Ambient catalyst-free conversion of methane to methanol by water radical cations.

Methane combustion contributes 30% to global warming, making its conversion to cleaner chemicals a critical challenge. Here, we report a catalyst-free ambient conversion of methane to methanol with a remarkable yield exceeding 650 millimoles per hour and a high conversion rate of ~35%, achieved using in situ-generated water dimer radical cations, [Formula: see text] , in a specially designed batch reactor operating under mild conditions. In a single run, the reactor was typically operated for 10 minutes.

Detection and Characterization of Water Radical Cations by Mass Spectrometry and Electron Paramagnetic Resonance Spectroscopy.

Water radical cations (HO) serve as key reactive intermediates in fundamental chemical processes, atmospheric chemistry, and energy-related applications due to their high reactivity and ability to initiate diverse chemical reactions. In this study, we investigated the generation of water dimer radical cations (/ 36, (HO)) and their reaction products with different substrates using multiple soft ionization techniques. Our comprehensive analytical platform incorporates corona discharge ionization (CDI), electrospray ionization (ESI), dielectric barrier discharge ionization (DBDI), and microwave plasma torch (MPT), coupled with complementary mass analyzers, including ion trap, Orbitrap, and quadrupole time-of-flight (Q-TOF) mass spectrometers.

Rapid evaluation of vegetable oil varieties and geographical origins by ambient corona discharge ionization mass spectrometry.

The composition and ratio of unsaturated fatty acids in vegetable oils play a crucial role in determining their overall quality. In this study, we present a corona discharge ionization mass spectrometry (MS) method for the rapid differentiation of vegetable oil varieties and their geographical origins under environmental conditions. Abundant water dimer radical cations, (HO), were generated by the ionization setup, which effectively activated carbon‑carbon double bonds (C=C) to form epoxidized products.

Chemical Fingerprinting of PM2.5 via Sequential Speciation Analysis Using Electrochemical Mass Spectrometry.

Chemical fingerprinting to characterize the occurrence state and abundance of organic and inorganic constituents within fine particulate matter (PM2.5) is useful in evaluating the associated health risks and tracing pollution sources. Herein, an analytical strategy for the rapid analysis of metal and organic constituents in PM2.

Ambient catalyst-free oxidation reactions of aromatic amines using water radical cations.

Water radical cations play a pivotal role in various scientific and industrial fields due to their unique reactivity and capacity to drive complex chemical transformations. Here we explored the formation of quaternary ammonium cations through the direct oxidation reaction of aromatic amines, facilitated by water radical cations within water microdroplets. This process was monitored mass spectrometry and occurs under ambient conditions, negating the need for traditional chemical catalysts or oxidants and achieving an impressive yield of approximately 80%.

Rapid analysis of untreated food samples by gel loading tip spray ionization mass spectrometry.

Rapid, efficient, versatile, easy-to-use, and non-expensive analytical approaches are globally demanded for food analysis. Many ambient ionization approaches based on electrospray ionization (ESI) have been developed recently for the rapid molecular characterization of food products. However, those approaches mainly suffer from insufficient signal duration for comprehensive chemical characterization by tandem MS analysis.

Determination of C═C Positions of Unsaturated Fatty Acids in Foods via Ambient Reactive Desorption Ionization with Water Dimer Radical Cations.

The positions of C═C bonds in unsaturated fatty acids (FAs) are one of the main factors determining the quality of food flavor. Herein, we developed an approach for the determination of C═C bonds of FAs by online epoxidation reaction with water dimer radical cations. The limit of detection for octenoic acid isomers was ∼9 μg/L.

Direct mass spectrometry analysis of exhaled human breath in real-time.

The molecular composition of exhaled human breath can reflect various physiological and pathological conditions. Considerable progress has been achieved over the past decade in real-time analysis of exhaled human breath using direct mass spectrometry methods, including selected ion flow tube mass spectrometry, proton transfer reaction mass spectrometry, extractive electrospray ionization mass spectrometry, secondary electrospray ionization mass spectrometry, acetone-assisted negative photoionization mass spectrometry, atmospheric pressure photoionization mass spectrometry, and low-pressure photoionization mass spectrometry. Here, recent developments in direct mass spectrometry analysis of exhaled human breath are reviewed with regard to analytical performance (chemical sensitivity, selectivity, quantitative capabilities) and applications of the developed methods in disease diagnosis, targeted molecular detection, and real-time metabolic monitoring.

Online Sequential Determination of Organic/Inorganic Lead Speciation in PM2.5 Using Electrochemical Mass Spectrometry.

The information regarding the occurrence and abundance of lead (Pb) in PM2.5 is useful for the evaluation of air pollution status and tracing the pollution source. Herein, electrochemical mass spectrometry (EC-MS) for sequential determination of Pb species in PM2.

Polarity-Specific Profiling of Metabolites in Single Cells by Probe Electrophoresis Mass Spectrometry.

Sensitive analysis of metabolites in a single cell is of fundamental significance for the better understanding of biological variability, differential susceptibility in disease therapy, and cell-to-cell heterogeneity as well. Herein, polarity-specific profiling of metabolites in a single cell was implemented by probe electrophoresis mass spectrometry (PEMS), which combined electrophoresis sampling of metabolites from a single cell and nanoelectrospray ionization-mass spectrometry (nanoESI-MS) analysis of the sampled metabolites. Enhanced extraction of either negatively or positively charged metabolites from a single cell was achieved by applying a DC voltage offset of +2.

Formation of protonated water-hydrogen clusters in an ion trap mass spectrometer at room temperature.

Protonated water-hydrogen clusters [H(HO)·m(H)] present an interesting model for fundamental water research, but their formation and isolation presents considerable experimental challenges. Here, we report the detection of [H(HO)·m(H)] (2 ≤ ≤ 3, ≤ 2) clusters alongside protonated water clusters H(HO) (2 ≤ ≤ 3) in a linear ion trap mass spectrometer under two different experimental conditions: (1) when water vapor was ionized by +5.5 kV ambient corona discharge in front of the mass spectrometer inlet; (2) when isolated H(HO) clusters were exposed to H gas inside the linear trap.

Generation of Phenol and Molecular Hydrogen through Catalyst-Free C-H Activation of Benzene by Water Radical Cations.

Here, we report on the abundant formation of phenol and molecular hydrogen when benzene vapor was exposed to gas plasma generated by +5.5 kV corona discharge of water vapor in argon in the absence of oxygen. Systematic analysis using a series of isotopic standards (-benzene, DO, and HO) and benzene derivatives (mono-, di-, trichlorobenzene, and ,-dimethylaniline) indicated that the formation of phenol occurred through the reaction between neutral benzene and the radical cation of water dimer, (HO).

Molecular differentiation of Panax notoginseng grown under different conditions by internal extractive electrospray ionization mass spectrometry and multivariate analysis.

Panax notoginseng is a highly valuable and widely used herb in traditional Chinese medicine. The quality and efficacy of Panax notoginseng grown under different conditions can greatly vary due to the differences in chemical composition. The analysis of chemical composition in Panax notoginseng typically involves various experimental steps including extraction, chromatographic separation and characterization, which can be time- and labor-consuming.

Rapid and sensitive detection of acetone in exhaled breath through the ambient reaction with water radical cations.

The levels of acetone and other ketones in exhaled human breath can be associated with various metabolic conditions, e.g. ketosis, lung cancer, dietary fat loss and diabetes.

Direct quantitative profiling of amino acids in tissues for the assessment of lung cancer.

Direct molecular analysis of tissue samples is a promising approach to increase the accuracy, speed and molecular specificity of cancer diagnosis. Herein, alterations of amino acids between human lung cancer tissues and matched adjacent normal tissues were profiled by internal extraction electrospray ionization mass spectrometry (iEESI-MS). The results indicated that the levels of 11 detected amino acids (including serine, proline, valine, threonine, asparagine, aspartic acid, methionine, histidine, phenylalanine, arginine and tyrosine) in the cancerous tissues were lower than that in the adjacent normal tissues.

Alterations in lipid profile upon uterine fibroids and its recurrence.

Uterine fibroids (UF) is the most common (about 70% cases) type of gynecological disease, with the recurrence rate varying from 11 to 40%. Because UF has no distinct symptomatology and is often asymptomatic, the specific and sensitive diagnosis of UF as well as the assessment for the probability of UF recurrence pose considerable challenge. The aim of this study was to characterize alterations in the lipid profile of tissues associated with the first-time diagnosed UF and recurrent uterine fibroids (RUF) and to explore the potential of mass spectrometry (MS) lipidomics analysis of blood plasma samples for the sensitive and specific determination of UF and RUF with low invasiveness of analysis.

Online discovery of the molecular mechanism for directionally detoxification of Fuzi using real-time extractive electrospray ionization mass spectrometry.

Ethnopharmacological Relevance: Aconitum carmichaelii Debeaux, a famous traditional medicinal herb for collapse, rheumatic fever, and painful joints, always raises global concerns about its fatal toxicity from toxic alkaloids when improperly processed. Therefore, it is urgent to clarify the internal molecular mechanism of processing detoxification on Aconitum and develop simple and reliable approaches for clinical application, which is also of great significance to the rational medicinal use of Aconitum.

Aim Of The Study: The study aimed at developing a complete molecular mechanism exploration strategy in complex medicinal herb decocting system, clarifying the internal molecular mechanism of processing detoxification on Aconitum, and exploring valid approaches for detoxification.

Vertical Transmission of SARS-CoV-2 in Second Trimester Associated with Severe Neonatal Pathology.

The effects of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in women on the gestation course and the health of the fetus, particularly in the first and second trimesters, remain very poorly explored. This report describes a case in which the normal development of pregnancy was complicated immediately after the patient had experienced Coronavirus disease 2019 (COVID-19) at the 21st week of gestation. Specific conditions included critical blood flow in the fetal umbilical artery, fetal growth restriction (1st percentile), right ventricular hypertrophy, hydropericardium, echo-characteristics of hypoxic-ischemic brain injury (leukomalacia in periventricular area) and intraventricular hemorrhage at the 25th week of gestation.

Applications of direct analysis in real time mass spectrometry in food analysis: A review.

Rationale: Direct analysis in real time (DART) combined with mass spectrometry (MS) detection has become one of the most broadly used analytical approaches for the direct molecular characterization of food samples with regard to their chemical quality, safety, origin, and authentication. The major advantages of DART-MS for food analysis include high chemical sensitivity and specificity, high speed and throughput of analysis, simplicity, and the obviation of tedious sample preparation and solvents.

Methods: The recent applications of DART coupled with different mass analyzers, including quadrupole, ion trap, Orbitrap, and time of flight, are discussed.

Mass spectrometry distinguishing C=C location and cis/trans isomers: A strategy initiated by water radical cations.

We present an approach for the elucidation of C=C bond position and cis/trans isomers, which is achieved by the reaction of ambient water radical cations and double bonds, followed by the fragmentation of epoxide radical cations to generate diagnostic ions in tandem mass spectrometry. Hexenol double bond positional isomers and cis/trans isomers which exhibit different properties and biological functions are characterized as a proof of concept. The merits of the approach include the simplicity of experimental setup, rapid derivatization (within seconds), the obviation of organic solvents, as well as easy spectral interpretation.

Selective detection of phospholipids in human blood plasma and single cells for cancer differentiation using dispersed solid-phase microextraction combined with extractive electrospray ionization mass spectrometry.

Phospholipids in microvolume biofluid samples (≤0.5 μL), including human plasma and single cells, were selectively captured by dispersed magnetic Fe3O4@TiO2 nanocomposite particles (40 μg). A suspension containing Fe3O4@TiO2 nanoparticles was loaded into a glass capillary (i.

Comparative study of alterations in phospholipid profiles upon liver cancer in humans and mice.

Comparative studies of molecular alterations upon cancer between mice and humans are of great importance in order to determine the relevance of research involving mouse cancer models to the development of diagnostic and therapeutic approaches in clinical practice as well as for the mechanistic studies of pathology in humans. Herein, using molecular fingerprinting by internal extractive electrospray ionization mass spectrometry (iEESI-MS), we identified 50 differential signals in mouse liver tissue and 62 differential signals in human liver tissue that undergo significant intensity alterations (variable importance in the project (VIP) >1.0) upon liver cancer, out of which only 27 were common in both mouse and human tissues.

Water Radical Cations in the Gas Phase: Methods and Mechanisms of Formation, Structure and Chemical Properties.

Water radical cations, (HO), are of great research interest in both fundamental and applied sciences. Fundamental studies of water radical reactions are important to better understand the mechanisms of natural processes, such as proton transfer in aqueous solutions, the formation of hydrogen bonds and DNA damage, as well as for the discovery of new gas-phase reactions and products. In applied science, the interest in water radicals is prompted by their potential in radiobiology and as a source of primary ions for selective and sensitive chemical ionization.