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A single nanoparticle (NP) attached to a nanoelectrode is a very useful system in understanding the relationship between the size of nanoparticles and their electrochemical properties. In this study, a single Au NP was spontaneously formed on a Pt nanoelectrode. The potential measured on such a system can be employed to study the effect of size of an Au nanoparticle on the Nernst potential of the reaction, AuCl4− +3e → Au(s) +4Cl−. Moreover, the nucleation period and the growth period can be distinguished from the potential graph, and the nucleation rate of the spontaneously formed Au NP can be evaluated. [ABSTRACT FROM AUTHOR]

A new solid-contact ion-selective electrode (ISE) sensitive to lead (II) ions, obtained by modifying a polymer membrane with a nanocomposite of carbon nanofibers and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, is presented. Electrodes with a different amount of nanocomposite in the membrane (0–9% w/w), in which a platinum wire or a glassy carbon electrode was used as an internal electrode, were tested. Potentiometric and electrochemical impedance spectroscopy measurements were carried out to determine the effect of the ion-sensitive membrane modification on the analytical and electrical parameters of the ion-selective electrode. It was found that the addition of the nanocomposite causes beneficial changes in the properties of the membrane, i.e., a decrease in resistance and an increase in capacitance and hydrophobicity. As a result, the electrodes with the modified membrane were characterized by a lower limit of detection, a wider measuring range and better selectivity compared to the unmodified electrode. Moreover, a significant improvement in the stability and reversibility of the electrode potential was observed, and additionally, they were resistant to changes in the redox potential of the sample. The best parameters were shown by the electrode obtained with the use of a platinum wire as the inner electrode with a membrane containing 6% of the nanocomposite. The electrode exhibited a Nernstian response to lead ions over a wide concentration range, 1.0 × 10−8–1.0 × 10−2 mol L−1, with a slope of 31.5 mV/decade and detection limit of 6.0 × 10−9 mol L−1. In addition, the proposed sensor showed very good long term stability and worked properly 4 months after its preparation without essential changes in the E0 or slope values. It was used to analyze a real sample and correct results of lead content determination were obtained. [ABSTRACT FROM AUTHOR]

Free fluoride ions are effective in combating caries in children, and their supplementation in milk has been widely used worldwide for this purpose. Furthermore, it is known that ionic fluoride added to milk is distributed among its components, but little is known about their quantitative relationships. This is likely due to the absence of an analytical protocol aimed at differentiating and quantifying the most important forms of fluorine present in milk. For the first time, a comprehensive protocol made up of six potentiometric methods devoted to quantifying the most important fractions of fluorine in milk (i.e., the free inorganic fluoride, the inorganic bonded fluorine, the caseins-bonded fluorine, the whey-bonded fluorine, the lipid-bonded fluorine, and the total fluorine) has been developed and tested on real samples. Four of the six methods of the procedure are original, and all have been validated in terms of limit of detection and quantification, precision, and trueness. The data obtained show that 9% of all fluorine was in ionic form, while 66.3% of total fluorine was bound to proteins and lipids, therefore unavailable for human absorption. Beyond applications in dental research, this protocol could be extended also to other foods, or used in environmental monitoring. [ABSTRACT FROM AUTHOR]

Regardless of glucose concentration, the Bland-Altman graph (Figure 2) showed a NaID mean bias of -2.6 mmol L SP -1 sp (95% limits of agreement from -6.4 to 1.2) and 303 (52%) results were <=3 mmol L SP -1 sp . Then, to test whether NaID was strictly caused by pathologic hyperglycemia, we compared NaI and NaD on spurious hyperglycemia samples due to infusion glucose solution. According to the regression equation y=-0.062x (95%CI: y=[-0.065; -0.058]x) and the cut-off of 3 mmol L SP -1 sp , NaID starts to be significant above a calculated glucose concentration of 34.8 mmol L SP -1 sp (95%CI: 33.2; 36.6). Keywords: analytical interference; hyperglycemia; pseudohyponatremia; sodium ion-selective electrode EN analytical interference hyperglycemia pseudohyponatremia sodium ion-selective electrode e25 e28 4 12/22/22 20230201 NES 230201 To the Editor, Dysnatremia is the most frequently encountered and mismanaged electrolyte disorder in clinical practice [[1]]. [Extracted from the article]

[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]

Bioelectronic sensors that report charge changes of a biomolecule upon target binding enable direct and sensitive analyte detection but remain a major challenge for potentiometric measurement, mainly due to Debye Length limitations and the need for molecular‐level platforms. Here, we report on a magneto‐controlled potentiometric method to directly and sensitively measure the target‐binding induced charge change of DNA aptamers assembled on magnetic beads using a polymeric membrane potentiometric ion sensor. The potentiometric responses of the negatively charged aptamer, serving as a receptor and reporter, were dynamically controlled and modulated by applying a magnetic field. Based on a potentiometric array, this non‐equilibrium measurement technique combined with deep learning algorithms allows for rapidly and reliably classifying and quantifying diverse small molecules using antibiotics as models. This potentiometric strategy opens new modalities for sensing applications. [ABSTRACT FROM AUTHOR]

Bioelectronic sensors that report charge changes of a biomolecule upon target binding enable direct and sensitive analyte detection but remain a major challenge for potentiometric measurement, mainly due to Debye Length limitations and the need for molecular‐level platforms. Here, we report on a magneto‐controlled potentiometric method to directly and sensitively measure the target‐binding induced charge change of DNA aptamers assembled on magnetic beads using a polymeric membrane potentiometric ion sensor. The potentiometric responses of the negatively charged aptamer, serving as a receptor and reporter, were dynamically controlled and modulated by applying a magnetic field. Based on a potentiometric array, this non‐equilibrium measurement technique combined with deep learning algorithms allows for rapidly and reliably classifying and quantifying diverse small molecules using antibiotics as models. This potentiometric strategy opens new modalities for sensing applications. [ABSTRACT FROM AUTHOR]

Carbon fibers (CFs) of high quality were produced from hydrocarbons such as isobutane or ethylene using the catalytic chemical vapor deposition method (CCVD) and Ni catalyst. The as-prepared samples were functionalized with acidic groups using concentrated sulfuric acid or 4-benzenediazonium sulfonate (BDS) generated in situ from sulfanilic acid and sodium nitrite. The morphological features of the materials were confirmed by transmission electron microscopy, whereas their physicochemical properties were characterized by means of elemental and textural analyses, thermogravimetric (TG) method, Raman spectroscopy, potentiometric back titration, and X-ray diffraction analysis. The obtained CFs were used as catalysts in glycerol etherification with tert-butyl alcohol at 110 °C under autogenous pressure. The BDS-modified CFs were particularly effective in the reaction, showing high glycerol conversions (of about 45–55% after 6 h) and substantial yields of mono- and di-glycerol ethers. It was found that the chemistry of the sample surface was crucial for the process. The high concentration of -SO3H groups decorating CFs boosted the formation of di- and tri-tert-butyl glycerol ethers. Surface oxygen functionalities also had a positive effect on the reaction, however, their impact on the catalytic performances of CFs was significantly weaker compared to that shown by -SO3H groups and it was probably due to the adsorption of reagents on the catalyst surface. [ABSTRACT FROM AUTHOR]

Abstract The current study reports a successful cation-selective electrode based on CoNiFe2O4 magnetic nanocomposite to determine the Ce3+ ion. The results revealed this new nanocomposite can be applied as an excellent modifier in lieu of common organic modifiers that are used in the construction of ion-selective electrodes. The replacement of nanocomposite can significantly boost the performance of the electrode compared with organic modifiers. Under optimal conditions, the sensor exhibited a Nernstian slope of roughly 17.5 mV per decade in the linear range of 1.0 × 10−8–1.0 × 10−1 mol/L. Also, the detection limit was 7.0 × 10−9 mol/L. This electrochemical sensor showed a stable potential in 5 s. The optimum pH for electrode operation is in the range of 2–10. Among various interferences ions, this electrochemical sensor manifested high selectivity toward Ce3+ cation. The obtained results in analytical applications demonstrated the excellent ability of this electrode to determine Ce3+ cation via titration with ethylene diamine tetra acetic acid. Moreover, this indicator electrode was used for the measurement of Ce3+ cations in various samples. [ABSTRACT FROM AUTHOR]

Multiplexed solid‐contact ion‐selective electrodes (SCISEs) are fabricated using printed circuit board (PCB) and mesoporous carbon black (MCB) as ion‐to‐electron transducer (solid contact). Four sensor configurations were examined and showed that in addition to MCB, the sensor configuration plays crucial role in the stability of the potential response. The enhanced sensor stability was also linked with suppression of transmembrane flux of water. The sensors exhibited near‐Nernstian sensitivity (58.1 mV/dec for K+ ISEs and −55.1 mV/dec for NO3‐ ISEs), low detection limits (1.5–2.2 μM), and good short‐term stability (∼0.1 mV/min). Sensors can be stored dry and used without preconditioning. This work demonstrates a promising approach to combining PCB technology and carbon black for large‐scale production of low cost ISEs for point‐of‐care testing, wearables, or in situ field measurements. [ABSTRACT FROM AUTHOR]

This work represents first attempt for potentiometric determination of the most recent antidiabetic; omarigliptin. Three sensors, employing potassium tetrakis (p‐chlorophenyl) borate as a lipophilic cation exchanger, were developed and compared. One liquid contact ion‐selective electrode and two carbon paste‐based solid contact ones, plain one and another one modified with polyaniline nanoparticles, were employed. Performances of fabricated sensors were assessed as per IUPAC recommendations. Incorporation of hydrophobic polyaniline nanoparticles as ion‐to‐electron transducer layer at solid contact/ion‐sensitive membrane interface enhanced sensitivity and stability of the third sensor showing LOD of 2.5×10−7 mol L−1 and slope of 58.57 mV decade−1. The three sensors were applied for omarigliptin determination in presence of its degradation products, in dosage form and spiked human plasma. [ABSTRACT FROM AUTHOR]

The evaluation of the biogenic amines (BAs) profile of different types of craft beers is herein presented. A previously developed and validated analytical method based on ion-pair chromatography coupled with potentiometric detection was used to determine the presence of 10 BAs. Good analytical features were obtained for all amines regarding linearity (R2 values from 0.9873 ± 0.0015 to 0.9973 ± 0.0015), intra- and inter-day precision (RSD lower than 6.9% and 9.7% for beer samples, respectively), and accuracy (recovery between 83.2–108.9%). Detection and quantification limits range from 9.3 to 60.5 and from 31.1 to 202.3 µg L−1, respectively. The validated method was applied to the analysis of four ale beers and one lager craft beer. Ethylamine, spermidine, spermine, and tyramine were detected in all analyzed samples while methylamine and phenylethylamine were not detected. Overall, pale ale beers had a significantly higher total content of BAs than those found in wheat pale and dark samples. A general least square regression model showed a good correlation between the total content of BAs and the brewing process, especially for Plato degree, mashing, and fermentation temperatures. Knowledge about the type of ingredients and manufacturing processes that contribute to higher concentrations of these compounds is crucial to ensuring consumer safety. [ABSTRACT FROM AUTHOR]

Mechano- and sonochemical treatments were proposed as facile procedures for doping of precipitated SnO2 with silver. All obtained samples have been studied using XRD, SEM and EDS, XPS, adsorption–desorption of nitrogen, UV–Vis spectroscopy and potentiometric titration. XRD and SEM–EDS data showed that silver was uniformly distributed at surface of SnO2. The doped samples have a developed meso–macroporous structure. Narrowing the band gap and increasing in absorption of visible light result in high photocatalytic activity of doped SnO2 in the degradation of dyes and 4-clorophenol under visible irradiation. Relationship between physicochemical and photocatalytic properties of prepared samples has been discussed. [ABSTRACT FROM AUTHOR]

Nitrite is an important food additive for cured meats; however, high nitrite levels pose adverse health effects to humans. Hence, monitoring nitrite concentration is critical to comply with limits imposed by regulatory agencies. Laser-induced graphene (LIG) has proven to be a scalable manufacturing alternative to produce high-performance electrochemical transducers for sensors. Herein, we expand upon initial LIG studies by fabricating hydrophilic and hydrophobic LIG that are subsequently converted into ion-selective sensors to monitor nitrite in food samples with comparable performance to the standard photometric method (Griess method). The hydrophobic LIG resulted in an ion-selective electrode with improved potential stability due partly to a decrease in the water layer between the electrode and the nitrite poly(vinyl) chloride-based ion-selective membrane. These resultant nitrite ion-selective sensors displayed Nernstian response behavior with a sensitivity of 59.5 mV dec−1, a detection limit of 0.3 ± 0.1 mg L-1 (mean ± standard deviation), and a broad linear sensing range from 10−5 to 10−1 M, which was significantly larger than currently published nitrite methods. Nitrite levels were determined directly in food extract samples of sausage, ham, and bacon for 5 min. These sensor metrics are significant as regulatory agencies limit nitrite levels up to 200 mg L-1 in finished products to reduce the potential formation of nitrosamine (carcinogenic compound). These results demonstrate the versatility of LIG as a platform for ion-selective-LIG sensors and simple, efficient, and scalable electrochemical sensing in general while demonstrating a promising alternative to monitor nitrite levels in food products ensuring regulatory compliance. [ABSTRACT FROM AUTHOR]

The development of carbon paste electrodes in the 1970s generated considerable interest in the scientific community, because they offered several advantages over conventional membrane electrodes. At the beginning of the new millennium, the use of carbon nanomaterials as a new trend in their development gave additional impetus. After CPEs were successfully developed for potentiometric determination of more than 70 chemical elements, these electrodes gained additional interest for pharmaceutical and medical applications. This paper reviews the scientific literature of the last decade related to the development of CPEs for the quantitative determination of active pharmaceutical ingredients and their application in real samples. [ABSTRACT FROM AUTHOR]

In this study, polypyrrole-based molecularly imprinted polymer (MIP) containing phosphate selective site as a conductive polymer material for phosphate ion sensor was successfully synthesized and characterized. The synthesis of MIP-phosphate was carried out using pyrrole as a functional monomer by cyclic voltammetry on the surface of gold wire electrode. The MIP-phosphate electropolymerization was performed in potential range from −0.8 to 0.6 V at a scan rate of 100 mV/s for 10 cycles. According to the FTIR spectra and visual observation of SEM images, the MIP-phosphate was successfully synthesized as a homogenous and well-ordered porous structure. The MIP electrode response to phosphate was examined by potentiometry method, showing an excellent linear response for , , and within the concentration range of 1 × 10–7 to 0.1 M with good sensitivity. The selectivity coefficient result also indicates good selectivity toward phosphate ions against the interfering anions (Cl–, , and ). [ABSTRACT FROM AUTHOR]

A carbon electrode utilizing an ion pairing agent for the potentiometric determination of nonyltrimethylammonium bromide (NTAB) was developed. The sensitivity of the developed sensor was established through the formation of ion pair between NTAB and the proposed ion pairing agent on the surface of the sensor paste which was characterized by morphological tools. The developed sensor revealed a monovalent Nernstian slope of 58.4 ± 0.8 mV/decade within the acceptable working concentration range of NTAB from 1.0 × 10−6 to 0.01 M with the detection limit of 1.0 μM. [ABSTRACT FROM AUTHOR]

In the present study, we developed a cadmium(II)-selective sensor using a novel poly(vinyl chloride) membrane, containing synthesised (E)-2-benzylidenehydrazinecarbothioamide as an ionophore. This newly developed cadmium(II)-selective sensor exhibits best performance with a membrane composition of poly(vinyl chloride) (PVC), bis(2-ethylhexyl) adipate (DEHA), ionophore, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) at 32.0:63.0:4.0:1.0 ratio (%, w/w). The cadmium(II)-selective sensor exhibits a lower detection limit of 1.77 × 10−6 mol L−1. This potentiometric sensor displays a stable potential response in the pH range of 5.0–10.0 and it shows a good selectivity for Cd2+ in the presence of interfering ions. The developed sensor shows a relatively fast response time (10 s), good reusability and stability. The proposed cadmium(II)-selective sensor was successfully applied as an indicator electrode in potentiometric titration of Cd2+ ions with EDTA and for the direct determination of Cd2+ ions in different environmental samples and in a waste battery sample. [ABSTRACT FROM AUTHOR]

Electrochemical sensors with polymeric films as a sensitive layer are of high interest in current electroanalysis. A voltammetric sensor based on multi-walled carbon nanotubes (MWCNTs) and electropolymerized 4-aminobenzoic acid (4-ABA) has been developed for the simultaneous determination of synthetic food azo dyes (sunset yellow FCF and tartrazine). Based on the voltammetric response of the dyes' mixture, the optimal conditions of electropolymerization have been found to be 30-fold potential scanning between −0.3 and 1.5 V, at 100 mV s−1 in the 100 µmol L−1 monomer solution in phosphate buffer pH 7.0. The poly (4-ABA)-based electrode shows a 10.5-fold increase in its effective surface area and a 17.2-fold lower electron transfer resistance compared to the glassy carbon electrode (GCE). The sensor gives a sensitive and selective response to sunset yellow FCF and tartrazine, with the peak potential separation of 232 mV in phosphate buffer pH 4.8. The electrooxidation parameters of dyes have been calculated. Simultaneous quantification is possible in the dynamic ranges of 0.010–0.75 and 0.75–5.0 µmol L−1 for both dyes, with detection limits of 2.3 and 3.0 nmol L−1 for sunset yellow FCF and tartrazine, respectively. The sensor has been tested on orange-flavored drinks and validated with chromatography. [ABSTRACT FROM AUTHOR]

Advancing electronics to interact with tissue necessitates meeting material constraints in electrochemical, electrical, and mechanical domains simultaneously. Clinical bioelectrodes with established electrochemical functionalities are rigid and mechanically mismatched with tissue. Whereas conductive materials with tissue-like softness and stretchability are demonstrated, when applied to electrochemically probe tissue, their performance is distorted by strain and corrosion. We devise a layered architectural composite design that couples strain-induced cracked films with a strain-isolated out-of-plane conductive pathway and in-plane nanowire networks to eliminate strain effects on device electrochemical performance. Accordingly, we developed a library of stretchable, highly conductive, and strain-insensitive bioelectrodes featuring clinically established brittle interfacial materials (iridium-oxide, gold, platinum, and carbon). We paired these bioelectrodes with different electrochemical probing methods (amperometry, voltammetry, and potentiometry) and demonstrated strain-insensitive sensing of multiple biomarkers and in vivo neuromodulation. [ABSTRACT FROM AUTHOR]

A highly efficient hybrid adsorbent has been synthesized, which is based on an industrially available biodegradable nontoxic flax cellulose modified with hyperbranched polyester polybenzoylthiocarbamate. The synthesis has been carried out using toluene diisocyanate (TDI) as a linker. The second-generation hyperbranched polyester polybenzoylthiocarbamate contains eight terminal benzoylthiocarbamate and eight hydroxyl groups according to 1H NMR, 13C NMR, and IR spectroscopy. In the first stage, the reaction of TDI with flax cellulose has been carried out, which provided 27% content of TDI according to potentiometric titration. The resulting modified flax cellulose has reacted with hyperbranched polyester polybenzoylthiocarbamate. The content of hyperbranched polymer in cellulose (5%) has been evaluated by the weight method. The unreacted isocyanate groups have been neutralized with isobutyl alcohol. The structure of the hybrid material has been proven by IR spectroscopy. The adsorption properties of the polydentate adsorbent have been studied with for the Cu(II) ions. It has been found that the adsorption capacity of the adsorbent is 6.93 mg/g. The methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been used to evaluate the temperature characteristics, thermal effects, and mass loss of the obtained polydentate compound and its complexes. Desorption of the Cu(II) and Co(II) ions with the regeneration of the hybrid adsorbent has been shown to occur in an acidic medium at pH 3–4. [ABSTRACT FROM AUTHOR]

Abstract—A promising direction for improving protective polymer coatings for highly aggressive environments is the implementation of the mechanism of self-adaptation and increase of the protective properties of the coating, as well as self-healing. In multilayer composite coatings, in addition to primer layers, this approach is relevant for insulating upper layers based on thermosets. Such modern materials, as a rule, contain active functional groups and oligomeric additives. This paper presents the results of a study of the electrochemical characteristics (EIS and potentiometry) of polymeric epoxy protective coatings on an inert platinum substrate during long-term exposure to NaCl solution. It is shown that, when active organic additives are used in a polymer coating, it is fundamentally possible to find the effect of self-adaptation and an increase in the protective properties (impedance modulus, active resistance, angle of loss of the polymer film, and an increase in the potential of the substrate under it) when exposed to a chloride-containing aggressive environment. At the stage of the beginning of coating destruction at a certain time intervals for a model epoxy–phenol–furan coating, a behavior was registered that allows us to speak about the manifestation of the self-healing effect, namely, the restoration (up to 100%) of the full coating impedance combined with the restoration of a high (up to 89 degrees) dielectric loss angle. [ABSTRACT FROM AUTHOR]

To characterize the oxidizing ability of the H2SO4–H3PO4–H2O–Fe(III) system, we measured the electrode potentials of the Fe(III)/Fe(II) redox couple and the half-wave potentials of the Fe3+ + e– = Fe2+ and Fe2+ – e– = Fe3+ transitions (reactions) on the cyclic voltammogram of a platinum electrode in acid solutions containing Fe(III) salts. It is shown that the values of these experimentally obtained parameters are close. The decrease in the oxidizing ability of H2SO4 and H3PO4 mixtures containing Fe(III) with an increase in the molar fraction of H3PO4 in them occurs due to the formation of Fe(III) complexes with phosphate anions, which are inferior in oxidizing ability to their hydrate and sulfate complexes. The temperature coefficients of the electrode potential (dE/dt) of the Fe(III)/Fe(II) redox couple in the H2SO4–H2O, H2SO4–H3PO4–H2O, and H3PO4–H2O systems were experimentally determined. Based on the Randles–Sevcik equation, the diffusion coefficients of Fe(III) in the studied solutions were calculated. The temperature dependence of the diffusion coefficients of Fe(III) cations is satisfactorily described by the Arrhenius equation. The parameters of this equation are calculated. [ABSTRACT FROM AUTHOR]

In this report, we have presented our experience about a facile method for synthesis of tofacitinib citrate (TFC). The developed analytical methods for identification and qualifications are also included. As TFC seems to be effective in treatment of the symptoms of COVID-19 (SARS family), manufacturing of this active pharmaceutical ingredient (API) could be helpful. The API of TFC was prepared from the diamine intermediate in an ambient and solvent-free condition. Elimination of the reaction solvent resulted in decreasing the cost and preventing the rejection of the organic volatile impurity (OVI) test. The final citrate addition step was carried out using water as a solvent (the citrate content was 37.5% by potentiometry). Moreover, the results of the Karl-Fischer (KF) titration analysis was about 0.24%, which showed that the use of water does not increase the water content of the crystal structure. [ABSTRACT FROM AUTHOR]

Ti/TiO2-Sb-SbOx multifunctional sensors were obtained by plasma electrolytic oxidation in the anodic–cathodic mode. The resulting films contain TiO2 and up to 5 at.% Sb in the form of Sb0 and Sb6O13. Electrode functions E vs pH are linear in the range of pH 2 ÷ 10 with slopes of 68 ± 6 and 48 ± 2 mV·pH−1 for sensors formed at iC/iA = 1 and 1.2, respectively. The Ti/TiO2-Sb-SbOx sensor obtained at iC/iA = 1.2, despite its low response, shows results similar to the glass electrode in acid–base titration and can be used to accurately determine the alkalinity of natural and technogenic waters. The possibility of application of such sensors in potentiometric acid–base, redox, complexometric, and precipitation chemical reactions was revealed. The multifunctionality of the Ti/TiO2-Sb-SbOx sensor makes it possible to analyze aqueous solutions of complex composition using the same electrode. [ABSTRACT FROM AUTHOR]

A poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based conducting polymer, which has biorecognition capabilities, has promising biosensing applications. Previously, we developed a facile method for post-printing chemical modification of PEDOT:PSS thin films from commercial sources. Molecular recognition elements were directly introduced into the PSS side chain by a two-step chemical reaction: introduction of an ethylenediamine linker via an acid chloride reaction of the sulfonate moiety, and subsequent receptor attachment to the linker via amine coupling. In this study, the same method was used to introduce 6-carboxypyridine- 3-boronic acid (carboxy-PyBA) into the linker for specifically detecting N-acetylneuraminic acid (sialic acid, SA), as a cancer biomarker. The surface-modified PEDOT:PSS films were characterized by X-ray photoelectron spectroscopy, attenuated total reflection Fourier-transform infrared spectroscopy, and static water contact angle and conductivity measurements. The specific interaction between PyBA and SA was detected by label-free reagent-free potentiometry. The SA specific negative potential responses of modified PEDOT:PSS electrodes, which was ascribed to an SA carboxyl anion, were observed in a physiologically relevant SA range (1.6-2.9 mM) at pH 5, in a concentration-dependent manner even in the presence of 10% fetal bovine serum. The sensitivity was -2.9 mV/mM in 1-5 mM SA with a limit of detection of 0.7 mM. The sensing performances were almost equivalent to those of existing graphene-based electrical SA sensors. These results show that our chemical derivatization method for printing PEDOT:PSS thin films will have applications in SA clinical diagnostics. [ABSTRACT FROM AUTHOR]

Peptide nucleic acids (PNAs) are neutral mimics of natural DNA and RNA biopolymers that have caught the attention of researchers working on the identification of specific sequences of nucleobases in DNA/RNA strands. For this purpose, specific analytical protocols need to be developed to optimize the nucleic acid recognition ability of PNAs, exploiting both the high intrinsic affinity of PNA/DNA(RNA) couples as well as suitable markers, either linked to the PNA backbone or properly interacting with it in the working medium. In this context, the paper reports on phthalimide and 4‐nitrophthalimide as two cheap, metal‐free electroactive markers covalently bound to the pseudo‐peptide backbone of a PNA decamer. After a preliminary characterization of the markers, as such and in PNA conjugates, attention has been moved toward the optimization of the detectability of the labeled PNA decamers in aqueous solutions. Exploiting the potentiometric stripping analysis on hanging mercury drop electrode it has been possible to reach satisfactory detection limits of ca. 10 nM avoiding the use of expensive transition metal complexes as labels and/or of co‐reagents. [ABSTRACT FROM AUTHOR]

Potentiometry with membrane selective electrodes is preferable for measuring the various constituents of pharmaceuticals. In this work, carbon paste electrodes (CPE) were prepared, modified, and tested for the determination of maprotiline hydrochloride, which acts as an antidepressant. The proposed CPE was based on an ionic association complex of maprotiline-tetraphenylborate, 2-nitrophenyloctyl as a binder, and sodium tetraphenylborate as an ionic lipophilic additive. The optimized composition improved potentiometric properties up to theoretical Nernst response values of −59.5 ± 0.8 mV dec−1, in the concentration range of maprotiline from 1.6 × 10−7 to 1.0 × 10−2 mol L−1, and a detection limit of 1.1 × 10−7 mol L−1. The CPE provides excellent reversibility and reproducibility, exhibits a fast response time, and is applicable over a wide pH range. No significant effect was observed in several interfering species tested. The proposed electrode was used for the precise determination of maprotiline in pure solutions, urine samples, and a real sample—the drug Ludiomil. [ABSTRACT FROM AUTHOR]

A low-cost and fast potentiometric surfactant sensor for cationic surfactants, based on the new ion-pair 1,3-dioctadecyl-1H-imidazol-3-ium-tetraphenylborate (DODI-TPB), is presented. The new cationic surfactant DODI-Br was synthesized and characterized by NMR, LC-MS, and elemental analysis, and was used for synthesis of the DODI-TPB ionophore. The DODI-TPB surfactant sensor was obtained by implementation of the ionophore in PVC. The sensor showed excellent response characteristics with near-Nernstian slopes to the cationic surfactants DMIC, CPC, CTAB, and Hyamine 1622. The highest voltage responses were obtained for DMIC and CPC (58.7 mV/decade of activity). DMIC had the lowest detection limit (0.9 × 10−6 M) and the broadest useful linear concentration range (1.8 × 10−6 to 1.0 × 10−4 M). An interference study showed remarkable stability. Potentiometric titration curves for the titration of cationic surfactants (DMIC, CPC, CTAB, and Hyamine 1622), with DDS and TPB used as titrants, showed sigmoidal curves with well-defined inflexion points and a broad signal change. The standard addition method was successfully applied with recovery rates from 98.9 to 101.2 at two concentrations. The amount of cationic surfactant found in disinfectants and antiseptics was in good agreement with the referent two-phase titration method and the surfactant sensor on the market. This new surfactant sensor represents a low-cost alternative to existing methods for cationic surfactant detection. [ABSTRACT FROM AUTHOR]

Herein, we developed a new pencil graphite ion-selective electrode strategy for the broadly used erectile dysfunction medication, sildenafil citrate (SC, vitamin V), for its automated potentiometry and potentiometric titration profiling in marketed tablets and human urine samples. The method was based on ion-pair complexation between SC and sodium tetraphenylborate (Na-TPB) or phosphotungstic acid (PTA), embedded into a pencil-fabricated graphite sensor electrode coated with poly(vinyl chloride, PVC) matrix, which is pre-plasticized with two different pre-studied plasticizers. The modern fabricated electrodes have a proven fast near-Nernstian response for SC over the concentration range of 1.0 × 10−6 to 1.0 × 10−2 and 1.0 × 10−5 to 1.0 × 10−2 M, with LODs of 6.5 × 10−7 and 5.5 × 10−6 over a pH 3–6 for (SC-TPB)- and (SC-PTA)-based membrane sensors, of O-nitrophenyl octyl ether (O-NPOE) and dioctyl phthalate (DOP), respectively. The selectivity coefficients for different interferents, including many inorganic cations, sugars, and/or nitrogenous compounds, were tested and confirmed. Applications of the proposed method were conducted on the determination of SC in its tablets and urine samples under the proper conditions. The percent recovery values were compared with those obtained by an official method and showed an RSD ≤ 0.3% (n = 5). [ABSTRACT FROM AUTHOR]

This work is a mini-review highlighting the relevance of the θ metallabis(dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− with its peculiar and differentiating characteristics, among them the capacity to generate hydrogen and dihydrogen bonds, to generate micelles and vesicles, to be able to be dissolved in water or benzene, to have a wide range of redox reversible couples and many more, and to use these properties, in this case, for producing potentiometric membrane sensors to monitor amine-containing drugs or other nitrogen-containing molecules. Sensors have been produced with this monoanionic cluster [3,3′-Co(1,2-C2B9H11)2]−. Other monoanionic boron clusters are also discussed, but they are much fewer. It is noteworthy that most of the electrochemical sensor species incorporate an ammonium cation and that this cation is the species to be detected. Alternatively, the detection of the borate anion itself has also been studied, but with significantly fewer examples. The functions of the borate anion in the membrane are different, even as a doping agent for polypyrrole which was the conductive ground on which the PVC membrane was deposited. Apart from these cases related to closo borates, the bulk of the work has been devoted to sensors in which the θ metallabis (dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− is the key element. The metallabis (dicarbollide) anion, [3,3′-Co(1,2-C2B9H11)2]−, has many applications; one of these is as new material used to prepare an ion-pair complex with bioactive protonable nitrogen containing compounds, [YH]x[3,3′-Co(1,2-C2B9H11)2]y as an active part of PVC membrane potentiometric sensors. The developed electrodes have Nernstian responses for target analytes, i.e., antibiotics, amino acids, neurotransmitters, analgesics, for some decades of concentrations, with a short response time, around 5 s, a good stability of membrane over 45 days, and an optimal selectivity, even for optical isomers, to be used also for real sample analysis and environmental, clinical, pharmaceutical and food analysis. [ABSTRACT FROM AUTHOR]

This study presents the composition of the state primary standard of the pH indicator of hydrogen ion activity in aqueous solutions GET 54-2019. The standard includes the measures of acidity and a coulometric titrator, with a hydrogen index (HI) measurement range of 0.01–12.00. The methods and techniques applied for reproducing the HI values of GET 54-2019 reduced the total standard uncertainty to 0.0012, corresponding to the accuracy of the gold standard analogs of pH standards. The study also presents the metrological characteristics of GET 54-2019 and the results of key international comparisons to determine the HI of the borax buffer CCQM-K19.2018. The state primary pH standard GET 54-2019 is used in several industries and science and technology fields; pH measurement is especially significant in the chemical, pharmaceutical, and food industries, where HI control is crucial at all stages of the production cycle. Recently, controlling the pollution of water bodies with human waste products has become a pressing need; consequently, pH measurements have become essential in environmental monitoring. The scope of GET 54-2019 has expanded due to the increased HI measurement range in strongly acidic environments. In this regard, improving the pH measurement accuracy in studies on acidity of the human gastrointestinal tract can significantly reduce the risk of false diagnosis. [ABSTRACT FROM AUTHOR]

Isomerization of d‐glucose (Glc) into d‐fructose (Fru) is of great importance for food sector as well as for valorization of lignocellulosic biomass. Soluble and solid bases exhibit high catalytic activity for the isomerization. Here, we report a salt effect on the base‐catalyzed aqueous‐phase Glc‐Fru isomerization. Addition of soluble salts (Na2SO4, NaNO3, K2SO4, and NaCl) results in an increased apparent reaction rate (factors of 1.5 to 6). The salt effect was observed both in the presence of soluble base NaOH at constant pH value and solid bases MgO, Li3PO4, and Mg−Al hydrotalcite. Apparent activation energy and UV absorption spectra were not significantly influenced by addition of salts. Potentiometric titration showed that the acidity constants of the saccharides increase in the presence of electrolytes. Since the rate of the isomerization depends on the thermodynamic acidity constant of Glc, the isomerization is accelerated by the presence of electrolytes. [ABSTRACT FROM AUTHOR]

Electrode miniaturization has profoundly revolutionized the field of electrochemical sensing, opening up unprecedented opportunities for probing biological events with a high spatial and temporal resolution, integrating electrochemical systems with microfluidics, and designing arrays for multiplexed sensing. Several technological issues posed by the desire for downsizing have been addressed so far, leading to micrometric and nanometric sensing systems with different degrees of maturity. However, there is still an endless margin for researchers to improve current strategies and cope with demanding sensing fields, such as lab-on-a-chip devices and multi-array sensors, brain chemistry, and cell monitoring. In this review, we present current trends in the design of micro-/nano-electrochemical sensors and cutting-edge applications reported in the last 10 years. Micro- and nanosensors are divided into four categories depending on the transduction mechanism, e.g., amperometric, impedimetric, potentiometric, and transistor-based, to best guide the reader through the different detection strategies and highlight major advancements as well as still unaddressed demands in electrochemical sensing. [ABSTRACT FROM AUTHOR]

Hexachlorobenzene (HCB) is a pollutant still found in the environment despite being widely banned. Considering that basidiomycetes are useful to degrade a variety of organochlorinated pollutants, we therefore report the influence of HCB on the ligninolytic enzymatic system of Deconica castanella. The inoculum was prepared with sugarcane bagasse and soybean flour and was added in soil with and without HCB (2000 mg kg soil−1), 5% emulsion containing soybean oil and Tween 20 at proportion 9:1, v:v; with 70% moisture at 25°C. Fungal biomass was quantified by widely acknowledged growth biomarker ergosterol. The extraction of the enzymatic complex was performed and laccase, Mn‐dependent peroxidase (MnP), and lignin peroxidase (LiP) activities were determined. Furthermore, HCB and its metabolites were quantified by gas chromatography and chlorides by potentiometric titration. Results evidenced that HCB did not interfere in fungal growth, though the only detected enzymatic activity was laccase. MnP and Lip were not detected during D. castanella growth in soil. The peak of laccase enzymatic activity occurred in the presence of HCB. In addition, the laccase exhibited thermostability. Therefore, we hereby shed light on the role of laccase in the degradation of HCB by an efficient low‐cost and environmentally safe detoxification mechanism. [ABSTRACT FROM AUTHOR]

It has been established that the correct choice of the plasticizer and the measurement conditions makes it possible to achieve better analytical characteristics of verapamil-sensitive electrodes based on commercially available components in comparison with the best described in the literature. Particularly, the effect of pH on the verapamil-sensitive electrodes response was found to manifest itself in much more acidic media than might be expected from protolytic equilibrium and is due to the non-exchangeable extraction of verapamil into the membrane phase. The best parameters of selectivity, lower detection limit (4 × 10−8 M), and potential reproducibility (0.15–0.22 mV) are achieved when using ortho-nitrophenyloctyl ether as a plasticizer and creating conditions that exclude non-exchangeable extraction of verapamil into the membrane. The proposed methods for the determination of verapamil in dosage forms are characterized by simplicity, rapidity, and high metrological characteristics. [ABSTRACT FROM AUTHOR]

The radioactive and hazardous nature of thorium demands the fabrication of efficient electrodes for its sensitive and selective monitoring in aqueous environments. The present paper reports the construction and characterization of a new carbon paste electrode (CPE) chemically modified by octyl phenyl acid phosphate (OPAP) as a selective recognition agent for the potentiometric assay of thorium(IV) ions. Improved sensitivity, electrical conductivity, and selectivity were achieved by incorporating oxidized multi-walled carbon nanotubes (o-MWCNTs) into the carbon paste composition. The electrochemical performance of the developed electrode was evaluated regarding the paste ingredients, response time, and working pH range. The standard CPE potentials, E°, were determined at various temperatures and the isothermal temperature coefficient was calculated. The optimized CPE showed a Nernstian slope of 14.65 ± 0.38 mV decade−1 over the concentration range of 4.82 × 10–7–1.00 × 10–1 mol L−1. The electrode possessed a short response time (9 s), independence of the solution pH over the range of 2.5–5.5, and a relatively long operational lifetime (˃ 3 months). The selectivity coefficients indicated the good discrimination ability of the developed CPE towards thorium(IV) ion compared to various common ions. Aiming to judge the practical utility of the developed CPE, it was successfully used for the potentiometric analysis of thorium(IV) ions in various real aqueous matrices with sensible results. [ABSTRACT FROM AUTHOR]

Eugenol is a compound with well‐known bioactivity; however, its volatility limits its therapeutic applicability. In the present study, carboxymethylated xanthan gum (CXG) is synthesized and characterized regarding its degree of substitution (DS) by potentiometric titration and by infrared spectroscopy (FTIR). Oil‐in‐water xanthan gum‐based nanoemulsions enriched with eugenol have been prepared in variable conditions, using XG (xanthan gum) and CXG as matrices to produce a stable formulation with an effective ovicidal activity. Physical–chemical characterizations are performed, besides ovicidal activity on Haemonchus contortus, the main gastrointestinal nematode infecting and affecting small ruminants. FTIR results indicate the insertion of the carboxymethyl groups in the structure of xanthan gum through the peaks at 1100 and 1600 cm−1, and titration shows a DS of 1.25 for CXG. XG and CXG emulsions present stability over 30 days and encapsulation efficiency higher than 50%. The CXG2 emulsion (CXG:oil:tween 4:2:1) shows better stability concerning the lower zeta potential value, and the morphology shows domains with smaller sizes in the range of 1.41 µm. The evaluated nanoemulsions show ovicidal activity against H. contortus, which encourages their future use as an alternative to control haemonchosis in sheep and goats. [ABSTRACT FROM AUTHOR]

Higher stability of tetrahedral hydroxyboronate cyclic esters of 1,2‐diols in comparison with the respective trigonal esters and the associated increased acidity of the trigonal esters in comparison with free boronic acids are well‐known and important aspects of the thermodynamics of boronate ester formation usually attributed to the strain in O–B–O angle created in the trigonal esters and released in the tetrahedral hydroxyboronates. The stability constants of tetrahedral (Ktet) and trigonal (Ktrig) boronate esters of several aliphatic and aromatic 1,2‐ and 1,3‐diols with a series of five boronic acids of variable acidity were determined by potentiometric titrations in water. The ratio Ktet/Ktrig varies from ~10 for cis‐1,2‐cyclopentanediol to ~104 for catechol entirely due to the increase in Ktet for more acidic diols and is weakly affected by the acidity of boronic acids. Analysis of DFT minimized structures of trigonal and tetrahedral esters of phenylboronic acid with cis‐1,2‐cyclopentanediol, 1,4‐anhydroerythritol, and catechol demonstrates the absence of postulated strain release in the tetrahedral esters. A global analysis of new and previously reported relevant data on Ktet, Ktrig, and Ktet/Ktrig values for 1,2‐ and 1,3‐diols and different boronic acids in terms of the Brønsted‐type correlations with pKa values of the reaction components shows that Ktet/Ktrig values vary in a wide range from ~1 to ~106, and this variation can be satisfactorily explained by the stabilization of tetrahedral hydroxyboronate cyclic esters by more acidic diols without invoking of the strain release effect. [ABSTRACT FROM AUTHOR]

Antioxidant properties of synthetic 2,5-substituted 6H-1,3,4-thiadiazines were comprehensively studied using potentiometric methods based on the reactions of electron transfer (ET mechanism) and hydrogen atom transfer (HAT mechanism) from the anti-oxidant to oxidant molecule. The kinetic parameters of the reactions with various oxidizing agents were estimated taking into account peculiarities of the transformation of 2,5-substituted 6H-1,3,4-thiadiazines in solution. The relationships "structure—antioxidant properties" are established. The role of the electron-donating and electron-withdrawing properties of substituents in positions 2 and 5 of the 1,3,4-thiadiazine ring in the manifestation of antioxidant properties is examined. [ABSTRACT FROM AUTHOR]

In current research, we determined the stability constants and kinetic properties of Bi3+ complexes with the benzoazacrown ligand H4BATA along with the H4DOTA ligand. Correct determination of the stability constants is possible when equilibrium with the free forms of the cation is observed. Unlike potentiometric titration, it is possible to apply the free‐ion selective radiotracer extraction (FISRE) method with highly stable complexes at low pH values, where the true equilibrium with the free cation forms in the solution is achieved. FISRE clarified the stability constants of Bi3+ complexes with H4BATA towards higher values. According to the UV spectroscopy data, the H4BATA ligand binds Bi3+ at room temperature within a few minutes at pH 1. We also defined the acid‐assisted mechanism of complex dissociation, where monoprotonated and deprotonated forms of the complex were found to be inert. In summary, the H4BATA ligand is highly suitable for use as a component of bismuth‐based radiopharmaceuticals. [ABSTRACT FROM AUTHOR]

Researchers seeking for green chemistry to help safeguard and boost the economy and the environment by discovering unique ways to decrease waste and find substitutes for dangerous chemicals. In this study, a green potentiometric ion-selective electrode (ISE) was developed for measurement of tolperisone HCl (TOLP) in bulk and Pharmaceutical dosage forms in presence of diclofenac sodium and paracetamol as co-formulated drugs. This paper presents the manufacture and characterization of a disposable potentiometric ion-selective strip with an enhanced detection limit for (TOLP) measurement in its tablet dosage form either alone or in presence of the co-formulated drugs. Numerous ion pairs (IPs), such as TOLP-tetraphenylborate (TOLP-TPB), TOLP-phosphotungstic acid (TOLP-PTA), and TOLP-ammonium Reinecke (TOLP- RKT) are tested in presence of different plasticizers. The optimal potentiometric response with a near Nernstian slope of 55.949 mV/decade was achieved within a linear concentration range of 5 × 10–5 − 1 × 10–2 M using (PTA) and ortho nitrophenyl octyl ether (o-NPOE) as a plasticizer. The effect of the nanoparticles on the membrane stability was studied using the graphene nanoplatelets which have an effective role in the enhancement of some constructed sensors stability. Finally, the developed technique is validated for the estimation of TOLP with high accuracy and precision. [ABSTRACT FROM AUTHOR]

This paper is part of a research project deals with the study of the possible use of by-product materials such as fly ash (FA) and silica fume (SF) with Ordinary Portland Cement (OPC) in ternary system in different applicable measured properties of concrete. In this research, six concrete mixtures with water/cement ratios 0.4 and 0.5 have been investigated. Trial mixes were carried out to produce concrete with same slump and air content percentage. Also, the influence of using fly ash and silica fume with Portland cement on the concrete performance against chloride attack has been studied. The potentiometric apparatus was used to measure the chloride concentrations through the concrete samples by titration chemical analysis. In addition, the diffusion coefficients were determined for the tested specimens. It is concluded that the addition of fly ash and silica fume to Portland cement in ternary system improved concrete resistance to chloride attack and reduced its diffusion coefficient as well as can be reasonably used in concrete industry with considerable proportions. Moreover, the change in the cementitious materials content, type and their replacement percent have significant effect in the studied properties of concrete. Furthermore, results show that the total and soluble chloride content for zone 10~20 mm and zone 20~30 mm are very low. This result leads that such type of concrete needs less concrete cover depth which leads to protect the reinforcement. [ABSTRACT FROM AUTHOR]

Stability and structure of complexes between silver (I) and l-methionine (L) deduced from potentiometric and 1H NMR measurements allow to assume the prevailing of several protonated species. The experimental data are compatible with the formation of the following complexes: AgL, AgL2, AgH2L, AgH1L2, AgH2L2, AgH3L2 and AgH4L2. The coordination sites are obtained by 1H NMR spectra, showing that only the bond between the methylthioether sulfur atom and silver (I) is responsible of the complex stability. The system is studied potentiometrically with silver and glass electrodes at 25 °C and 1.00 mol·dm−3 NaClO4 as ionic medium. Amino acids containing sulfur are few and not extensively studied. In particular, l-methionine, even if it is the most important, enantiomer and their complexes with silver (I) present anticarcinogenic properties, is quite not investigated. In the same experimental conditions, l-methionine protonation constants are determined. The 1H NMR data allow one to assume that, in moderately alkaline solution, silver (I) is bond with six membered chelate rings with sulfur and amino nitrogen, while carboxylic groups are not involved. No polynuclear species are present. The high stability of the complex with ratio 1:2 (silver (I)/l-methionine), involving also two hydrogen ions, predominating in a wide range of hydrogen ion concentration suggests to propose a study for the preparation of an electrode to measure the deprotonated l-methionine concentration. [ABSTRACT FROM AUTHOR]

In the present study, the complexing properties of ceftazidime with Fe(III) ions in aqueous solutions were characterized by UV-vis spectrophotometric and potentiometric methods. Using the UV-vis spectrophotometric method, the absorbance values for Fe(III) ions, a third-generation cephalosporin antibiotic (ceftazidime), and the Fe(III)-ceftazidime system were determined. Based on pH-metric studies, the value of the stability constant for the Fe(III)-ceftazidime complex was calculated. [ABSTRACT FROM AUTHOR]

Analyses of potentiometric measurements were conducted on ternary complexes of copper(II) with dipicolinic acid and quinolinic acid, as well as lactic acid, oxalic acid, citric acid, and phosphoric acid, which are components of blood plasma. Studies on chemical speciation showed that ternary compounds were more likely to be formed. In systems with quinolinic acid, the solubility was small, and most complexes precipitated at pH ≤ 2. In situ isolated ternary and binary complexes of CuDiPic(H2O)2 were evaluated for antioxidant activity, as shown by their inhibiting activity of superoxide anion (O2.−), which demonstrates copper(II) complexes provide protective effects. Docking studies of ligands with a protein kinase revealed that the Cu(II) metal centre is crucial for the successful interaction of the complex with the receptor's active site. [ABSTRACT FROM AUTHOR]

We studied the thermodynamic properties of the lithium perchlorate (LiClO4) + ethylene carbonate (EC) +water ternary system by using cell potential measurements. Thermodynamic properties reported were obtained using the electrochemical cell: Li-ISE|LiClO4(m)|ClO4-ISE in a variety of mixed solvent systems containing 0, 10, 20 and 30% mass fractions of ethylene carbonate in water + EC mixtures (wEC/wmixture% = 0, 10, 20 and 30) on the wide range of ionic strength from 0.0090 to 2.4900 mol.kg−1 at T = (298.2, 308.2 and 318.2) K. The obtained results were analysed using Extended Debye-Huckel equation and Pitzer model. The values of Pitzer ion-interaction parameters β(0), β(1) and Cϕ were used to drive the values of thermodynamic properties such as the excess Gibbs free energy, the solvent activity, mean activity coefficients, the osmotic coefficients and diffusion coefficients for this system. [ABSTRACT FROM AUTHOR]

A potentiometric metformin-sensitive detector with a plasticized polyvinyl chloride membrane has been developed. The sensor contains an ion associate of metformin with bromophenol blue dye. The response is linear within the range of metformin ion concentrations 1 × 10–-4–1 × 10–-1 M. The slope of the electrode function is characteristic of a singly charged cation. The limit of detection is 8 × 10–-5 M. The sensor can be used for detecting and determining metformin in medicines (RSD = 0.59 – 2.52%). [ABSTRACT FROM AUTHOR]

Zirconium is a highly demanded element widely used in various fields of science and technology. There are 39 known zirconium isotopes, among which zirconium-89 (T1/2 = 78.42 h) attracts increasing attention of the scientific community in connection with the radionuclide diagnostics of various diseases. The radiopharmaceuticals based on 89Zr are currently actively developed and introduced into clinical practice. The 89Zr isotope is in demand to develop agents based on monoclonal antibodies, which are mainly used for cancer diagnosis and therapy monitoring. For incorporation of 89Zr into vector molecules that would allow selective isotope accumulation in various foci, an appropriate chelating agent is required. Furthermore, specific features of application of zirconium-89 complexes in radiopharmaceuticals impose additional requirements on the chelator properties. First, this is high complex formation efficiency without heating of the reaction mixture at approximately neutral pH. Also, the complexes should be stable not only in vitro, but also in vivo. The main difficulty hampering the design of new chelators is the intricate coordination chemistry of zirconium, that is, the formation of polynuclear species with different degrees of polymerization and composition varying depending on pH and time. Therefore, conventional techniques such as EXAFS, X-ray diffraction, and potentiometric titration in aqueous media are often of low utility, and chemists have to resort to some alternative methods for studying these compounds. Thus, the integration of experimental data from various sources is of high practical value. The review discusses problems associated with the use of the popular chelator deferoxamine, recent advances in the search and synthesis of new chelators, and the application of various methods to evaluate the applicability of the obtained complexes for advanced nuclear medicine procedures. [ABSTRACT FROM AUTHOR]

The copper(ii) complex [Cu(H2L1)2(H2O)2] with (2-hydroxyphenyl)phosphonic acid (H3L1) was synthesized. The composition and structure of the complex were determined by X-ray diffraction, elemental analysis, and IR spectroscopy. Quantum chemical calculations of the structure of the H3L1 molecule were performed by the density functional theory (DFT). The protonation constants of H3L1 and the stability constants of its complexes with Cu2+ in water were determined by potentiometric titration. The cytotoxic properties and the accumulation of the [Cu(H2L1)2(H2O)2] complex in human cervical adenocarcinoma HeLa cells were evaluated for the first time, thereby demonstrating that this complex is promising for further biological studies. [ABSTRACT FROM AUTHOR]