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Complex formation of vanadium(V) with 4-(2',3',4'-trihydroxyphenyl)-3-nitro-5-sulfoazobenzene (R) in the presence of cationic surfactants (CS), cetylpyridinium chloride (CPCl), cetylpyridinium bromide (CPBr), and cetyltrimethylammonium bromide (CTMABr), is studied. Vanadium(V) and R form a colored complex at a component ratio of 1 : 2 and pH of 5.0–5.5. The absorbance maximum of the complex is at 449 nm, while the reagent under these conditions absorbs light at 395 nm. In the presence of cationic surfactants, mixed-ligand complexes with a component ratio of V(V) : R : CS = 1 : 2 : 2 are formed, which results in a bathochromic shift of the absorbance maximum. Additionally, the pH value for the maximum complex formation shifts to a more acidic medium compared to the homoligand V(V)–R complex. The absorbance of the V(V) : R : CPCl, V(V): R : CPBr, and V(V) : R : CTMABr complexes is maximal at 457, 461, and 466 nm, respectively. The yield of these complexes is the highest at pH of 3.5–4.0 for VV(V) : R : CPCl and V(V): R : CPBr, and at a pH of 2.5–3.0 for V(V) : R : CTMABr. The formation of both homoligand and mixed-ligand vanadium(V) complexes depends on the reaction time, temperature, and concentrations of the reacting components. The determined stability constants indicate the high stability of the resulting mixed-ligand complexes. The specific conductivity of the complexes under the optimal conditions of complex formation was determined using conductometric titration. Calibration curves for the determination of vanadium(V) as homoligand and mixed-ligand complexes are linear. The effect of foreign ions and masking agents on the determination of V(V) as homoligand and mixed-ligand complexes was analyzed; it was shown that the presence of cationic surfactants significantly increases the selectivity of the reaction. An analysis of water samples from Lake Khanbulan, Lankaran District, Azerbaijan Republic using the developed procedure showed the presence of small amounts of vanadium(V). [ABSTRACT FROM AUTHOR]

Iron-based magnetic nanoparticles (MNPs) have attracted considerable attention as promising draw solutes in forward osmosis processes due to various advantages. In the present study, magnetite (Fe3O4) nanoparticles (MNPs) with diameters in the range of 12 ± 2 nm were synthesized by applying the coprecipitation method and stabilized using (3-aminopropyl)triethoxysilane (APTES). The amino groups of APTES were further functionalized with various amounts of citric acid (CA) and poly(acrylic acid) (PAA) to achieve higher osmotic pressure. The as-prepared and functionalized nanoparticles were characterized using different methods: Fourier-transform infrared spectroscopy (FTIR) confirmed the binding of APTES and CA/PAA on the surface of the MNPs, while the size of the particles was determined by transmission electron microscopy (TEM) and X-ray powder diffraction. The isoelectric point, zeta potential, and the particle size in suspension were determined by dynamic light scattering (DLS)/zeta potential measuring system. The amount of free –COOH groups was determined by conductometric titrations. The amount of organic matter (APTES, CA, and PAA) bound on the surface was determined by thermogravimetric analysis (TG), giving results between 7.6% for samples stabilized with APTES only and 17.5% for samples functionalized with APTES + PAA. TG provides a simple and efficient method for determining the amount of organic compounds bound to the surface of MNPs. The osmotic pressure measurements of double-layer coated MNPs provided encouraging results of up to 28 bar, enabling using the samples as draw solutions in an experimental forward osmosis system. [ABSTRACT FROM AUTHOR]

Electrical conductimetry and dynamic light scattering (DLS) were used to investigate the aggregation behaviors of four amino acid-based surfactants (AABSs; undecanoyl-glycine, undecanoyl-l-alanine, undecanoyl-l-valine, undecanoyl-l-leucine) in the presence of five linear diamine counterions (1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane). Electrical conductimetry was used to measure the CMCs for each system, which ranged from 5.1 to 22.5 mM. With respect to counterions, the obtained CMCs decreased with increases in the interamine spacer length; this was attributed to the improved torsional binding flexibility in longer counterions. Strong linear correlations (mean R2 = 0.9443) were observed between the CMCs and predicted surfactant partition coefficients (logP; water/octanol), suggesting that micellization is primarily driven by the AABS's hydrophobicity for these systems. However, significant deviations in this linear relationship were observed for systems containing 1,2-diaminoethane, 1,4-diaminobutane, and 1,6-diaminohexane (p = 0.0774), suggesting altered binding dynamics for these counterions. pH measurements during the CMC determination experiments indicated the full deprotonation of the AABSs but did not give clear insights into the counterion protonation states, thus yielding an inconclusive evaluation of their charge stabilization effects during binding. However, DLS measurements revealed that the micellar size remained largely independent of the counterion length for counterions longer than 1,2-diaminoethane, with hydrodynamic diameters ranging from 2.2 to 2.8 nm. This was explained by the formation of charge-stabilized noncovalent dimers, with each counterion bearing a full +2 charge. Conductimetry-based estimates of the degrees of counterion binding (β) and free energies of micellization (ΔG°M) revealed that bulky AABSs exhibit preferential binding to counterions with an even number of methylene groups. It is proposed that when these counterions form noncovalent dimers, perturbations in their natural geometries result in the formation of a binding pocket that accommodates the AABS steric bulk. While the direct application of these systems remains to be seen, this study provides valuable insights into the structure–property relationships that govern AABS aggregation. [ABSTRACT FROM AUTHOR]

The electrochemical detection of two pharmaceuticals, diclofenac (DCF) and carbamazepine (CBZ), was investigated as an oxidation current using boron‐doped nanocrystalline diamond (BDD) thin‐film electrodes. Both voltammetry and flow injection analysis with amperometric detection (FIA‐EC) were used to measure the drugs in standard solutions and a urine simulant. The oxidation potential for DCF was ca. 0.7 V vs. Ag/AgCl (3 M KCl) in 0.1 M phosphate buffer (pH 7.2) and was ca. 1.2 V for CBZ in 0.1 M perchloric acid. The DCF oxidation reaction was diffusion controlled at the detection potential with evidence of some surface fouling by reaction products. The CBZ oxidation reaction was also controlled by diffusion at the detection potential, but with no surface fouling. The voltammetric peak currents for both drugs increased linearly with the concentration in the micromolar range (r2≥0.994). FIA‐EC analysis of DCF and CBZ revealed a linear dynamic range from at least 0.1 to 100 μM with the actual minimum concentration detectable (S/N=3) being less than the lowest concentration measured. The recovery percentage for DCF in the urine simulant ranged from 94–108% and from 97–100% for CBZ, both assessed using square wave voltammetry. FIA‐EC data revealed that the BDD electrodes offer excellent intra and inter‐electrode repeatability with an RSD for DCF and CBZ of 4.90% and 3.81%, respectively. The BDD electrode provided good reproducibility and response stability over eight days of continuous use detecting both DCF and CBZ. Overall, BDD electrodes are a viable material  for the sensitive, selective, and reproducible electrochemical detection of these two pharmaceuticals. [ABSTRACT FROM AUTHOR]

Chitosan was subjected to a crosslinking reaction with three polyhydroxylated diacids (glucaric (GlcA), mannaric (ManA), and mucic (MucA) acids) that only differ in the spatial orientation of their hydroxyl groups. This work aimed to obtain experimental evidence of the impact of the three-dimensional arrangement of the crosslinkers on the resulting properties of the products. In all the cases, the products were hydrogels, and their chemical structures were fully elucidated by FT-IR spectroscopy and conductometric titration. Thermogravimetric and morphological studies were also carried out. The specific surface area of all the products was similar and higher than that of native chitosan. Moreover, all hydrogels were characterized in terms of viscoelastic properties and long-term stability under external perturbation. Furthermore, their lead adsorption efficiency and swelling capacity were assessed. Despite the resemblant chemical structure in all the hydrogels, Ch/ManA exhibited the highest lead adsorption capacity, (Ch/ManA: 93.8 mg g−1, Ch/GlcA: 82.9 mg g−1, Ch/MucA: 79.2 mg g−1), while Ch/GlcA exhibited a remarkably higher swelling capacity (i.e., ~30% more than Ch/MucA and ~40% more than Ch/ManA). The results obtained herein evidenced that the selection of the polyhydroxylated crosslinker with the appropriate three-dimensional structure could be crucial to finely adjust the final materials' features. [ABSTRACT FROM AUTHOR]

The mixed surfactant system of tetradecyldimethylamine oxide (TDMAO) and lithium perfluorooctanoate (LiPFO) is known to spontaneously self-assemble into well-defined small unilamellar vesicles. For a quantitative analysis of small-angle x-ray scattering on this model system, we complemented the measurements with densitometry, conductimetry, and contrast-variation small-angle neutron scattering. The analysis points to two main findings: first, the vesicles formed to contain a much higher mole fraction (0.61–0.64) of TDMAO than the bulk sample (0.43) and predicted by Regular Solution Theory (RST, 0.46). In consequence, the unimer concentration of LiPFO is more than 5 times higher than predicted by RST. Second, the vesicle bilayer is asymmetric with a higher fraction of LiPFO on the outside. These findings on a model system should be of broader relevance for the understanding of similar mixed surfactant vesicle systems and thereby also be of importance for their use in a number of applications. [ABSTRACT FROM AUTHOR]

The recent steady demand for products with increased antioxidant properties largely determines the direction of research in the field of creating high‐quality products with increased biological value. Insufficient knowledge of the antioxidant activity and potential biological value of whiskey makes this area of research relevant and in demand. This study presents the results of an analysis of the influence of distillate aging conditions on the phenolic composition and antioxidant capacity of whiskey, obtained using coulometric, chromatographic, and amperometric methods of analysis. During the study, samples of whiskey with increased antioxidant capacity were obtained based on the use of alcoholic extracts of grape stems of the Vitis vinifera species. The data obtained as a result of the study can be used in the future both to improve the efficiency of methods for monitoring and regulating the circulation of alcoholic products based on the developed methodology for determining antioxidant capacity and to contribute to the creation of a new type of alcoholic products with an increased content of bioavailable biologically active substances and antioxidant capacity. [ABSTRACT FROM AUTHOR]

The detection and quantification of pharmaceutical compounds in various matrices, including environmental and biological samples, has received a great deal of attention due to their potential impact on human health and the environment. In this study, we present an electrochemical approach for the determination of nimesulide, a commonly used non-steroidal anti-inflammatory drug, in water supply, synthetic urine and drug samples. A 3D-printed electrochemical sensor was fabricated and modified by an electrochemical treatment in alkaline medium with KOH, followed by the electrodeposition of silver nanoparticles to improve its detection capabilities. The performance of the electrochemical sensor was evaluated by multiple techniques and a flow injection analysis with amperometric detection was applied for the quantification of nimesulide. The FIA-AMP system allowed for the efficient introduction of samples, promoting rapid analysis and minimizing memory effects. The sensor connected to the method showed good sensitivity (0.171 ± 0.002 µA L mol−1 cm−2) and improved stability (RSD < 7%) and its electrochemical responses were correlated with the concentration of nimesulide present in the samples tested, with recovery values in the 92 to 104% range. The method developed showed a good linear range from 5 to 25 µmol L−1 and a low detection limit of 0.81 µmol L−1, which makes it suitable for the quantitative analysis of nimesulide over a range of concentrations. The sensor applied to the determination of nimesulide offers a promising platform for the sensitive and selective detection of pharmaceutical compounds, contributing to greater safety and sustainability in these fields. [ABSTRACT FROM AUTHOR]

Three new copper(II) mononuclear complexes containing different organoselenium groups (1–3) were synthesized and characterized by the following techniques: elemental analysis, IR and UV‐Vis spectroscopies, electrochemical and conductimetric analysis, and mass spectrometry. Three new complexes, with substituents made in the para position of the aromatic portion of the N,N‐bis(2‐(phenylselanyl)ethyl)amine ligand: p‐OCH3 (1), p‐CH3 (2), and p‐Cl (3), were synthetized to compare with the already published complex (4), with no substituents. The ligand coordinates to the copper(II) center in a tridentate way with Se, N, Se as donor atoms. The hydrolytic activity in phosphate diester cleavage of the complexes was investigated using 2,4‐BDNPP as substrate. The modifications in the ligand are reflected in the difference between the catalytic and activation parameters, where the kcat values follow the order: 4 > 2 > 3 > 1. [ABSTRACT FROM AUTHOR]

This paper compares materials potentially suitable for preparing solid reference electrodes, which could be used in miniaturized flow electrochemical cells. The tested electrodes are based on Sb, Bi, Pd, Pt, and Ag. The stable potential of the reference electrodes was maintained by the pH of the electrolyte, except for the AgCl electrode, whose potential was given by the concentration of chlorides. The performance of the reference electrodes was evaluated through a series of experiments focusing on potential dependences, long‐term and short‐term stability, cyclic voltammetry, and flow injection analysis with amperometric detection. Potentiometric experiments showed that Sb‐based electrodes had the closest slope to theoretical values with minor changes over five weeks. Theory‐consistent results of potential dependence were also observed for AgCl electrodes. The results of the voltammetric and flow amperometric experiment suggest that Sb‐based reference electrodes are the most suitable tools for electrochemical measurement. AgCl electrodes are limited by the necessity of maintaining a high chloride concentration. Bi‐based and PdH electrodes provide unstable results, the latter particularly due to hydrogen desorption. Although able to provide the stable potential to some extent, Pt electrodes are not suitable as the reference electrodes due to the deformation of mainly hydrodynamic voltammograms. [ABSTRACT FROM AUTHOR]

A hybrid synthetic-natural, thermoresponsive graft copolymer composed of poly(N-isopropyl acrylamide) (PNIPAM) side chains, prepared via RAFT polymerization, and a chitosan (Chit) polysaccharide backbone, was synthesized via radical addition-fragmentation reactions using the "grafting to" technique, in aqueous solution. ATR-FTIR, TGA, polyelectrolyte titrations and 1H NMR spectroscopy were employed in order to validate the Chit-g-PNIPAM copolymer chemical structure. Additionally, 1H NMR spectra and back conductometric titration were utilized to quantify the content of grafted PNIPAM side chains. The resulting graft copolymer contains dual functionality, namely both pH responsive free amino groups, with electrostatic complexation/coordination properties, and thermoresponsive PNIPAM side chains. Particle size measurements via dynamic light scattering (DLS) were used to study the thermoresponsive behavior of the Chit-g-PNIPAM copolymer. Thermal properties examined by TGA showed that, by the grafting modification with PNIPAM, the Chit structure became more thermally stable. The lower critical solution temperature (LCST) of the copolymer solution was determined by DLS measurements at 25–45 °C. Furthermore, dynamic and electrophoretic light scattering measurements demonstrated that the Chit-g-PNIPAM thermoresponsive copolymer is suitable of binding DNA molecules and forms nanosized polyplexes at different amino to phosphate groups ratios, with potential application as gene delivery systems. [ABSTRACT FROM AUTHOR]

The aim of the work was to investigate treatment parameters that exert most influence on performance of cellulose fibers carboxymethylated from aqueous solutions. Viscose fibers were carboxymethylated in alkaline solutions of sodium monochloroacetate at two temperatures (30 °C, 50 °C) and with different levels of alkali (0.5 mol/L and 4 mol/L NaOH). The degree of carboxymethylation was assessed with both back titration and conductometric titration methods, and the performance of carboxymethylated fibers was assessed from their propensity for sorption of the cationic dye methylene blue, a putative wastewater contaminant. Higher degrees of carboxymethylation were generally observed for fibers carboxymethylated in 4 mol/L NaOH, but in dye sorption propensities, the fibers carboxymethylated in 0.5 mol/L NaOH performed better. A combination of observations from dye sorption, color measurement and conductometric titration suggested that dye permeation was greater through fibers carboxymethylated in 0.5 mol/L NaOH as compared to 4 mol/L NaOH. As permeability differences were evinced in cases also where the degrees of carboxymethylation were very similar, it appears that the reaction conditions (i.e., alkali content during carboxymethylation), in addition to degree of carboxymethylation, affected fiber performance. The effect of alkali may stem from their influence on the topographical distribution of the substituted carboxymethyl functional groups. [ABSTRACT FROM AUTHOR]

We used to consider native cellulose to be composed of microfibrils continuously crystalline along the chain direction with constant lateral dimension. To sulfate the surface of cellulose microfibrils, we activated cotton fibers by pre-swelling in water or DMF followed by immersion in an excess amount of sulfamic acid in dimethylformamide (DMF) in heterogeneous conditions. The degree of sulfation was followed by elemental analysis and conductometric titration, while the structural changes associated with the sulfation and the homogenization were investigated by infrared spectroscopy, solid-state NMR, and X-ray diffraction. The initial sulfation of the cellulose surface was well described as a first order reaction with a kinetic constant of 2 × 10 - 3 s - 1 at 80 °C using 3.6% sulfamic, indicating that about half of the available hydroxy groups were sulfated within the first 5 min. A water pre-swelling step, followed by solvent exchange with DMF, increased the amount of available hydroxy groups by up to a factor of two. At long reaction times, there was a gradual increase in the degree of sulfation beyond the initially available surface by up to 20% during the two hours reaction investigated. FTIR and solid-state NMR spectra both suggest the reaction of surface primary hydroxy groups with sulfamic acid. While the apparent lateral crystallite size of cotton is unaffected by sulfation treatment, X-ray diffraction suggested that homogenization resulted in cellulose nanofibers (CNFs) with a crystallite width below 3 nm, much smaller than the initial cellulose microfibrils (6–7 nm). This apparent crystallite splitting during homogenization suggests that cotton microfibrils have an intertwined polycrystalline structure, rather than being monocrystalline along the whole length. [ABSTRACT FROM AUTHOR]

This scientific article presents research on the electrical conductivity of imidazole-derived ionic liquids (1-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride and 1-methyl-3-octylimidazolium chloride) in the temperature range of 278.15–313.15 K in N,N-Dimethylformamide. The measurement methods employed relied mainly on conductometric measurements, enabling precise monitoring of the conductivity changes as a function of temperature. Experiments were conducted at various temperature values, which provided a comprehensive picture of the conducting properties of the investigated ionic liquids. The focus of the study was the analysis of the conductometric results, which were used to determine the conductivity function as a function of temperature. Based on the obtained data, a detailed analysis of association constants (KA) and thermodynamic parameters such as enthalpy (∆H0), entropy (∆S0), Gibbs free energy (∆G0), Eyring activation enthalpy for charge transport ( Δ H λ ‡ ) and diffusion processes (D0) was carried out. The conductometric method proved to be an extremely effective tool for accurately determining these parameters, significantly contributing to the understanding of the properties of imidazole-derived ionic liquids in the investigated temperature range. As a result, the obtained results not only provide new insights into the electrical conductivity of the studied ionic liquids but also broaden our knowledge of their thermodynamic behavior under different temperature conditions. These studies may have significant implications for the field of ionic liquid chemistry and may be applied in the design of modern materials with desired conducting properties. [ABSTRACT FROM AUTHOR]

The combination of amoxicillin (AMX) and clavulanic acid (CLA) is one of the most widely used antibiotic medicines in the world. This paper describes a novel electrochemical method for the fast sequential determination of AMX and CLA using batch injection analysis with amperometric detection (BIA‐AD) and boron‐doped diamond (BDD) as the working electrode. In the proposed strategy, AMX was selectively detected at +1.3 V and both compounds (AMX+CLA) at +1.8 V. The oxidation current from CLA was accessed by subtracting the currents detected at both potential pulses (i+1.8 V–i+1.3V) and using a simple correction factor. The developed method proved to be simple, cost‐effective, precise (RSD<1.3 %, n=10), rapid (>200 injection h−1), required simple sample preparation steps (dissolution and dilution only) and can be used in laboratories with minimal infrastructure (portable characteristics). The limits of detection were 0.31 (0.13) and 1.99 (0.47) μmol L−1 (mg L−1) for AMX and CLA, respectively. The results obtained by the proposed BIA‐AD method were comparable to those obtained by capillary electrophorese (95 % confidence level). [ABSTRACT FROM AUTHOR]

Herein, the novel hollow ZnO@SnS 2 core-shell nanorods with variable shell thickness have been synthesized by a chemical synthesis approach. The transmission electron microscopy (TEM) images signified the creation of a hollow core-shell nanostructure. The SnS 2 layer coating on ZnO nanorods broadens visible light absorption and suppresses near-band edge emission of ZnO nanorods. Interestingly, the band gap (optical) of the developed ZnO nanorods decreased from 3.3 eV to 2.1 eV after the coating of SnS 2 shell. Consequently, the coated hollow ZnO@SnS 2 core-shell nanorods displayed a significant enhancement in catalytic activity for the decomposition of toxic industrial dyes, pharmaceutical pollutant tetracycline, and Cr(VI) ion in comparison to hollow ZnO NRs. The photon-induced charge carrier generation and separation were confirmed by the three-electrode electrochemical amperometric analysis and impedance analysis under illumination of simulated solar light (AM 1.5, One Sun). Moreover, an exceptionally higher photocurrent generation (∼10 times higher than ZnO nanorod). The improved ZnO@SnS 2 core shell NRs catalytic activity was attributed to its core-shell structure, proper band structure, and effective charge carrier transfer across the core shell interface. This work offers new insights for the design and growth of visible light-active core shell nanorods for resolving environmental pollution and photocurrent generation. [Display omitted] • Rational construction of novel hollow ZnO@SnS 2 core-shell nanorods (NRs). • Thickness of SnS 2 was optimized for enhanced photocatalytic performance. • Hollow core-shell NRs exhibit enhanced reduction of toxic Cr(VI) ions and industrial dyes. • The SnS 2 layer coated on ZnO NRs enhances the light harvesting efficiency. • ZnO@SnS 2 core-shell NRs shows 10 times higher photocurrent than the ZnO NRs. [ABSTRACT FROM AUTHOR]

A zero-waste simple method was developed to produce carboxy nanocellulose directly from the untreated barley and wheat straw by treating with nitric acid (55%) and sodium nitrite at 40 °C for 12 h. This method significantly reduced the need for toxic chemicals such as TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)-oxyl) and radical generating chemicals. The process also reduced the usage of corrosive bases and acids and energy demand during the pretreatment process for the multi-step acid hydrolysis of biomass. Moreover, the by-product can be easily neutralized with the addition of NaOH, and the neutralized solution can be concentrated to obtain sodium nitrate which can be utilized as a fertilizer. The current method produces rod shaped and spherical particles of carboxy nanocellulose from the barley and wheat straw respectively with lower crystallinity (ca. ⁓30% of crystallinity index) than the barley and wheat straw itself (ca. ⁓60% of crystallinity index) as evidenced from the grazing incidence X-ray diffraction (GIXRD) technique. The conductometric titration revealed a high concentration (ca. ⁓2.6 mmol/g) of surface carboxylic (-COOH) acid groups and this result is supported by the high zeta potential value (ca ⁓-40mV) for the synthesized carboxy nanocellulose. [ABSTRACT FROM AUTHOR]

A technique for accelerated tolperisone hydrochloride (TH) determination in tablet dosage form based on titration of the analytical form with a solution of photogenerated iodine obtained by irradiation of an auxiliary solution containing KI and a mixture of sensitizers (nsodium eosinate:nsodium fluorescein:nuranine = 1:1:1) at pH 5.5 was developed. Stabilization of the current in the amperometric unit circuit indicated the reaction of the titrant with TH was complete, thereby providing regulation of the TH content in the preparation, when the iodine content in the solution was controlled by a voltammetric method (amperometric titration with two polarized electrodes). Further irradiation of the solution and measurement of the generation time required for replenishment of the lost titrant also provided regulation of the TH content in the preparation. The technique was tested on samples of a solid dosage form. The dependence of the analytical signal on the TH concentration was linear in the range 8.0 – 20.0 mg. The determined TH concentration (49.0 – 49.9 mg) fell within the interval recommended by GPM 1.4.2.0009.15 (47.7 – 52.5 mg), which confirmed the compliance of the preparation quality with the requirements stated in the regulations. The calculated detection limits (DL) and limits of quantification (QL) were 0.57 mg and (1.73, 1.74) mg as measured by changes in the current and generation time, respectively. The developed technique was easy to use, met the requirements set forth in the manual on validation of bioanalytical methods, and did not require expensive equipment and reagents. Therefore, it could be recommended for routine control of the drug quality parameters in any control and analytical laboratory. [ABSTRACT FROM AUTHOR]

MicroGraphited-Diamond-Multi Electrode Arrays (μG-D-MEAs) can be successfully used to reveal, in real time, quantal exocytotic events occurring from many individual neurosecretory cells and/or from many neurons within a network. As μG-D-MEAs arrays are patterned with up to 16 sensing microelectrodes, each of them recording large amounts of data revealing the exocytotic activity, the aim of this work was to support an adequate analysis code to speed up the signal detection. The cutting-edge technology of microGraphited-Diamond-Multi Electrode Arrays (μG-D-MEAs) has been implemented with an automated analysis code (APE, Amperometric Peak Analysis) developed using Matlab R2022a software to provide easy and accurate detection of amperometric spike parameters, including the analysis of the pre-spike foot that sometimes precedes the complete fusion pore dilatation. Data have been acquired from cultured PC12 cells, either collecting events during spontaneous exocytosis or after L-DOPA incubation. Validation of the APE code was performed by comparing the acquired spike parameters with those obtained using Quanta Analysis (Igor macro) by Mosharov et al. [ABSTRACT FROM AUTHOR]

A cellulose graft copolymer (cellulose nanoresin) was synthesized by the all-aqueous functionalization of cellouronic acid with poly (vinyl benzyl trimethyl ammonium chloride) (poly(vbTMAC)). Cellulose was oxidized using the highly reported 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated selective C-6 oxidation reaction. Fischer–Speier esterification of cellouronic acid was used to graft poly(vbTMAC) to the cellulosic backbone in a facile click-like mechanism. Synthesis of cellulose nanoresin was confirmed using dynamic light scattering and zeta potential measurements. Conductometric titration was used to determine the carboxylate content of cellouronic acid and the percent functionalization of the cellulose nanoresin, which was 1.69 ± 0.03 mmol/g and 61.2 ± 4%, respectively. Using a disodium fluorescein (NaFL) surrogate adsorbate, the maximum adsorption capacity of CNR was measured to be 26.8 ± 1.3 mg NaFL per gram of CNR with a Langmuir equilibrium binding constant of Ks = 10.5 ± 2 ppm−1. When examined as a thin film membrane, a breakthrough study of CNR showed that equilibrium loading was achieved in less than 30 s, and that > 90% of loading occurred in under 5 s. This data suggests that these films can be used as contact resins for anion-exchange water purification. We show in this work that these films maintain > 99% of loading performance over 40 trials of regeneration and reuse, meaning that these films are green and regenerable. Initial testing shows that CNR is effective at the removal of perfluorooctane sulfonate (PFOS) from water to below our limit of detection of 100 ppt. [ABSTRACT FROM AUTHOR]

A laboratory procedure has been suggested for determining the concentration of carboxyl groups at the surface of polystyrene microspheres at the latex concentration of a few hundredths of weight percentage (the COOH groups concentration below 4 × 10−4 mol/L). The procedure is based on conductometric and potentiometric titration. The influence of polymer particles concentration in the system, ionic strength of the solution, titration duration, and the system inertness on the obtained values of the carboxyl groups concentration and the determination accuracy have been investigated. [ABSTRACT FROM AUTHOR]

In this work, the volumetric, conductometric and potentiometric methods for the determination of Cl- ions in commercial NaCl samples were compared with the method established in NC-ISO 2481. Hg(NO3)2 was replaced by AgNO3 as the titrant in the normalized method. The percentage of halogens expressed as Cl-, NaCl, and I- were determined. The analysis performance parameters sensitivity, and repeatability were evaluated as precision and truthfulness criteria. One way Anova as carried out, where the Cochran C test was applied to verify the homogeneity of variance, with the p-Value = 0,82, which indicated the equality of the homogeneity of the same. The pvalue show in ANOVA table is 0,99, and it was confirmed that there are no significant statistical differences between the means of the calculated percentage of NaCl. [ABSTRACT FROM AUTHOR]

The current work reports the effect of palladium nanoparticles and their nanogeometry on the redox electrochemistry of tetracyanoquinodimethane (TCNQ) modified electrodes. Palladium nanoparticles were prepared with different concentrations of 3-aminopropyltrimethoxysilane and calcination at 600 °C to yield PdNP-1 and PdNP-2 of the average size of 1 µm and 12 nm, respectively. The palladium nanoparticles were characterized by TEM, XRD, and AFM techniques. The electrochemical excellence of ascorbic acid was resoluted using cyclic voltammetry amperometry, electrochemical impedance spectroscopy, and differential pulse voltammetry. A limit of detection (LOD) was found to be 51.61, 44.38 and 30.10 µM over a linear range from 50 to 625 µM for modified CPE/TCNQ, CPE/TCNQ-PdNP-1, and CPE/TCNQ-PdNP-2, respectively, determined by amperometric analysis for ascorbic acid at pH 7. The synergistic effect of Palladium and π* orbital of TCNQ played an important role in the enhancement of the catalytic activity of the modified electrode. The modified electrode showed good sensitivity, stability, and reproducibility which was confirmed by cyclic voltammetry, and amperometric analysis. The charge transfer resistance value also indicated that the modified electrode hads good electrocatalytic activity. [ABSTRACT FROM AUTHOR]

High fabrication cost, chemical instability, and complex immobilization of enzyme molecules are critical issues of enzyme‐based glucose sensors. Designing state‐of‐the‐art, binder‐free, and non‐enzymatic glucose sensing probes plays an imperative role to cope with the aforementioned issues. 3D carbonaceous nanomaterials coated with transition metal vanadates (TMVs) are a favorable biomimetic platform for glucose quantification. Peculiar hierarchical structure, enhanced conductivity, synergistic interaction, multiple oxidation states, and high catalytic activity would make such composite a potential contender for non‐enzymatic glucose sensing. Herein, 3D helical‐shaped carbon nanocoils (CNCs) are grown on nickel foam (NF) via chemical vapor deposition method to prepare a robust CNCs/NF scaffold. Then, a hydrothermal route is followed to grow interconnected free‐standing Ni3V2O8 nanosheets (NSs) on CNCs/NF scaffold. This novel and binder‐free Ni3V2O8 NSs/CNCs/NF hierarchical composite possesses superior electrochemical active area (ECSA) and exceptional electrochemical efficacy. Amperometric analysis exhibits extremely prompt detection time (0.1 s), elevated sensitivity (5214 µA mM−1 cm−2), and low detection limit (0.04 µM). Developed sensor demonstrates appreciable recoveries (93.3 to 103.3%) regarding glucose concentration in human serum. The appealing analytical results show that deployment of a 3D helical‐shaped hierarchical smart scaffold can be an effective strategy for developing efficient and advanced non‐enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

Methods using fluorescence polarization analysis and an amperometric immunosensor for the immunochemical determination of the non-steroidal anti-inflammatory drug diclofenac in drugs, artificial urine, and surface water are proposed. High analytical sensitivity was achieved by using promising nanomaterials, in particular, silicon nanoparticles doped with highly luminescent ruthenium complexes and electrochemically active hexarhenium cluster complexes. The relative standard deviation was (0.070. It was shown that the developed procedures for immunochemical determination of diclofenac had a wider range of determined concentrations than other methods. [ABSTRACT FROM AUTHOR]

[Display omitted] The superchaotropic Keggin polyoxometalate α-SiW 12 O 40 4− (SiW) was recently shown to stabilize non-ionic surfactant (C 18:1 E 10) foams owing to electrostatic repulsion that arises from the adsorption of SiW-ions to the foam interfaces. The precise mechanism of foam stabilization by SiW however remained unsolved. Imaging and conductimetry were used on macroscopic foams to monitor the foam collapse under free drainage and small angle neutron scattering (SANS) at a given foam height allowed for the tracking of the evolution of film thickness under quasi-stationary conditions. Thin film pressure balance (TFPB) measurements enabled to quantify the resistance of single foam films to external pressure and to identify intra-film forces. At low SiW/surfactant ratios, the adsorption of SiW induces electrostatic repulsion within foam films. Above a concentration threshold corresponding to an adsorption saturation, excess of SiW screens the electrostatic repulsion that leads to thinner foam films. Despite screened electrostatics, the foam and single foam films remain very stable caused by an additional steric stabilizing force consistent with the presence of trapped micelles inside the foam films that bridge between the interfaces. These trapped micelles can serve as a surfactant reservoir, which promotes self-healing of the interface leading to much more resilient foam films in comparison to bare surfactant foams/films. [ABSTRACT FROM AUTHOR]

Biopolymers are common ingredients in medical, technological, and industrial products. This paper presents the experimental analysis of conductometric properties of polysaccharides of chitosan (CH) in solutions in water W. The electrical conductivity was measured under the influence of increasing concentration of (0.5 to 10) g/l and increasing temperature of (288.15 to 318.15) K. The reduced electrical conductivity and the activation energy of reduced electrical conductivity Eσ are calculated. Biopolymer solutions exhibit a critical recovery of intrinsic electrical conductivity σ ∗ and a critical concentration c*, separating solutions into dilute solutions and semi-dilute solutions. The dependencies of the activation energy with solution concentration and intrinsic electrical conductivity are discussed. The polysaccharide CH behaviour can be extrapolated from the Flory-Huggins theory by decomposing such as E σ = E σ d + E σ s d = E σ S + E σ H . Where the E σ S = E σ d is the entropy-originated term that reflects the tendency of molecules to adopt as many configurations as possible on the network and the E σ H = E σ s d is associated with the energy variation that occurs when two molecules of different species are brought into contact. This enthalpy contribution represents well the non-Arrhenius behaviour. Principles that aid one to understand and interpret such results are discussed. [ABSTRACT FROM AUTHOR]

This paper presents the experimental analysis of conductometric properties of polysaccharide Sodium carboxymethyl cellulose (CMC) in solutions in water W. For the conductometric study of solutions of CMC + W, the electrical conductivity was measured under the influence of increasing concentration of (0.5 g/l to 10 g/l) and increasing temperature of (288.15 to 318.15) K. The reduced electrical conductivity and the activation energy of reduced electrical conductivity Eσ are calculated. Polysaccharides solutions exhibit a critical region, separating dilute solutions into semi-dilute solutions. The dependence of the activation energy on solution concentration and temperature is discussed. The polysaccharide CMC behaviour can be extrapolated from the Flory-Huggins theory by decomposing such as: Eσ = (Eσ)d + (Eσ)sd + (Eσ)cri. The dilute solution behaviour of Arrhenius is described by the CMC-W interaction and represented by the function (Eσ)d. For the semi-dilute solution behaviour of non-Arrhenius which is described by the interaction between the CMC-CMC and represented by the function (Eσ)sd. The critical solution behaviour is described by the CMC-CMC and CMC-W interactions and represented by the function (Eσ)cri. Principles that aid one to understand and interpret such results are discussed. [ABSTRACT FROM AUTHOR]

Modern progress in photopharmocology calls for new generation of compounds joining bioactivity, photoswitchable properties and high selectivity of response to light wavelength. Introduced here, phosphonate–fullerene hybrids are the first representatives of such compounds. Phosphonate–fullerene hybrids were synthesized on a base of fullerene C60 and organophosphates with the function of photoswitchable cholinesterase activity—phosphorylated thiazolotriazole and aminomalonate compounds and studied with FTIR, UV–VIS spectroscopy and IPC‐micro neurotoxin amperometric analysis. As a result of spectroscopic and bioactivity characterization, it was not only demonstrated butyrylcholinesterase (BuChE) inhibition increase in phosphonate–fullerene hybrids compared with pure phosphonates but also pronounced response of inhibition degree to laser irradiation of hybrids. It was found opposite behavior of hybrids as a result of laser irradiation—BuChE inhibition drop‐off for thiazolotriazole–fullerene and pronounced growth for aminomalonate–fullerene. The other remarkable peculiarity of presented phosphonate–fullerene hybrids is high selectivity of inhibition change degree to laser wavelength (266 or 325 nm). [ABSTRACT FROM AUTHOR]

Earth-abundant copper-tin (CuSn) electrocatalysts are potential candidates for cost-effective and sustainable production of CO from electrochemical carbon dioxide reduction (eCO2R). However, the requirement of highoverpotential for obtaining reasonable current, low Faradaic efficiencies (FE) and low intrinsic catalytic activities require the optimisation of the CuSn nanoarchitecture for the further advancement in the field. In the current work, we have optimised Sn loading on Cu gas diffusion electrodes (GDEs) by electrochemical spontaneous precipitation. Samples with various Sn loadings were tested in a three-chamber GDE reactor to evaluate their CO2 reduction performances. The best performance of 92% CO Faradaic efficiency at a cathodic current density of 120 mA cm-2 was obtained from the 20 min Sn deposited Cu2O sample operated at -1.13 V vs. RHE. The electrocatalyst had ~13% surface coverage of Sn on Cu GDE surface, and had Sn in oxide form and copper in metallic form. The catalyst also showed stable performance and was operable for >3 h under chronoamperometric conditions. The surface of the GDE reduces from Cu2O to Cu during eCO2R and goes further reconstruction during the eCO2R. This study demonstrates the potential of Cu--Sn for selective CO production at high current densities. [ABSTRACT FROM AUTHOR]

The objective of this study was to reexamine the general statement declaring that cationic and anionic species cannot be compatible in cosmetic products. This research demonstrated that there are considerable differences between the binding of cationic preservatives and various anionic compounds used in cosmetics, depending on the anionic functional group. Sulfate- and sulfonate-based molecules showed significantly stronger interactions with cationic surfactants than carboxylate-based anionic surfactants: This difference of affinity could reach a ratio of 1 to 10. We validated that conductimetry and isothermal titration calorimetry (ITC) can be used as predictive tools to determine the molecular interactions between any cationic and anionic species. Consequently, the correlation between compatible and incompatible cationic/anionic mixtures were verified and their corresponding anti-microbial activity using the challenge test was assessed. [ABSTRACT FROM AUTHOR]

A method for accelerated determination of diphenhydramine hydrochloride (dimedrol, DPH) in liquid and solid dosage forms (DFs) that is based on titration of the analytical form with a solution of photogenerated iodine obtained by irradiation of an auxiliary solution containing potassium iodide and uranine at pH 6.0 has been developed. Stabilization of the current in the amperometric circuit indicated that the reaction was complete and; therefore, provided control of the DPH content in the DF because the titrant content in the solution was controlled by a voltammetric method (amperometric titration with two polarized electrodes). Further irradiation of the solution and measurement of the time required to regenerate the lost titrant also made it possible to regulate the DPH content in the DF. The technique was tested on a solid DF and sterile solutions of DPH intended for intramuscular and intravenous administration. Stabilizers (HCl, lactose monohydrate) present in the DF had insignificant effects on photogeneration of the titrant. The dependence of the analytical signal on DPH concentration was linear in the range 0.1 – 20.0 mg for the drug "Diphenhydramine, tablets 50 mg." The limits of detection (DL) and quantitation (LOQ) for this drug that were calculated from the changes in the current and regeneration time were (1.26; 0.108) mg and (0.382; 0.329) mg, respectively. The developed photochemical method of determination complies with the requirements in the guidelines for validation of bioanalytical methods. The method is easy to use and does not require expensive equipment. Therefore, it can be recommended for routine control of the quality indicators under control or analytical laboratory conditions. [ABSTRACT FROM AUTHOR]

Direct electrochemical detection of histamine (HS) in peanuts was carried out using MW@GCE. MW (MnO4W) was prepared by the hydrothermal treatment of γ-MnOOH and W3O10 nanostructures. The synthesized γ-MnOOH (MNO), W3O10 (WO), and MnO4W (MW) nanostructures were characterized using XRD, FE-SEM, HR-TEM, XPS, and SECM techniques for structural, morphological, and electrochemical properties. MW@GCE was the superior electrode in comparison with MNO@GCE and WO@GCE, as confirmed by CV, Mott-Schottky, and impedance analyses. The limit of detection for the MW@GCE sensor was recorded as 5.817 nM and 3.7 nM from DPV and amperometric analyses, respectively. HS sensitivity was also recorded as 233.99 μA μM−1 cm−2 and 664.20 μA μM−1 cm−2 from DPV (0.1–0.16 μM) and amperometric analyses, respectively. Furthermore, HS detection in the peanut extract was done, and ∼0.16 μM (average amount) HS was quantified based on 18 concentrations. The usual spiking approach was also used for HS validation in peanuts with recoveries ranging from 105.3 to 106.2% and relative standard deviations ranging from 2.41 to 3.19%. The MW@GCE electrode's robustness was explored in terms of long-term storage, repeatability, and reproducibility Because of the direct detection capabilities of HS in peanuts and its resilience, this sensing system is useful for food and pharmaceutical sample analysis. [ABSTRACT FROM AUTHOR]

The non-enzymatic glucose sensing response of pure and Ag-decorated vertically aligned ZnO nanorods grown on Si substrates was investigated. The simple low-temperature hydrothermal method was employed to synthesize the ZnO NRs on the Si substrates, and then Ag decoration was achieved by sputtering. The crystal structure and surface morphologies were characterized by X-ray diffraction, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The Ag incorporation on the ZnO NR surfaces was confirmed using EDS mapping and spectra. Furthermore, the chemical states, the variation in oxygen vacancies, and the surface modifications of Ag@ZnO were investigated by XPS analysis. Both the glucose/ZnO/Si and glucose/Ag@ZnO/Si device structures were investigated for their non-enzymatic glucose sensing performances with different glucose concentrations. Based on EIS measurements and amperometric analysis, the Ag@ZnO-NR-based glucose sensor device exhibited a better sensing ability with excellent stability over time than pure ZnO NRs. The Ag@ZnO NR glucose sensor device recorded 2792 µA/(mM·cm2) sensitivity with a lowest detection limit of 1.29 µM. [ABSTRACT FROM AUTHOR]

Nickel hydroxides are widely used as electrochemically active substances in alkaline batteries and hybrid supercapacitors; they can be used for electrocatalysis, in electrochemical sensors, and as pigments. Knowledge of the formation mechanism of nickel hydroxides is necessary for developing and optimizing targeted synthesis methods. The thermal effects of processes in the formation of nickel hydroxide from nitrate were studied by the calorimetry method. The mechanism of precipitate formation was investigated by the method of simultaneous potentiometric (with a glass universal electrode) and conductometric titration. The nickel content in the samples obtained at the determined NaOH/Ni2+ ratios was investigated by the chemical method of trilonometry after preliminary dissolution. Calorimetric investigations showed that the reaction of nickel nitrate with NaOH was exothermic with ΔНreaction=‒28328.5 J/mol. The exothermic nature of the NaOH dilution process was revealed with ΔНdilution =‒2454 J/mol. According to the results of potentiometric titration, the formation of a basic salt of the NiOHNO3 type was not detected. Analysis of the results of conductometric titration revealed a two-stage chemical mechanism for the formation of nickel hydroxide from nitrate. At the first stage, which had a high rate, due to the liquid-phase reaction of the nickel cation with the hydroxyl anion, a primary precipitate of the composition Ni(OH)1.87(NO3)0.13 was formed. In the second stage, as a result of a slow topochemical reaction of the primary precipitate with hydroxyl anions, nitrate ions were displaced from the precipitate to form nickel hydroxide. These data are confirmed by the analysis of precipitate obtained at NaOH/Ni2+ ratios of 1.87 and 2.2: the Ni content was 52.95 % and 55.63 %, corresponding to the formulas Ni(OH)1.87(NO3)0.13∙0.68H2O and Ni(OH)2∙0.71H2O. This clearly indicated that the primary precipitate was nitratedoped α-Ni(OH)2 and the final precipitate corresponded to the α-modification of nickel hydroxide. [ABSTRACT FROM AUTHOR]

[Display omitted] The surface of silica nanoparticles (NP) may be covalently grafted with two amino ligands to balance colloidal stability and interfacial activity via formation of in situ Janus particles. The modified NP may be combined with a like-charged diamine surfactant to create ultra-stable CO 2 foam at low NP concentrations. The NP colloidal stability was measured up to 80 °C in 230 g/L TDS brine with dynamic light scattering. The NP surface was characterized using zeta potential, TEM, TGA, conductometric and potentiometric titrations, NMR and interfacial measurement. CO 2 /brine foam was generated at 60–80 °C and 15 MPa and apparent viscosity was measured vs foam quality. The foam stability was measured in-situ with an optical microscope. Upon adding only 0.1 wt% NP, ultra-stable CO 2 foam was observed at 60 °C with a bubble coarsening rate 3 orders of magnitude lower than with surfactant alone. Foam bubbles were spherical with NP present, but became polyhedral for the much less stable surfactant-only foams. For this novel like-charged surfactant-NP system, the limited surfactant adsorption on the NP resulted in NP stabilized CO 2 foam, while maintaining NP colloidal stability at high surfactant concentrations and high salinity, providing a new perspective of NP-surfactant design. [ABSTRACT FROM AUTHOR]

The copolymer of N,N-diallyl-N,N-dimethylammonium chloride and N-[3-(Dimethylamino)propyl]methacrylamide (DADMAC–DMAPMA) was synthesized by radical polymerization reaction in an aqueous solution in the presence of the initiator ammonium persulfate (NH4)2S2O8. The molar compositions of the synthesized copolymers were determined using FTIR and 1H NMR-spectroscopy, elemental analysis, and conductometric titration. It was found that in the radical copolymerization reaction, the DMAPMA monomer was more active than the DADMAC monomer; for this reason, the resulting copolymers were always enriched in the DMAPMA monomers. The study of the influence of the DADMAC–DMAPMA copolymer on structure-formation in the bentonite suspension showed that this copolymer significantly increased the static shear stress (SSS) of the system. In this case, the structure-forming properties of the copolymer depended on the pH of the medium. The lower the pH level, the better the structure-formation was in the suspension in the presence of the copolymer. The study of antibacterial activity showed that the DADMAC–DMAPMA copolymer had a biocidal effect against sulfate-reducing bacteria (CRB) at a concentration of not less than 0.05 wt.% and can be used to inhibit the growth of this bacteria. [ABSTRACT FROM AUTHOR]

The surface sulfate groups of cotton-derived cellulose nanowhiskers (CNWs) were quantified using three different methods: conductometric titration, adsorption of toluidine blue O (TBO), and sulfur elemental analysis. The former two methods indicated comparable values, whereas the last method indicated a considerable overestimation of up to 1.4 times the sulfate content compared to the values obtained by titration. This overestimation may be due to the inaccessibility of the sulfates inside the CNWs to the titrant and TBO, and/or the presence of non-sulfate sulfur elements. In addition to the quantitativeness of the TBO adsorption method, the present results also demonstrate the desulfation efficiency under several different desulfation conditions, where the sulfate content decreased by only half after alkali-mediated desulfation even with 2 M NaOH, whereas quite effective desulfation (ca. 90% decrease) was achieved with dilute HCl (0.25 M). [ABSTRACT FROM AUTHOR]

The purpose of conservation is to preserve the physical structure of the buildings along with their symbolic and artistic values and to ensure their sustainability. As a study reflecting this view, the structural and decorative materials of the Ahirardi Mosque, located in the historical city center of Kütahya, were examined from an archeometric point of view. Physical, chemical and petrographic analyzes were applied to stone, brick, plaster, mortar and tile samples from different parts of the mosque, which was built in 1876 and underwent various interventions over time. Within the scope of archaeometric studies, the physical properties of stone and brick samples were determined by basic physical tests, and the amount of salt dissolved in water and salt (anion) types of the same samples were determined by conductometric analysis. Aggre- gate/binder in mortars and plasters and particle size distribution (granulometric) analyses in aggregate were applied. The petrographic properties of all structural samples were determined by optical microscopy analysis on thin sections. The stones used in the construction of the mosque are mostly ignimbrite rock type. As with the stones, petrographic analyzes of the brick samples also showed that they have a volcanic origin. Mortar samples, whose aggregate/binder compositions were examined, were classified under 2 groups and plaster samples were classified under 3 groups. It has been determined that the binder content of mortars and plasters, all of which are repair examples, consists of cement/ash, clay/ash mixture binders. Repair mortar and plaster samples, whose aggregate/binder contents are quite similar, reflect recent repairs and the original mortar and plaster of the mosque has been destroyed in these processes. [ABSTRACT FROM AUTHOR]

Molecularly imprinting technology was applied for preparing selective sorbents for benzophenone-4 (BP4), an organic UV filter used in sunscreens and cosmetics. Several imprinted polymers were prepared by bulk polymerization, using BP4 as template. Combination of stability (mechanical and chemical), selectivity and robustness of the imprinted polymers with BP4 properties resulted in a successful imprinting process (imprinting factors in range 1.05-2.60). The prepared polymers were characterised by infrared spectroscopy, elemental analysis, conductometric titrations and nitrogen physisorption at 77 K. Adsorption capacities and selectivity towards 7 other organic UV filters (benzophenone-3, benzophenone-8, homosalate, butyl methoxydibenzoylmethane, ethyl hexyl salicylate, ethyl hexyl p-dimethylamino benzoate and ethyl hexyl p-methoxycinnamate) were determined, proving high adsorption capacity and high selectivity for BP4 binding. The highest adsorption capacity was observed for 4-vinylpyridine/ethylene glycol dimethacrylate co-polymer prepared in dimethyl sulfoxide (1.108 mmol g-1). The imprinted polymer with the highest binding capacity was applied to solid phase extraction of BP4 from aqueous solutions with 98.5 % efficiency. [ABSTRACT FROM AUTHOR]

In this investigation, the supramolecular interaction between a surfactant- tetradecyltrimethylammonium bromide (TTAB) and an antidiabetic drug metformin hydrochloride (MNH) was studied in the presence of some additives (alcohols/urea). The conductometric analysis as a function of surfactant concentration was used to assess the critical micelle concentration (CMC) of TTAB + MNH mixed system. The effect of a gradual change of temperature on CMC within a certain range (298.15–318.15 K) was monitored to assess the thermodynamic nature of micellisation process. In addition, estimation of thermodynamic parameters ( Δ G m o , Δ H m o , and Δ S m o ) and the determination of the degree of counter ion binding (β) give insight into the relative viability of a micellisation process. The values of Δ G m o were negative in all the mixed solvents studied and this was dependent on the chain length of the used alcohols. The thermodynamic parameters of transfer for shifting the micelles from aq. medium to aq. alcohols media and enthalpy-entropy compensation were also computed, compared with literature values and discussed with appropriate reasoning. Several supramolecular forces, including H-bonds, dipole–dipole, ion-dipole, hydrophobic, and electrostatic interactions, were recommended for the aggregation of the TTAB + MNH system. [ABSTRACT FROM AUTHOR]

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The current study aimed to examine how various growers in the Czech Republic hop-growing regions approached the production of hops (Saaz variety). The work also keeps track of how different growers approach fertilization and nutrition, as well as how often plant protection chemicals containing these ingredients are used. The Saaz hop variety samples from the primary Czech hop-growing regions, gathered in 2020 and 2021, were assessed. The average spindle length (14-18 mm), average number of spindle segments (9.3-11.9 pcs/needle) and conductometric parameters (2.7-4.7% w/w) in the samples were identified. [ABSTRACT FROM AUTHOR]

The demand for new renewable energy sources, improved energy storage and exhaust-free transportation requires the use of large quantities of rare earth (REE) and late transition (LTM, group 8–12) elements. In order to achieve sustainability in their use, an efficient green recycling technology is required. Here, an approach, a synthetic route and an evaluation of the designed bio-based material are reported. Cotton-derived nano cellulose particles were functionalized with a polyamino ligand, tris(2-aminoethyl) amine (TAEA), achieving ligand content of up to ca. 0.8 mmol g−1. The morphology and structure of the produced adsorbent were revealed by PXRD, SEM-EDS, AFM and FTIR techniques. The adsorption capacity and kinetics of REE and LTM were investigated by conductometric photometric titrations, revealing quick uptake, high adsorption capacity and pronounced selectivity for LTM compared to REE. Molecular insights into the mode of action of the adsorbent were obtained via the investigation of the molecular structure of the Ni(II)–TAEA complex by an X-ray single crystal study. The bio-based adsorbent nanomaterial demonstrated in this work opens up a perspective for tailoring specific adsorbents in the sequestration of REE and LTM for their sustainable recycling. [ABSTRACT FROM AUTHOR]

We report on the analytical performance of boron‐doped diamond thin‐film electrodes for the detection of the virulence factor, pyocyanin (PYO). The results reported herein confirm the utility of diamond electrodes for the sensitive and reproducible detection of pyocyanin in a 0.1 mol L−1 phosphate buffer (pH 7.4) when using amperometric detection coupled with flow injection analysis (FIA) or square wave voltammetry (SWV). Pyocyanin was reductively detected by hydrodynamic voltammetry in FIA at an E1/2 of −0.31 V vs. Ag/AgCl (3 mol L−1 KCl). The detection figures of merit were a linear dynamic range from 100 to 0.08 μmol L−1, a response reproducibility of 1.3 % (RSD), and a limit of detection of 0.09 μmol L−1 (S/N=3). A comparable linear dynamic range, response reproducibility and limit of detection were observed in preliminary square wave voltammetry measurements. Importantly, these detection figures of merit were obtained using boron‐doped diamond electrodes that received no conventional pretreatment. Some comparison data are presented for nitrogen‐incorporated tetrahedral amorphous carbon (ta‐C : N) and glassy carbon (GC) electrodes. [ABSTRACT FROM AUTHOR]

Lab-on-a-chip has recently become an alternative for in situ monitoring for its portability and simple integration with an electrochemical immunoassay. Here, we present an electrochemical cell-on-a-chip configured in a three-electrode system to detect benzo(a)pyrene (BaP) in water. 11-Mercaptoundecanoic acid (MUA), a self-assembled monolayer (SAM), was used to modify a gold chip surface to reduce the randomness of antibody binding. A carboxylic acid group was activated with -ethyl-3-(3-dimethylaminopropyl) (EDC) in combination with N-hyrodsuccinimide (NHS) before antibody immobilisation. The mechanism of the electrochemical reactions on a gold surface and SAM formation were investigated by cyclic voltammetry and contact angle measurements. The data revealed a lower contact angle in the modified chip and a scan rate of 50 mV/s. Through the addition of modification layers and thiol end groups to the SAM, our design allowed the chip surface to became more insulated. All were tested by amperometric detection using the developed Q-sense system. This novel technique detected multiple samples, and completed the analysis reasonably quickly. While the integrated system proved successful in a lab setting, the aim of the research is to use this system for in situ analysis, which can be brought into a water environment to carry out tests with existing processes. In this way, any issues that may arise from an environmental setting can be rectified in an efficient manner. [ABSTRACT FROM AUTHOR]

Interactions in the Ba2+-WO4 2--H+-H2O system, that was acidified to the molar ratio (acidity) Z=(H+)/(WO4 2-)=1.00, in the range of Z=0.60-2.00 at 298±0.1 K with NaNO3 as the background electrolyte (I=0.1-0.3 mol·l-1), were studied by the methods of pH-potentiometry, mathematical modeling and conductometry. Logarithms of concentration constants of equilibrium were calculated by Newton's method. Previously unknown logarithms of thermodynamic constants and Gibbs energies of format ion react ions for some ion pai rs (BaOH+, [W12O40(OH)2]10-; Ba2+, [W12O40(OH)2]10-; Ba2+,H2[W12O40(OH)2]8-; Ba2+,H3[W12O40(OH)2]5-; Ba2+,[W12O18(OH)2]6-; and Ba2+,H[W12O18(OH)2]5-) were calculated by Pitzer's method. The formation of particles with a Ba2+:[W12O40(OH)2]10-=1:1 ratio in solutions was established by conductometric titration method. A scheme of interconversions between ion pairs in an aqueous solution was proposed. From acidified to different Z values aqueous solutions of Na2WO4, the normal and double barium(II) paratungstates B Ba5[W12O40(OH)2]30H2O (Z=1.17), Na4Ba2[W12O40(ÎÍ)2]28Í2Î (Z=1.25), and Na2Ba4[W12O40(ÎÍ)2]25Í2Î (Z=1.33) were synthesized. The data of FTIR spectroscopy showed that the isopoly anion in the salts' composition belongs to the paratungstate B structural type. [ABSTRACT FROM AUTHOR]

Copper(II) and lead(II) are hazardous ions in environmental samples. Determining these ions from the samples is an important issue in analytical chemistry. Currently, various methods with analytical reagents are used in the determination of Cu(II) and Pb(II) ions, however, these methods and analytical reagents are expensive, hazardous, time-consuming, and non-recyclable. In this research, it is recommended new analytical reagent named 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol in the determination of copper(II) and lead(II) by the amperometric titration method. It is found that this analytical reagent effectively determines the Cu(II) and Pb(II) ions from environmental samples by amperometric titration, which is time-saving and low-cost. This reagent is also recyclable. It was found: (i) the detection limit for lead(II) and copper(II) ions were 2.08 and 3 ppm, respectively; (ii) the complex of 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol with lead(II) and copper(II) ions have a sharp angle at 0.5 V and 0.75 V, respectively, indicating that these ions are determined at one solution with this reagent; (iii) it was found that the half-wave potential of 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol was 0.55 V, confirming that the reagent is a reducing agent. The selectivity of this reagent is very high. In the future, this reagent should be widely used in the analytical determination of Cu(II) and Pb(II) ions. [ABSTRACT FROM AUTHOR]

• The conductometric titration of SO 4 2- includes stages of under saturation, crystallization nucleation, crystal growth, quasi reaction end, reaction end and infinite titration. • The angle difference between left and right tangents at titration curve is used as the determination standard for the endpoint of the conductometric titration. • The volume of tested-solution and concentration of titrant are determined by minimum and maximum volume of tested-solution, volume of the titrant, and tangent angle difference at titration endpoint. Accurately obtaining the SO 4 2- content in concrete is a prerequisite for revealing mechanism of sulfate attack, establishing model of sulfate attack, proposing durability design methods. The feasibility of testing SO 4 2- in cement-based materials by conductivity titration was investigated by the author in previous research. Therefore, this study further investigated the optimal conductivity titration parameters and standard for determining the endpoint of titration curve by establishing a conductivity titration kinetic model (CTKM). Based on the proposed CTKM, optimal range of titration parameters such as the volume of measured solution, solution concentration standard titrant and titration rate were obtained, and the effects of other ions on optimal range of titration parameters were also discussed. The results show that among the six stages on the titration curve of SO 4 2- (undersaturation stage, crystal nucleation stage, crystal growth stage, quasi reaction end stage, reaction end stage and infinite titration stage), crystal growth stage and reaction end stage are essential. The titration curves calculated by the CTKM are in good agreement with the measured curves. The included angle between the left and right tangents of a point on the normalized conductivity titration curve can be a good criterion for determining the titration end point. When the included angle exceeds 10°, the titration end point is easily determined. The optimal range of titration parameters are confined by the minimum measured solution volume to submerge the conductivity electrode (about 5 mL), the maximum measured solution volume to be stirred evenly (about 10 mL), and the appropriate added volume of standard titrant to ensure titration accuracy (between 1 and 1.5 mL), and the included angle to be easily determined (greater than 10°). The influence of H+, OH–, Cl-, and Na+ on SO 4 2- titration gradually weakens. In composite solution containing 0.01 mol/L SO 4 2-, when the concentration of H+ exceeds 0.1 mol/L, or the concentration of OH– exceeds 0.2 mol/L, directly titrating SO 4 2- is difficult and a deionization process is required. [ABSTRACT FROM AUTHOR]

Developing new sensors presenting low-cost, portability, and disposability features is of paramount in the electrochemical field. Thus, this work proposes the fabrication of lab-made composite electrodes using acrylonitrile butadiene styrene, graphite, and aluminum oxide. In this investigation, the amount of aluminum oxide (0 to 12.25 w/w) was carefully optimized, and its impact on the electrochemical performance of the electrode was observed using the ferri-ferro redox probe and dopamine (DOP) as a proof of concept. This innovative electrode was characterized by spectroscopy, morphological, elemental, and electrochemical techniques. Using the alumina-loaded electrode, significantly improved cyclic voltammetric responses regarding peak currents and peak-to-peak separation were obtained for both evaluated species. This sensor was integrated into the batch injection analysis system for amperometric monitoring of DOP in synthetic biological fluids (saliva and urine) and tap water. The developed method showed a wide linear range (10 to 1000 µmol L−1), a low detection limit (2.6 µmol L−1), and a high analytical frequency (182 analyses per hour). Furthermore, it was precise (RSD < 5%), accurate (recoveries between 90.5 and 107.3%), and selective. Therefore, it can be considered a low-cost alternative analytical tool for electrochemical sensing of DOP in samples of clinical and environmental interest. [ABSTRACT FROM AUTHOR]