Ion Monitoring Research Articles

Eco-friendly fluorescent detection method for Cu2+ ions combined with smartphone-integrated paper strip sensors based on highly fluorescent 2-aminoterephthalic acid in milk samples

The creation of smart, real-time sensing devices is crucial in food monitoring, though it continues to be a major challenge. Here, we report an eco-friendly fluorescent detection method for Cu2+ ions using 2-aminoterephthalic acid (NH2-H2BDC). Fluorescence (FL) quenching occurs at 425 nm under excitation at 330 nm, with detection limits (LOD) as low as 16.25 nM for Cu2+ ions. Additionally, a smartphone can visually and quantitatively detect Cu2+ ions by analyzing the RGB values on test paper. The results show high sensitivity, with a LOD of 11.07 μM. This work not only reveals fluorescent detection methods but also develops a convenient, low-cost, and portable smartphone-integrated paper strip for Cu2+ ion sensing. Two metrics, AGREEprep and BAGI, were employed to assess the method's environmental friendliness. The evaluation confirmed its exceptional eco-friendliness. This method marks a significant advancement for Cu2+ ion monitoring in diverse fields, especially food monitoring.

Portable Sensing Platform for the Visual Detection of Iodide Ions in Food and Clinical Samples

The detection of iodide ions (I−), despite challenges due to low concentrations and potential masking, is crucial for studying physiological processes and diagnosing diseases. A colorimetric sensor was developed to improve I− ion monitoring and facilitate on-site detection based on filter paper, which is a cost-effective platform. The sensor observed color changes in response to the exposure of hydrogen peroxide (H2O2), 3,3′,5,5′-tetramethylbenzidine (TMB), from colorless to yellowish brown. The sensor demonstrated a detection limit of 0.125 × 10−6 M for I− ions in a relatively wide range of 0.01 to 15 × 10−6 M under optimized conditions including gel concentration, temperature, incubation time, TMB and H2O2 concentration, and pH. Furthermore, the proposed sensor was successfully employed in a variety of applications, such as biological (urine and blood serum), food (egg yolk and snacks), and environmental samples (tap water). The study established effective recoveries in complex media for visual on-site I− ion monitoring, indicating the developed assay as a potent, affordable, and practical platform.

Development and validation of high-performance liquid chromatography-Orbitrap mass spectrometric method for quantification of NDMA in ranitidine drug products and evaluation of antioxidants as inhibitors of classical nitrosation reaction.

N-Nitroso dimethylamine (NDMA) is a mutagenic impurity detected in several ranitidine products. The amino functional group of ranitidine is a risk factor for classical nitrosation-induced NDMA formation in ranitidine drug products during storage conditions. The United States Food and Drug Administration (US FDA) recommended the use of antioxidants to control NDMA in drug products. Considering the need for sensitive analytics, a liquid chromatography/high-resolution mass spectrometry (LC-HRMS) method was developed and validated to detect NDMA in this pilot study to demonstrate the antioxidants as inhibitors of nitrosation reactions. The method, utilizing an EC-C18 column and tuned to atmospheric pressure chemical ionization/selected ion monitoring (APCI/SIM) mode, separated NDMA (m/z: 75.0553; tR: 3.71 min) and ranitidine (m/z: 315.1485; tR: 8.61 min). APCI mode exhibited four times higher sensitivity to NDMA than electrospray ionization (ESI) mode. Classical nitrosation of the dimethyl amino group of ranitidine was studied with sodium nitrite in solid pellets. Antioxidants (alpha-tocopherol, ascorbic acid, and trolox) were evaluated as NDMA attenuators in ranitidine pellets under vulnerable storage conditions. The developed method quantified NDMA levels in samples, extracted with methanol through vortex shaking for 45 min. The method achieved a limit of detection (LOD) and limit of quantitation (LOQ) of 0.01 and 0.05 ng/mL, respectively, with linearity within 1-5000 ng/mL (R1: 0.9995). It demonstrated good intra-day and inter-day precision (% RSD [relative standard deviation]: <2) and accuracy (96.83%-101.72%). Nitrosation of ranitidine induced by nitrite was significant (p < 0.001; R2 = 0.9579) at various sodium nitrite levels. All antioxidants efficiently attenuated NDMA formation during ranitidine nitrosation. Ascorbic acid exhibited the highest NDMA attenuation (96.98%), followed by trolox (90.58%). This study recommends 1% ascorbic acid and trolox as potent NDMA attenuators in ranitidine drug products. This study compared the effectiveness of antioxidants as NDMA attenuators in ranitidine under storage conditions susceptible to NDMA generation. The study concluded that ascorbic acid and trolox are potent inhibitors of NDMA formation and nitrosation attenuators in ranitidine drug products.

Glutathione ligand self-assembly enables luminescence from Au15 nanoclusters for highly sensitive and selective monitoring of blood Pb(II) ions

Lead Pb(II) ions is a cumulative toxicant that impacts several biological systems and poses severe harm to young children. Accurate Pb(II) ions monitoring is thus of paramount importance. Here, we present the synthesis and application of glutathione-capped Au15 nanoclusters (Au15(SG)13) as a luminescence probe for the accurate and selective monitoring of blood Pb(II). The introduction of Pb(II) ions triggers orderly self-assembly of Au15 nanoclusters, resulting in the formation of rigid shell around Au nuclei. This limits the localized vibration of the glutathione ligands and their interaction with water molecules, greatly reducing non-radiative energy loss, and thereby enhancing the photoluminescence signal. Consequently, Au15(SG)13 nanoclusters exhibit high sensitivity for Pb(II) detection. The detection signal displays a linear relationship with Pb(II) over a wide detection range (0–800 μg/L), demonstrating a substantial sensitivity of 35.29 μg/L. Moreover, the developed nanoclusters show superior selectivity for Pb(II) ions, distinguishing them from other prevalent heavy metals. This work pave the way for the development of advanced Pb(II) sensors with high sensitivity and selectivity.

Fatty acid isomerism: analysis and selected biological functions.

The biological functions of fatty acids and the lipids in which they are esterified are determined by their chain length, double bond position and geometry and other structural motifs such as the presence of methyl branches. Unusual isomeric features in fatty acids of human foods such as conjugated double bonds or chain branching found in dairy products, some seeds and nuts, and marine foods potentially have important effects on human health. Recent advancements in identifying fatty acids with unusual double bond positions and pinpointing the position of methyl branches have empowered the study of their biological functions. We present recent advances in fatty acid structural elucidation by mass spectrometry in comparison with the more traditional methods. The double bond position can be determined by purely instrumental methods, specifically solvent-mediated covalent adduct chemical ionization (SM-CACI) and ozone induced dissociation (OzID), with charge inversion methods showing promise. Prior derivatization using the Paternò-Büchi (PB) reaction to yield stable structures that, upon collisional activation, yield the double bond position has emerged. The chemical ionization (CI) based three ion monitoring (MRM) method has been developed to simultaneously identify and quantify low-level branched chain fatty acids (BCFAs), unattainable by electron ionization (EI) based methods. Accurate identification and quantification of unusual fatty acid isomers has led to research progress in the discovery of biomarkers for cancer, diabetes, nonalcoholic fatty liver disease (NAFLD) and atherosclerosis. Modulation of eicosanoids, weight loss and the health significance of BCFAs are also presented. This review clearly shows that the improvement of analytical capacity is critical in the study of fatty acid biological functions, and stronger coupling of the methods discussed here with fatty acid mechanistic research is promising in generating more refined outcomes.

An analytical approach for on-site analysis of breath samples for Δ9-tetrahydrocannabinol (THC).

Increased acceptance of cannabis containing the psychoactive component, Δ9-tetrahydrocannabinol (THC), raises concerns about the potential for impaired drivers and increased highway accidents. In contrast to the "breathalyzer" test, which is generally accepted for determining the alcohol level in a driver, there is no currently accepted roadside test for THC in a motorist. There is a need for an easily collectible biological sample from a potentially impaired driver coupled with an accurate on-site test to measure the presence and quantity of THC in a driver. A novel breath collection device is described, which includes three separate sample collectors for collecting identical A, B, and C breath samples from a subject. A simple one-step ethanol extraction of the "A" breath collector sample can be analyzed by UHPLC/selected ion monitoring (SIM) liquid chromatography/mass spectrometry (LC/MS) to provide qualitative and quantitative determination of THC in breath sample in less than 4 min for samples collected up to 6 h after smoking a cannabis cigarette. SIM LC/MS bioanalyses employed d3-THC as the stable isotope internal standard fortified in negative control breath samples for quantitation including replicates of six calibrator standards and three quality control (QC) samples. Subsequent confirmation of the same breath sample in the B collectors was then confirmed by a reference lab by LC/MS/MS analysis. Fit-for-purpose bioanalytical validation consistent with pharmaceutical regulated bioanalyses produced pharmacokinetic (PK) curves for the two volunteer cannabis smokers. These results produced PK curves, which showed a rapid increase of THC in the breath of the subjects in the first hour followed by reduced THC levels in the later time points. A simpler single-point calibration curve procedure with calibrators and QC prepared in ethanol provided similar results. Limitations to this approach include the higher cost and operator skill sets for the instrumentation employed and the inability to actually determine driver impairment.

Analysis of Polycyclic Aromatic Hydrocarbons Using Magnetic Three-Dimensional Graphene Solid-Phase Extraction Coupled with Gas Chromatography–Mass Spectrometry

In this study, a composite material consisting of three-dimensional graphene aerogel and iron oxide nanoparticles (3DG/Fe3O4) was created and utilized for the purpose of magnetic solid-phase extraction (MSPE) of thirteen polycyclic aromatic hydrocarbon (PAH) compounds via gas chromatography–mass spectrometry/selected ion monitoring (GC-MS/SIM) analysis. The synthesized adsorbent underwent a range of characterization techniques, including scanning electron microscopy, vibrating sample magnetometry, Raman spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, Fourier transform-infrared spectroscopy, and Barrett–Joyner–Halenda techniques, to examine its properties and morphology. The synthesized adsorbent integrates the benefits of superior adsorption capacity from modified graphene oxide (GO) with the magnetic separability of magnetite microparticles, resulting in a high adsorption capacity with easy separation from sample solutions. The efficiency of the proposed method was optimized and modeled using a central composite design (CCD), which considered the primary factors influencing it. The optimal conditions were obtained as the adsorbent dosage of 10 mg, the extraction time of 4 min, and the salt concentration of 3% w/v. The limit of detection for the target PAHs was established to range from 0.016 to 0.2 ng mL−1 in optimal conditions, exhibiting a signal-to-noise ratio of 3. The linear dynamic range spanned from 5 to 100 ng mL−1, with determination coefficients (R2) ranging from 0.9913 to 0.9997. The intra- and inter-day precisions were calculated as relative standard deviations (RSDs) equal to 3.9% and 4.7%, respectively. The proposed method was successfully applied to the determination of PAHs in water samples (tap, river, and rainwater), and recoveries in the range of 71–110% (RSDs &lt; 5.2%, n = 3) were obtained.

Ligand imprinted composite adsorbent for effective Ni(II) ion monitoring and removal from contaminated water

Heavy metal especially nickel (Ni(II)) is the most pernicious kind of pollution since it is both poisonous and difficult to break down in nature and can cause many human disorders and diseases. The monitoring and removal of Ni(II) ions optically is required to enhance the quality of the water and make it appropriate for drinking as well as other uses around the residence. Therefore, the goal of the current work was to synthesize ligand imprinted composite adsorbent (MCA) and utilize it as an adsorbent to monitor and remove Ni(II) ions from the water. Based on the findings gathered, the MCA that was synthesized had a large particle size with a high surface area even after the ligand impregnation. The MCA was enhanced significantly in color with the contact of Ni(II) ion with limit detection at 0.35 µg/L. The maximum level of Ni(II) ions was eliminated (99 %) when the pH was adjusted to 5.50. The Langmuir model was also used to study the adsorption equilibrium data and the maximum adsorption capacity was 167.55 mg/g. Additionally, the method can selectively detect and remove Ni(II) even in the presence of diverse metal ions. Overall, the MCA offers an ideal platform for the on-site monitoring and removal of heavy metal ions, especially in resource-limited areas.

Facial conjugate adsorbent for sustainable Pb(II) ion monitoring and removal from contaminated water

The chemical ligand-based conjugate adsorbent was prepared for selective and sensitive toxic lead (Pb(II)) ions monitoring and removal from contaminated water to save water quality and human health. Both in the monitoring and removal operations, the solution pH played a vital role by the conjugate adsorbent. The data clarified that pH 3.50 was suitable for simultaneous monitoring and removal of Pb(II) ions. In the monitoring, a significant color was formed upon the addition of Pb(II) ion even in the presence of ultra-trace level. Then the solution pH, reaction time, foreign ion, and initial concentration effect were systematically measured. The conjugate adsorbent exhibited an extremely low detection limit (0.35 µg/L) to comply with the material’s applicability in real sample onsite monitoring. In the reaction time effect, color optimization and high removal efficiency was achieved by increasing the reaction time. However, the diverse foreign ions were not adversely affected in the monitoring and removal to clarify the conjugate adsorbent as sensitive and selective towards the Pb(II) ions. The conjugate adsorbent was shown highly ordered structure and was able to open high functionality for Pb(II) ion monitoring and removal. The adsorption data also revealed that the present conjugate adsorbent exhibited adsorption capacity (172.87 mg/g) and was well fitted by the Langmuir adsorption isotherm with monolayer coverage. The adsorbed Pb(II) ion was desorbed using 0.30 M HCl and then simultaneously regenerated into the initial form for several cycles use after rinsing with water. Then it is expected that the optimum protocol effectively captured the Pb(II) in a sustainable and environmentally friendly manner for the production of clean water to safeguard public health and environmental remediation.

Handling Severe Intraoperative Hemorrhage and Avoiding Iatrogenic Stroke During Brain Tumor Surgery: Techniques for Prevention of Hemorrhagic and Ischemic Complications

Nationwide databases show that iatrogenic stroke and postoperative hematoma are among the commonest complications in brain tumor surgery, with a 10-year incidence of 16.3/1000 and 10.3/1000, respectively. However, techniques for handling severe intraoperative hemorrhage and dissecting, preserving, or selectively obliterating vessels traversing the tumor are sparse in the literature. Records of the senior author's intraoperative techniques during severe haemorrhage and vessel preservation were reviewed and analyzed. Intraoperative media demonstrations of key techniques were collected and edited.In parallel,aliterature search investigating technique description in handling severe intraoperative hemorrhage and vessel preservation in tumor surgery was undertaken. Histologic, anesthetic, and pharmacologic prerequisites of significant hemorrhagic complications and hemostasis were analyzed. The senior author's techniques for arterial and venous skeletonization, temporary clipping with cognitive or motor mapping, and ION monitoring were categorized. Vessels interfacing with tumor are labeled intraoperatively as supplying/draining the tumor, or traversing en passant, while supplying/draining functional neural tissue. Intraoperative techniques of differentiation were analyzed and illustrated. Literature search found 2 vascular-related complication domains in tumor surgery: perioperative management of excessively vascular intraparenchymal tumors and lack of intraoperative techniques and decision processes for dissecting and preserving vessels interfacing or traversing tumors. Literature searches showed a dearth of complication-avoidance techniques in tumor-related iatrogenic stroke, despite its high prevalence. A detailed preoperative and intraoperative decision process was provided along with a series of case illustrations and intraoperative videos showing the techniques required to reduce intraoperative stroke and associated morbidity addressing a void in complication avoidance of tumor surgery.

Disposable electrochemical sensor based on ion imprinted polymeric receptor for Cd(II) ion monitoring in waters

Cadmium is a highly toxic heavy metal, even at low concentrations. Moreover, it bio-accumulates with a long biological half-life producing a wide variety of acute and chronic effects like cancer in humans. Therefore, there is significant interest in providing a portable and user-friendly sensor for heavy metal detection. A highly sensitive and selective electrochemical sensor for Cd(II) determination was developed as an alternative. The Cd (II) receptors were integrated into the sensor using an ion-imprinted polymer film (IIPs film). Accordingly, 4-aminophenylacetic acid (4-APA) was electropolymerised in the presence of Cd(II) ions as a template using cyclic voltammetry (CV) on screen-printed carbon electrodes (SPCEs). Imprinted cavities were obtained after the alkaline elution of ions. Sensor characterisation was performed using SEM, ATR-FTIR and electrochemical methods, such as cyclic voltammetry (CV) and electrochemical Impedance Spectroscopy (EIS), and compared to control experiments (not imprinted polymeric film, NIP film). Analytical performances of the IIP sensor revealed a sensitivity 5-order of magnitude higher than the NIP response in a concentration range from 10 to 1200 nM of Cd (II). This technology can potentially be applied for water quality control and monitoring of heavy metals.

TEER and Ion Selective Transwell-Integrated Sensors System for Caco-2 Cell Model.

Monitoring of ions in real-time directly in cell culture systems and in organ-on-a-chip platforms represents a significant investigation tool to understand ion regulation and distribution in the body and ions' involvement in biological mechanisms and specific pathologies. Innovative flexible sensors coupling electrochemical stripping analysis (square wave anodic stripping voltammetry, SWASV) with an ion selective membrane (ISM) were developed and integrated in Transwell™ cell culture systems to investigate the transport of zinc and copper ions across a human intestinal Caco-2 cell monolayer. The fabricated ion-selective sensors demonstrated good sensitivity (1 × 10-11 M ion concentration) and low detection limits, consistent with pathophysiological cellular concentration ranges. A non-invasive electrochemical impedance spectroscopy (EIS) analysis, in situ, across a selected spectrum of frequencies (10-105 Hz), and an equivalent circuit fitting were employed to obtain useful electrical parameters for cellular barrier integrity monitoring. Transepithelial electrical resistance (TEER) data and immunofluorescent images were used to validate the intestinal epithelial integrity and the permeability enhancer effect of ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) treatment. The proposed devices represent a real prospective tool for monitoring cellular and molecular events and for studies on gut metabolism/permeability. They will enable a rapid integration of these sensors into gut-on-chip systems.

Automated sample preparation and fast GC-MS determination of fatty acids in blood samples and dietary supplements.

The present research is focused on the optimization of an automatized sample preparation and fast gas chromatography-mass spectrometry (GC-MS) method for the analysis of fatty acid methyl esters (FAMEs) in blood samples and dietary supplements, with the primary objective being a significant reduction of the analysis time and, hence, an enhanced sample throughput. The mass spectrometer was operated in the scan/selected ion monitoring (SIM) acquisition method, thus enabling the obtainment of qualitative and (highly sensitive) quantitative data. The separation of FAMEs was obtained in about 11min by using a micro-bore column of dimensions 15m × 0.10mm ID × 0.10µm df with a polyethylene glycol stationary phase. The novelty of the research involves reducing analysis time by using the novel fast GC-MS method with increased identification reliability and sensitivity in a single chromatographic run. With regard to the figures of merit, linearity, accuracy, and limits of detection (LoD) and quantification (LoQ) were determined. Specifically, regression coefficients were between 0.9901 and 0.9996; the LoDs ranged from 0.05 to 1.02µgg-1 for the blood analysis method, and from 0.05 to 0.26mgg-1 in the case of the dietary supplement approach. With respect to LoQs, the values were in the ranges of 0.15-3.39µgg-1 and 0.15-0.86mgg-1 for blood and dietary supplements analysis methods, respectively. Accuracy was evaluated by analyzing certified reference materials (human plasma, fish oil).

The LC-MS/MS-Based Measurement of Isopimaric Acid in Rat Plasma and Application of Pharmacokinetics.

Isopimaric acid (IPA) exhibits a diverse array of pharmacological activities, having been shown to function as an antihypertensive, antitumor, antibacterial, and hypocholesterolemic agent. However, few studies of the pharmacokinetics of IPA have been performed to date, and such analyses are essential to explore the in vivo mechanisms governing the biological activity of this compound. As such, we herein designed a selective LC-MS approach capable of quantifying serum IPA levels in model rats using an Agilent HC-C18 column (250 mm × 4.6 mm, 5 μm) via isocratic elution with a mobile phase composed of methanol 0.5% formic acid (91 : 9, v/v) at a 1 mL/min flow rate. Ion monitoring at m/z 301.2 [M-H]− was used to quantify IPA levels in plasma samples from these rats, while internal standard (IS) levels were assessed at m/z 455.3 [M-H]−. After validation, this approach was employed to conduct a pharmacokinetic analysis of rats administered IPA via the oral (p.o. 50, 100, or 200 mg/kg) and intravenous (i.v. 5 mg/kg) routes. Analyses of noncompartmental pharmacokinetic parameters revealed that IPA underwent secondary absorption following oral administration to these animals, with the two tested oral doses (50 and 100 mg/kg) being associated with respective absolute bioavailability values of 11.9% and 17.5%. In summary, this study may provide a foundation for future efforts to explore the mechanistic basis for the pharmacological activity of IPA, offering insights to guide its subsequent clinical utilization.

Real-Time Multi-Ion-Monitoring Front-End With Interference Compensation by Multi-Output Support Vector Regressor.

Ion-sensors play a major role in physiology and healthcare monitoring since they are capable of continuously collecting biological data from body fluids. Nevertheless, ion interference from background electrolytes present in the sample is a paramount challenge for a precise multi-ion-monitoring. In this work, we propose the first system combining a battery-powered portable multi-channel electronic front-end, and an embedded Multi-output Support Vector Regressor (M-SVR), that supplies an accurate, continuous, and real-time monitoring of sodium, potassium, ammonium, and calcium ions. These are typical analytes tracked during physical exercise. The front-end interface was characterized through a sensor array built with screen-printed electrodes. Nernstian sensitivity and limit of detection comparable to a bulky laboratory potentiometer were achieved in both water and artificial sweat. The multivariate calibration model was deployed on a Raspberry Pi where the activity of the target ions were locally computed. The M-SVR model was trained, optimized, and tested on an experimental dataset acquired following a design of experiments. We demonstrate that the proposed multivariate regressor is a compact, low-complexity, accurate, and unbiased estimator of sodium and potassium ions activity. A global normalized root mean-squared error improvement of 6.97%, and global mean relative error improvement of 10.26%, were achieved with respect to a standard Multiple Linear Regressor (MLR). Within a real-time multi-ion-monitoring task, the overall system enabled the continuous monitoring and accurate determination of the four target ions activity, with an average accuracy improvement of 27.73% compared to a simple MLR, and a prediction latency of [Formula: see text].

Multifunctional hybrid soret nanoarchitectures for mobile phone-based picomolar Cu2+ ion sensing and dye degradation applications

The ability of nanoscale materials to trap electromagnetic field beyond the diffraction limit is seldom studied using multifunctional nanohybrids. To this end, we demonstrate a thermo-migratively assembled Soret nanoassembly that enable unique metal-metal, metal-graphene and metal-dielectric resonances. In contrast to the well-explored standalone plasmonic and dielectric platforms, the Soret colloids possess salient nanogaps that exhibit delocalized Bragg and localized Mie plasmon resonances with effective EM field confinement. Accordingly, the Soret colloids of silver metal with plasmonic NPs: platinum (AgPtSC), 2D material: graphene oxide (AgGOSC) and dielectric NPs: TiC (AgTiCSC), TiN (AgTiNSC) and TiCN (AgTiCNSC) comprehensively have been utilized to achieve >600-fold fluorescence enhancements. The ability to tailor the highly directional and p-polarized emission enhancements using these well-characterized multifunctional sorets has been experimentally demonstrated on surface plasmon-coupled emission (SPCE) platform. The mobile phone-based detection of environmentally relevant Cu 2+ ions in drinking water using AgPtSC presents low-cost, rapid, simple, sensitive and reliable sensing strategy for Cu 2+ ion monitoring in resource-limited settings. Further, dye-degradation of xenobiotic pollutants for environmental remediation presents multifarious applications with these nano-architectures. This study opens a new window to explore synergy of nanomaterials constituting elements from different parts of periodic table to accomplish essential properties for desired applications. The hybrid multifunctional soret colloids assisting metal-metal, metal-dielectric and metal-π-plasmon resonances are most suitable candidates for plasmonic as well as xenobiotic dye degradation applications. Mobile phone-based surface plasmon-coupled emission platform was utilized for sensing Cu 2+ ions at picomolar concentration. • An adiabatic cooling based synthesis of hybrid multifunctional soret nanoassembly. • Utility of synergistic metal-metal, metal-dielectric and metal-π-plasmon resonances. • Multifold hot-spots from localized and delocalized plasmons of nanohybrids in SPCE. • Enhanced 600-fold polarized SPCE for mobile phone-based picomolar Cu 2+ ion sensing. • Xenobiotic degradation using π-plasmon and electron relay in hybrid silver sorets.

Simple Smartphone Merged Rapid Colorimetric Platform for the Environmental Monitoring of Toxic Sulfide Ions by Cysteine Functionalized Silver Nanoparticles

Simple Smartphone Merged Rapid Colorimetric Platform for the Environmental Monitoring of Toxic Sulfide Ions by Cysteine Functionalized Silver Nanoparticles

Characterization of Li+ and Na+ Insertion into Sodium Titanium Phosphate

Due to their high energy density, lithium-ion batteries based on organic electrolytes are ubiquitous in applications such as consumer electronics. However, high capital costs and flammability of the electrolyte have limited their use in residential or grid storage. An alternative involves replacing the organic solvent-based electrolytes with aqueous electrolytes and using electrochemical couples that operate within the water electrolysis stability window. Aqueous electrolytes have several advantages, such as ease of manufacturing, greater safety, and more cell design flexibility due to the higher conductivity compared to organic electrolytes 1.In addition to aqueous Li-ion batteries, aqueous Na-ion batteries have attracted significant interest due to the increased availability of Na on earth and further cost reductions1,2. Furthermore, aqueous commercial batteries using electrolytes containing both Li+ and Na+ exist. For example, one such battery using a lithium manganese oxide cathode, a sodium titanium phosphate (NTP) anode, and a Li2SO4/Na2SO4 electrolyte has been commercialized by companies such as Aquion Energy and BenAn Energy2. Despite the advantages described previously, the operating voltage window of aqueous electrolytes is smaller than that of its organic counterparts. In addition, insertion behavior in aqueous electrolytes is more complex than what is observed in organic electrolyte systems3. This can be further complicated when using electrolytes with more than one cation4,5. One such example involves the insertion of Li+ and Na+ into NTP. In electrolytes where Na+ is the only cation, a single redox couple attributed to Na+ insertion is observed on CV experiments. Meanwhile, when both Li+ and Na+ are present, insertion of both cations occurs, with equilibration occurring after 10 CV cycles4. Despite this interesting behavior, little is known as to how the Li2SO4/Na2SO4 ratio affects the insertion behavior of NTP.In this work, the effect of Li2SO4 and Na2SO4 concentration in the insertion behavior will be characterized using CV and galvanostatic cycling with ion monitoring. CV experiments will be used to characterize the relative extent of insertion for both Li+ and Na+ and the insertion potentials. Meanwhile, galvanostatic cycling will be used to assess the connection between the CV results and charge/discharge plateaus observed under different Li2SO4/Na2SO4 ratios. In addition, ion monitoring will be performed every 50 cycles at relevant conditions (bottom and top of charge and intermediate points) to measure concentration changes in the electrolyte concentrations. Furthermore, galvanostatic intermittent titration cycles will be incorporated into the cycling regime to characterize the effect of concentration in the open circuit voltage (OCV) and resistance, as well as exploring changes in these variables as a function of cycling.

Evaluation of human macrophage functional state by voltammetric monitoring of nitrite ions.

The method for assessing the level of nitric oxide (II) (NO) by voltammetric monitoring of nitrite ions was carried out on models M1 and M2 of polarized macrophages induced from monocytes of human peripheral blood with the addition of lipopolysaccharide (LPS) and interleukin-4 (IL-4), respectively. The model of induction of M1 and M2 macrophages was used in the work to achieve the corresponding shifts in the functional status of studied cells. Ethyl nitrite (EtONO) was used as a standard compound of nitrite ions for electrochemical measurements. Electrochemical determination of nitrite ions was performed by anodic linear sweep voltammetry in the first-order derivative mode (ALSV FOD) in Britton-Robinson (BR) buffer with pH4.02 on carbon ink modified graphite electrode. EtONO calibrations were linear over a concentration range from 2 to 9μmolL-1 with corresponding regression equation y = 0.768c - 0.048. Limit of detection (LOD) (S/N = 3) was 0.38μmolL-1. The results of the study showed the fundamental possibility of using voltammetry to assess indirectly the production of nitric oxide by cells in supernatants of the monocytic macrophage lineage. The level of nitric oxide metabolites (nitrite ions) in supernatants was associated with the functional state of macrophages.

Microanalyser Prototype for On-Line Monitoring of Copper(II) Ion in Mining Industrial Processes.

A microanalyzer prototype for copper(II) ion monitoring in mining industrial processes is presented. The microanalyzer is designed as an assembly of different modules, each module being responsible for a unit operation. In order to optimize the industrial processes, the microanalyzer can automate all sample management, signal processing, and mathematical calculations and wirelessly transfer data to a control room. The determination of copper(II) ion is done using a colorimetric reaction and the microanalyser performs autocalibration by in situ dilution of a stock solution, matching the higher analyte concentration of the working range defined for the sample to be determined, using a multicommutation approach. The performance of the microanalyzer for monitoring copper(II) ion in water effluents of mining facilities was optimized in the working range from 1 to 10 mg/L to match Mexican environmental law regulations, which allow a maximum concentration of 4 mg/L of copper(II) ion in these circumstances.