Specific Ionization Research Articles

Fully Integrated Recognition and Enrichment Electrospray Ionization Source for High-Sensitivity Mass Spectrometry Determination of Bioamine.

The development of a highly specific recognition electrospray ionization source presents a major challenge for achieving rapid ambient mass spectrometry (AMS) detection of trace harmful substances in complex samples. In this study, we constructed a molecular imprinting nanofiber electrospinning membrane-coated steel substrate (MINMCS) based on the electrospinning strategy. This was designed as a highly specific recognition and enrichment electrospray ionization source module for AMS, where the molecular imprinting nanofiber membrane served as an excellent extraction and enrichment layer. The prepared ionization source demonstrated a sufficient loading capacity for three bioamines (BAs): histamine (HIS), tyramine (TYR), and tryptamine (TRY). With simplified sample pretreatment, this ionization source exhibited sensitivity comparable to that of high performance liquid chromatography-mass spectrometry (HPLC-MS/MS). Moreover, the entire analysis process could be completed within 1 min with acceptable recoveries (83.21-101.80%). In brief, this study introduces a new integrated recognition and enrichment electrospray ionization source for the detection of harmful substances such as bioamines, showcasing significant commercial potential for the rapid detection of foodborne harmful compounds.

Molecularly Imprinted Heterostructure-Assisted Laser Desorption Ionization Mass Spectrometry Analysis and Imaging of Quinolones.

Quinolone residues resulting from body metabolism and waste discharge pose a significant threat to the ecological environment and to human health. Therefore, it is essential to monitor quinolone residues in the environment. Herein, an efficient and sensitive matrix-assisted laser desorption/ionization mass spectrometry (MALDI/MS) method was devised by using a novel molecularly imprinted heterojunction (MIP-TNs@GCNs) as the matrix. Molecularly imprinted titanium dioxide nanosheets (MIP-TNs) and graphene-like carbon nitrides (GCNs) were associated at the heterojunction interface, allowing for the specific, rapid, and high-throughput ionization of quinolones. The mechanism of MIP-TNs@GCNs was clarified using their adsorption properties and laser desorption/ionization capability. The prepared oxygen-vacancy-rich MIP-TNs@GCNs heterojunction exhibited higher light absorption and ionization efficiencies than TNs and GCNs. The good linearity (in the quinolone concentration range of 0.5-50 pg/μL, R2 > 0.99), low limit of detection (0.1 pg/μL), good reproducibility (n = 8, relative standard deviation [RSD] < 15%), and high salt and protein resistance for quinolones in groundwater samples were achieved using the established MIP-TNs@GCNs-MALDI/MS method. Moreover, the spatial distributions of endogenous compounds (e.g., amino acids, organic acids, and flavonoids) and xenobiotic quinolones from Rhizoma Phragmitis and Rhizoma Nelumbinis were visualized using the MIP-TNs@GCNs film as the MALDI/MS imaging matrix. Because of its superior advantages, the MIP-TNs@GCNs-MALDI/MS method is promising for the analysis and imaging of quinolones and small molecules.

Polyelectrolyte Brushes with Protein-Like Nanocolloids.

Electrostatic interaction of ampholytic nanocolloidal particles (NPs), which mimic globular proteins, with polyelectrolyte brushes is analyzed within mean-field Poisson-Boltzmann approximation. In accordance with experimental findings, the theory predicts that an electrostatic driving force for the particle uptake by the brush may emerge when the net charge of the particle in the buffer and the charge of the brush are of the same sign. The origin of this driving force is change in the ionization state of weak cationic and anionic groups on the NP surface provoked by interaction with the brush. In experimental systems, the ionic interactions are complemented by excluded-volume, hydrophobic, and other types of interactions that all together control NP uptake by or expulsion from the brush. Here, we focus on the NP-brush ionic interactions. It is demonstrated that deviation between the buffer pH and the NP isoelectric point, considered usually as the key control parameter, does not uniquely determine the insertion free energy patterns. The latter depends also on the proportion of cationic and anionic groups in the NPs and their specific ionization constants as well as on salt concentration in the buffer. The analysis of the free energy landscape proves that a local minimum in the free energy inside the brush appears, provided the NP charge reversal occurs upon insertion into the brush. This minimum corresponds either to a thermodynamically stable or to a metastable state, depending on the pH offset from the IEP and salt concentration, and is separated from the bulk of the solution by a free energy barrier. The latter, being fairly independent of salt concentration in height, may strongly impede the NP absorption kinetically even when it is thermodynamically favorable. Hence, change reversal is a necessary but insufficient condition for the uptake of the NPs by similarly charged polyelectrolyte brushes.

Caffeine quantification in dietary supplements using high-throughput on-line solid phase extraction coupled to Venturi easy ambient sonic-spray ionization mass spectrometry.

Caffeine is present in a large number of beverages and is an additive used in dietary supplements. Therefore, the concern about its quality and safety for consumers has been increasing and hence requires faster and simpler analytical methods to determine the caffeine amount. The high-throughput analysis is an appropriate solution to pharmaceuticals, bioanalysis, forensic and food laboratory routines. In this sense, Venturi easy ambient sonic-spray ionization mass spectrometry (V-EASI-MS), a specific ambient ionization source, is suitable to enable direct analysis of sample solutions in real time and is appropriate to be coupled to liquid chromatography (LC). The development of an on-line solid phase extraction system coupled to V-EASI-MS optimizes the advantages of LC-MS hyphenation by enhancing the figures of merit of the analytical method according to AOAC guidelines and simultaneously minimizing the runtime analysis to 1.5 min per sample, as well as sample preparation steps and solvent consumption, which is currently a challenge for quantitative applications of ambient ionization MS.

Identification of deuterons at BESIII* *Supported by the National Natural Science Foundation of China (11975118, 12205141, 12375071)

The identification of deuterons with momenta in the range of 0.52−0.72 GeV/c is studied with specific ionization energy loss information using a data sample collected by the BESIII detector at center-of-mass energies between 4.009 and 4.946 GeV. Clean deuteron samples are selected using time of flight information. For all data samples, the deuteron identification efficiencies are higher than 95%, with a maximum difference of % between data and Monte Carlo simulation. This verifies the effectiveness of the deuteron identification method based on specific ionization energy loss and provides valuable information for future studies on processes involving deuterons in the final state at BESIII.

Search for heavy, long-lived, charged particles with large ionisation energy loss in pp collisions at sqrt{s} = 13 TeV using the ATLAS experiment and the full Run 2 dataset

This paper presents a search for hypothetical massive, charged, long-lived particles with the ATLAS detector at the LHC using an integrated luminosity of 139 fb−1 of proton–proton collisions at sqrt{s} = 13 TeV. These particles are expected to move significantly slower than the speed of light and should be identifiable by their high transverse momenta and anomalously large specific ionisation losses, dE/dx. Trajectories reconstructed solely by the inner tracking system and a dE/dx measurement in the pixel detector layers provide sensitivity to particles with lifetimes down to mathcal{O} (1) ns with a mass, measured using the Bethe–Bloch relation, ranging from 100 GeV to 3 TeV. Interpretations for pair-production of R-hadrons, charginos and staus in scenarios of supersymmetry compatible with these particles being long-lived are presented, with mass limits extending considerably beyond those from previous searches in broad ranges of lifetime.

Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry Estimation of Quercetin-Loaded Nanoemulsion in Rabbit Plasma: In Vivo-In Silico Pharmacokinetic Analysis Using GastroPlus.

In the present study, we developed and validated a rapid, specific, sensitive, and reproducible liquid chromatography-electrospray ionization tandem mass spectrometry method for quantifying quercetin (QT) in rabbit plasma using hydrochlorothiazide as the internal standard. Animals were orally administered with optimized QT-loaded nanoemulsion (QTNE) and QT suspension (QTS), equivalent to 30 mg/kg, to the test and control group, respectively. The blood samples were collected at pre-determined time points up to 48 h. The linearity range was from 5 to 5000 ng mL-1 with R 2 = 0.995. Further, we analyzed the various pharmacokinetic parameters and established the in vitro-in vivo correlation (IVIVC) of QTNE using GastroPlus software. The method was successfully developed and validated, and when applied for the determination of QT in rabbit plasma, it exhibited an increase in C max from 122.56 ng mL-1 (QTS) to 286.51 ng mL-1 (QTNE) (2.34-fold) and AUC0-48 from 976 ng h mL-1 (QTS) to 4249 ng h mL-1 (QTNE) (4.35-fold), indicating improved oral bioavailability QT when administered as QTNE. Statistical analysis revealed that the Loo-Riegelman method (two-compartmental method) best fitted the deconvolution approach (R 2 = 0.998, SEP = 4.537, MAE = 2.759, and AIC = 42.38) for establishing the IVIVC. In conclusion, the established bioanalytical method and IVIVC studies revealed that QTNE is a potential carrier for the effective delivery of QT with enhanced oral bioavailability.

Evaluation of a Capillary Microsampling Device for Analyzing Plasma Lenvatinib Concentration in Patients With Hepatocellular Carcinoma.

The anticancer drug, Lenvima (lenvatinib), has severe side effects. Therapeutic drug monitoring helps ensure its efficacy and safety. Regular and optimally timed blood sampling is tough, especially when lenvatinib is self-medicated. Microsampling using the easy to handle Microsampling Wing (MSW) may help circumvent this problem. However, current lenvatinib detection methods are not sensitive enough to detect its concentrations in microsamples (<50-250 μL). Thus, the aim of this study was 2-fold (1) develop an analytic method to estimate plasma lenvatinib concentrations in microsamples and (2) verify whether this method works on micro (5.6 μL) blood plasma samples obtained clinically through MSW from patients with unresectable hepatocellular carcinoma (HCC). A simple, highly sensitive, and specific liquid chromatography-electrospray ionization tandem mass spectrometry method was developed. Using this novel protocol, the trough blood plasma concentration of lenvatinib was measured for both blood sampled conventionally and that using MSW. Thirty-five venous whole blood samples were obtained from 11 patients with HCC. Furthermore, the stability of lenvatinib in MSW samples during storage was evaluated. The mean plasma lenvatinib concentration estimates were not significantly different between the MSW and conventional venous blood samples. CV for interday and intraday assays was low. Up to day 5, the lenvatinib concentration in the MSW samples was 85%-115% of the initial day concentration (when stored at 25°C or 4°C). The interference of endogenous matrix components in the human plasma was low. These results indicate that the novel mass spectrometry protocol accurately measures lenvatinib in human plasma and is reproducible. Thus, MSW could be a useful microsampling device for lenvatinib therapeutic drug monitoring in patients with HCC when used in combination with this novel liquid chromatography-electrospray ionization tandem mass spectrometry detection method.

Analysis of sex steroids in human tears using LC-MS and GC-MS: Considerations and developments to improve method sensitivity and accuracy.

Sex steroids play a role in regulation of tear film function and may exert their action locally at the ocular surface. However, measurement of sex steroids in tears is difficult due to small-volume tear samples and very low concentrations of the hormones. This short communication highlights what has been achieved to date in the analysis of tear sex steroids using ultra-performance LC-MS (UPLC-MS) as previously published, and reports further and more recent investigations toward optimising mass spectrometry method sensitivity and accuracy. The published UPLC-MS method successfully measured progesterone, androsterone glucuronide and 5α-androstane-3α,17β-diol in pooled basal tears of postmenopausal women, and fourteen sex steroid standards in methanol. Limitations included sub-optimal limits of detection (LOD) and lower limits of quantification (LLOQ) for some analytes (particularly oestrogens), exclusion of sample matrix effects and no use of internal standards. This update reports on further experiments carried out to improve sensitivity and accuracy. Sample matrix effects, internal standard spiking, and derivatisation with dansyl chloride and oximes were investigated. Dansylation significantly improved the LOD and LLOQ of oestrogens and their metabolites, by a factor of 10 for oestradiol and a factor of 5 for oestrone, but sensitivity of this updated method is not sufficient however for analysis of these oestrogens in human tears. Using gas chromatography-mass spectrometry (GC-MS) as an alternative technique to LC-MS, improved sensitivity for derivatised oestradiol is reported. This work demonstrates the need to develop higher sensitivity methods and points researchers towards specific MS ionisation techniques for future analysis of sex steroids in tears, in order to progress current understanding of the role of sex steroids in tear function and dry eye.

Mouse pharmacokinetics and metabolism of the phenylurea thiocarbamate NSC 161128

NSC 161128, a phenylurea thiocarbamate, displays activity against the NCI60 anti-cancer cell line panel and xenograft models. The metabolite N-methyl-N'-phenylurea (M10) has been detected in animal plasma; however, detection and quantification of other putative NSC 161128 metabolites have not been undertaken. The purpose of this study was to characterize the pharmacokinetics and metabolism of NSC 161128 in mice and under in vitro conditions. An LC-MS/MS assay was developed to evaluate stability and in vitro metabolism of NSC 161128 in liver microsomes and S9 fractions. Single-dose pharmacokinetic profiles for NSC 161128 and its metabolite M10 were obtained following intraperitoneal (I.P.) administration. A sensitive and specific positive ionization LC-MS/MS method for measuring NSC 161128 and its metabolites was developed. HPLC separation was achieved under gradient elution using an aqueous methanol mobile phase containing 0.05% formic acid and 0.05% ammonium hydroxide. The assay was linear over the range 1.0-1000ng/mL. NSC 161128 was stable in aqueous solution and tissue culture media, but not in plasma, where rapid degradation of NSC 161128 to the metabolite M10 was observed. Following I.P. administration of a 200mg/kg dose to male CD1 mice, the peak plasma concentration of NSC 161128 was 255ng/mL after 5min with a plasma half-life of 138min. Potential bioactivation of NSC 161128 was explored using mouse S9. An analytical LC-MS/MS method was successfully developed for the detection and quantification of NSC 161128 and its metabolites. These results increase the understanding of NSC 161128 pharmacokinetic and metabolic properties.

Investigation of (p,xd) reaction on 120Sn nucleus at proton energy of 30 MeV

For the first time, the double-differential and integral cross-sections of the reaction (p,xd) on the 120Sn nucleus were measured at the energy of the bombarding protons of 30 MeV. Tin is the structural material of the nuclear power plants being designed, in particular, the promising ADS (Accelerator Driven System) hybrid electro-nuclear installations consisting of a high-energy proton accelerator and a deeply subcritical nuclear reactor. The main idea is to use high-energy charged particle accelerators to produce neutrons in heavy element targets. For registration and identification of reaction products, the dE-E method was used, where two parameters of the detected particle are registered: specific ionization and total energy. The total error of the measured double-differential cross sections did not exceed 20%. After integrating the double-differential cross sections by angle, the integral energy spectrum was determined. The theoretical analysis is carried out within the framework of the TALYS calculation code, which is based on modern theoretical models of nuclear decay. The mechanisms of nuclear reactions responsible for the formation of the energy spectrum of outgoing deuterons are determined. The obtained experimental results fill in the missing values of the cross-sections of the studied reactions and can be used in the development of new approaches to the theory of nuclear reactions, as well as in the design of hybrid nuclear power plants.

Estimation and analysis of the influence of ionizing radiation on the operation of nanosatellite onboard radio electronic equipment

The paper presents the results of a calculation aimed to study the influence of ionizing, bremsstrahlung radiation on the operation of a nanosatellite obtained during the implementation of the project 0777-2020-0018 in 2020. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the Information system Spenvis of the European Space Agency. The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. The radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex-4QV, Virtex-5QV included in the SamSat ION avionics and its ability to operate during a year was assessed.

Crystalline-to-Amorphous Phase Transformation in CuO Nanowires for Gaseous Ionization and Sensing Application.

We report a dramatic reduction of operation voltage of a CuO nanowire-based ionization gas sensor due to the crystalline-to-amorphous phase transformation. The structural change is attributed to the ion bombardment and heating effect during the initial discharge, which brings about the formation of abundant nanocrystallites and surface states favoring gaseous ionization. The gas-sensing properties of the CuO nanowire sensor are confirmed by differentiating various types or concentrations of volatile organic compounds diluted in nitrogen, with a low detection limit at the ppm level. Moreover, a sensing mechanism is proposed on the basis of charge redistribution by electron-gas collision related to the specific ionization energy. The insightful study of the electrode microstructure delivers an exploratory investigation to the effect of gas ionization toward the discharge system, which provides new approaches to develop advanced ionization gas sensors.

Оценка и анализ радиационной стойкости радиоэлектронных элементов на кремниевой основе бортовой аппаратуры наноспутника при воздействии ионизирующего излучения солнечно-синхронной орбиты.

The paper presents the results of a calculation to study the influence of ionizing, bremsstrahlung radiation on the functioning of a nanosatellite. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat-ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the "Information system Spenvis of the European Space Agency". The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. Estimation of the radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex - 4QV, Virtex -5QV included in the SamSat - ION in the approximation of a double-layer stack was made for various thickness of Si and its ability to operate during the year.

Thin silicon solid-state detectors for energetic particle measurements

Context. Silicon solid-state detectors are commonly used for measuring the specific ionization, dE∕dx, in instruments designed for identifying energetic nuclei using the dE∕dx versus total energy technique in space and in the laboratory. The energy threshold and species resolution of the technique strongly depend on the thickness and thickness uniformity of these detectors. Aims. Research has been carried out to develop processes for fabricating detectors that are thinner than 15 μm, that have a thickness uniformity better than 0.2 μm over cm2 areas, and that are rugged enough to survive the acoustic and vibration environments of a spacecraft launch. Methods. Silicon-on-insulator wafers that have a device layer of the desired detector thickness supported by a thick handle layer were used as starting material. Standard processing techniques were used to fabricate detectors on the device layer, and the underlying handle-layer material was etched away leaving a thin, uniform detector surrounded by a thick, supporting frame. Results. Detectors as thin as 12 μm were fabricated in two laboratories and successfully subjected to environmental and performance tests. Two detector designs were used in the High-energy Energetic Particles Instrument, which is part of the Integrated Science Investigation of the Sun instrument suite on NASA’s Parker Solar Probe spacecraft. These detectors have been performing well for more than two years in space. Conclusions. Thin silicon detectors in d E∕dx versus total energy instruments enable the identification of nuclei with energies down to ~1 MeV nuc−1. This research suggests that detectors at least a factor of two thinner should be achievable using this fabrication technique.

LDI-MS scanner: Laser desorption ionization mass spectrometry-based biosensor standardization

Amperometric biosensors have been widely utilized for the cost-effective and rapid analysis of various bioanalytes, for example glucose. However, a lack of standardization and validation procedures remains a major limitation in biosensor development. Therefore, despite rapid advances in material science driving the development of amperometric biosensors, to date only a few biosensors, detecting a limited range of analytes, are available on the market. It is believed, once this issue is addressed, it can significantly facilitate the next step in the overall concept “go to the market” production and implementation of amprerometric biosensors for a large industrial scale.Herein, we report on the use of laser desorption ionization mass spectrometry (LDI-MS) for the standardization of amperometric biosensors, based upon a complete and non-destructive characterization and validation of layer-by-layer (LbL) biosensors at each fabrication step. We reveal that specific ionization pathways of mediators, polymers and enzymes from the biosensor surface allows for robust quality control during LbL biosensor manufacture. Furthermore, this LDI-MS approach can also be used to monitor, and therefore ensure, the encapsulation of enzymes in one-step nanobiosensors. Specifically, we show that LDI-MS can be used for the rapid chemical profiling of LbL biosensors and one-step synthesized nanobiosensors, as well as to assess their synthesis quality and to monitor for batch-to-batch and intra- and inter-day changes in their function and behavior. Our novel approach will thus contribute to the future development, improved design and fine tuning of both conventional LbL-fabricated amperometric biosensors and one-step designed nanobiosensors.

The electronic structure of bicyclo[2.2.2]octa-2,5-dione

Understanding the structure of strained hydrocarbons is important for understanding bonding and controlling reactivity and selectivity. Here we report an experimental and theoretical investigation into the valence electronic structure of bicyclo[2.2.2]octa-2,5-dione (BCOD). A high-resolution electron momentum spectroscopy (EMS) technique was employed to investigate the momentum dependence of specific ionization channels. These experiments were supplemented by an analysis of a measured photoelectron spectrum. Computational chemistry was used to explain the complex electronic structure of BCOD. We analyzed the influence of strain in bridged cyclic diketones by comparison of BCOD with corresponding results from structurally similar molecules to elucidate π/σ through-bond interactions.

Beta Decay of Molecular Tritium.

The beta decay of tritium in the form of molecular T_{2} is the basis of sensitive experiments to measure neutrino mass. The final-state electronic, vibrational, and rotational excitations modify the beta spectrum significantly and are obtained from theory. We report measurements of the branching ratios to specific ionization states for the isotopolog HT. Two earlier, concordant measurements gave branching ratios of HT to the bound HHe^{+} ion of 89.5% and 93.2%, in sharp disagreement with the theoretical prediction of 55%-57%, raising concerns about the theory's reliability in neutrino mass experiments. Our result, 56.5(6)%, is compatible with the theoretical expectation and disagrees strongly with the previous measurements.

On the Connection of Cascade-Probability Function on the Formation of Primary-Knocked on Atoms for Ions Taking into Account Energy Losses with a Boltzman Equation

The integral-differential equation of the cascade process for ions was solved using the Laplace transform and the method of successive approximations, taking into account the energy loss during the formation of primary-knocked-on atoms (PKA) in a one-dimensional model of an elementary atom. It is shown that the solution includes a cascade-probability function (CPF) for these particles. The main properties of CPF are considered and its graphical dependencies on the depth of registration are presented. It is shown that with the specific ionization loss coefficient k = 0, the FQM turns into the simplest cascade-probability function. When λ0→ 0, λ0→∞ and n→∞, the KV-function is equal to 0. The sum of the probabilities for all possible collisions from 0 to ∞ is 1. As the detection depth h increases, for all values of n, the CRF increases, reaches a maximum and then decreases . With increasing n, the curves shift to the right.

Influence of the hyperfine structure on plutonium in resonant laser-SNMS

Resonance ionization mass spectrometry is an ultra-sensitive and highly element selective tool for spectroscopy, ionization and detection of atoms and thus enables rare isotope determination. In combination with spatially resolved sputtering of neutrals by an initial ion beam, e.g. within a commercial secondary ion mass spectrometer, an isotope and isobar selective analysis technique with resolution on the micrometer scale for particles and surfaces is realized. Detection of minuscule amounts of specific actinides, e.g. of plutonium, in environmental and technical samples by this ultra-trace analysis technique requires detailed knowledge about the atomic physics of the element. Identification and characterization of the specific resonance ionization scheme applied within the particular geometry of the apparatus in use is needed. An analysis of the dependence of the specifications, specifically regarding the influence of the relative laser beam polarizations is presented here as an aspect, that could have a severe impact on isotope ratio precision and overall efficiency in the resulting ion signal.