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Various charged thorium ions such as singly charged, doubly charged, and triply charged thorium ions trapped in the ion trap can be used to excite the Th-229 first nuclear excited state via the electronic bridge process. We present an integration of a linear ion trap with a time-of-flight mass spectrometer to investigate trapped Th-232 ions. Various charged thorium ions are produced by laser ablation and dynamically loaded into the ion trap. After sufficient collisional cooling, thorium ions are extracted along one of the radial directions for time-of-flight mass spectrometry by rapidly quenching the trapping potential and applying high-voltage extracting pulses. The charge states of thorium ions are identified and the maximum mass resolutions of thorium ions reach ∼100 with initial 300 K collisional cooling. The velocity distributions of ablated various charged thorium ions are measured, and the results agree well with Monte Carlo simulation. Lifetimes of thorium ions are determined to be a few tens of seconds in the ion trap, which are helpful for further spectroscopic studies of Th-229 nuclear transition. [ABSTRACT FROM AUTHOR]

A guided ion beam tandem mass spectrometer was employed to study the reactions of U+ + CO2, UO+ + O2, and the reverse of the former, UO+ + CO. Reaction cross sections as a function of kinetic energy over about a three order of magnitude range were studied for all systems. The reaction of U+ + CO2 proceeds to form UO+ + CO with an efficiency of 118% ± 24% as well as generating UO2+ + C and UCO+ + O. The reaction of UO+ + O2 forms UO2+ in an exothermic, barrierless process and also results in the collision-induced dissociation of UO+ to yield U+. In the UO+ + CO reaction, the formation of UO2+ in an endothermic process is the dominant reaction, but minor products of UCO+ + O and U+ + (O + CO) are also observed. Analysis of the kinetic energy dependences observed provides the bond energies, D0(U+–O) = 7.98 ± 0.22 and 8.05 ± 0.14 eV, D0(U+–CO) = 0.73 ± 0.13 eV, and D0(OU+–O) = 7.56 ± 0.12 eV. The values obtained for D0(U+–O) and D0(OU+–O) agree well with the previously reported literature values. To our knowledge, this is the first experimental measurement of D0(U+–CO). An analysis of the oxide bond energies shows that participation of 5f orbitals leads to a substantial increase in the thermodynamic stability of UO2+ relative to ThO2+ and especially transition metal dioxide cations. [ABSTRACT FROM AUTHOR]

A systematic spectroscopic study of the dicarbon molecule C2 has important applications in various research fields, such as astrochemistry and combustion. In the short vacuum ultraviolet (VUV) wavelength region, recent theoretical calculations have predicted many absorption band systems of C2, but only few of them have been verified experimentally yet. In this work, we employed a tunable VUV laser radiation source based on the two-photon resonance-enhanced four-wave mixing method and a time-of-flight mass spectrometer to investigate the absorption bands of C2 in the VUV range of 64 000–66 000 cm−1. The electronic transition 23Σg−(v′)–a3Πu(v″) of C2 has been observed and identified experimentally for the first time. The term value Te for the 23Σg− state is determined to be 66 389.9 ± 0.5 cm−1 above the ground state X1Σg+, and the vibrational and rotational constants are also determined. The experimentally measured spectroscopic parameters in this study are in excellent agreement with the theoretical results based on high-level ab initio calculations. [ABSTRACT FROM AUTHOR]

Gaseous fragment ions generated in mass spectrometers may be employed as "building blocks" for the synthesis of novel molecules on surfaces using ion soft-landing. A fundamental understanding of the reactivity of the fragment ions is required to control bond formation of deposited fragments in surface layers. The fragment ion [B12X11]− (X = halogen) is formed by collision-induced dissociation (CID) from the precursor [B12X12]2− dianion. [B12X11]− is highly reactive and ion soft-landing experiments have shown that this ion binds to the alkyl chains of organic molecules on surfaces. In this work we investigate whether specific modifications of the precursor ion affect the chemical properties of the fragment ions to such an extent that attachment to functional groups of organic molecules on surfaces occurs and binding of alkyl chains is prevented. Therefore, a halogen substituent was replaced by a thiocyanate substituent. CID of the precursor [B12I11(SCN)]2− ion preferentially yields the fragment ion [B12I8S(CN)]−, which shows significantly altered reactivity compared to the fragment ions of [B12I12]2−. [B12I8S(CN)]− has a previously unknown structural element, wherein a sulfur atom bridges three boron atoms. Gas-phase reactions with different neutral reactants (cyclohexane, dimethyl sulfide, and dimethyl amine) accompanied by theoretical studies indicate that [B12I8S(CN)]− binds with higher selectivity to functional groups of organic molecules than fragment ions of [B12I12]2− (e.g., [B12I11]− and [B12I9]−). These findings were further confirmed by ion soft-landing experiments, which showed that [B12I8S(CN)]− ions attacked ester groups of adipates and phthalates, whereas [B12I11]− ions only bound to alkyl chains of the same reagents. [ABSTRACT FROM AUTHOR]

Normal-phase liquid chromatography (NPLC) plays a pivotal role in the rapid separation of non-polar compounds, facilitating isomer separation and finding applications in various crucial areas where aprotic solvents are necessary. Similar to reversed-phase liquid chromatography (RPLC), NPLC requires a robust and sensitive detector to unequivocally identify the analytes, such as a mass spectrometer. However, coupling NPLC with mass spectrometry (MS) poses challenges due to the incompatibility between the non-polar solvents used as the mobile phase and the primary ionization techniques employed in MS. Several analytical methods have been developed to combine NPLC with electrospray ionization (ESI), but these methods are restricted to the analysis of polar compounds. In most cases, atmospheric pressure chemical ionization (APCI) becomes necessary to expand the range of analysis applications. To overcome these limitations and fully realize the potential of NPLC-MS coupling, a technique termed liquid electron ionization-mass spectrometry (LEI-MS) can be used. LEI-MS offers a straightforward solution by enabling the effective coupling of NPLC with both low and high-resolution MS. LEI allows for the comprehensive analysis of non-polar compounds and provides a powerful tool for isomer separation and precise identification of analytes. Optimal separations, mass spectral qualities, and matches with the NIST library were obtained in both configurations, demonstrating the potential of the proposed approach. [ABSTRACT FROM AUTHOR]

Long-term measurements of the mass concentration of black carbon (BC) in the atmosphere (MBC) with well-constrained accuracy are indispensable to quantify its emission, transport, and deposition. The aerosol light absorption coefficient (babs), usually measured by a filter-based absorption photometer, including an Aethalometer (AE), is often used to estimate MBC. The measured babs is converted to MBC by assuming a value for the mass absorption cross section (MAC). Previously, we derived the MAC for AE (MAC (AE)) from measured babs and independently measured MBC values at two sites in the Arctic. MBC was measured with a filter-based absorption photometer with a heated inlet (COSMOS). The accuracy of the COSMOS-derived MBC (MBC (COSMOS)) was within about 15%. Here, we obtained additional MAC (AE) measurements to improve understanding of its variability and uncertainty. We measured babs (AE) and MBC (COSMOS) at Alert (2018–2020), Barrow (2012–2022), Ny-Ålesund (2012–2019), and Pallas (2019–2022). At Pallas, we also obtained four-wavelength photoacoustic aerosol absorption spectrometer (PAAS-4λ) measurements of babs. babs (AE) and MBC (COSMOS) were tightly correlated; the average MAC (AE) at the four sites was 11.4 ± 1.2 m2 g−1 (mean ± 1σ) at 590 nm and 7.76 ± 0.73 m2 g−1 at 880 nm. The spatial variability of MAC (AE) was about 11% (1σ), and its year-to-year variability was about 18%. We compared MAC (AE) in the Arctic with values at mid-latitudes, measured by previous studies, and with values obtained by using other types of filter-based absorption photometer, and PAAS-4λ. Copyright © 2024 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

In a forensic scenario, if biological stains are found in very small quantities, these are usually collected for DNA analyses, considered essential for the forensic investigation and thus excluding possible investigations by other forensic disciplines as forensic toxicology. We developed an experimental study to evaluate the feasibility of analyzing DNA extraction residues obtained from DNA extraction procedures to perform toxicological analysis, with the aim to extract both genetic and toxicological information without affecting or compromising the genetic sample and/or DNA extraction. DNA extraction from four blood samples (fortified with 5 molecules of interest with a final concentrations of 1 µg/mL, 100 ng/mL, 10 ng/mL and 5 ng/mL, respectively) were analyzed with QIAGEN QIAmp® DNA Mini kit. Three waste residues collected from the DNA extraction were analyzed for the toxicological investigation via Solid-Phase Extraction and High-Performance Liquid Chromatography—Tandem Mass Spectrometry analyses (Thermo Scientific™ TSQ Fortis™ II Triple-Quadrupole Mass Spectrometer). The analytical investigation revealed that our analytes of interest were detected in two different residues of the DNA extraction procedure, allowing both genetic and toxicological analyses without affecting the DNA identification. At last, the experimental protocol was applied to a hypothetical case, with encouraging results and allowing the identification of our molecules of interest. [ABSTRACT FROM AUTHOR]

Rationale: Mass spectrometry imaging (MSI) has been widely used in biomedical research fields. Each pixel in MSI consists of a mass spectrum that reflects the molecule feature of the tissue spot. Because MSI contains high-dimensional datasets, it is highly desired to develop computational methods for data mining and constructing tissue segmentation maps. Methods: To visualize different tissue regions based on mass spectrum features and improve the efficiency in processing enormous data, we proposed a computational strategy that consists of four procedures including preprocessing, data reduction, clustering, and quantitative validation. Results: In this study, we examined the combination of t-distributed stochastic neighbor embedding (t-SNE) and hierarchical clustering (HC) for MSI data analysis. Using publicly available MSI datasets, one dataset of mouse urinary bladder, and one dataset of human colorectal cancer, we demonstrated that the generated tissue segmentation maps from this combination were superior to other data reduction and clustering algorithms. Using the staining image as a reference, we assessed the performance of clustering algorithms with external and internal clustering validation measures, including purity, adjusted Rand index (ARI), Davies-Bouldin index (DBI), and spatial aggregation index (SAI). The result indicated that SAI delivered excellent performance for automatic segmentation of tissue regions in MSI. Conclusions: We used a clustering algorithm to construct tissue automatic segmentation in MSI datasets. The performance was evaluated by comparing it with the stained image and calculating clustering validation indexes. The results indicated that SAI is important for automatic tissue segmentation in MSI, different from traditional clustering validation measures. Compared to the reports that used internal clustering validation measures such as DBI, our method offers more effective evaluation of clustering results for MSI segmentation. We envision that the proposed automatic image segmentation strategy can facilitate deep learning in molecular feature extraction and biomarker discovery for the biomedical applications of MSI. [ABSTRACT FROM AUTHOR]

In this study, an online electrochemistry coupling high-performance liquid chromatography-mass spectrometry (EC-HPLC-MS) technology has been developed for simulating metabolic reactions and rapid analysis of metabolites of flavone, quercetin, and rutin, which are not only widely present compounds with pharmacological activity in nature, but also have structural similarity and variability. The simulated metabolic processes of the substrates (phase I and phase II metabolism) were implemented on the surface of glassy carbon electrode (GCE) by using different electrochemical methods. After online chromatographic separation, the products were transmitted to a mass spectrometer for detection, in order to speculate relevant reaction pathways and structural information of the reaction product. The main metabolites, including methylation, hydroxylation, hydrolysis, and conjugation reaction products, had been successfully identified through the designed in situ hyphenated technique. Furthermore, compared with metabolites produced by in vitro incubation of rat liver microsomes, it was found that the products of electrochemical simulated metabolism were more abundant with diverse metabolic pathways. The results indicated that the proposed method exhibited advantages in the sample pretreatment process and detection cycle without compromising the reliability and accuracy of the results. [ABSTRACT FROM AUTHOR]

New standard zircons applicable to in situ analysis of Hf/W ratio by Nanoscale secondary ion mass spectrometer (NanoSIMS) were prepared and applied to Hf-W dating of a differentiated meteorite classified as mesosiderite. The standard zircons were synthesized by high-pressure experiment from starting materials which were mixture of hafnium oxide, tungsten oxide and high-purity zircon powder. The mixed powders were stirred and pulverized by a high-energy ball mill. They were then sintered at 1000 °C and 6 GPa using multi-anvil apparatus. Homogeneity of Hf/W ratios of synthesized zircons was examined by SEM–EDS, EPMA, and Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICPMS). Hf/W ratios of the same zircons were measured by a NanoSIMS with 2 nA oxygen primary beam and mass resolving power of 10,000. The relative sensitivity factor (RSF) of Hf/W ratio was determined by comparing zircon data measured by LA-ICPMS and NanoSIMS. Observed RSF (Hf/W) of zircon is 0.585 ± 0.180 (hereafter all error 2σ) consistent with 0.855 ± 0.468 of previous work within experimental error margin. The value is higher than observed RSF of glass matrix, 0.301 ± 0.062, and significantly higher than glass data of 0.21–0.22 in references. Based on the RSF, the Hf/W ratios of zircons extracted from mesosiderite "Asuka 882,023" were measured together with W isotopic compositions by NanoSIMS. Observed data in 180Hf/186W–182W/186W diagram are fitted by a straight line, yielding a slope (182Hf/180Hf) of 8.19 ± 3.50 × 10–6. This slope is converted into an absolute zircon Hf-W age of 4536.5+4.6–7.2 Ma using the age anchor of CV3 chondrite. This age agrees well with a reference value of 4532.0+11.4–20.8 Ma. [ABSTRACT FROM AUTHOR]

Monitoring the concentration fluctuations of neurotransmitters in vivo is valuable for elucidating the chemical signals that underlie brain functions. Microdialysis sampling is a widely used tool for monitoring neurochemicals in vivo. The volume requirements of most techniques that have been coupled to microdialysis, such as HPLC, result in fraction collection times of minutes, thus limiting the temporal resolution possible. Further the time of analysis can become long for cases where many fractions are collected. Previously we have used direct analysis of dialysate by low-flow electrospray ionization-tandem mass spectrometry (ESI-MS/MS) on a triple quadrupole mass spectrometer to monitor acetylcholine, glutamate, and γ-amino-butyric acid to achieve multiplexed in vivo monitoring with temporal resolution of seconds. Here, we have expanded this approach to adenosine, dopamine, and serotonin. The method achieved limits of detection down to 2 nM, enabling basal concentrations of all these compounds, except serotonin, to be measured in vivo. Comparative analysis with LC-MS/MS showed accurate results for all compounds except for glutamate, possibly due to interference for this compound in vivo. Pairing this analysis with droplet microfluidics yields 11 s temporal resolution and can generate dialysate fractions down to 3 nL at rates up to 3 fractions per s from a microdialysis probe. The system is applied to multiplexed monitoring of neurotransmitter dynamics in response to stimulation by 100 mM K+ and amphetamine. These applications demonstrate the suitability of the droplet ESI-MS/MS method for monitoring short-term dynamics of up to six neurotransmitters simultaneously. [ABSTRACT FROM AUTHOR]

Many gregarious insect species use aggregation and alarm pheromones. The bed bug, Cimex lectularius L., emits an alarm pheromone (AP), a 70/30 blend of (E)-2-hexenal and (E)-2-octenal, when threatened. Bed bugs avoid temperatures above 43 °C, which are lethal to bugs and used commercially as spatial heat treatments to manage infestations. However, the interaction of bed bug AP in heat avoidance has not been investigated. The goal of this research was to: 1) determine if bed bugs emit AP as an alarm response to heat exposure, and 2) quantify the behavioral responses of conspecifics to AP emitted by heat-exposed bed bugs. Using a selected ion flow tube mass spectrometer, we found that bed bugs responded to lethal and sublethal heat exposure by emitting AP. The Harlan laboratory population emitted more pheromone than a laboratory adapted field population from Florida (McCall). Harlan females emitted the most AP, followed by Harlan males, McCall females and males. In separate behavioral experiments, we showed that conspecifics (i.e., recipients) reacted to AP released by heat exposed bed bugs (i.e., emitters) by frantically moving within 50 mm and 100 mm test arenas. The Harlan recipients reacted to AP in 100 mm areas, whereas the McCall strain did not, indicating a short area of effectiveness of the AP. Synthetic AP components tested in behavioral experiments caused identical effects as the natural AP blend released by heat-exposed bed bugs. [ABSTRACT FROM AUTHOR]

Summary The Integrated Database of Small Molecules (IDSM) integrates data from small-molecule datasets, making them accessible through the SPARQL query language. Its unique feature is the ability to search for compounds through SPARQL based on their molecular structure. We extended IDSM to enable mass spectra databases to be integrated and searched for based on mass spectrum similarity. As sources of mass spectra, we employed the MassBank of North America database and the In Silico Spectral Database of natural products. Availability and implementation The extension is an integral part of IDSM, which is available at https://idsm.elixir-czech.cz. The manual and usage examples are available at https://idsm.elixir-czech.cz/docs/ms. The source codes of all IDSM parts are available under open-source licences at https://github.com/idsm-src. [ABSTRACT FROM AUTHOR]

A method was developed to determine glyphosate and their metabolites in water. The widespread use of this herbicide in agricultural activities worldwide, despite the reported adverse effects on both the environment and health, is a cause for concern and makes it necessary to monitor its presence through a method that guarantees the determination at trace levels. A direct extraction of the analytes with phosphate buffer was performed with subsequent derivatization with 9-fluorenylmethyl chloroformate. The quantification was determined by Ultra Performance Liquid Chromatography-tandem mass spectrometer. The method was validated through the following parameters: selectivity, detection and quantification limits, linearity, accuracy, precision and uncertainty. The average recoveries ranged between 94.08 and 103.31%. Additionally, detection limits from 0.396 to 0.433 μg/L, and the quantification limit was 5.0 μg/L for all the analytes evaluated. In terms of linearity and precision, the results obtained were in the ranges considered adequate (R 2 ≥ 0.99 and CV ≤ 20%), the estimated expanded uncertainty was 12.95, 11.15 and 13.83% for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. This method was successfully applied for the determination of the target analytes in irrigation water samples, detecting concentrations of aminomethylphosphonic acid over limit detection for some sampling sites. [ABSTRACT FROM AUTHOR]

According to physical property tests of lead-containing slag, the volatilisation behaviour of lead slag will have adverse impacts on test accuracy and further affect the control of chemical reactions, solidification and removal of inclusions during smelting. To analyse the volatilisation characteristics of lead slag, in this paper, four kinds of lead slags from lead direct reduction smelting with different PbO and ZnO content are taken. thermogravimetry, ISP-TOF were used. Additionally, the changes in volatiles and slag composition and phases were analysed with XRD and ICPS, and the volatilisation reaction mechanism was discussed. The results indicated that the volatilisation of lead slag can lead to a big weight loss of about to the slag with higher PbO content. The weight loss increases with the PbO content in slag increases. The volatile corresponding to the weight loss above 900 °C is mainly PbO and less ZnO. The higher the temperature is, the stronger the volatilisation is. With the increase in temperature and keeping time, most of the PbO can be evaporated and leaves little PbO in the residual slag. This will has great effect to physico-chemical property measurement of the slag with higher PbO content, especially to the property measurement that be kept at high temperature for a long time. Because the volatiles is trend to condense with the temperature decrease, mass spectrometer is limited by the condensation of volatiles, i.e., PbO, ZnO and so on, in the connection pipeline. The device should be modified for this use. [ABSTRACT FROM AUTHOR]

New 40Ar/39Ar ages, combined with selected ages from published studies, provide detailed insight into the late Quaternary (<500 ka) eruptive history and related hazards of the Rio Grande rift and Jemez lineament of New Mexico, USA. Most eruptions in the region during this time were within monogenetic volcanic fields, which largely produced cinder cones and mafic lava flows. 40Ar/39Ar ages of mafic groundmass determined using the high-sensitivity ARGUS VI multicollector mass spectrometer are significantly more precise, by as much as an order of magnitude, than prior 40Ar/39Ar dates. The high-precision data permit more rigorous interpretation of age spectra and isochrons, leading to a greater confidence in assigning eruption ages, and thus allowing more accurate and thorough calculations of eruptive rates and repose periods. For most fields, comprehensive dating identifies a greater number of late Quaternary eruptions than previously known and, for some fields, determines younger-than-previously established ages for the last eruptive events. Repose periods in the fields range from too short to measure with the 40Ar/39Ar method to a few hundred thousand years, which suggests that all 12 fields in the rift and lineament with late Quaternary activity should be considered dormant rather than extinct, with the possibility of future eruptions. Average recurrence intervals for these fields during the late Quaternary range from 16.5 k.y. to 170.8 k.y. Many fields display peak periods of activity where rates spike to a recurrence interval of 5 k.y. or less. At the scale of the entire rift and lineament, 75 late Quaternary eruptions were dated, yielding an average recurrence interval of 6.5 k.y., which is a minimum estimate considering the likelihood of undated eruptions (either not studied or buried). During the last 100 k.y., the volcanic record is better preserved, and the recurrence interval is 3.2 k.y., which indicates that the current hiatus of 3.9 ± 1.2 k.y. is typical for the region. Since ca. 36 ka, the average recurrence interval decreased to 2.3 k.y., which suggests a slight increase in recent activity. When ages are compared to vent locations, a previously unrecognized migrational pattern is observed in nearly all of the fields studied. Migration vectors vary from 1.0 cm/yr to 4.0 cm/yr, and always with an eastward component--similar to migration patterns at some other late Cenozoic fields throughout the American Southwest. Volcanic migration is attributed to a combination of mechanisms including asthenospheric convection along the margin of the Colorado Plateau, North American plate motion over partial mantle melt, and extensional tectonics. Developing similar high-precision chronologies for other Quaternary fields throughout southwestern North America will be necessary to better understand the volcanic hazards of the region. [ABSTRACT FROM AUTHOR]

Large-geometry secondary ion mass spectrometry (LG-SIMS) is routinely used to determine the elemental and isotopic compositions, thanks to its high sensitivity and in situ micro-analysis capability. Its large volumes of transfer and coupling column, however, might bring low vacuum and high background of volatile elements (esp. H), which hampers its application in ultralow H2O content measurement. In this study, we report a modified analytical procedure to accurately analyze samples with ultralow-level H2O content by using a LG-SIMS of type CAMECA IMS 1280-HR. Based on four new water content working reference materials of quartz glasses with H2O contents ranging from ca. 0 to 39 ppm, the estimated detection limit of LG-SIMS is 0.15 ppm for H2O. This ultralow detection limit is achieved mainly by the intrinsic high sensitivity of the instrument and the conjunctive usage of a stabilized temperature-controlled cooling trap device and a novel tin–bismuth alloy mount preparation technology, which are able to maintain a vacuum pressure at 1.7 × 10−9 mbar in the analysis chamber. Based on these new improvements, our approach can potentially become a routine choice for analyses of H2O content and oxygen–hydrogen isotopes for (extra)terrestrial materials with ultralow-level water content. [ABSTRACT FROM AUTHOR]

Time-of-flight ICP-mass spectrometry (ICP-ToF-MS) allows acquisition of almost the entire periodic table in only a few tens of microseconds, with several mass spectra combined into a single readout. When hyphenated with a low-dispersion laser ablation (LA) unit, it allows for 2D elemental mapping at a laser repetition rate of several hundred hertz, with each laser shot recorded as a single pixel. Although its use in geosciences is increasing, the technique is often referred to as semi-quantitative. Here, we present the outcomes of ultra-fast high-resolution 2D mapping and quantification of the constituting elements of geological reference materials and micrometeorites with LA-ICP-ToF-MS, carried out in a period of over a year. Quantitative data for each pixel were obtained through a combination of multi-point external calibration and normalization of the sum of all element oxide contents to 100%. Detection limits ranging from 0.1 to 10 μg g−1 were attained for most elements when using a 5 μm × 5 μm square laser spot. Repeated analysis of reference materials in a period of over one year demonstrates an intermediate precision down to 3% RSD. [ABSTRACT FROM AUTHOR]

Primary aldosteronism is the most common cause of endocrine hypertension and is associated with significant cardiovascular morbidities. The diagnostic workup depends on determinations of plasma aldosterone and renin which are highly variable and associated with false-positive and false-negative results. Quantification of aldosterone in 24 h urine may provide more reliable results, but the methodology is not well established. We aimed to establish an assay for urinary aldosterone and related steroids with suitability for clinical routine implementation. Here, we report on the development and validation of a quantitative LC-MS/MS method for six urinary steroids: aldosterone, cortisol, 18-hydroxycorticosterone, 18-hydroxycortisol, 18-oxocortisol, tetrahydroaldosterone. After enzymatic deconjugation, total steroids were extracted using SepPak tC18 plates and quantified in positive electrospray ionization mode on a QTRAP 6500+ mass spectrometer. Excellent linearity was demonstrated with R2>0.998 for all analytes. Extraction recoveries were 89.8–98.4 % and intra- and inter-day coefficients of variations were <6.4 and <9.0 %, establishing superb precision. Patients with primary aldosteronism (n=10) had higher mean 24 h excretions of aldosterone-related metabolites than normotensive volunteers (n=20): 3.91 (95 % CI 2.27–5.55) vs. 1.92 (1.16–2.68) µmol/mol for aldosterone/creatinine, 2.57 (1.49–3.66) vs. 0.79 (0.48–1.10) µmol/mol for 18-hydroxycorticosterone/creatinine, 37.4 (13.59–61.2) vs. 11.61 (10.24–12.98) µmol/mol for 18-hydroxycortisol/creatinine, 1.56 (0.34–2.78) vs. 0.13 (0.09–0.17) µmol/mol for 18-oxocortisol/creatinine, and 21.5 (13.4–29.6) vs. 7.21 (4.88–9.54) µmol/mol for tetrahydroaldosterone/creatinine. The reported assay is robust and suitable for routine clinical use. First results in patient samples, though promising, require clinical validation in a larger sample set. [ABSTRACT FROM AUTHOR]

The study investigates ion flux variations for the substorms in the inner magnetosphere. The effect of substorm-induced magnetic field dipolarization on the O+ and H+ ion flux is analysed for 22 events from the year 2018 using the Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer data on board the Van Allen Probes (VAP/RBSP) satellite. The clear dipolarization signatures are observed using the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) suite from the VAP. These observations provide evidence of the ion flux enhancement at 1–50 keV energy after the substorm onset, in particular, the energy range of 20–50 shows dominance. The typical characteristics of magnetic field dipolarization and its time scales are investigated. It is found that the O+ ion flux enhances greater in magnitude than H+ ion flux at energies 20–50 keV after the substorm onset. In addition to it, the correlation of these enhanced oxygen fluxes with the related interplanetary magnetic field (IMF) B z , solar wind velocity (V sw), and the auroral electrojet (AE) index are found good. The new results reports that the ion flux variation ratio shows the MLT dependence for different energy ranges and found that the peak of the O+/ H+ ion flux ratio centred near midnight for the energy range of 8–20 keV, whereas the O+/ H+ ion flux ratio of the energy 20–50 keV is high within the post-midnight. The possible mechanisms for the enhanced ion flux are discussed. [ABSTRACT FROM AUTHOR]

• ON particles increased as NO x enhancement at night. • ON particles were mainly produced via heterogeneous reactions between NO x and organics. • The decrease of ON particles was associated with photo-bleaching effect. Organic nitrogen (ON) compounds play a significant role in the light absorption of brown carbon and the formation of organic aerosols, however, the mixing state, secondary formation processes, and influencing factors of ON compounds are still unclear. This paper reports on the mixing state of ON-containing particles based on measurements obtained using a high-performance single particle aerosol mass spectrometer in January 2020 in Guangzhou. The ON-containing particles accounted for 21% of the total detected single particles, and the particle count and number fraction of the ON-containing particles were two times higher at night than during the day. The prominent increase in the content of ON-containing particles with the enhancement of NO x mainly occurred at night, and accompanied by high relative humidity and nitrate, which were associated with heterogeneous reactions between organics and gaseous NO x and/or NO 3 radical. The synchronous decreases in ON-containing particles and the mass absorption coefficient of water-soluble extracts at 365 nm in the afternoon may be associated with photo-bleaching of the ON species in the particles. In addition, the positive matrix factorization analysis found five factors dominated the formation processes of ON particles, and the nitrate factor (33%) mainly contributed to the production of ON particles at night. The results of this study provide unique insights into the mixing states and secondary formation processes of the ON-containing particles. [Display omitted] [ABSTRACT FROM AUTHOR]

Rationale: The electrostatic linear ion trap (ELIT) can be operated as a multi‐reflection time‐of‐flight (MR‐TOF) or Fourier transform (FT) mass analyzer. It has been shown to be capable of performing high‐resolution mass analysis and high‐resolution ion isolations. Although it has been used in charge‐detection mass spectrometry (CDMS), it has not been widely used as a conventional mass spectrometer for ensemble measurements of ions, or for tandem mass spectrometer. The advantages of tandem mass spectrometer with high‐resolution ion isolations in the ELIT have thus not been fully exploited. Methods: A homebuilt ELIT was modified with BaF2 viewports to facilitate transmission of a laser beam at the turnaround point of the second ion mirror in the ELIT. Fragmentation that occurs at the turnaround point of these ion mirrors should result in minimal energy partitioning due to the low kinetic energy of ions at these points. The laser was allowed to irradiate ions for a period of many oscillations in the ELIT. Results: Due to the low energy absorption of gas‐phase ions during each oscillation in the ELIT, fragmentation was found to occur over a range of oscillations in the ELIT generating a homogeneous ion beam. A mirror‐switching pulse is shown to create time‐varying perturbations in this beam that oscillate at the fragment ion characteristic frequencies and generate a time‐domain signal. This was found to recover FT signal for protonated pYGGFL and pSGGFL precursor ions. Conclusions: Fragmentation at the turnaround point of an ELIT by continuous‐wave infrared multiphoton dissociation (cw‐IRMPD) is demonstrated. In cases where laser power absorption is low and fragmentation occurs over many laps, a mirror‐switching pulse may be used to recover varying time‐domain signal. The combination of laser activation at the turnaround points and mirror‐switching isolation allows for tandem MS in the ELIT. [ABSTRACT FROM AUTHOR]

Rationale: SLAP is one of the two calibration materials for the isotopic water scale. By consensus the established δ18O value is −55.5‰, although several expert laboratories measure significantly more negative δ18OSLAP values. The real δ18OSLAP value as such does not influence the isotopic water scale; however, knowledge of the size of isotopic scale contraction in stable isotope measurements is vital for second‐order isotopes. This study describes the quantification of δ18OSLAP with respect to δ18OVSMOW. Methods: SLAP‐like water was quantitatively mixed with highly 18O‐enriched water to mimic VSMOW. The 18O concentration was determined using an electron ionization quadrupole mass spectrometer. The isotopic composition of the SLAP‐like and VSMOW‐like waters was measured using an optical spectrometer, alongside original VSMOW and SLAP. Results: This study resulted in a much more negative δ18O value for SLAP than expected. The averaged outcome of seven independent experiments is δ18OSLAP = −56.33 ± 0.03‰. There is a large discrepancy between the actual isotopic measurements of even the most carefully operating isotope laboratories and the true δ18O value. Conclusions: Although this finding as such does not influence the use of the VSMOW–SLAP scale, it raises the intriguing question of what we actually measure with our instruments and why even a fully corrected measurement can be so far off. Our result has consequences for issues like the transfer of δ18O from and to the VPDB scale, various fractionation factors, and Δ17O. The absolute 18O abundance for SLAP was calculated as (1887.98 ± 0.43) × 10−6 based on the absolute 18O abundance of VSMOW and the presented δ18OSLAP in this paper. [ABSTRACT FROM AUTHOR]

Background: Fruits of Hunteria umbellata (HU) have been utilized in folk medicine as potent against Staphylococcus aureus (SA) infections, particularly skin and nasal related conditions. However, there is scarcity of literature concerning toxicological evaluation of graded doses of HU fruit, especially at molecular level, specifically targeting the accessory gene regulator (AGR) system to prevent abuse of doses in the treatment of bacterial infections. This research evaluated molecular toxicological property of SA exposed to varied concentrations of aqueous HU fruit extract ranging from 500 to 3.90625 µg/µL using broth microdilution method and quantification of AGR I and II genes' expression employing two-step reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). We first identified quality and quantity of chemical compounds in aqueous fruit of HU using phytochemistry and hybrid gas chromatograph–mass spectrometer (GC–MS) technique. Additionally, preliminary bactericidal potential of HU was assessed before molecular toxicology. Results: Results revealed six phytochemicals and twenty analytical grade compounds from a standard library were identified from chromatograms of HU fruit extract. Some main compounds detected are n-Hexadecanoic acid (25.24%), 2-Pentadecanone, 6,10,14-trimethyl (16.08%), Cuparene (16.63%), Tetradecanoic acid (6.21%) and 9-Octadecenoic acid, (E)- (5.70%). Bactericidal activity shows significant (p < 0.05) toxicity in the tested (8) concentrations of HU fruits in a dose-response relationship compared to the controls (positive and negative). The quantified expression of AGR I and II genes in SA was most significantly increased (p < 0.05) at both 250 and 500 µg/µL of HU fruit extract while least significant increase (p < 0.05) was recorded at 125 µg/µL compared to control. Conclusions: Notably, the study highlighted a potential risk of augmented bacterial infection especially with higher doses of HU extracts during boils' treatment and other epidermal infections instigated by Staph. Expression of both AGR genes at higher doses (250 and 500 µg/µL) is indicative of further expression of several other genes responsible for virulence factors in a variety of human bacterial infections. Thus, consumption of HU fruit to treat boils and blisters should be with great caution especially at high doses. [ABSTRACT FROM AUTHOR]

Mass spectrometry (MS) and MS imaging (MSI) are used extensively for both the spatial and bulk characterization of samples in lipidomics and proteomics workflows. These datasets are typically generated independently due to different requirements for sample preparation. However, modern omics technologies now provide higher sample throughput and deeper molecular coverage, which, in combination with more sophisticated bioinformatic and statistical pipelines, make generating multiomics data from a single sample a reality. In this workflow, we use spatial lipidomics data generated by matrix-assisted laser desorption/ionization MSI (MALDI-MSI) on prostate cancer (PCa) radical prostatectomy cores to guide the definition of tumor and benign tissue regions for laser capture microdissection (LCM) and bottom-up proteomics all on the same sample and using the same mass spectrometer. Accurate region of interest (ROI) mapping was facilitated by the SCiLS region mapper software and dissected regions were analyzed using a dia-PASEF workflow. A total of 5525 unique protein groups were identified from all dissected regions. Lysophosphatidylcholine acyltransferase 1 (LPCAT1), a lipid remodelling enzyme, was significantly enriched in the dissected regions of cancerous epithelium (CE) compared to benign epithelium (BE). The increased abundance of this protein was reflected in the lipidomics data with an increased ion intensity ratio for pairs of phosphatidylcholines (PC) and lysophosphatidylcholines (LPC) in CE compared to BE. [ABSTRACT FROM AUTHOR]

X-linked hypophosphatemia (XLH) is a rare genetic disorder that increases fibroblast growth factor 23 (FGF23). XLH patients have an elevated risk of early-onset hypertension. The precise factors contributing to hypertension in XLH patients have yet to be identified. A multicenter cross-sectional study of adult patients diagnosed with XLH. Metabolomic analysis was performed using ultra-performance liquid chromatography (UPLC) coupled to a high-resolution mass spectrometer. Twenty subjects were included, of which nine (45%) had hypertension. The median age was 44 years. Out of the total, seven (35%) subjects had a family history of hypertension. No statistically significant differences were found between both groups for nephrocalcinosis or hyperparathyroidism. Those with hypertension exhibited significantly higher levels of creatinine (1.08 ± 0.31 mg/dL vs. 0.78 ± 0.19 mg/dL; p = 0.01) and LDL-C (133.33 ± 21.92 mg/dL vs. 107.27 ± 20.12 mg/dL, p = 0.01). A total of 106 metabolites were identified. Acetylcarnitine (p = 0.03), pyruvate p = (0.04), ethanolamine (p = 0.03), and butyric acid (p = 0.001) were significantly different between both groups. This study is the first to examine the metabolomics of hypertension in patients with XLH. We have identified significant changes in specific metabolites that shed new light on the potential mechanisms of hypertension in XLH patients. These findings could lead to new studies identifying associated biomarkers and developing new diagnostic approaches for XLH patients. [ABSTRACT FROM AUTHOR]

Rationale: High costs and student numbers can often hinder implementation of mass spectrometry (MS) in the undergraduate teaching laboratory, often with technicians running samples on students' behalf, and the implementation of MS only in discrete or isolated experiments. This study explores the use of atmospheric solids analysis probe MS (ASAP‐MS) as a relatively low‐cost, benchtop instrument, and its potential for application as a 'bolt‐on' to existing undergraduate organic chemistry experiments. Methods: Thirteen products synthesised in undergraduate laboratory experiments were analysed by ASAP‐MS, along with their starting materials. Analysis was carried out with a Waters RADIAN ASAP mass spectrometer, at four different cone voltages simultaneously to provide fragmentation information. Results: Out of the 13 undergraduate experiments, ASAP‐MS was shown to be complementary in 11 of these, either through simple analysis of the precursor ion or by a more complex analysis of the fragments. Conclusions: ASAP‐MS provided spectra that both complement and enhance intended learning outcomes in existing organic chemistry experiments, showing its versatility as a bolt‐on technique. Moving forward, ASAP‐MS will be integrated into the University of Surrey's undergraduate teaching laboratory. [ABSTRACT FROM AUTHOR]

A methanol‐based economy offers an efficient solution to current energy transition challenges, where the zeolite‐catalyzed methanol‐to‐hydrocarbons (MTH) process would be a key enabler in yielding synthetic fuels/chemicals from renewable sources. Despite its original discovery over half a century ago over the zeolite ZSM‐5, the practical application of this process in a CO2‐neutral scenario has faced several obstacles. One prominent challenge has been the intricate mechanistic complexities inherent in the MTH process over the zeolite ZSM‐5, impeding its widespread adoption. This work takes a significant step forward by providing critical insights that bridge the gap in our understanding of the MTH process. It accomplishes this by connecting the (Koch‐carbonylation‐led) direct and dual cycle mechanisms, which operate during the early and steady‐state phases of MTH catalysis, respectively. To unravel these mechanistic intricacies, we have performed catalytic and operando (i.e., UV/Vis coupled with an online mass spectrometer) and solid‐state NMR spectroscopic‐based investigations on the MTH process, involving co‐feeding methanol and acetone (cf. a key Koch‐carbonylated species), including selective isotope‐labeling studies. Our iterative research approach revealed that (Koch−)carbonyl group selectively promotes the side‐chain mechanism within the arene cycle of the dual cycle mechanism, impacting the preferential formation of BTX fraction (i.e., benzene‐toluene‐xylene) primarily. [ABSTRACT FROM AUTHOR]

We present a method for the reconstruction of ion kinetic energy distributions from ion time-of-flight mass spectra through ion trajectory simulations. In particular, this method is applicable to complicated spectrometer geometries with largely anisotropic ion collection efficiencies. A calibration procedure using a single ion mass peak allows the accurate determination of parameters related to the spectrometer calibration, experimental alignment, and instrument response function, which improves the agreement between simulations and experiment. The calibrated simulation is used to generate a set of basis functions for the time-of-flight spectra, which are then used to transform from time-of-flight to kinetic-energy spectra. We demonstrate this reconstruction method on a recent pump–probe experiment by Asmussen et al. [Asmussen et al., Phys. Chem. Chem. Phys., 23, 15138, (2021)] on helium nanodroplets and retrieve time-resolved kinetic-energy-release spectra for the ions from ion time-of-flight spectra. [ABSTRACT FROM AUTHOR]

The aviation sector, like most other sectors, is moving towards becoming net zero. In the medium to long term, this will mean an increase in the use of sustainable aviation fuels. Research exists on the impact of fuel composition on non-volatile particulate matter (nvPM) emissions. However, there is more sparsity when considering the impact on volatile particulate matter (vPM) emissions. Here, nine different fuels were tested using an open-source design combustor rig. An aerosol mass spectrometer (AMS) was used to examine the mass-loading and composition of vPM, with a simple linear regression algorithm used to compare relative mass spectrum similarity. The diaromatic, cycloalkane and aromatic contents of the fuels were observed to correlate with the measured total number concentration and nvPM mass concentrations, resulting in an inverse correlation with increasing hydrogen content. The impacts of fuel properties on other physical properties within the combustion process and how they might impact the particulate matter (PM) are considered for future research. Unlike previous studies, fuel had a very limited impact on the organic aerosol's composition at the combustor exit measurement location. Using a novel combination of Positive Matrix Factorization (PMF) and high-resolution AMS analysis, new insight has been provided into the organic composition. Both the alkane organic aerosol (AlkOA) and quenched organic aerosol (QOA) factors contained CnH2n+1, CnH2n−1 and CnH2n ion series, implying alkanes and alkenes in both, and approximately 12% oxygenated species in the QOA factor. These results highlight the emerging differences in the vPM compositional data observed between combustor rigs and full engines. [ABSTRACT FROM AUTHOR]

Over the past few years, the biological properties of garlic have been utilized as an attractive natural alternative to many therapeutic drugs. The biological effects of garlic have been ascribed to organosulfur compounds, secondary metabolites derived from amino acids. The present study aimed to investigate the extracts of a novel garlic variety (Hisar garlic 17) after processing it as fresh, dry, heated, and aged in different solvents and then analyzed with highly sensitive and rapid technique i.e., High resolution liquid chromatograph mass spectrometer quadrupole time of flight (HR-LCMS-QTOF) Mass spectrometer to study the amino acids and organosulfur compounds. 47 amino acids and 11 organosulfur compounds were detected out of which 8 organosulfur compounds were found as secondary metabolites of amino acids. Among the 22 crucial a-amino acids, garlic extracts revealed the presence of 18 amino acids, either in their native state or associated with various complex compounds. The study reported major organosulfur compounds, including Alliin, S-allyl cysteine, S-methyl cysteine, N-gamma-Glutamyl-Sallylcysteine, and 2-Propenyl 1-(2-propenylsulfinyl)propyl disulfide. This study demonstrated that HG17 garlic is abundant in amino acids and organosulfur compounds, suggesting its potential utilization as a supplement in nutraceuticals. [ABSTRACT FROM AUTHOR]

As part of the development and production of pharmaceuticals, the purity of Active Pharmaceutical Ingredients stands as a fundamental parameter that significantly influences the quality, safety, and efficacy of the final drug product. Impurities in Active Pharmaceutical Ingredients are various unwanted substances that can appear during the whole manufacturing process, from raw materials to the final product. These impurities can stem from multiple sources, including starting materials, intermediates, reagents, solvents, and even degradation products resulting from exposure to environmental factors such as heat, light, or moisture. Their presence can potentially compromise the therapeutic effect of the drug, introduce unexpected side effects, or even pose safety risks to patients. This study aims to conduct the forced degradation of linagliptin and subsequently attempt to identify the resulting degradants. The degradation procedures were carried out in accordance with the guidelines of the International Committee for Harmonization. The degradation profile of linagliptin was investigated under various conditions, including acid hydrolysis, alkaline hydrolysis, oxidation, heat, and light exposure, utilizing ultra-performance liquid chromatography connected to a photo array detector. Identification and characterization of the degradation products were achieved using an ultra-performance liquid chromatography coupled with a single quadrupole detector mass spectrometer and also a liquid chromatography coupled with a high-resolution mass spectrometry. The identified degradation products demonstrate that linagliptin is particularly susceptible to degradation when exposed to acid and peroxide. Whereas, no significant degradation effects were observed under alkali, thermolytic, and photolytic conditions. [ABSTRACT FROM AUTHOR]

The enzyme α‐amylase has long been a commonly targeted protein in serological tests for saliva. While being especially abundant in saliva, α‐amylase is detectable in vaginal secretions, sweat, fecal matter, breast milk and other matrices. As a result, assays for α‐amylase only provide a presumptive indication of saliva. The availability of mass spectrometry‐based tools for the detection of less abundant, but more specific, protein targets (e.g., human statherin) has enabled the development of high confidence assays for human saliva. Sample throughput, however, has traditionally been low due to multi‐step workflows for protein extraction, quantitation, enzymatic digestion, solid phase cleanup, and nano‐/capillary‐based chromatography. Here, we present two novel "direct" single‐stage extraction strategies for sample preparation. These feature immunoaffinity purification and reversed‐phase solid‐phase microextraction in conjunction with intact mass analysis of human statherin for saliva identification. Mass analysis was performed on the Thermo Scientific Q‐Exactive™ Orbitrap mass spectrometer with a 10‐min analytical run time. Data analysis was performed using Byos® from Protein Metrics. Two sample sets were analyzed with a population of 20 individuals to evaluate detection reliability. A series of casework‐type samples were then assayed to evaluate performance in an authentic forensic context. Statherin was confidently identified in 92% and 71% of samples extracted using the immunoaffinity purification and solid phase microextraction approaches, respectively. Overall, immunoaffinity purification outperformed the solid phase microextraction, especially with complex mixtures. In toto, robotic extraction and intact mass spectrometry enable the reliable identification of trace human saliva in a variety of sample types. [ABSTRACT FROM AUTHOR]

Esophagogastroduodenoscopies (EGD) are aerosol-generating procedures that may spread respiratory pathogens. We aim to investigate the production of airborne aerosols and droplets during Cytosponge procedures, which are being evaluated in large-scale research studies and National Health Service (NHS)implementation pilots to reduce endoscopy backlogs. We measured 18 Cytosponge and 37 EGD procedures using a particle counter (diameters = 0.3–25 μm), taking measurements 10 cm from the mouth. Two particle count analyses were performed: whole procedure and event-based. Direct comparison with duration-standardized EGD procedures shows that Cytosponge procedures produce 2.16× reduction (P  < 0.001) for aerosols and no significant change for droplets (P =  0.332). Event-based analysis shows that particle production is driven by throat spray (aerosols: 138.1× reference, droplets: 16.2×), which is optional, and removal of Cytosponge (aerosols: 14.6×, droplets: 62.6×). Cytosponge burping produces less aerosols than EGD (2.82×, P  < 0.05). Cytosponge procedures produce significantly less aerosols and droplets than EGD procedures and thus reduce two potential transmission routes for respiratory viruses. [ABSTRACT FROM AUTHOR]

A 30 year old man was found with no signs of life in front of the house. The cyanide concentration in blood and urine was determined five years after the man's death. What is more, a stability study was conducted for 730 days in an authentic casework blood sample. Sample preparation procedure included precipitation with methanol:water mixture, solid phase extraction (SPE) and derivatization with the use of PFB-Br (pentafluorobenzyl bromide). The sample was analyzed using GC-QqQ-MS/MS (gas chromatopraphy coupled with tandem mass spectrometry) isotope dilution method. Separation was done using a SH-RXI-5MS column (30 m x 0.25 mm, 0.25 µm). Detection of PFB-CN and PFB-13CN was achieved using a triple-quadrupole mass spectrometer with an electron ionization (EI) ion source in multiple reaction monitoring (MRM) mode. After 5 years from the man's death, cyanide concentration was: 1900 ng/mL in blood and 500 ng/mL in urine. Stability study performed in an authentic blood sample 6 and 7 years after the man's death revealed cyanide concentrations of 1898.2 ng/mL and 1618.7 ng/mL, respectively. While spectrophotometric and colorimetric methods recorded both decrease and increase in cyanide concentration over time, newer chromatographic methods mainly indicate a decrease. The studies presented in this paper seem to confirm this trend. However, in order to interpretate the results of cyanide concentration in biological material reliably, more research is still necessary. [ABSTRACT FROM AUTHOR]

Xylosyltransferase-I and -II (XT-I, -II) possess a central role during the glycosylation of proteoglycans (PGs). They catalyze the formation of an O-glycosidic bond between the xylosyl residue of uridinediphosphate-xylose and the core protein of a PG. Thereafter, three following glycosyltransferases lead to the generation of a tetrasaccharide linker, which connects the PG core protein to the respective glycosaminoglycan. The selective quantification of XT-I and XT-II activity is of biological and clinical interest due to their association with fibrotic processes and skeletal dysplasia. There is no assay available to date that simultaneously determines the activity of the two XT isoforms. Although an XT-I selective UPLC MS/MS-based assay was published by Fischer et al., in 2021, the determination of XT-II activity can only be performed simultaneously by the improved assay presented here. To establish the assay, two synthetic peptides, selectively xylosylated by the respective isoform, were identified and the associated measurement parameters for the mass spectrometer were optimized. In addition, the quantitative range of the xylosylated peptides were validated, and the incubation time of the enzyme reaction was optimized for cell culture samples and human sera. The specific enzyme kinetics (K M and V max) of the respective XT isoform for the two peptides were also determined. Subsequently, a mathematical model was developed, allowing the simultaneous determination of XT-I and XT-II activity from the chromatographic results. Summarized, a mass spectrometric method suitable for the simultaneous analysis of XT-I and XT-II activity in cell culture lysates, supernatants and human sera was successfully developed. • Novel isoform-selective xylosyltransferase MS/MS-based activity assay. • Suitable for use with human serum and cell culture samples. • Broad spectrum of activity measurable. • Mathematical model allowing simultaneous determination of XT-I and XT-II. [ABSTRACT FROM AUTHOR]

Biomass‐derived degraded lignin and cellulose serve as possible alternatives to fossil fuels for energy and chemical resources. Fast pyrolysis of lignocellulosic biomass generates bio‐oil that needs further refinement. However, as pyrolysis causes massive degradation to lignin and cellulose, this process produces very complex mixtures. The same applies to degradation methods other than fast pyrolysis. The ability to identify the degradation products of lignocellulosic biomass is of great importance to be able to optimize methodologies for the conversion of these mixtures to transportation fuels and valuable chemicals. Studies utilizing tandem mass spectrometry have provided invaluable, molecular‐level information regarding the identities of compounds in degraded biomass. This review focuses on the molecular‐level characterization of fast pyrolysis and other degradation products of lignin and cellulose via tandem mass spectrometry based on collision‐activated dissociation (CAD). Many studies discussed here used model compounds to better understand both the ionization chemistry of the degradation products of lignin and cellulose and their ions' CAD reactions in mass spectrometers to develop methods for the structural characterization of the degradation products of lignocellulosic biomass. Further, model compound studies were also carried out to delineate the mechanisms of the fast pyrolysis reactions of lignocellulosic biomass. The above knowledge was used to assign likely structures to many degradation products of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

With the goal of enhancing the low sensitivity of the conventional atmospheric pressure chemical ionization (APCI) source due to the ion divergence, here is reported a T-shaped ion source to improve the sensitivity with a portable mass spectrometer for the rapid determination of the pesticides ethoprophos and atrazine in water. Compared with conventional APCI, the ion source improves the sensitivity for the analytes. The results show that the analysis requires less than 2 s, the limit of detection (LOD) is better than 0.1 μ g · mL − 1 , and the relative standard deviation (RSD) is 16% at 1, 5, and 25 μ g · mL − 1 . The recoveries of the analytes are between 80% and 130%, meeting the requirements for rapid pesticide determination in water. [ABSTRACT FROM AUTHOR]

The kinetics of the reaction of H‐atom with carbonyl sulfide (OCS) has been investigated at nearly 2 Torr total pressure of helium over a wide temperature range, T = 255–960 K, using a low‐pressure discharge flow reactor combined with an electron impact ionization quadrupole mass spectrometer. The rate constant of the reaction H + OCS → SH + CO (1) was determined under pseudo‐first order conditions, monitoring the kinetics of H‐atom consumption in excess of OCS, k1 = 6.6 × 10−13 × (T/298)3 × exp(−1150/T) cm3 molecule−1 s−1 (with estimated total uncertainty on k1 of 15% at all temperatures). Current measurements of k1 at intermediate temperatures (520–960 K) appear to reconcile previous high and low temperature data and allow the above expression for k1 to be recommended for use in the extended temperature range between 255 and 1830 K with a conservative uncertainty of 20%. [ABSTRACT FROM AUTHOR]

• Construct a superactive, friendly and cost-effective catalyst from natural tourmaline. • Catalyst is superior to P25 in activating PMS and degrading antibiotic in real waters. • It can degrade tetracycline in a wide concentration range. • Above 98.7% of tetracycline was degraded in seawater within 5 min. • The catalytic reaction mechanism was explored and proposed. • The eco-friendly catalyst can be recycled and reused for multiple cycles. Reasonably designing highly active, environmentally friendly, and cost-effective catalysts for efficient elimination of pollutants from water is desirable but challenging. Herein, an efficient heterogeneous photo-Fenton catalyst tourmaline (TM)/tungsten oxide (WO 3-x) (named TW10) containing tungsten/boron/iron (W/B/Fe) synergistic active centers and 90% of cheap natural tourmaline (TM) mineral rich in Fe and B elements. The TW10 catalyst can quickly activate peroxymonosulfate (PMS) to generate massive active free radicals, which may induce the rapid and efficient degradation of tetracycline (TC). The TW10/PMS/Visible light system can effectively degrade up to 98.7% of tetracycline (TC) in actual waters (i.e. seawater, Yellow River, and Yangtze River water), and the catalytic degradation rates reach 1.65, 5.569, and 2.38 times higher than those of TM, WO 3-x , and commercial P25 (Degussa, Germany), respectively. In addition, the catalyst can be recycled and reused multiple times. Electron spin resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS), and liquid chromatograph-mass spectrometer (LC-MS) analyses confirm that the synergistic catalytic effect of W/B/Fe sites on the TW10 catalyst accelerates the electron transfer between Fe(II) and Fe(III), as well as between W(V) and W(VI), and thus promotes the rapid degradation of TC. The catalytic reaction mechanism and degradation pathway of TC were explored. This work provides a feasible route for the design and development of new eco-friendly and efficient catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

The dicarbon radical, C2, is one of the most abundant molecules in the universe, and has been widely observed in various energetic environments. Even though numerous experimental and theoretical investigations on C2 have been done during the last two centuries, spectroscopic study of C2 in vacuum ultraviolet (VUV) region has been rare. The only three known absorption band systems in VUV region were identified by Herzberg and co-workers in 1969 by VUV spectrograph, namely the electronic transitions F1Πu(v′)–X1Σg+(v″), f3Σg−(v′)–a3Πu(v″) and g3Δg(v′)–a3Πu(v″) (Herzberg-Lagerqvist-Malmberg transitions). In this study, we employ a two-photon resonance-enhanced four-wave mixing based VUV laser source and a time-of-flight mass spectrometer for reinvestigating the above three electronic transitions of C2 through a resonant (1VUV + 1′UV) photoionization scheme. Besides those vibronic transitions as identified by Herzberg and co-workers, many more absorption bands belonging to the electronic transitions f3Σg−(v′)–a3Πu(v″) and g3Δg(v′)–a3Πu(v″) are observed with their spectroscopic parameters determined. The rather astrophysically important F1Πu state is not observed here by the resonant (1VUV + 1′UV) photoionization scheme, which must be due to its fast predissociation process. Instead, our study shows that the vibronic band g3Δg(v′ = 2)–a3Πu(v″ = 0) exactly overlaps with F1Πu(v′ = 0)–X1Σg+(v″ = 0), which was not realized in previous studies. The potential implications of these findings to astronomical observations are discussed. [ABSTRACT FROM AUTHOR]

Background: Presently, antibody concentration measurements for patients undergoing treatment are predominantly determined by ELISA, which still comes with known disadvantages. Therefore, our aim was to establish a targeted mass-spectrometric assay enabling the reproducible absolute quantification of peptides from the hypervariable and interaction regions of infliximab. Methods: Peptides of infliximab were measured post-trypsin digestion and subsequent separation on a Vanquish Horizon UHPLC coupled to a TSQ Altis Triple-Quad mass spectrometer. Normalization and absolute quantification were conducted using stable isotope-synthesized peptides. Calibration curves covering a range of 0.25-50 µg/ml were employed for quantitation. Results: We demonstrated the substantial influence of peptide selection, choice of hydrolase for digestion, and digestion time on absolute peptide yield (28–44% for peptide 1 and 64–97% for peptide 2). Furthermore, we showed that the generated calibration curves for absolute quantification were highly reproducible and robust (LLOQ1 0.72 µg/ml and LLOQ2 1.00 µg/ml) over several months. In comparison to ELISA values, the absolute values obtained by mass spectrometry often yielded lower results for both targeted peptides. Conclusions: In this study, a semi-automated workflow was employed and tested with 8 patients and corresponding replicates (n = 3–4). We demonstrated the robust implementation of calibration curves for the absolute quantification of infliximab in patient samples, with coefficients of variation ranging from 0.5 to 9%. Taken together, we have developed a platform enabling the rapid (2 days of sample preparation and 30 min of measurement time per sample) and robust quantification of Infliximab antibody concentration in patients. The use of mass spectrometry also facilitates the straightforward expansion of the method to include additional antibody peptides. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) play a key role in tropospheric chemistry, giving rise to secondary products such as highly oxygenated organic molecules (HOMs) and secondary organic aerosols (SOA). HOMs, a group of low-volatility gas-phase products, are formed through the autoxidation process of peroxy radicals (RO2) originating from the oxidation of VOCs. The measurement of HOMs is made by a NO3¯ ToFCIMS instrument, which also detects other species like small highly oxygenated VOCs (e.g. dicarboxylic acids) and sulfuric acid (H2SO4). The instrument response to HOMs is typically estimated using H2SO4, as HOMs are neither commercially available nor easily synthesized in the laboratory. The resulting calibration factor is then applied to quantify all species detected using this technique. In this study, we explore the sensitivity of the instrument to commercially available small organic compounds, primarily dicarboxylic acids, given the limitations associated with producing known amounts of HOMs for calibration. We compare these single compound calibration factors to the one obtained for H2SO4 under identical operational conditions. The study found that the sensitivity of the NO3¯ ToFCIMS varies depending on the specific type of organic compound, illustrating how a single calibration factor derived from sulfuric acid is clearly inadequate for quantifying all detected species using this technique. The results highlighted substantial variability in the calibration factors for the tested organic compounds, with 4-nitrocatechol exhibiting the highest sensitivity, and pyruvic acid the lowest. The obtained sulfuric acid calibration factor agreed well with the previous values from the literature. In summary, this research emphasized the need to develop reliable and precise calibration methods for progressively oxygenated reaction products measure with NO3¯ CIMS, for example, HOMs. [ABSTRACT FROM AUTHOR]

Native mass spectrometry (MS) has become widely accepted in structural biology, providing information on stoichiometry, interactions, homogeneity, and shape of protein complexes. Yet, the fundamental assumption that proteins inside the mass spectrometer retain a structure faithful to native proteins in solution remains a matter of intense debate. Here, we reveal the gas-phase structure of β-galactosidase using single-particle cryo-electron microscopy (cryo-EM) down to 2.6-Å resolution, enabled by soft landing of mass-selected protein complexes onto cold transmission electron microscopy (TEM) grids followed by in situ ice coating. We find that large parts of the secondary and tertiary structure are retained from the solution. Dehydration-driven subunit reorientation leads to consistent compaction in the gas phase. By providing a direct link between high-resolution imaging and the capability to handle and select protein complexes that behave problematically in conventional sample preparation, the approach has the potential to expand the scope of both native mass spectrometry and cryo-EM. [ABSTRACT FROM AUTHOR]

Conventional mass spectrometry does not distinguish between enantiomers, or mirror-image isomers. Here we report a technique to break the chiral symmetry and to differentiate enantiomers by inducing directional rotation of chiral gas-phase ions. Dual alternating current excitations were applied to manipulate the motions of trapped ions, including the rotation around the center of mass and macro movement around the center of the trap. Differences in collision cross section were induced, which could be measured by ion cloud profiling at high resolutions above 10,000. High-field ion mobility and tandem mass spectrometry analyses of the enantiomers were combined and implemented by using a miniature ion trap mass spectrometer. The effectiveness of the developed method was demonstrated with a variety of organic compounds including amino acids, sugars, and several drug molecules, as well as a proof-of-principle ligand optimization study for asymmetric hydrogenation. [ABSTRACT FROM AUTHOR]

Background: As a gold-standard quantitative technique based on mass spectrometry, multiple reaction monitoring (MRM) has been widely used in proteomics and metabolomics. In the analysis of MRM data, as no peak picking algorithm can achieve perfect accuracy, manual inspection is necessary to correct the errors. In large cohort analysis scenarios, the time required for manual inspection is often considerable. Apart from the commercial software that comes with mass spectrometers, the open-source and free software Skyline is the most popular software for quantitative omics. However, this software is not optimized for manual inspection of hundreds of samples, the interactive experience also needs to be improved. Results: Here we introduce MRMPro, a web-based MRM data analysis platform for efficient manual inspection. MRMPro supports data analysis of MRM and schedule MRM data acquired by mass spectrometers of mainstream vendors. With the goal of improving the speed of manual inspection, we implemented a collaborative review system based on cloud architecture, allowing multiple users to review through browsers. To reduce bandwidth usage and improve data retrieval speed, we proposed a MRM data compression algorithm, which reduced data volume by more than 60% and 80% respectively compared to vendor and mzML format. To improve the efficiency of manual inspection, we proposed a retention time drift estimation algorithm based on similarity of chromatograms. The estimated retention time drifts were then used for peak alignment and automatic EIC grouping. Compared with Skyline, MRMPro has higher quantification accuracy and better manual inspection support. Conclusions: In this study, we proposed MRMPro to improve the usability of manual calibration for MRM data analysis. MRMPro is free for non-commercial use. Researchers can access MRMPro through http://mrmpro.csibio.com/. All major mass spectrometry formats (wiff, raw, mzML, etc.) can be analyzed on the platform. The final identification results can be exported to a common.xlsx format for subsequent analysis. [ABSTRACT FROM AUTHOR]

Developing green analytical approaches has become a crucial trend in green chemistry. These approaches encourage direct analysis to avoid any sample treatment that involves energy and reagent consumption or the generation of waste. In this study, a green sensitive analytical workflow was developed for the direct analysis of anionic compounds via a charge inversion strategy using matrix-assisted ionization and a miniature mass spectrometer. Per- and polyfluoroalkyl substances (PFAS), which are a representative category of emerging pollutants, were selected as model analytes for method development. An imidazolium-based germinal dicationic ionic liquid (DIL), 1,1-bis(3-methylimidazolium-1-yl) butylene difluoride ([C4(MIM)2]F2), was chosen as a charge donor to form positively charged complexes with the PFAS for mass spectrometry (MS) analysis. Without any sample treatment, 1 μL of sample was loaded on a paper strip, followed by the addition of a mixture of 3-nitrobenzonitrile and [C4(MIM)2]F2. The adduct complexes were analyzed using a miniature mass spectrometer with tandem MS capability. The signal intensity was enhanced by up to two orders of magnitude in positive ion mode compared to negative ion mode without a DIL. The developed protocol was validated and satisfactory sensitivity was obtained, with limits of detection and quantitation ranging from 5 to 10 μg L−1. Recoveries ranging from 86.6% to 106.3% were achieved, with relative standard deviations between 3.5% and 9.3%. As indicated by three typical green analytical chemistry metric tools, this analytical procedure had a high degree of greenness. The developed protocol was applied to the analysis of real environmental and municipal water samples, demonstrating good potential for the rapid on-site analysis of anionic compounds. [ABSTRACT FROM AUTHOR]

Rosmarinus officinalis L. is a Mediterranean medicinal and aromatic plant, widely used in several industries. The present study aimed to characterize the chemical composition of volatile compounds, encompassing essential oils (EO): hydrosol extract (HE): and water residue extract (WRE1). Additionally, the investigation focused on non-volatile components, including powder phenolic extract (PPE): water residue extract (WRE2): and solid residue extract (SRE): while also assessing their antioxidant and antibacterial activities. The chemical compositions of volatile components were determined by using a Gas Chromatograph equipped with a Mass Spectrometer (GC/MS): while polyphenol extracts were analyzed using Ultra-High-Performance Liquid Chromatograph equipped with a photodiode array detection Mass Spectrometer (UHPLC-DAD-ESI/MS). The antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl free radical scavenging (DPPH) and ferric reducing antioxidant power (FRAP): while the antibacterial effect was evaluated against four pathogenic bacterial strains using disc diffusion and broth microdilution methods. The GC/MS analysis showed that R. officinalis EO was dominated by 1,8-cineole (47.70%) and α-pinene (15.50%). 1,8-cineole (56.67%) and camphor (26.27%) were found as the predominant constituents of HE, while volatile components of WRE1 were mainly dominated by camphor (10.11%). The UHPLC-DAD-ESI/MS analysis revealed the existence of a plethora of polyphenolic components. In PPE and SRE, the predominating compounds were carnosic acid and carnosol, respectively. Rosmarinic acid was the main constituent in WRE2. The results of DPPH free radical scavenging and FRAP activities showed that PPE exhibited strong antioxidant activity, followed by SRE and WRE2. EO and HE showed moderate antioxidant activity, while volatile components of WRE1 exhibited the lowest antioxidant effect. Regarding the antibacterial activity, PPE and SRE indicated the highest effect against the pathogenic bacteria, while WRE1 volatile components had the weakest antibacterial activity. The conducted study showed that material plant left after hydrodistillation of R. officinalis may be used as a new source of bioactive volatile and polyphenolic components with valuable pharmacological activities. [ABSTRACT FROM AUTHOR]

We report on the precise mass measurements of the 91 Sr and 95 Y isotopes performed using the JYFLTRAP double Penning trap mass spectrometer. The mass-excess values from this work, ME (91 Sr) = - 83645.5 (13) keV and ME (95 Y) = - 81226.4 (10) keV, deviate by 6.5(52) keV and - 18 (7) keV from the Atomic Mass Evaluation 2020 (AME20). In the case of 91 Sr the new result disagrees with the ISOLTRAP value, while for 95 Y, it agrees with the older JYFLTRAP value. [ABSTRACT FROM AUTHOR]

Background Massive modular endoprostheses have become a primary means of reconstruction after oncologic resection of a lower extremity tumor. These implants are commonly made with cobalt-chromium alloys that can undergo wear and corrosion, releasing cobalt and chromium ions into the surrounding tissue and blood. However, there are few studies about the blood metal levels in these patients. Question/purpose What is the whole blood cobalt and chromium ion level in patients with massive modular endoprostheses? Methods We performed a cross-sectional study of our total joints registry to identify patients with a history of an endoprosthetic reconstruction performed at our institution. Patients who were alive at the time of our review in addition to those undergoing an endoprosthetic reconstruction after an oncologic resection were included. Whole blood samples were obtained from 27 (14 male and 13 female) patients with a history of a lower extremity oncologic endoprosthesis. The median time from surgery to blood collection was 8 years (range 6 months to 32 years). Blood samples were collected and stored in metal-free ethylenediaminetetraacetic acid tubes. Samples were analyzed on an inductively coupled plasma mass spectrometer in an International Organization for Standardization seven-class clean room using polytetrafluoroethylene-coated instruments to reduce the risk of metal contamination. The analytical measuring range was 1 to 200 ng/mL for chromium and cobalt. Cobalt and chromium levels were considered elevated when the blood level was $ 1 ppb. Results Cobalt levels were elevated in 59% (16 of 27) of patients, and chromium levels were elevated in 26% (seven of 27). In patients with elevated metal ion values, 15 of 17 patients had a reconstruction using a Stryker/Howmedica Global Modular Replacement System implant. Conclusion Blood metal levels were elevated in patients who received reconstructions using modular oncology endoprostheses Future work is needed to establish appropriate follow-up routines and determine whether and when systemic complications occur because of elevated metal levels and how to potentially address these elevated levels when complications occur. Prospective and retrospective collaboration between multiple centers and specialty societies will be necessary to address these unknown questions in this potentially vulnerable patient group. Level of Evidence Level IV, therapeutic study. [ABSTRACT FROM AUTHOR]