and those from the stated method of inductively coupled plasma. Low standard and relative standard deviation values, good percentage recovery, and modest detection and quantification limitations were all displayed by the electrodes. The outcomes showed the potentiometric method‘s effectiveness in detecting Cd(II) in actual samples and its potential for use in routine analysis.

The behavior of indium in dilute sodium tetraborate containing bromide ions in the presence of some ethoxylated surfactants

The potentiometric technique was used to study the oxide film repair and destruction on indium electrodes in 0.01 M Na2B4O7 containing various amounts of Br- ions. Higher amounts of Br- ions, ≥5 × 10−2 M, reduces the oxide film growth and initiate the destruction of oxide film by inducing pitting corrosion. The initiation of pitting corrosion is raised with the addition of more concentrations of Br- ions and raising the temperature. Some freshly prepared ethoxylated surfactant molecules, ETO I, ETO II, and ETO III were utilized as inhibitors to resist the oxide film destruction and sustain the oxide film repair with the formation of a layer of surfactant molecules. The protection efficacy of such molecules is found to rely on the concentration of the surfactant besides the number of ethylene oxide monomers per molecule. The inhibition efficacy reaches 87.8 %, 83.1 %, and 79.5 % with ETO III, ETO II, and ETO I, successively, at 0.01 M inhibitor concentration and 25 ºC. The inhibition mechanism relies on an adsorption process obeying Langmuir's model. The thermodynamic adsorption functions. Viz, Kads, and ∆G°ads are computed and explained. The inhibition efficacy of such compounds decreases in the order, ETO III> ETO II> ETO I.

MBE Grown Vanadium Oxide Thin Films for Enhanced Non‐Enzymatic Glucose Sensing

AbstractIn the search for non‐enzymatic alternatives to glucose oxidase, reliable and microchip‐compatible approaches to catalyst development are highly desirable. Herein, the electrochemical behavior of thin films of VOx deposited by molecular beam epitaxy (MBE) on glassy carbon electrodes is reported . A process of partial etching during polarization is observed. Thereafter, highly active and stable traces of VOx act as catalytic centers for glucose electrooxidation. A mechanistic description of the electrochemical process is proposed based on evidence provided by voltammetric measurements. The sensors are calibrated both with potentiometric and amperometric techniques, the former showing a wide linear range (1–10 mM), good sensitivity (14.93 ± 0.39 µA cm−2 × mM–1) and a limit of detection (0.32 m‐M). Unlike most metal oxides, it is shown that VOx on glassy carbon is capable of successfully oxidizing glucose at −0.4 V. Such a one‐of‐kind behavior can have important ramifications for energy‐efficient integrated electrochemical sensors and non‐enzymatic glucose sensing as a whole.