Ambient Ionization Research Articles

Influence of the C + H2O -> H2CO solid-state reaction onastrochemical networks and the formation of complex organic molecules

The solid-state reaction C + H$_2$O rightarrow H$_2$CO has recently been studied experimentally and claimed as a new `non-energetic' pathway to complex organic and prebiotic molecules in cold astrophysical environments. We compared results of astrochemical network modelling with and without the C + H$_2$O surface reaction. A typical, generic collapse model in which a dense core forms from initially diffuse conditions was used along with the astrochemical kinetics model MAGICKAL. The inclusion of the reaction does not notably enhance the abundance of formaldehyde itself; however, it significantly enhances the abundance of methanol (formed by the hydrogenation of formaldehyde) on the dust grains at early times, when the high gas-phase abundance of atomic C leads to relatively rapid adsorption onto the grain surfaces. As a result, the gas-phase abundance of methanol is also increased due to chemical desorption, quickly reaching abundances close to sim 10$^ $ n$_H$, which decline strongly under late-time, high-density conditions. The reaction also influences the abundances of simple ice species, with the CO$_2$ abundance increased in the earliest, deepest ice layers, while the water-ice abundance is somewhat depressed. The abundances of various complex organic molecules are also affected, with some species becoming more abundant and others less. When gas-phase atomic carbon becomes depleted, the grain-surface chemistry returns to behaviour that would be expected if there had been no new reaction. Our results show that fundamental reactions involving the simplest atomic and molecular species can be of great importance for the evolution of astrochemical reaction networks, thus providing motivation for future experimental and theoretical studies.

Infrared Photoactivation Enables nano-DESI MS of Protein Complexes in Tissue on a Linear Ion Trap Mass Spectrometer.

Native mass spectrometry analysis of proteins directly from tissues can be performed by using nanospray-desorption electrospray ionization (nano-DESI). Typically, supplementary collisional activation is essential to decluster protein complex ions from solvent, salt, detergent, and lipid clusters that comprise the ion beam. As an alternative, we have implemented declustering by infrared (IR) photoactivation on a linear ion trap mass spectrometer equipped with a CO2 laser (λ = 10.6 μm). The prototype system demonstrates declustering of intact protein complex ions up to approximately 50 kDa in molecular weight that were sampled directly from brain and eye lens tissues by nano-DESI. For example, signals for different metal binding states of hSOD1G93A homodimers (approximately 32 kDa) separated by only approximately 6 Th (10+ ions) were resolved with IR declustering, but not with collisional activation. We found IR declustering to outperform collisional activation in its ability to reduce chemical background attributable to nonspecific clusters in the nano-DESI ion beam. The prototype system also demonstrates in situ native MS on a low-cost mass spectrometer and the potential of linear ion trap mass spectrometers for this type of analysis.

Chemical Pathways of SO2 with Hydrogen Atoms on Interstellar Ice Analogues

Sulfur dioxide (SO2) is a sulfur-containing molecule expected to exist as a solid in the interstellar medium. In this study, we have performed laboratory experiments and computational studies on the surface reactions of solid SO2 with hydrogen atoms on amorphous solid water (ASW) at low temperatures. After 40 minutes of exposure of SO2 deposited on ASW to H atoms, approximately 80% of the solid SO2 was lost from the substrate at 10–40 K, and approximately 50% even at 60 K, without any definite detection of reaction products. Quantum chemical calculations suggest that H atoms preferentially add to the S atom of solid SO2, forming the HSO2 radical. Further reactions of the HSO2 radical with H atoms result in the formation of several S-bearing species, including HS(O)OH, the S(O)OH radical, HO–S–OH, HS–OH, and H2S. In codeposition experiments involving H and SO2, we have confirmed the formation of H2S, HS(O)OH, and/or HO–S–OH. However, the yields of these S-bearing species are insufficient to account for the complete loss of the initial SO2 reactant. These findings suggest that some products are desorbed into the gas phase upon formation. This study indicates that a portion of the SO2 in ice mantles may remain unreacted, avoiding hydrogenation, while the remainder is converted into other species, some of which may be subject to chemical desorption.

Double alkali metal salts synergistic activation coupled with S-doped cotton derived honeycomb porous carbon for enhanced zinc ion storage capability

Biomass-derived carbon materials are ideal electrode materials due to their inherent eco-friendliness, easily available and unique micro-morphology. Herein, zinc ion capacitors (ZICs) are designed utilizing S doped honeycomb porous carbon nanosheet cathode, which is obtained via synergistic activation from sodium thiosulfate and potassium carbonate. The honeycomb microstructure is result from the pore-forming effect of double alkali metal salts, which can promote the electrolyte ion fast migration in the cathode. Besides, the S doping in carbon array can regulate the electron distribution within the carbon framework and lower the energy barrier for the chemical absorption of Zn2+/H+, which is demonstrated by density functional theory calculation and expected to produce additional capacitance. Further, the ex-situ X-ray photoelectron spectroscopy reveals the consistent changes in C-O-H and C-O-Zn throughout the charging and discharging cycles, which demonstrate the S doping can promote the reversible chemical adsorption and desorption reaction of Zn2+/H+. As a result, the S doping honeycomb porous carbon nanosheet cathode can achieves a high discharge capacity of 147.2 mAh g−1 and high energy density of 92.7 Wh kg−1. Additionally, the obtained material exhibits good cycling stability at 20 A g−1, retaining 99.9 % of its initial capacity after 2000 cycles. This research presents a versatile approach to synthesizing heteroatom-doped carbon materials from biomass waste for ZICs.

Identification strategy of wild and cultivated Astragali Radix based on REIMS combined with two-dimensional LC-MS

A rapid and real-time method was established based on the combination of rapid evaporative ionization mass spectrometry (REIMS) and two-dimensional liquid chromatography mass spectrometry (2DLC-MS) for identification of wild Astragali Radix (WAR) and cultivated AR (CAR). The samples were analyzed under ambient ionization without time-consuming sample preparation. The phenotypic data of WAR and CAR were used to develop a real-time recognition model. Subsequently, the compounds in these two species were comprehensively characterized based on 2DLC-MS, and 45 different compounds were screened out by multivariate statistical analysis. A semi-quantitative method for 45 different compounds was established based on ultrahigh-performance liquid chromatography/quadrupole-linear ion trap mass spectrometry (UHPLC-QTRAP-MS). The results showed that the relative content of most compounds in WAR was higher than in CAR. In summary, the method has demonstrated remarkable performance in distinguishing between WAR and CAR, providing a reference in the field of traditional Chinese medicine (TCM) analysis and identification.

DART isotope dilution high resolution mass spectrometry and 19F-NMR detection of fluorotelomeric alcohols in hydrolyzed food contact paper

Fluorotelomer-based acrylate polymers and surfactants used to grease-proof food contact paper (FCP) are potential sources of dietary exposure to perfluoroalkyl substances (PFAS). Food contact substances (FCS) containing polyfluorinated long-chains (≥C8) were voluntarily removed by their manufacturers from the U.S. market in 2011 due to health concerns and largely replaced with FCSs containing short-chain (≤C7) PFAS. In 2020, FDA findings of potential biopersistence of 6:2 FTOH (CF3(CF2)5CH2CH2OH) similarly prompted an additional voluntarily phase-out of FCSs containing 6:2 FTOH by their manufacturers that was completed by the end of 2023. To monitor the phase-out process, a screening method was developed to detect FCPs containing ester-linked polyfluorinated pendant chains. Direct Analysis in Real Time-Isotope Dilution-High Resolution Mass Spectrometry (DART-ID-HRMS) enabled rapid semi-quantitative detection of 6:2 FTOH in FCP saponification reaction headspace without requiring sample concentration or chromatography. 19F-NMR analysis confirmed 6:2 FTOH pendant chain identity and detection dependence on saponification. The speed and specificity of this approach arise from ester saponification in the presence of stable isotopically labeled 6:2 FTOH; high FTOH differential volatility relative to nonfluorinated matrix, and the facile production of FTOH gas-phase anions (e.g., [M + O2]·−, [M-H + CO2]−) under ambient ionization conditions. The efficiency of this simple workflow makes it well-suited for monitoring the phase-out of FCS containing ester-linked polyfluorinated chains from the U.S. marketplace.

Expanding Spatial Metabolomics Coverage with Lithium-Doped Nanospray Desorption Electrospray Ionization Mass Spectrometry Imaging.

Spatial metabolomics has emerged as a powerful tool capable of revealing metabolic gradients throughout complex heterogeneous tissues. While mass spectrometry imaging (MSI) technologies designed to generate spatial metabolomic data have improved significantly over time, metabolite coverage is still a significant limitation. It is possible to achieve deeper metabolite coverage by imaging in positive and negative polarities or imaging several serial sections with different targeted biomolecular classes. However, this significantly increases the number of tissue samples required for biological studies and reduces the capacity for larger sample cohorts. Herein, we introduce lithium-doped nanospray desorption electrospray ionization (nano-DESI) as a simple and robust method to increase spatial metabolomics coverage, which is achieved through enhancements to ionization efficiencies in positive ion mode for metabolites and lipids lacking basic moieties, and improved structurally diagnostic tandem mass spectra for [M + Li]+ adducts. Specifically, signal intensities were found to be enhanced by 10-1000× for 96 compounds including small molecule metabolites, fatty acids, neutral lipids (e.g., diacylglycerols, DAG), and phospholipids when lithium was added to the ESI solvent. In addition, proof-of-principle results reveal that lithium-doped nano-DESI MSI was able to comprehensively visualize metabolites and lipids in the prostaglandin (PG) biosynthetic pathway with PG isomeric resolution in an ovarian tumor section. These data show colocalization of fatty acid (FA) 20:4 containing DAGs, FA 20:4 monoacylglycerols (MAGs), and FA 20:4 with PGE2 and disparate localizations of PGD2. Overall, this study describes a simple and powerful approach to more comprehensively probe the spatial metabolome with MSI.

Integrated strategy of mass spectrometry imaging and LC/MS-based GNPS for spatial characterization of alkaloids from Menispermi Rhizoma and study on potential anti-inflammatory mechanism by network pharmacology and molecular docking

Menispermi Rhizoma (MR) is the dried rhizome of Menispermum dauricum DC, which has been used to treat sore throat, enteritis, and rheumatic arthralgia. These therapeutic effects are attributed to its alkaloid ingredient. However, the chemical composition, anti-inflammatory mechanisms and the spatiotemporal distribution of the bioactive ingredients in MR have seldom been investigated. This study aims to clarify the anti-inflammation mechanism, material basis, and their spatial distribution of MR. Here, a LC/MS-based Global Natural Products Social Molecular Networking (GNPS) strategy was used to rapidly exhibit alkaloid molecular clusters that improve annotation accuracy and discover more unknown compounds. Then, a high-sensitive air flow-assisted ionization mass spectrometry imaging (AFAI-MSI) method was developed to visualize the spatial distributions alkaloids in different botanical parts of MR. The anti-inflammation mechanism was investigated based on network pharmacology and verified by molecular docking experiment. Finally, a total of 106 alkaloids including 24 aporphines, 23 monobenzylisoquinolines, 20 morphinanes, 20 proberberines, 12 bisbenzylisoquinolines, and 7 amides were identified in MR as well as 24 alkaloids were visualized in the medullary ray, cortex and epidermis regions. Moreover, the targets with a higher degree in the PPI network were TNF, GAPDH, AKT1, ALB, STAT3. GO and KEGG analysis revealed that MR in anti-inflammatory mechanism mainly involved plasma membrane, ATP binding, cytoplasm, identical protein binding and ATP binding. The signaling pathways mainly included NOD-like receptor signaling pathway, PI3K-Akt signaling pathway, AGE-RAGE signaling pathway in diabetic complications. The molecular docking results indicated that stepharanine-2-O-glucoside, bianfugedine, bianfugecine, dehydrostephanine had excellent affinity with SRC, MMP9 AKT1, STAT3 and TNF. This study comprehensively characterized the alkaloid ingredients and spatial distribution of MR, and revealed potential mechanism of MR in inflammation, which provides a reference for development and application of MR and other Traditional Chinese medicines (TCMs).

Microwave plasma torch desorption ionization mass spectrometry for chemical characterization of aromatic secondary organic aerosol

Benzene and toluene, primarily emitted from vehicle exhaust, are common volatile organic compounds (VOCs). These aromatic compounds in the atmosphere undergo further photooxidation to form secondary organic aerosol (SOA), which are a primary factor in haze weather. Aromatic SOA is more difficult to detect by traditional detection methods. Microwave plasma torch (MPT) is an ambient ionization source based on microwave plasma developed in recent years. Herein, a microwave plasma torch desorption ionization high-resolution mass spectrometry (MPT-HRMS) technique was designed for the direct analysis of aromatic SOA in the environment. For environmental haze samples, no pretreatment is required, and over twenty types of aromatic hydrocarbon derivatives or oxidation products can be detected in situ using MPT-HRMS. The possible mechanisms underlying the formation of aromatic SOA were investigated. MPT-HRMS is a powerful technical tool for rapidly tracking non-targeted aromatic SOA and their transformations in the environment. This contributes to an in-depth understanding of the formation mechanisms of SOA and their impact on air pollution.

Quantitative Analysis of Drugs in a Mimetic Tissue Model Using Nano-DESI on a Triple Quadrupole Mass Spectrometer.

Mass spectrometry is a powerful analytical technique used at every stage of the pharmaceutical research process. A specialized branch of this method, mass spectrometry imaging (MSI), has emerged as an important tool for determining the spatial distribution of drugs in biological samples. Despite the importance of MSI, its quantitative capabilities are still limited due to the complexity of biological samples and the lack of separation prior to analysis. This makes the simultaneous quantification and visualization of analytes challenging. Several techniques have been developed to address this challenge and enable quantitative MSI. One such approach is the mimetic tissue model, which involves the incorporation of an analyte of interest into tissue homogenates at several concentrations. A calibration curve that accounts for signal suppression by the complex biological matrix is then created by measuring the signal of the analyte in the series of tissue homogenates. Herein, we use the mimetic tissue model on a triple quadrupole mass spectrometer (QqQ) in multiple reaction monitoring mode to demonstrate the quantitative abilities of nanospray desorption electrospray ionization (nano-DESI) and compare these results with those obtained using atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI). For the tested compounds, our findings indicate that nano-DESI achieves lower standard deviations than AP-MALDI, resulting in superior limits of detection for the studied analytes. Additionally, we discuss the limitations of the mimetic tissue model in the quantification of certain analytes and the challenges involved with the implementation of the model.

Evolution of Chemistry in the envelope of HOt CorinoS (ECHOS). II. The puzzling chemistry of isomers as revealed by the HNCS/HSCN ratio

The observational detection of some metastable isomers in the interstellar medium with abundances comparable to those of the most stable isomer, or even when the stable isomer is not detected, highlights the importance of non-equilibrium chemistry. This challenges our understanding of the interstellar chemistry and shows the need to study isomeric forms of molecular species to constrain chemical processes occurring in the interstellar medium. Our goal is to study the chemistry of isomers through the sulphur isomer pair HNCS and HSCN, since HSCN has been observed in regions where its stable isomer has not been detected, and the observed HNCS/HSCN ratio seems to significantly vary from cold to warm regions. We used the Nautilus time-dependent gas-grain chemical code to model the formation and destruction paths of HNCS and HSCN in different astrochemical scenarios, as well as the time evolution of the HNCS/HSCN ratio. We also analysed the influence of the environmental conditions on their chemical abundances. We present an observational detection of the metastable isomer HSCN in the Class I object B1-a ($N$=(1.1pm 0.6)times 1012 cm$^ $), but not of the stable isomer HNCS, despite HNCS lying 3200 K lower in energy than HSCN. Our theoretical results show an HNCS/HSCN ratio sensitive to the gas temperature and the evolutionary time, with the highest values obtained at early stages ($t$lesssim 10$^4$ yr) and low ($T_ g $lesssim 20 K) temperatures. A more detailed analysis also shows that the main mechanism forming HNCS in young ($t$$<$10$^5$ yr) and cold ($T_ g $$=$10 K) objects at moderate-low densities ($n$$_ H $leq 10$^5$ cm$^ $) is a grain surface reaction (the chemical desorption reaction N$_ solid $+HCS$_ solid $rightarrow HNCS), unlike previous predictions that suggest only gas-phase chemistry for its formation. However, for the formation of its metastable isomer HSCN, over the same time range and physical conditions, we find that both surface and gas-phase reactions (through the ion H$_2$NCS$^+$) play important roles. In warmer ($T_ g $geq 50 K) regions, the formation of this isomer pair is only dominated by gas-phase chemistry through the ions H$_2$NCS$^+$ (mainly at low densities) and HNCSH$^+$ (mainly at high densities). The results suggest a different efficiency of the isomerisation processes depending on the source temperature. The progressive decrease of HNCS/HSCN with gas temperature at early evolutionary times derived from our theoretical results indicates that this ratio may be used as a tracer of cold young objects. This work also demonstrates the key role of grain surface chemistry in the formation of the isomer pair HNCS and HSCN in cold regions, as well as the importance of the ions H$_2$NCS$^+$ and HNCSH$^+$ in warm/hot regions. Since most of the interstellar regions where HSCN is detected are cold regions (starless cores, Class 0/I objects), a larger sample including sources characterised by high temperatures (e.g. hot cores) are needed to corroborate the theoretical results.

Photoinduced Online Enrichment-Deglycosylation of Glycolipids for Enhancing Lipid Coverage and Identification in Single-Cell Mass Spectrometry.

Single-cell lipidomics provides important information for molecular mechanisms of living processes and diseases at the individual cell level. However, single-cell lipidomic mass spectrometry (MS) techniques suffer from low lipid coverage and incomplete structural elucidation, especially for poorly ionizable glycosphingolipids (GSLs). Herein, a photoinduced enrichment-deglycosylation method of GSLs was developed and introduced into an ambient liquid extraction MS system for enhancing detection coverage and identification accuracy of GSLs in single-cell MS. GSL standards were selectively adsorbed on TiO2 in ammonia-added protic solvents. Under UV irradiation, the adsorbed GSLs would lose one hexosyl group (deglycosylation), and the products (>70% conversion efficiency) were desorbed from TiO2. By coating porous TiO2 into the capillary of the ambient liquid extraction MS system, online adsorption of GSLs and their separation from high-abundance phospholipids were achieved, largely reducing ion suppression. By UV irradiation, captured GSLs were rapidly deglycosylated and photodesorbed from TiO2 coating without solvent switching, resulting in 6-fold enrichment. With the new method, the detection coverage of GSLs was enhanced 9-fold without losing other lipidomes, compared with the conventional method. Moreover, deglycosylated GSLs from photodesorption had more MS/MS fragments than intact GSLs, facilitating detailed fatty acyl and sphingosine chain elucidation. Seven deglycosylated GSL peaks were identified with the confirmed hydroxyl group location in the fatty acyl chain, while only 1 was identified for intact GSL. The new method was applied to the single-cell lipidomics study of two types of nerve cells. Totally, 31 lipids including 11 GSLs were identified in a single cell, and 5 hexosylceramides were found significantly altered after neuron injury.

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, (H2O)2+•, were generated by the ionization setup, which effectively activated carbon‑carbon double bonds (C=C) to form epoxidized products. These epoxidation products were analyzed using tandem MS, generating diagnostic fragment ions that precisely identified CC bond positions. Statistical analysis models were subsequently developed using the resulting MS fingerprint data, revealing significant differences between various vegetable oils and olive oils from different origins. Key advantages of this method include minimal sample preparation, rapid analysis, and easily interpretable spectra. This study provides a new MS-based strategy for food quality assessment and offers a promising tool for identifying CC positional isomers in complex systems.

Metal and metal oxide nanomaterials for heavy metal remediation: novel approaches for selective, regenerative, and scalable water treatment

Heavy metal contamination in water sources poses a significant threat to environmental and public health, necessitating effective remediation strategies. Nanomaterial-based approaches have emerged as promising solutions for heavy metal removal, offering enhanced selectivity, efficiency, and sustainability compared to traditional methods. This comprehensive review explores novel nanomaterial-based approaches for heavy metal remediation, focusing on factors such as selectivity, regeneration, scalability, and practical considerations. A systematic literature search was conducted using multiple academic databases, including PubMed, Web of Science, and Scopus, to identify relevant articles published between 2013 and 2024. The review identifies several promising nanomaterials, such as graphene oxide, carbon nanotubes, and metal-organic frameworks, which exhibit high surface areas, tunable surface chemistries, and excellent adsorption capacities. Surface functionalization with specific functional groups (e.g., carboxyl, amino, thiol) significantly enhances the selectivity for target heavy metal ions. Advances in regeneration strategies, including chemical desorption, electrochemical regeneration, and photocatalytic regeneration, have improved the reusability and cost-effectiveness of these materials. Scalability remains a critical challenge, but recent developments in synthesis methods, such as green synthesis and continuous-flow synthesis, offer promising solutions for large-scale production. The stability and longevity of nanomaterials have been improved through surface modification and the development of hybrid nanocomposites. Integrating nanomaterials with existing water treatment infrastructure and combining them with other remediation techniques, such as membrane filtration and electrochemical methods, can enhance overall treatment efficiency and feasibility. In conclusion, nanomaterial-based approaches hold immense promise for revolutionizing heavy metal remediation and advancing sustainable water management practices. As future research is geared towards retrofitting existing treatment plants, it is equally critical to mitigate unintended environmental and public health consequences associated with the widespread production and use of nanomaterials, such as their leachability into water systems and environmental persistence.

Sensitive determination of volatile nitrosamines with ambient pressure ammonium-adduct ionization mass spectrometry.

In recent years, the control of volatile N-nitrosamines (NAs) has been of interest in the pharmaceutical and food industries, as many of these compounds are probable human carcinogens. Thus, rapid and trace-level quantitative determination methods are in urgent demand. In this work, ambient pressure ammonium-adduct ionization mass spectrometry was proposed for the sensitive detection of volatile nitrosamines in various pharmaceutical headspaces. The ammonium ions produced through electrospray ionization acted as reactant ions for NAs to generate ammonium-NA adduct ions and underwent in-source collision-induced dissociation to produce protonated NAs, which were detected by mass spectrometry. The ionization selectivity and sensitivity for various volatile NAs were improved significantly using the developed method, which was demonstrated by the limit of quantification (LOQ) below 52ng L-1 for all NAs, and the quantitative performance was consequently improved. Different NAs exhibited almost equimolar response using NH4+ as the reactant ion, with at least a twofold enhancement in intensity for the individual compounds relative to when using H+ as the reactant ion. The proposed method is a rapid, sensitive, and environmentally economical approach that uses few reagents.

Rapid and sensitive determination of bongkrekic acid with molecularly imprinted polymer-coated wooden-tip electrospray ionization mass spectrometry

In this study, a novel methodology has been developed for the rapid and sensitive analysis of bongkrekic acid (BA), a highly toxic bacterial metabolite, using a molecularly imprinted polymer-coated wooden-tip coupled with electrospray ionization mass spectrometry (MIPWT-ESI-MS). A MIPWT solid phase microextraction (SPME) probe specifically tailored for BA was fabricated, by employing dummy template molecules/functional monomers in the imprinting coating modification. This approach exhibits an enrichment factor (EF) of 683 ± 53 for efficient extraction of BA from aqueous matrices, demonstrating the utility of dummy templates in enhancing the selectivity and sensitivity of the MIPWT-ESI-MS method. The analytical performance of the MIPWT-ESI-MS method was evaluated, demonstrating a desirable linear correlation (r = 0.9988), along with remarkable sensitivity by a limit of detection (LOD) and limit of quantitation (LOQ) at 0.05 μg/L and 0.16 μg/L in pure water, respectively. Additionally, the method demonstrated high repeatability with a relative standard deviation (RSD) < 3.9 % (n = 6) and reproducibility with an RSD < 13.4 %. The practical application of the method was confirmed through the successful analysis of real-world samples, including tap water, wastewater from a food processing factory, and the aqueous extracts of food samples, with BA detected at 0.296 µg/L in Tremella. Spiking experiments further validated the accuracy of the method, with recoveries ranging from 81 % to 97 %. This study integrates MIP with ambient mass spectrometry, offering a robust, selective, and sensitive tool for the monitoring of trace BA levels in complex food and environmental samples, contributing significantly to public health safety and food quality control.

Anthocyanin Profiles in the Tropical Fruits Eugenia jambolana and Inga edulis: A Comparative Study Using Paper Spray Ionization (PSI-MS), Tissue Spray Ionization (TSI-MS), and Direct Infusion (DI-MS).

Paper spray ionization (PSI-MS) and tissue spray ionization (TSI-MS) mass spectrometry are simple and rapid ambient ionization mass spectrometry techniques that offer numerous advantages over conventional analysis methods. This study aims to analyze the efficiency of detecting anthocyanins from Eugenia jambolana fruit peel and Inga edulis seeds using PSI-MS, TSI-MS, and DI-MS (direct infusion). DI-MS exhibited high efficiency, detecting all compounds in abundance, with anthocyanins malvidin 3,5-O-diglucoside (1) and petunidin 3,5-O-diglucoside (2) being the most prevalent. PSI-MS, however, struggled to detect delphinidin 3-O-glucoside and showed lower abundances for compounds 1, 2, 3 (delphinidin 3,5-O-diglucoside), and 4 (petunidin 3-O-glucoside) compared to DI-MS, attributed to the technique's challenges with molecular weight and polarity. TSI-MS was least effective, detecting only compounds 1, 2, and 3 at low intensities. The overall unique compounds identified across techniques were 134, emphasizing the importance of comprehensively employing multiple methods to analyze anthocyanins in these edible plants.

Magnetic particle spray mass spectrometry for the determinationof beta-blockers in plasma samples.

Magnetic particle spray mass spectrometry (MPS-MS), an innovative ambient ionization technique proposed by our research group, was employed to determine beta-blockers in human plasma samples. A dispersive solid phase extraction of atenolol, metoprolol, labetalol, propranolol, nadolol, and pindolol was carried out using magnetic molecularly imprinted polymer (M-MIP) particles that were attached to the tip of a metal probe, which was placed in the mass spectrometer inlet. A solvent (1% formic acid in methanol) was dispensed on the particles, and the Taylor cone was formed around them (in high voltage). The analytes were desorbed/ionized and determinedby a triple quadrupole mass spectrometer. M-MIP was synthesized with oxprenolol as a pseudo-template, demonstrating good selectivity to beta-blockers compared withno-analog molecules, with an adsorption process occurring in monolayers, according to isotherm studies. Kinetic experiments indicated chemisorption as the predominant M-MIP/analyte interaction. The analytical curves were linear (R2 > 0.98), and the limit of quantification was 3µg L-1 for all the analytes. Limits of detection ranged from 0.64 to 2.41µg L-1. Precisions (relative standard deviation) and accuracies (relative error) ranged from 3.95 to 21.20% and-17.05 to 18.93%, respectively. MPS-MS proved to be a simple, sensitive, and advantageous technique comparedwithconventional approaches. The analyses were fast, requiring no chromatographic separation and without ionic suppression. The method is aligned with green chemistry principles, requiring minimal sample, solvent, and sorbent amounts. MPS-MS successfully integrates sample preparation and ambient ionization mass spectrometry and holds great potential for application with other sorbents, samples, and analytes.

Determination and identification of polyphenols in wine using mass spectrometry techniques

Mass spectrometry is crucial for analysing physicochemical and sensory properties, including colour, astringency, taste, and flavour, predicting ageing characteristics, and addressing stability issues in wine. Polyphenols are key chemical constituents in wine that are associated with health benefits and improve circulatory conditions. Advances in mass spectrometry ionisation techniques such as matrix-assisted laser desorption and ionisation and direct analysis in real-time offer high sensitivity for identifying important polyphenolic constituents in wine. High-resolution mass spectrometry, in combination with liquid chromatography, accurately identify and quantify polyphenolic compounds, even at low concentrations, and provides the possibility for further retrospective analysis and non-targeted analysis using statistical methods of data analysis. Ambient mass spectrometry techniques such as paper spray and low-temperature plasma allow solventless analysis, determining the geographical origin, authentication, and quality control of wine samples. This review will explore the potential benefits of using mass spectrometry to identify various polyphenols and polymeric polyphenols in wine, as well as recent developments and applications. Additionally, we will discuss determining antioxidant activity and total polyphenol content in wine.

Rapid detection of ingested acetaminophen on face mask by ambient ionization tandem mass spectrometry

BackgroundA regular face mask is comprised of three layers for resisting moisture, filtration, and absorbing oral fluid, respectively. Since the polymers with different polarities are used to make the layers, a face mask can be used as a sampling tool to retain polar or non-polar chemical and biochemical substances in the exhaled breath. In this study, thermal desorption-electrospray ionization tandem mass spectrometry (TD-ESI/MS/MS), an ambient ionization mass spectrometric technique, was used to detect trace acetaminophen that were exhaled and retained on the surface of different layers in a face mask. ResultsWith probe sampling combined with TD-ESI/MS/MS, the acetaminophen ion signal can be detected at the mouth/nostril region of the face mask after taking the acetaminophen tablet. The experimental results were similar to previous studies for the detection of acetaminophen in blood over time using LC/MS/MS. In addition, the intensities of acetaminophen on different layers of the face mask could reveal the differing distributions of exhaled acetaminophen on each layer. To explore the distribution of acetaminophen on the face mask surface, multiple probes were used to collect samples from different locations of the face mask for analysis. The molecular mapping of acetaminophen on the face mask was rendered by scaling the analyte ion signal intensity based on a temperature color gradient. The cartography showed a higher acetaminophen ion signal distribution on the mouth and nostril regions than in other areas of the face mask. SignificanceOwing to the advantages of a simple, sensitive, and non-invasive sampling approach, drug monitoring could be potentially performed to provide useful information for anti-drug of precision medicine in the future.