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The acid ionization constants (pKa) of the N-benzoylthiourea / 2-thiohydantoin-pyrrolidines were determined by the potentiometric titration method. Titrations were performed by adding sodium chloride, which gives ionic strength, and hydrochloric acid, which is required for the protonation of the ionizable groups, to 2x10-4 M solutions of the synthesized compounds prepared in an acetonitrile-water (20:80, v / v) solvent system at 25 ± 0.1 °C and sodium hydroxide was used as a titrant. The HYPERQUAD computer program was utilized to determine acid ionization constants based on the data obtained from the Molspin Titration System. Analyzing the obtained results, it is possible to propose three pKa (pKa1, pKa2, and pKa3) values that correspond to the enol, thiol, and NH species for N-benzoylthiourea derivatives in the range of 3.02-10.91 and carboxyl, enol and enthiol species for thiohydantoin derivatives in the range of 2.13-10.96. [ABSTRACT FROM AUTHOR]

The suitability of various nitrogen, sulfur, oxygen, and phosphorus compounds as complexing agents in a silver electrolyte was examined by using potentiometric titration under practical conditions. The setup consisted of three electrodes to measure the pH and the activity of the silver ions simultaneously. Different ratios of silver to complexing agent from 1:10 to 1:1 at a constant ionic strength of 0.2 mol/L were investigated. The type of the complexes and their corresponding critical stability constants were evaluated by fitting the measured data using a self-developed algorithm. The pH and Nernst potential curve were calculated for the assumed complexes based on the law of mass action to find the best approximation. The correct definition of the occurring species is challenging and can lead to significant changes in the calculation of stability constants. For this reason, the measured silver potential curves were primarily used for the rating of the complexing agents. An evaluation of the measurements shows that the donor atom of the complexing agent and its ligand field strongly affected the stability and type of the complexes. Only a few complexing agents were found to be suitable for use in the cyanide-free silver electrolyte. [ABSTRACT FROM AUTHOR]

A new construction of a potentiometric sensor was introduced for the first time. It relies on the use of two membranes instead of one, as in the well-known coated-disc electrode. For this purpose, a new electrode body was constructed, including not one, but two glassy carbon discs covered with an ion-selective membrane. This solution allows for the sensor properties to be enhanced without using additional materials (layers or additives) on the membrane. The new construction is particularly useful for in situ measurements in environmental samples. Two ion-selective polymeric membranes were used, namely H+ and K+-selective membranes, to confirm the universality of the idea. The tests conducted included chronopotentiometric tests, electrochemical impedance spectroscopy, and potentiometric measurements. The electrical and analytical parameters of the sensors were evaluated and compared for all tested electrodes to evaluate the properties of the planar electrode versus previously known constructions. Research has shown that the application of two membranes instead of one allows for the resistance of an electrode to be lowered and for the electrical capacitance to be elevated. Improving the electrical properties of an electrode resulted in the enhancement of its analytical properties. The pH measurement range of the planar electrode is 2–11, which is much wider in contrast to that of the single-membrane electrode. The linear range of the K+-selective planar electrode is wider than that of the coated-disc electrode and equals 10−6 to 10−1 M. The response time turned out to be a few seconds shorter, and the potential drift was smaller due to the application of an additional membrane in the electrode construction. This research creates a new opportunity to design robust potentiometric sensors, as the presented construction is universal and can be used to obtain electrodes selective to various ions. [ABSTRACT FROM AUTHOR]

Two new surfactant sensors were developed by synthesizing Pt-doped acid-activated multi-walled carbon nanotubes (Pt@MWCNTs). Two different ionophores using Pt@MWCNTs, a new plasticizer, and (a) cationic surfactant 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-DHBI (Pt@MWCNT-DHBI ionophore) and (b) anionic surfactant dodecylbenzenesulfonate-DBS (Pt@MWCNT-DBS ionophore) composites were successfully synthesized and characterized. Both surfactant sensors showed a response to anionic surfactants (dodecylsulfate (SDS) and DBS) and cationic surfactants (cetylpyridinium chloride (CPC) and hexadecyltrimethylammonium bromide (CTAB)). The Pt@MWCNT-DBS sensor showed lower sensitivity than expected with the sub-Nernstian response of ≈23 mV/decade of activity for CPC and CTAB and ≈33 mV/decade of activity for SDS and DBS. The Pt@MWCNT-DHBI surfactant sensor had superior response properties, including a Nernstian response to SDS (59.1 mV/decade) and a near-Nernstian response to DBS (57.5 mV/decade), with linear response regions for both anionic surfactants down to ≈2 × 10−6 M. The Pt@MWCNT-DHBI was also useful in critical micellar concentration (CMC) detection. Common anions showed very low interferences with the sensor. The sensor was successfully employed for the potentiometric titration of a technical grade cationic surfactant with good recoveries. The content of cationic surfactants was measured in six samples of complex commercial detergents. The Pt@MWCNT-DHBI surfactant sensor showed good agreement with the ISE surfactant sensor and classical two-phase titration and could be used as an analytical tool in quality control. [ABSTRACT FROM AUTHOR]

The understanding of the thermodynamic stability and speciation of metal complexes in solution requires access to their enthalpy and entropy of formation. In this work, we specifically focus our investigation on the complexation process of silver(I) ion in acetonitrile (AN) with substituted mono pyridines and cyclic monoamines. The aim of this study is to provide reliable thermodynamic data to obtain insights on metal complex formation, focusing on ligands donor properties and solvation effects. Carefully designed potentiometric and calorimetric experiments allowed to define the species present at different ligand/metal ratios and to obtain the complex formation constants and enthalpies. In general, the enthalpy terms associated with the complex formation are highly exothermic, while the entropy values are always unfavorable. The formation constants of AgLj species for the ligands investigated in AN are compared with those previously obtained in dimethyl sulfoxide (DMSO) and water. The trends in stability constants and enthalpy values are discussed in relation to the pKa data available in the different solvents. Higher pKa values correspond to greater ligand basicity and result in more stable and more enthalpy stabilized complexes. [ABSTRACT FROM AUTHOR]

Amine solvents remain popular in the industries for post combustion carbon dioxide (CO2) capture. Dissociation constant of basic amine solvents plays significant role to influence the CO2 absorption. It is thus important to study the dissociation of new amine solvents for assessing their viability for CO2 capture. In the present work, potentiometric titration method is employed to determine the dissociation constants of dibasic (e. g. Piperazine (PZ), 1‐methyl piperazine (1‐MPZ) and tribasic amines (1‐(2‐aminoethyl‐piperazine) (AEPZ) which could be promising for formulating blended solvent system towards enhancing the rate of CO2 absorption. The estimated dissociation constants for the PZ and 1‐MPZ while match well with reported results, the dissociation constants for AEPZ has been determined newly here within the temperature range 298—318 K. In addition, the structural geometric parameters and Natural Bond Order (NBO) calculations of the amine solvents are performed based on Density Functional Theory (DFT). The NBO calculations predict charge distribution on the nitrogen and other elements, and envisage its effect on the pKa values of the amines. Further, potential energy surface (PES) scanning calculations are performed for AEPZ to explain it's ring inversion which is responsible for obtaining a single pKa value in experimental studies. [ABSTRACT FROM AUTHOR]

The kinetic features of electrodeposition of wear- and corrosion-resistant composite electrochemical coating (CEC) of nickel–cobalt–alumina from a chloride colloidal electrolyte are studied. The application of potentiodynamic, chronopotentiometric and temperature–kinetic methods, as well as the use of the calculated temperature coefficient of reaction rate and the diffusion coefficients of nickel ions, enabled us to determine the mechanism of CEC electrodeposition. The analysis of the data on the kinetic features of CEC electrodeposition showed that the nature of the slow stage of the process is associated with the electrophoretic transfer of electroactive particles to the cathode and the stage of the overgrowth of dispersed particles adsorbed on the cathode surface with the electrodeposited metals, which proceed at comparable rates. [ABSTRACT FROM AUTHOR]

In this research, a coated graphite polyvinyl chloride (PVC) membrane electrode was fabricated for the potentiometric determination of lithium based on 13-(3-nitrophenyl)-12H,14H-benzo[g]chromeno[2,3-b]chromene-7,12,14(13H)-trione (L) as the ionophore. The best Nernstian response was observed from the membrane composition of 31% PVC, 7% L, 2% NaTPB, and 60% dioctyl phthalate (DOP) as the plasticizer. The designed sensor showed a wide linearity over the concentration range of 1 x 10-8-1 x 10-3 M with a slope of 60.2 ± 0.3 mV decade-1, and the limit of detection (LOD) of 7.5 x 10-9 M. The selectivity of the designed sensor was investigated by the matched potential method and no serious interference was observed. The response time and life span of the electrode were 5 s and 16 weeks, respectively. The potential response of the electrode was independent of solution pH in the pH range of 3.0-12.0. The influence of the presence of organic solvents on the potential response of the electrode was also scrutinized, and the results showed that the designed sensor keeps its Nernstian behavior in solutions with 20% non-aqueous content. In the end, the electrode was successfully applied to determine lithium carbonate in tablet, urine, and serum samples with recovery% values of 96.0 to 106.33 and RSD% 1.99-4.45. [ABSTRACT FROM AUTHOR]

Silicotungstic acid potassium salts had the silicon heteroatom substituted by Co(III) or Co(II) cations and were evaluated as catalysts in oxidation reactions of terpenic alcohols with hydrogen peroxide. Borneol was the model molecule selected. All the catalyst salts were characterized by Fourier-transformed infrared, ultraviolet–visible and Raman spectroscopies, thermal analyses, powder X-rays diffraction and cyclic voltammetry analyses, energy dispersive X-ray spectroscopy and scam electronic microscopy (SEM) analyses, potentiometric titration. This set of techniques revealed that salts containing Co(II) or Co(III) as the heteroatom were successfully obtained. The activity of potassium dodecatungstocobaltate(III) (i.e., K5CoIIIW12O40) was compared to other tungsten heteropoly catalysts (i.e., H4SiW12O40, K4SiW12O40, K6CoIIW12O40, Co2SiW12O40) and the precursor CoCl2. Among the various heteropoly compound investigated, the K5CoIIIW12O40 salt was the most active and selective catalyst toward oxidation product (i.e., camphor). Conversion and selectivity higher than 90% were achieved, indicating the high efficiency of this catalyst. The effects of the main reaction parameters such as temperature, the stoichiometry of reactants, type and catalyst load, were investigated. Special attention was given to correlating the structural properties of catalysts with their activity. Based on experimental data, a reaction pathway was proposed. As far as we know, it is the first time that silicotungstic acid-derived salts having heteroatom Co(II) or Co(III) cations, were used as catalysts in oxidation reactions of terpene alcohols. The effect of the oxidation state and position of Co on the activity of silicotungstic acid was evaluated. The H4SiW12O40 had the Si(IV) heteroatom exchanged with Co(II) or Co(III). Their potassium salts were tested in borneol oxidation reactions with H2O2 being the K5CoIIIW12O40 the most active and selective catalyst. [ABSTRACT FROM AUTHOR]

The use of an electrochemical approach for assessment of the oxidative stress severity is a promising direction for point-of-care testing development, which is especially important for critically ill patients. The aim of this study was to determine the influence of different types of blood collection tubes (with clot activator and separating gel, lithium heparin, sodium citrate and K2EDTA) and storage conditions (at 25, 4 and -23 °C up to 5 days) on the electrochemical analysis of the antioxidant status of blood plasma, assessed by measuring the open circuit potential of platinum electrode (OCP) and antioxidant capacity via cyclic voltammetry method (q). It was obtained that blood collection tubes with lithium heparin and clot activator are the most suitable for the electrochemical analysis of antioxidant status of blood plasma, since they do not affect the results of measurements. Furthermore, data obtained during storage blood plasma samples in different temperature conditions indicate that it is preferable to perform electrochemical analysis in fresh samples. [ABSTRACT FROM AUTHOR]

Purpose: Degraded soils are unable to perform key functions and, thus, it is very important to develop effective reclamation methods. To restore utility or natural values to degraded ecosystems, various compounds are applied. In this study, the impacts of additives of various origin and composition on Polish (Eutric Cambisol) and Bulgarian (Epicalcic Chernozem) soils were compared. The main goal of the study was to make a comprehensive assessment of the validity of using popular soil additives in a real context. Materials and methods: Physicochemical and hydrophysical parameters including pH, variable surface charge, porosity, specific surface area, wettability, sorption capacity relative to trace metals, and water retention of soils were taken into account. Surface charge and porosity of soils were determined using potentiometric titration and nitrogen adsorption/desorption method, respectively. Wettability was measured by sessile-drop method, whereas water retention, using different matric potentials (pF curves). Sorption study on trace metals included isotherm and kinetics determination as well as experimental data modeling. Results and discussion: The most positive effect on soil surface charge, porosity, wettability, and cadmium (Cd) sorption was observed for synthetic zeolite, zeolite-carbon composite, and vermicompost. This effect was noted only for Polish soil characterized by poor porosity, low content of organic carbon, and moderately acidic reaction. For eroded Bulgarian soil, the condition of which was definitely better, the impact of modifiers was not spectacular. Among tested amendments, only divergan increased water retention properties of both examined soils significantly. Conclusions: Zeolite, zeolite-carbon composite, and vermicompost can be apply for degraded soils of low organic carbon content, poor porosity, and moderately acidic pH to improve their physicochemical parameters and sorption ability toward trace metals. Divergan should be used to improve water retention of degraded soils during their reclamation. [ABSTRACT FROM AUTHOR]

In this study, a new sulfonyl hydrazone derivative molecule was synthesized, and its characterization was performed using several spectroscopic methods (1H–, 13C NMR, FT–IR and Q-TOF). New potentiometric sensors were developed using this molecule, and subsequently, their potentiometric performance properties were investigated. Based on the data obtained, we found that the prepared sensors are selective to Pb2+ ions. These novel lead(II)–selective sensors had a low detection limit of 2.89 × 10–6 M, and a Nernstian response (27.7 ± 1.3 mV/decade) over a wide concentration range of 1.0 × 10–5–1.0 × 10–1 M. They were also highly reproducible, selective and able to work in a wide pH range (3.0–9.0) without being affected by the changes in pH. We showed that these potentiometric sensors can detect Pb2+ ions with very high recoveries when applied to real samples. In conclusion, we here report the synthesis and characterization of a new molecule and its potentiometric sensor properties. [ABSTRACT FROM AUTHOR]

Objective: The determination of pKa values holds paramount importance in the field of medicinal chemistry, serving as a critical parameter for understanding the ionization behavior of pharmaceutical compounds. This study employs potentiometric titration as a precise method to elucidate the pKa values of diverse molecules. The experimental methodology involved a carefully controlled titration setup, utilizing a pH meter to monitor the titration curve and identify inflection points corresponding to the dissociation of acidic or basic functional groups. Methods: Potentiometric titration was conducted using a standardized protocol. Each compound was titrated with a titrant solution of known concentration, and pH measurements were recorded throughout the titration process. The titration curves were analyzed to determine the pKa values of the compounds based on the points of inflection. Results: The potentiometric titration method successfully provided accurate and reproducible pKa values for the studied compounds. The pKa values for the active ingredients Diclofenac, Clavunate potassium, and Levetiracetam are 3.31, 3.53, and 11.3, respectively. Compounds with pKa values below 7 are unlikely to be significantly protonated at physiological pH, which is approximately 7.4. Conclusion: The study underscores the critical role of pKa values in guiding medicinal chemistry efforts. The potentiometric titration method proved to be an effective tool for determining these constants, contributing essential data for rational drug design. The correlation between pKa values and pharmacokinetic properties emphasizes the relevance of this approach in optimizing drug candidates for enhanced therapeutic outcomes. [ABSTRACT FROM AUTHOR]

The present work aimed at comparing the capabilities and efficiency of symmetric and asymmetric electrodes for potentiometric detection of Cu2+. Initially, we synthesized N-(benzothiazol-2-ylcarbamothioyl)benzamide, and ¹H-NMR, 13C-NMR, and FT-IR spectroscopy approaches were used for characterization. Subsequently, it was employed as an ionophore to fabricate asymmetric electrodes of coated wire (CWE) and solid-state (SSE) and symmetric electrodes with liquid internal electrolyte (LIE). The best liquid membrane was prepared with an Ionophore: DBP: PVC: NaTPB ratio of 12:56:30:2. All electrodes exhibited Nernstian responses. The detection limits for SSE (1×10-9 mol/L) and CWE (1×10-7 mol/L) were superior to LIE (2×10-6 mol/L). Moreover, all three electrodes demonstrated very short response times (approximately 6 seconds) and exhibited large selectivity coefficient values for different cations. Asymmetric electrodes displayed longer lifetimes (SSE: 13 weeks and CWE: 12 weeks) compared to the symmetric electrode (LIE: 10 weeks). Finally, the electrodes were utilized for potentiometric titration of Cu2+ with ethylenediaminetetraacetic acid. [ABSTRACT FROM AUTHOR]

Abstract Self‐powered pressure detection using smart wearable devices is the subject of intense research attention, which is intended to address the critical need for prolonged and uninterrupted operations. Current piezoelectric and triboelectric sensors well respond to dynamic stimuli while overlooking static stimuli. This study proposes a dual‐response potentiometric pressure sensor that responds to both dynamic and static stimuli. The proposed sensor utilizes interdigital electrodes with MnO2/carbon/polyvinyl alcohol (PVA) as the cathode and conductive silver paste as the anode. The electrolyte layer incorporates a mixed hydrogel of PVA and phosphoric acid. The optimized interdigital electrodes and sandpaper‐like microstructured surface of the hydrogel electrolyte contribute to enhanced performance by facilitating an increased contact area between the electrolyte and electrodes. The sensor features an open‐circuit voltage of 0.927 V, a short‐circuit current of 6 µA, a higher sensitivity of 14 mV/kPa, and outstanding cycling performance (>5000 cycles). It can accurately recognize letter writing and enable capacitor charging and LED lighting. Additionally, a data acquisition and display system employing the proposed sensor, which facilitates the monitoring of athletes’ rehabilitation training, and machine learning algorithms that effectively guide rehabilitation actions are presented. This study offers novel solutions for the future development of smart wearable devices.

This paper presents the development of a non-toxic and low-cost potassium ion sensor utilizing an Extended Gate Field-Effect Transistor (EGFET) configuration with all-solid-state electrodes fabricated on a printed circuit board (PCB) substrate. An Ag/AgCl-based pseudo-reference electrode (PRE) has been fabricated planar to a ion-selective membrane (ISM) coated on the gold solid-contact electrode (SCE). The PRE has shown $\lt 1~mV/day$ drift potential, exhibiting exceptional stability and reproducibility. While the SCE has demonstrated a high sensitivity of $49~mV/log[K^{+}]$ , covering a wide linear detection range from $10^{-4}~M$ to $1~M$ with a rapid response time of less than 10 seconds. The sensor has displayed minimal hysteresis ( $\lt 15~mV$ ) and remained stable over a broad pH range ( $pH~4$ to $pH~10$ ). These uni-planar, all-solid-state electrodes along with off-the-shelf FET mitigate the requirement of additional wire bonding by utilizing a common PCB platform for sensing as well as circuitry area. Additionally, the PRE, SCE and the FET in the EGFET-configuration-based sensing system have exhibited a high current sensitivity of $1.43~(\mu A)^{1/2}/log[K^{+}]$ . Our sensor presents a practical and reliable solution for soil nutrient measurement in precision agriculture, offering significant advantages over existing potassium sensors in terms of cost-effectiveness, sensitivity, stability, and environmental safety. The presented approach holds promise for optimizing agricultural productivity and minimizing environmental impact through efficient nutrient monitoring and smart irrigation and fertilization management systems.

Ensuring the long-term stability of screen-printed (SP) reference electrodes (REs) is increasingly essential because a major technical challenge in fabricating electrochemical sensors using screen printing is preparing an RE with a stable potential as it scales down in size. In this study, we fabricated SP electrodes that exhibit long-term stability in voltammetric and potentiometric experiments. The SP electrodes consisted of carbon working electrodes, a carbon counter electrode, an Ag/AgCl RE, and an ion-selective electrode (ISE) for detecting nitrate ions. The Ag/AgCl RE featured an electrolyte layer, a hydrophobic junction layer, and a small hole, collectively contributing to its long-term stability. This design achieved potential stability with minimal drift over extended periods in both 0.01 M PBS (pH 7.4) and 0.1 M Bis-tris (pH 6.5) buffer solutions. Additionally, the SP Ag/AgCl RE exhibited relatively low potential drift in the presence of various chemicals and different pH solutions. We analyzed the electrochemical behavior of two redox species, Fe(CN)63-/4− and Ru(NH3)62+/3+, using cyclic voltammetry and electrochemical impedance spectroscopy techniques at the SP electrodes. Potentiometric experiments confirmed the sensitivity, long-term stability, and selectivity of the SP ISE for nitrate ion detection, even in the presence of interfering ions.

Mobile phase pH is a critically important parameter in reversed-phase liquid chromatographic (RPLC) separations involving analytes that display acidic or basic properties in the pH range used for the mobile phase. The main problem in measuring mobile phase pH lies in the fact that RPLC mobile phases are typically aqueous–organic mixtures. In addition to experimental difficulties, the pH values refer to different aqueous–organic compositions that cannot be correctly compared. Given this situation, the unified pH (wabs pH, also termed as) based on the absolute chemical potential of the solvated proton has been proposed as a rigorous way of characterising mobile phase acidity that is fully inter-comparable between mobile phases of any composition. Here we report the wabs pH values of 78 reversed-phase liquid chromatography-mass spectrometry mobile phases that were carefully measured by potential differences in a symmetric cell with two glass electrode half-cells and almost ideal ionic liquid triethylamylammonium bis((trifluoromethyl)sulfonyl)imide [N2225][NTf2] salt bridge with multiple overlapping measurements. The system of altogether 300 Δ wabs pH values was anchored to the pH value of standard pH 7.00 aqueous buffer solution. The consistency standard deviation of the whole set of measurements was 0.09 pH units. In addition to the differential potentiometric reference method, simpler measurement methods that use double junction reference or double junction combined electrodes were tested and were found suitable for routine laboratories if high accuracy is not required. [ABSTRACT FROM AUTHOR]

The new era of solid contact ion selective electrodes (SC-ISEs) miniaturized design has received an extensive amount of concern. Because it eliminated the requirement for ongoing internal solution composition optimization and created a two-phase system with stronger detection limitations. Herein, the determination of venlafaxine HCl is based on a comparison study between different ion- to electron transduction materials (such as; multiwalled carbon nanotubes (MWCNTs), polyaniline (PANi), and ferrocene) and illustrating their mechanisms in their applied sensors. Their different electrochemical features (such as bulk resistance (Rb**), double-layer capacitance (Cdl), geometric capacitance (Cg), and specific capacitance (Cp)) were evaluated and discussed by using the Electrochemical Impedance Spectroscopy (EIS), Chronopotentiometry (CP), and Cyclic Voltammetry (CV) experiments. The results indicated that each transducer's influence on the proposed sensor's electrochemical characteristics is determined by their unique chemical and physical properties. The electrochemical features vary for different solid contact materials used in transduction mechanisms. The results confirm that the MWCNT sensor revealed the best electrochemical behavior with the potentiometric response of a near-Nernestian slope of 56.1 ± 0.8 mV/decade with detection limits of 3.8 × 10−6 mol/L (r2 = 0.999) and a low potential drift (∆E/∆t) of 34.6 µV/s. Also, the selectivity study was performed in the presence of different interfering species either in single or complex matrices. This demonstrates excellent selectivity, stability, conductivity, and reliability as a VEN-TPB ion pair sensor for accurately measuring VEN in its various formulations. The proposed method was compared to HPLC reported technique and confirmed no significant difference between them. So, the proposed sensors fulfill their solutions' demand features for VEN appraisal. [ABSTRACT FROM AUTHOR]

Skin cancer and other skin-related inflammatory pathologies are rising due to heightened exposure to environmental pollutants and carcinogens. In this context, natural products and repurposed compounds hold promise as novel therapeutic and preventive agents. Strengthening the skin's antioxidant defense mechanisms is pivotal in neutralizing reactive oxygen species (ROS) and mitigating oxidative stress. Sunset Yellow (SY) exhibits immunomodulatory characteristics, evidenced by its capacity to partially inhibit the secretion of proinflammatory cytokines, regulate immune cell populations, and modulate the activation of lymphocytes. This study aimed to investigate the antioxidant and anti-genotoxic properties of SY using in-silico, in vitro, and physiochemical test systems, and to further explore its potential role in 7,12-dimethylbenz(a) anthracene (DMBA)/ 12-o-tetradecanoylphorbol-13-acetate (TPA)-induced two-stage skin carcinogenesis. In vitro experiments showed that pre-treatment of SY significantly enhanced the cell viability of HaCaT cells when exposed to tertiary-Butyl Hydrogen Peroxide (tBHP). This increase was accompanied by reduced ROS levels, restoration of mitochondrial membrane potential, and notable reduction in DNA damage in (SY + tBHP) treated cells. Mechanistic investigations using DPPH chemical antioxidant activity test and potentiometric titrations confirmed SY's antioxidant properties, with a standard reduction potential ( E o ) of 0.211 V. Remarkably, evaluating the effect of topical application of SY in DMBA/TPA-induced two-step skin carcinogenesis model revealed dose-dependent decreases in tumor latency, incidence, yield, and burden over 21-weeks. Furthermore, computational analysis and experimental validations identified GSK3β, KEAP1 and EGFR as putative molecular targets of SY. Collectively, our findings reveal that SY enhances cellular antioxidant defenses, exhibits anti-genotoxic effects, and functions as a promising chemopreventive agent. [ABSTRACT FROM AUTHOR]

In general, concepts such as chemical equilibria and classical analytical chemistry, as well as instrumental methods such as potentiometry and flow injection analysis (FIA), are taught separately in the curricula of chemistry-related degree programs. However, FIA provides an opportunity to connect all of these important topics. This article shows how simple experiments can be used to link the fundamentals of FIA and potentiometry to the fundamentals of chemical equilibria and teach them in a sustainable way. The experiments were designed for undergraduate environmental science students with basic knowledge of chemical equilibria and classical analytical chemistry and minimal knowledge of electrochemistry. However, they can also be integrated into various courses on instrumental analysis in chemistry-related degree programs. [ABSTRACT FROM AUTHOR]

The potential of several ion-sensitive electrodes responds to the incorporated cations and anions. This has led some authors to misinterpret the potential of metal salt membrane electrodes and of electrodes of the second kind. Neglecting the kinetics of potential establishment and interpreting the potentials solely based on thermodynamics produce completely irrelevant data and suggest that ion concentrations down to 10−45 mol L−1 are accessible by simple potentiometric measurements. The switching from cation to anion response mechanism cannot be derived from thermodynamic equations. It bears complete similarity to the switching of response in the case of foreign interfering ions. [ABSTRACT FROM AUTHOR]

Cisplatin is an anticancer drug that can be used to treat a variety of solid tumors, where clinical use may be affected by several factors, including dose-limiting side effects and the emergence of drug resistance. Micellar-forming polymeric conjugates are a type of polymeric nanocarrier that can preferentially accumulate in tumors, thereby increasing therapeutic efficacy. In the current study, carboxylated PiPOx was synthesized first using a click reaction of 2-isopropenyl 2-oxazoline (iPOx) with thioglycolic acid (TGA) or methyl thioglycolate, followed by methyl triflate-initiated cationic ring opening polymerization (CROP). Next, different strategies were employed to prepare carboxylated PiPOx-mPEG copolymers: (a) CROP was initiated by iPOx-modified mPEG-thiol, (b) TGA-modified PiPOx were end-capped with mPEG-NH2, or (c) TGA-modified iPOx and iPOx-modified mPEG-thiol were randomly copolymerized. 1H-NMR, FT-IR, SEC, and potentiometric titration methods were used to characterize the synthesized polymers. Cisplatin-polymer conjugation was performed at three ratios of drug-to-polymer carboxyl groups (0.25, 0.5, and 1), and the conjugated cisplatin content was determined using UV–vis spectroscopy at 705 nm with O-phenylenediamine reagent. The cisplatin loading efficiencies (%) were 59.3, 26.7, and 91.0 for the respective copolymers at the chosen cisplatin/carboxyl 1:1 mol ratio. Cisplatin-conjugated PiPOx(TGA)-b-mPEG and mPEG-g-PiPOx(TGA) had mean hydrodynamic sizes of 113.3 and 178.8 nm, respectively. TEM imaging confirmed the formation of discrete and spherical particles of the cisplatin-conjugated copolymer. The MTT cytotoxicity assay demonstrated higher cytotoxicity of PiPOx(TGA)-b-mPEG compared to PiPOx(TGA)-g-mPEG polymers in both sensitive and resistant ovarian cancer cells. The IC50 values were approximately 113 µg/ml for PiPOx(TGA)-b-mPEG and 232 µg/ml for PiPOx(TGA)-g-mPEG in resistant tumor cells, confirming the potential application of cisplatin-conjugated copolymers in cancer chemotherapy. [ABSTRACT FROM AUTHOR]

The syntheses of two macrocycles containing original imidazothiadiazole heterocycles are presented. The protonation constants of the ligands have been determined by potentiometry and photophysical measurements. The photophysical properties of the corresponding Tb3+ complexes have been analyzed and the sensitization of the Tb3+ by the heterocyclic moiety demonstrated with modest quantum yields. The corresponding Gd3+ complexes are monohydrated and display higher relaxivities than GdDOTA, which could be explained by the larger size of these complexes. The different substitutions on the heterocycle do not affect strongly the protonation constants of the ligand, the quantum yield, water exchange rate or relaxation properties of the system. [ABSTRACT FROM AUTHOR]

Organic ammonium and phosphonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Particularly, quaternary ammonium lipids have demonstrated efficiency both as gene vectors and antibacterial agents. Here, aiming at finding new antibacterial devices belonging to both classes, we prepared a water-soluble quaternary ammonium lipid (6) and a phosphonium salt (1) by designing a synthetic path where 1 would be an intermediate to achieve 6. All synthesized compounds were characterized by Fourier-transform infrared spectroscopy and Nuclear Magnetic Resonance. Additionally, potentiometric titrations of NH3+ groups 1 and 6 were performed to further confirm their structure by determining their experimental molecular weight. The antibacterial activities of 1 and 6 were assessed first against a selection of multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species, observing remarkable antibacterial activity of both compounds against Gram-positive isolates of Enterococcus and Staphylococcus genus. Further investigations on a wider variety of strains of these species confirmed the remarkable antibacterial effects of 1 and 6 (MICs = 4–16 and 4–64 µg/mL, respectively), while 24 h-time-killing experiments carried out with 1 on different S. aureus isolates evidenced a bacteriostatic behavior. Moreover, both compounds 1 and 6, at the lower MIC concentration, did not show significant cytotoxic effects when exposed to HepG2 human hepatic cell lines, paving the way for their potential clinical application. [ABSTRACT FROM AUTHOR]

Three liquid selective electrodes were synthesized based on particle pair to selective dopamine chloride. The construction electrodes consist of phosphomolybdic acid (dopamine), di-n-butyl phosphate, Di-n-butyl phthalate, and di-octylphenylphosphonate 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. [ABSTRACT FROM AUTHOR]

A new all-solid-state ion selective electrode (ASS-ISE) was developed for the determination of thulium trivalent cation. The potentiometric sensor was made by depositing a thin PVC membrane containing N'-[(2-hydroxyphenyl)methylidene]-2-furohydrazide (L) as a selectophore on a conducting solid-state electrode. The solid-state electrode was a thin copper wire coated by a mixture of multi-walled carbon nanotubes (MWCNTs) and an epoxy resin. The optimal composition of the PVC membrane was 25%wt. of PVC powder, 68% wt. of benzyl acetate, 2% wt. of sodium tetraphenyl borate (NaTPB)), and 5% wt. of L. The sensor showed good selectivity for Tm3+ ion with a Nernstian calibration plot slope of 19.6±0.4 mV/decade in Tm3+ ion solutions with concentrations ranging from 1.0×10-8 M to 1.0×10-3 M, and its limit of detection was as low as 6.3×10-9 M. The proposed sensor was able to detect Tm3+ cations in the wastewater matrix. [ABSTRACT FROM AUTHOR]

In the present work, N-(imidazol-2-ylcarbamothioyl)benzamide was developed and employed as an ionophore for preparing three kinds of membrane chromium(III) selective electrode including electrode with liquid internal electrolyte (LIE), solid-state electrode (SSE) and coated wire electrode (CWE). Optimal membrane composition was determined to be 2% sodium tetraphenylborate, 58% dibutyl phthalate, 10% ionophore, and 30% polyvinyl chloride, resulting in Nernstian slope behavior. Linear concentration range was 1×10-3 -7×10-6 mol L-1, 1×10-3 -3×10-7 mol L-1, and 7×10-3 -3×10 -9 mol L-1 of chromium(III) with Nernstian slope 20.76, 21.79 and 19.05 mV/decade for LIE, CWE and SSE, respectively. An improvement was note in detection limit for SSE (3×10-9 M) and CWE (2×10-7 M) in comparison with LIE (7×10-6 M). Response times were approximately 5 seconds for LIE and CWE, and 4-6 seconds for SSE. The applicable pH range for the electrodes was 3.0-5.0. SSE and CWE demonstrated longer lifetimes of about 13 and 12 weeks, respectively, compared to LIE (11 weeks). These electrodes were utilized as indicator electrodes in the chromium(III) potentiometric titration with ethylenediaminetetraacetic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] Manipulating metal valence states and porosity in the metal–organic framework (MOF) by alloying has been a unique tool for creating high-valent metal sites and pore environments in a structure that are inaccessible by other methods, favorable for accelerating the catalytic activity towards sensing applications. Herein, we report Fe3+-driven formation of catalytic active Ni3+ species in the amine-crafted benzene-dicarboxylate (BDC-NH 2)-based MOF as a high-performance electrocatalyst for glucose sensing. This work took the benefit of different bonding stability between BDC-NH 2 ligand, and Fe3+ and Ni2+ metal precursor ions in the heterometallic Ni x Fe (1- x) -BDC-NH 2 MOF. The FeCl 3 that interacts weakly with ligand, oxidizes the Ni2+ precursor to Ni3+-based MOF owing to its Lewis acidic behavior and was subsequently removed from the structure supported by Ni atoms, during solvothermal synthesis. This enables to create mesopores within a highly stable Ni-MOF structure with optimal feed composition of Ni 0.7 Fe 0.3 -BDC-NH 2. The Ni3+-based Ni 0.7 Fe 0.3 -BDC-NH 2 demonstrates superior catalytic properties towards glucose sensing with a high sensitivity of 13,435 µA mM−1 cm−2 compared to the parent Ni2+-based Ni-BDC-NH 2 (10897 μA mM−1 cm−2), along with low detection limit (0.9 μM), short response time (≤5 s), excellent selectivity, and higher stability. This presented approach for fabricating high-valent nickel species, with a controlled quantity of Fe3+ integrated into the structure allowing pore engineering of MOFs, opens new avenues for designing high-performing MOF catalysts with porous framework for sensing applications. [ABSTRACT FROM AUTHOR]

Developing electrochemical sensors for ascorbic acid, uric acid and glucose detection provides advantages of rapid, precise and economical monitoring of disease condition, and they have the potential to transform healthcare by enabling point-of-care diagnostic and personalised treatment. Facile and cost-effective potentiometric sensors have been developed in this work for selective and sensitive detection of ascorbic acid, uric acid and glucose, based on molecularly imprinted polymer (MIP). The imprinted polymeric matrix of para-aminobenzoic (pPABA) was developed on the surface of electrochemically reduced graphene oxide modified paraffin impregnated graphite rod electrode (rGO/PIGE). The monomeric para-aminobenzoic acid (PABA) was electropolymerised with template, viz., ascorbic acid, uric acid and glucose individually. The molecularly imprinted electrode surface was created by removing the trapped template molecule. The surface analysis of the modified electrodes was carried out by cyclic voltammetry (CV), scanning electron microscopy (SEM), attenuated total reflection spectroscopy (ATR), Raman spectroscopy and contact angle measurements. Parameters controlling the performance of the MIP (p-PABA), viz., pH of the supporting electrolyte and number of polymerisation cycle, were optimised. Under optimised conditions, the potentiometric responses of MIPs were linearly related to concentrations of ascorbic acid, uric acid and glucose in the range of 3.4 × 10−7 M–2.5 × 10−5 M, 3.3 × 10−7 M–1.3 × 10−5 M, and 3.5 × 10−7 M–2.9 × 10−5 M with a correlation coefficient, R2 of 0.99, 0.99 and 0.98 respectively. All three sensors showed high selectivity even in the presence of high concentration of similar interfering compounds. A limit of detection (LOD) for ascorbic acid, uric acid and glucose was found to be 1.1 × 10−8 M, 2.8 × 10−8 M and 1.3 × 10−8 M respectively. In addition, the developed sensors exhibited long-term stability and good reproducibility. [ABSTRACT FROM AUTHOR]

Electrodeposited amorphous hydrated iridium oxide (IrOx) is a promising material for pH sensing due to its high sensitivity and the ease of fabrication. However, durability and variability continue to restrict the sensor's effectiveness. Variation in probe films can be seen in both performance and fabrication, but it has been found that performance variation can be controlled with potentiostatic conditioning (PC). To make proper use of this technique, the morphological and chemical changes affecting the conditioning process must be understood. Here, a thorough study of this material, after undergoing PC in a pH-sensing-relevant potential regime, was conducted by voltammetry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Fitting of XPS data was performed, guided by raw trends in survey scans, core orbitals, and valence spectra, both XPS and UPS. The findings indicate that the PC process can repeatably control and conform performance and surface bonding to desired calibrations and distributions, respectively; PC was able to reduce sensitivity and offset ranges to as low as ±0.7 mV/pH and ±0.008 V, respectively, and repeat bonding distributions over ~2 months of sample preparation. Both Ir/O atomic ratios (shifting from 4:1 to over 4.5:1) and fitted components assigned hydroxide or oxide states based on the literature (low-voltage spectra being almost entirely with suggested hydroxide components, and high-voltage spectra almost entirely with suggested oxide components) trend across the polarization range. Self-consistent valence, core orbital, and survey quantitative trends point to a likely mechanism of ligand conversion from hydroxide to oxide, suggesting that the conditioning process enforces specific state mixtures that include both theoretical Ir(III) and Ir(IV) species, and raising the conditioning potential alters the surface species from an assumed mixture of Ir species to more oxidized Ir species. [ABSTRACT FROM AUTHOR]

To explore novel terpenoid repellents, 22 candidate terpenoid derivatives were synthesized and tested for their electroantennogram (EAG) responses and repellent activities against Aedes albopictus. The results from the EAG experiments revealed that 5-(2-hydroxypropan-2-yl)-2-methylcyclohex-2-en-1-yl formate (compound 1) induced distinct EAG responses in female Aedes albopictus. At concentrations of 0.1, 1, 10, 100, and 1000 mg/L, the EAG response values for compound 1 were 179.59, 183.99, 190.38, 193.80, and 196.66 mV, demonstrating comparable or superior effectiveness to DEET. Repellent activity analysis indicated significant repellent activity for compound 1, closest to the positive control DEET. The in silico assessment of the ADMET profile of compound 1 indicates that it successfully passed the ADMET evaluation. Molecular docking studies exhibited favourable binding of compound 1 to the active site of the odorant binding protein (OBP) of Aedes albopictus, involving hydrophobic forces and hydrogen bond interactions with residues in the OBP pocket. The QSAR model highlighted the influential role of hydrogen-bonding receptors, positively charged surface area of weighted atoms, polarity parameters of molecules, and maximum nuclear-nuclear repulsion force of carbon-carbon bonds on the relative EAG response values of the tested compounds. This study holds substantial significance for the advancement of new terpenoid repellents. [ABSTRACT FROM AUTHOR]

Drug plant raw materials represent an important source of biologically active substances (BASs), which are used in pharmaceutical, cosmetic, food, and other industries. This paper presents the results of studying colloidal properties of crushed sophora Japanese fruits (hereinafter referred to as sophora) in order to improve the extraction of BASs. To achieve the goal, the following tasks have been set: the study of the ζ potential of sophora particles at different times of contact between the particles and an extractant and the pH values of the medium; determining the isoelectric point (IEP) of the sophora particles by electrophoresis; finding the point of zero charge (PZC) of sophora particles using potentiometric titration; and studying the influence of medium pH, sophora particle size, temperature, the presence of surfactants and ions, and the nature of an extractant on sophora swelling. The points of zero charge ) of the aqueous dispersions of sophora and extracted flavonoids are 5.8 and 5.2, respectively, thus being close to the values . The swelling of sophora particles is limited and accompanied by the gradual fracture of the plant cells. Adsorption equilibrium is achieved within 30 min. In an alkaline region and in the presence of alcohol, the swelling of the sophora particles decreases, while it increases at elevated temperature and in the presence of NaI ions. [ABSTRACT FROM AUTHOR]

The reaction of the vanadyl ion (VO2+) with imidazole-4-carboxylic acid (Im4COOH), imidazole-2-carboxylic acid (Im2COOH) and methylimidazole-2-carboxylic acid (MeIm2COOH), respectively, in the presence of small bioligands (bL) [oxalate (Ox), lactate (Lact), citrate (Cit) and phosphate (Phos)] and high-molecular-weight (HMW) human serum proteins [albumin (HSA) and transferrin (hTf)] were studied in aqueous solution using potentiometric acid–base titrations. The species distribution diagrams for the high-molecular-mass (HMM) proteins with oxidovanadium(IV) under physiological pH were dominated by VO(HMM)2, VOL(HMM) for unsubstituted ligands (L− = Im4COO− and Im2COO−). However, for the N-substituted MeIm2COOH, the species distribution diagrams under physiological pH were dominated by VOL2, VO(HMM)2 and VO2L2(HMM). These species were further confirmed by LC-MS, MALDI-TOF-MS and EPR studies. The glucose-stimulated insulin secretion (GSIS) action of the complexes was investigated using INS-1E cells at a 1 µM concentration, which was established through cytotoxicity studies via the MTT assay. The neutral complexes, especially VO(MeIm2COO)2, showed promising results in the stimulation of insulin secretion than the cationic [VO(MeIm2CH2OH)2]2+ complex and the vanadium salt. Oxidovanadium(IV) complexes reduced insulin stimulation significantly under normoglycaemic levels but showed positive effects on insulin secretion under hyperglycaemic conditions (33.3 mM glucose media). The islets exposed to oxidovanadium(IV) complexes under hyperglycaemic conditions displayed a significant increase in the stimulatory index with 1.19, 1.75, 1.53, 1.85, 2.20 and 1.29 observed for the positive control (sulfonylurea:gliclazide), VOSO4, VO(Im4COO)2, VO(Im2COO)2, VO(MeIm2COO)2 and VO(MeIm2CH2OH)22+, respectively. This observation showed a potential further effect of vanadium complexes towards type 2 diabetes and has been demonstrated for the first time in this study. [ABSTRACT FROM AUTHOR]

The adsorption of divalent ions on metal oxides is controlled by the pH of a solution. It is commonly assumed that this is a reversible process for pH changes. However, there are reports that the sorption of ions on oxides may not be reversible. To verify this, we used potentiometric titration, ion-selective electrodes (ISEs), and electrokinetic measurements to examine the reversibility of the adsorption of hydrogen ions and three metal ions (Ca2+, Cu2+, and Fe2+) on TiO2. The ferrous ion was used as a reference because its adsorption is entirely irreversible. The surface charge determined by potentiometric titration and the adsorption edges measured using ISE indicate that the adsorption of copper ions is reversible with changes in pH. In the case of calcium ions, the results suggest a certain degree of irreversibility. There are apparent differences in the electrokinetic potential data obtained during titration with base and acid, which suggests that the adsorption is irreversible. We have explained this contradiction by considering the complex and dynamic nature of electrophoretic mobility. In our opinion, potentiometric titration may be the simplest and most reliable method for assessing the reversibility of multivalent ion adsorption. [ABSTRACT FROM AUTHOR]

The chemical speciation of binary and ternary VO2+-picolinic acid (HPic) complexes with the amino acids: Leucine (Leu, HL), Isoleucine (Ile, HL), Valine (Val, HL), Tryptophan (Thr, HL), Glutamine (Gln, HL), Lysine (Lys, HL), Arginine (Arg, HL) and Tyrosine (Tyr, H2L) were obtained. This study was performed by potentiometric titrations at 25 °C using 1.0 mol·dm−3 NaCl as the ionic medium. The experimental data were analyzed with the least squares program LETAGROP, and the respective distribution diagrams were obtained with the HYSS program. The relative stability parameters Δlog10K, log10X and %R.S were determined. [ABSTRACT FROM AUTHOR]

Effects of dry and wet grind on peanut oil and protein yield, oil bodies (OBs) stability, fatty acid composition, protein composition and functional characteristics were systematically analyzed. Results showed that peanut oil and protein yields reached highest at dry grind 90 s (92.56% and 83.05%, respectively), while peanut oil and protein yields were 94.58% and 85.36%, respectively, at wet grind 120 s. Peanut oil and protein yields by wet grind was 2.18% and 2.78% higher than that of dry grind, respectively. Surface protein concentration (Г) and absolute value of zeta potential of OBs extracted by wet grind (WOBs) were 11.53 mg/m2 and 18.51 mV, respectively, which were higher than OBs extracted by dry grind (DOBs), indicating stability of WOBs was higher than DOBs. Relative contents of oleic acid and linoleic acid in peanut oil, essential and hydrophobic amino acids in protein extracted by wet grind were higher than dry grind. There was little difference in protein composition between wet and dry grind, but thermal denaturation degree of protein obtained by wet grind was lower than dry grind. Solubility, oil retention, emulsion stability, foaming and foam stability of protein obtained by wet grind were better than dry grind. Results from this study provided theoretical basis for grind pretreatment selection of aqueous enzymatic method. [ABSTRACT FROM AUTHOR]

This work modified the carbon paste electrode (CPE) with MoS2 nanosheets and ionic liquid (IL), creating a simple and effective sensing platform. In contrast to oxidation at the bare CPE, which occurred at 518 mV (6.2 μA), the electro-oxidation of ascorbic acid at the MoS2-modified ILCPE occurred at 320 mV (20 μA). The MoS2/ILCPE also improved the rate of electrochemical reaction. When the concentration of ascorbic acid increased between 1.0 and 1000.0 μM, the peak current increased according to the differential pulse voltammetry (DPV) technique. The proposed MoS2/ILCPE sensor revealed a low limit of detection (LOD) of 0.2 μM and good sensitivity of 0.1011 μA μM− 1 for a wide range of concentrations of ascorbic acid from 1.0 to 1000.0 μM. A well-defined and distinct oxidation peak of ascorbic acid and vitamin B6 were found at 330 mV and 720 mV, respectively, according to the results of the analysis of ascorbic acid when vitamin B6 is present. Finally, in real-sample matrices, the proposed sensor showed a reasonable recovery of the spiked ascorbic acid and vitamin B6 (ascorbic acid injection, ascorbic acid tablet, vitamin B6 tablet, and urine samples). [ABSTRACT FROM AUTHOR]

In the present study, we have reported the synthesis of a novel thiophene-based dipodal chelator ligand MPT (N1, N3-bis(3-((E)-thiophen-2-yl)methylene)amino)propyl)malonamide). Further, the physio-chemical properties of as-synthesized ligand was analyzed employing state-of-the-art characterization tools such as 1H NMR, 13C NMR, and IR spectroscopy. In order to calculate the protonation constant for the ligand MPT and formation constants for the ligand MPT with Fe2+ metal ion potentiometric and spectrophotometric analysis were carried out. Further, to analyze the coordination behavior of the ligand MPT with Fe2+ metal ion at room temperature in a highly aqueous medium spectrophotometric analysis was carried out. On the other hand, the theoretical studies for the ligand MPT and its complex with Fe2+ ion were performed employing a semi-empirical method and density functional theory. Further, the structure optimization of the ligand MPT was obtained using the PM6 parameter and B3LYP/6-311(d,p) level for ligand and DGDZVP for metal complex calculations respectively. [ABSTRACT FROM AUTHOR]

The shelf life of a food product is a limited period of time after production and packaging, during which it maintains the necessary and acceptable level of quality for final consumption. The aim of the research was to predict the shelf life of chocolate packaged in two bilaminated containers with respect to peroxide value, using accelerated testing and constant relative humidity. The peroxide value was evaluated by potentiometric titration. The order of the reaction was defined and with the Arrhenius model the degradation rate constant was found for each container and temperature of study. Shelf life was determined with the kinetic equation of oxidation compound formation at 5, 20 and 35℃ at 217, 114 and 64 days for the 20 microns (μ) packages, and 114, 95 and 81 days for the 50 μ packages respectively. It is concluded that the 20 μ packaging between a storage temperature of 15 and 18℃ is the suggested packaging with a shelf life between 141 and 124 days. The results would enable those working in the chocolate manufacturing and packaging industry to take the temperatures and types of packaging studied as a reference in their production. [ABSTRACT FROM AUTHOR]

In this article, we present the synthesis and characterization of new acyclic pyridine-containing polyaminocarboxylate ligands H4aPyta and H6aPyha, which differ in structural rigidity and the number of chelating groups. Their abilities to form complexes with Cu2+, Ga3+, Y3+, and Bi3+ cations, as well as the stability of the complexes, were evaluated by potentiometric titration method, radiolabeling with the corresponding radionuclides, in vitro studies, mass spectrometry, and HPLC. The structures of the resulting complexes were determined using NMR spectroscopy and DFT calculations. The results obtained made it possible to evaluate the influence of the structural features of the complexes on their stability. The developed chelators H4aPyta and H6aPyha were proved to be promising for further research in the field of radiopharmaceuticals. [ABSTRACT FROM AUTHOR]

In this article, we present the synthesis and characterization of new acyclic pyridine-containing polyaminocarboxylate ligands H4aPyta and H6aPyha, which differ in structural rigidity and the number of chelating groups. Their abilities to form complexes with Cu2+, Ga3+, Y3+, and Bi3+ cations, as well as the stability of the complexes, were evaluated by potentiometric titration method, radiolabeling with the corresponding radionuclides, in vitro studies, mass spectrometry, and HPLC. The structures of the resulting complexes were determined using NMR spectroscopy and DFT calculations. The results obtained made it possible to evaluate the influence of the structural features of the complexes on their stability. The developed chelators H4aPyta and H6aPyha were proved to be promising for further research in the field of radiopharmaceuticals. [ABSTRACT FROM AUTHOR]

This study has introduced a pioneering methodology by employing biochars as a basic carbocatalyst in the context of multicomponent reactions. Biochars were produced from different manures and organic wastes using the pyrolysis-carbonization process under limited oxygen conditions. The prepared biochars were well characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) analysis, and powder X-ray diffraction (XRD). The chemical characteristics and potentiometric titration analysis provide compelling evidence of the intriguing basicity properties exhibited by the prepared biochars. The pH values, ash content, and potentiometric titration results confirmed the exceptional basicity characteristics of cow manure biochar formed at 600 oC (CB600), establishing it as the most basic carbocatalyst in this study. Encouraged by these initial results, the activity of the biochars as basic carbocatalysts was evaluated in multicomponent synthesis of 4H-benzo[h]chromene and pyranopyrazoles and 600 °C exhibited the most pronounced catalytic performance owing to its superior total basicity. By these findings, it can be asserted that this work introduces the groundbreaking application of biochars as potent basic carbocatalysts for the multicomponent synthesis of structurally diverse heterocycles. Unveiling the vital basic role of biochars will definitely open up new opportunities in organic chemistry and provide salient features for environmentally-friendly chemistry, including easy retrieval, non-toxicity, and widespread accessibility. Highlights: Biochars were introduced as potent basic carbocatalysts for multicomponent synthesis of heterocycles. Quantitatively assess basicity of the prepared biochars was performed using potentiometric titration. The activity of the biochars as basic carbocatalysts was evaluated in multicomponent synthesis of chromenes and pyranopyrazoles. [ABSTRACT FROM AUTHOR]

The pKa values of propanolamine hydrochloride (PAMH) and poly(allylamine hydrochloride) (PAAMH) in concentrated solutions were determined by both Fourier transform infrared spectroscopy (FT-IR) titration and classical potentiometric (POT) titration and compared. Starting with the respective fully protonated forms PAMH and PAAMH and increasing the pH value by sodium hydroxide addition in situ attenuated total reflection FT-IR (ATR FT-IR) spectra on PAMH and PAAMH solutions show the variation of diagnostic infrared (IR) bands. From the decrease of the most intense δ(NH3+) band the dissociation process of the NH3+ groups could be followed. Thereby, from the respective normalized band area A the dissociation degree αIR of the ammonium groups could be determined. Plotting pH versus αIR and fitting this curve by a modified Henderson–Hasselbalch function pH = pKa + B log (αIR/1 – αIR) the parameters pKa and cooperativity factor B were obtained. pKa values from FT-IR titration were qualitatively in line with respective pKa values from POT titration. Quantitative systematic pKa deviations between polyelectrolyte (PEL) and respective monoelectrolyte and the tentative effects of PEL molecular weight, ambient ionic strength, and titration concept (FT-IR and POT) are discussed based on classical models of weak PEL. Graphical abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties with respect to understanding the ocean carbon cycle and its link to global change (ocean carbon sinks and sources, ocean acidification) and ultimately finding carbon-based solutions or mitigation procedures (marine carbon removal). We present a database of more than 44 400 AT and CT observations along with basic ancillary data (spatiotemporal location, depth, temperature and salinity) from various ocean regions obtained, mainly in the framework of French projects, since 1993. This includes both surface and water column data acquired in the open ocean, coastal zones and in the Mediterranean Sea and either from time series or dedicated one-off cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ±4 µ mol kg -1 for both AT and CT. The data are provided in two separate datasets – for the Global Ocean and the Mediterranean Sea (10.17882/95414, Metzl et al., 2023), respectively – that offer a direct use for regional or global purposes, e.g., AT –salinity relationships, long-term CT estimates, and constraint and validation of diagnostic CT and AT reconstructed fields or ocean carbon and coupled climate–carbon models simulations as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. When associated with other properties, these data can also be used to calculate pH, the fugacity of CO 2 (f CO 2) and other carbon system properties to derive ocean acidification rates or air–sea CO 2 fluxes. [ABSTRACT FROM AUTHOR]

The present work describes the complexation of the anti-inflammatory sialorphin derivative Pal-Lys-Lys-Gln-His-Asn-Pro-Arg (palmitic acid-lysine-lysine-glutamine-histidine-asparagine-proline-arginine) with Cu(II) ions in an aqueous solution, at a temperature of 25.0 ± 0.1 °C, over the whole pH range. The complexing properties were characterized by potentiometric and UV-Vis spectrophotometric methods. The potentiometric method was used to calculate the logarithms of the overall stability constants (log β) and the values of the stepwise dissociation constants (pKa) of the studied complexes. The percentage of each species formed in an aqueous solution was estimated from the species distribution curve as a function of pH. The absorbance (A) and molar absorption coefficient (ε) values for the Cu(II)-sialorphin derivative system were determined with UV-Vis spectroscopy. Our studies indicate that the sialorphin derivative forms stable complexes with Cu(II) ions, which may lead to future biological and therapeutic applications. [ABSTRACT FROM AUTHOR]

The correlation between polycyclic aromatic hydrocarbons (PAHs) and organic carbon is an important indicator of the marine environment. In this paper, twenty-six surface sediment samples were collected from the Bohai Sea and the North Yellow Sea as the study area, and the contents of sixteen PAHs ranged from 71.34 ng·g−1 to 240.78 ng·g−1 with an average of 143.26 ng·g−1 by gas chromatography. The source analysis indicated the source of PAHs in the surface sediments of the study area was more complex, and the percentage of combustion sources was higher than that of petroleum sources, which might cause less negative ecological risks. The average content of total organic carbon (TOC) was 5.25%, as determined by automatic potentiometric titration, and the content of TOC was higher in the Bohai Sea than in the North Yellow Sea. TOC was significantly correlated with HWM-PAHs but was not correlated with LWM-PAHs, which proved organic matter was more effective in controlling high-molecular-weight PAHs than low-molecular-weight PAHs in the surface sediments of the Bohai Sea and the North Yellow Sea. [ABSTRACT FROM AUTHOR]

The fabrication of cathodes with carbonized Agave tequilana bagasse for Li–S batteries is performed for the first time. Three porous carbonaceous structures are developed and studied to elucidate the best carbon textural properties in terms of their surface area and pore size distribution: hierarchical porosity, highly microporous, and nonporous material, for sulfur hosting in Li–S cathodes. N2 physorption, scanning electron microscopy, infrared spectroscopy, and potentiometric titrations analysis are performed to determine the textural, morphology, and physicochemical properties. The fabricated coin cells, CR2032, with cathodes made of mesoporous carbons, display a high discharge current (≈1600 mAh g−1), superior performance, and cyclability up to 250 cycles. The performance of batteries is found to be strongly influenced by surface area and pore size of the carbon materials. The carbonized tequila bagasse hosting sulfur can be very useful to fabricate cathodes for Li–S batteries with high initial capacity and cycling stability. [ABSTRACT FROM AUTHOR]