Rapid Communications in Mass Spectrometry最新文献

{"title":"Phytochemical Analysis of Semen Hoveniae and Its Potential Mechanism Against Alcoholic Liver Disease via an Integrated Approach Combining UHPLC-Q-TOF MS, Network Pharmacology, and Molecular Docking","authors":"Min Li,&nbsp;Zhuo-chun Wei,&nbsp;Feng-xiang Zhang,&nbsp;Hai-jun Li","doi":"10.1002/rcm.10097","DOIUrl":"10.1002/rcm.10097","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Semen Hoveniae (SH), known as Zhijuzi in Chinese, is extensively utilized in China for the management of alcoholic liver disease (ALD) due to its recognized detoxification properties. Despite its extensive historical use, the detailed chemical profile and anti-ALD mechanisms of SH remain inadequately understood, significantly restricting its further therapeutic development.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The chemical constituents of SH were systematically profiled using ultra high-performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-Q-TOF MS). Potential molecular targets of identified compounds were predicted using the SwissTargetPrediction platform. Common targets were subsequently analyzed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis using the DAVID database. Network pharmacology results were validated by molecular docking.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Seventy-six compounds were identified or tentatively characterized in SH, including 50 flavonoids, 15 saponins, 5 terpenes, 3 alkaloids, 2 phenylpropanoids, and 1 other type, among which seven were unambiguously identified using reference standards. Furthermore, seven potentially novel components were identified. Network pharmacology and molecular docking analyses elucidated the molecular mechanisms underlying SH's therapeutic effects on ALD. Three core molecular targets—AKT1, SRC, and EGFR—were identified. Key pathways closely related to ALD, such as glutathione metabolism and arachidonic acid metabolism, were notably enriched, suggesting their crucial roles in SH's hepatoprotective mechanisms. Molecular docking studies confirmed strong binding affinities (binding energies lower than −5.0 kcal/mol) between six active compounds (laricetrin, apigenin, quercetin, kaempferol, myricetin, and syringetin) and the three core targets (AKT1, SRC, and EGFR).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study comprehensively characterizes the chemical compositions of SH and elucidates its potential mechanisms against ALD. These findings substantiate the hepatoprotective potential of SH, providing a solid scientific foundation for its traditional use and promoting the development of novel therapeutic approaches for ALD.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 20","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling Flavonoid Reactivity: A High-Resolution Mass Spectrometry Journey Through the Silylation of Quercetin","authors":"Thabang Bernette Ncongwane,&nbsp;Ntakadzeni Edwin Madala,&nbsp;Derek Tantoh Ndinteh,&nbsp;Elize Smit","doi":"10.1002/rcm.10101","DOIUrl":"10.1002/rcm.10101","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Quercetin is an example of a pentahydroxylated flavonol compound studied extensively due to its excellent biological activity (e.g., antioxidant, antiviral, and antimicrobial). The antioxidant properties of flavonoids are influenced by the arrangement of the substituents around the molecule, a phenomenon known as the structure–activity relationship (SAR). SAR studies the relationship between compounds' structural characteristics and their biological activity in drug design.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Quercetin was silylated with MTBSTFA using a semiautomated flow system, and the order in which hydroxyl groups were silylated was used to derive the sequential reactivity of quercetin.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The collision-induced dissociation MS/MS fragmentation of the precursor ion of quercetin is influenced by the electrospray ionization (+ and − modes) and an increase in collision energy (<span>CE</span>). Structure elucidation with in-depth high-resolution tandem mass spectrometric analysis revealed that silylation primarily occurs at A7 and is sequentially followed by B3′, B4′, C3, and A5.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Retro-Dials Alder cleavage of the C-ring plays a significant role in the MS/MS fragmentations of silylated quercetin, maintaining the integrity of the fragment ions and subsequently allowing tracking of the position of the silyl group.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 20","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10101","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impurity Profiling and Mechanistic Investigation of the Photochemical Degradation of Tetrandrine","authors":"Jinmei Tan,&nbsp;Feng Wang,&nbsp;Ruihan Zheng,&nbsp;Weiran Yang,&nbsp;Jinlong Chen","doi":"10.1002/rcm.10102","DOIUrl":"10.1002/rcm.10102","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Tetrandrine is a bisbenzylisoquinoline alkaloid with diverse pharmacological activities and faces critical pharmaceutical challenges due to its inherent photolability under environmental stressors. Despite its therapeutic potential, systematic investigations into its photodegradation mechanisms and impurity profiling remain conspicuously absent, posing risks to drug quality control and regulatory compliance.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Structural elucidation of degradation products (DPs) was achieved through advanced analytical techniques, including high-resolution mass spectrometry (HRMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopy, and comparative fragmentation analysis. Key degradation drivers—including light intensity, atmospheric composition, aqueous content, and pH extremes—were quantitatively assessed through designed single-variable experiments.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Seven photodegradants (DP-1 to DP-7) were structurally characterized, including two quaternary ammonium enantiomers (DP-2 and DP-3) from N-oxidation, a benzophenone derivative (DP-4) via benzylic C–H oxidation, and macrocyclic cleavage products (DP-1 and DP-7) through oxidative C–C bond scission. Degradation exhibited irradiance threshold behavior (&gt; 10 mW cm⁻² for 80% conversion) and oxygen dependency (<i>R</i>² = 0.98). Alkaline conditions (0.1 M NaOH) induced complete degradation within 0.5 h through ·OH-mediated radical chain reactions, while aqueous media (40% H₂O) accelerated hydrolysis.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study provides the first mechanistic atlas of tetrandrine's photodegradation, identifying three dominant pathways: oxidative skeletal modification, oxidative ring-opening, and radical-mediated C–N cleavage. This study establishes a robust framework for the impurity analysis of natural product-derived drugs and provides actionable guidelines for stabilizing tetrandrine during manufacturing and storage.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 20","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Differential Ion Mobility Spectrometry Based Tandem Devices for Ion Separation Prior to Mass Spectrometry Analysis","authors":"Simin Zhang,&nbsp;T.-Y. Lui,&nbsp;Danna Hu,&nbsp;Xiangfeng Chen,&nbsp;T.-W. Dominic Chan","doi":"10.1002/rcm.10099","DOIUrl":"10.1002/rcm.10099","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Differential ion mobility spectrometry (DMS) provides distinct potential in separation of gas phase ions. However, the resolving power still limits the widespread application of DMS technology and inspires to design tandem DMS for improvement of the performance.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A robust tandem DMS module was fabricated to enhance the separation performance of the DMS system. To achieve the optimal separation, two carrier gas composition modulation strategies were carried out by adding different types of organic modifiers and by changing the modifier concentration in each DMS channel. The working performance of the home-made CaptiveSpray-tandem DMS-MS was evaluated by investigating the peak intensity and FWHM using reserpine and comparing the peak positions of peptide mixtures in two DMS channels.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>When carrier gas composition in two channels was controlled appropriately, the tandem DMS system could provide the DMS system with another dimension for ion separation and therefore enhance the separation ability. Two gas modification methods could be applied in this system for enhancing analytical performance.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This tandem DMS platform allows precise control of the gap widths of the DMS channels and enables the modulation of carrier gas composition in two DMS channels separately. The developed method is capable of providing orthogonal separation behavior and achieving higher separation performance.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 19","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144367425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resonance-Enhanced Multiphoton Ionization Spectroscopy of Monocyclic and Polycyclic Aromatic Hydrocarbons in the Gas Phase","authors":"Carolin Schwarz,&nbsp;Fabian Etscheidt,&nbsp;Christian Gehm,&nbsp;Johannes Passig,&nbsp;Sven Ehlert,&nbsp;Thorsten Streibel,&nbsp;Ralf Zimmermann","doi":"10.1002/rcm.10096","DOIUrl":"10.1002/rcm.10096","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Aromatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) pose significant risks to human health and the environment due to their toxic and carcinogenic properties. These depend strongly on molecular structure, with even isomers exhibiting different characteristics. Consequently, when conducting a risk assessment of a sample, a rapid and reliable detection technique capable of differentiating between isomers is crucial.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Time-of-flight mass spectrometry (TOFMS) combined with (1 + 1) resonance-enhanced multiphoton ionization ((1 + 1)-REMPI) has proven to be a promising approach due to its wavelength selectivity for different structures. An optical parametric oscillator generated UV radiation from 213 to 300 nm from the third harmonic (355 nm) of a Nd:YAG laser beam. A thermogravimetric system was applied to transfer the substances into the gas phase.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We performed REMPI spectroscopy of 48 monocyclic and polycyclic aromatic hydrocarbons, including compounds with various substituents (alkyl groups, -OCH₃, -SH, -OH, -Cl) and heteroatoms (N, O, S). The observed spectral shifts correlate with ring number as well as the type, number, and position of substituents and heteroatoms. While these shifts are comparable to trends observed in absorption spectra, variations in intensity arise due to differences in excited-state lifetimes and the cross sections of both absorption steps. It was further demonstrated that the selected wavelength range, extending to a lower limit of 213 nm, is especially beneficial for the naphthalenes. The relative photoionization cross sections of the investigated compounds have been calculated, showing that the aforementioned structural dependencies also influence the ionization efficiency.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>In common applications, these results may be used to determine a suitable laser wavelength for the substances of interest in order to achieve a higher level of sensitivity. For tunable laser applications, they serve as a reference for distinguishing and quantifying isomers in complex mixtures based on spectral shifts.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 19","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10096","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144331958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct Identification of IMP and VIM Metallo-β-Lactamases in Gram-Negative Bacteria Using A-MALDI","authors":"Dong Huey Cheon,&nbsp;Seohyun Hwang,&nbsp;Yoon Kyung Choi,&nbsp;Saeyoung Lee,&nbsp;Won Suk Yang,&nbsp;Bo Kyung Kim,&nbsp;Min Jin Kim,&nbsp;Sun Hwa Lee,&nbsp;Je-Hyun Baek","doi":"10.1002/rcm.10095","DOIUrl":"10.1002/rcm.10095","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Rapid and accurate identification of carbapenemase-producing Enterobacteriaceae (CPE) is crucial for effective infection control and patient treatment. However, accurate identification of VIM and IMP metallo-β-lactamases remains still challenging using MALDI-TOF MS.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The A-MALDI method which incorporates sequential lysis steps and internal mass calibration, was used for the identification of IMP and VIM carbapenemases. Two <i>Escherichia coli</i> standard strains and 26 clinical isolates harboring IMP or VIM genes were tested by A-MALDI along with corresponding negative controls. Previously published carbapenemases-negative data (<i>n</i> = 112) were used to check the specificity of IMP and VIM identification.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>For IMP-positive isolates, proteoforms corresponding to amino acid residues 20–246 showed distinct peaks for IMP. For VIM-positive isolates, unique single peaks corresponding to amino acid residues 27–266 allowed clear identification of VIM. Clinical evaluation of A-MALDI demonstrated 93.9% accuracy for IMP identification (100% sensitivity, 93.3% specificity) and 100% accuracy for VIM identification.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study successfully expands the direct identification capabilities for VIM and IMP, achieving comprehensive identification of all six carbapenemases using A-MALDI. We anticipate that A-MALDI will provide clinical laboratories with a powerful tool for rapid identification of all types of carbapenemases in bacterial infections.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 19","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144300299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calcium Carbonate and Water Pyrolysis Measurements Suggest Minor Adjustment to the VPDB and VSMOW-SLAP δ18O Scale Relation","authors":"Anita Th. Aerts-Bijma,&nbsp;Dipayan Paul,&nbsp;Albert C. van Buuren,&nbsp;Vivian R. Kroon,&nbsp;Harro A. J. Meijer","doi":"10.1002/rcm.10093","DOIUrl":"10.1002/rcm.10093","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Measurements of the oxygen isotopic composition of materials are widely used in many fields. These oxygen isotopic compositions are expressed using different scales. These scales are only linked indirectly, because water and calcium carbonate reference materials, used to establish these oxygen isotope delta scales, have to be converted to CO₂ first, and the isotopic fractionation of these conversions has only been measured a few times in the past. The anchoring of the two oxygen isotope delta scales is therefore currently suboptimal.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Primary reference materials, both waters and calcium carbonates, were pyrolyzed within a single measurement sequence in a high-temperature elemental analyzer–pyrolysis system connected to an isotope ratio mass spectrometer in continuous-flow mode. As calcium carbonate is difficult to pyrolyze completely, additives were added to reach a 100% yield. The <i>δ</i>¹⁸O of the calcium carbonates were normalized on the VSMOW-SLAP scale using VSMOW2 and in-house water references.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The average results of 6 international calcites references measured in five independent sequences of pyrolysis measurements showed a difference of 0.07 to 0.09‰ with the presently described relationship in literature between the <i>δ</i>¹⁸O VPDB and <i>δ</i>¹⁸O VSMOW-SLAP scale.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The outcome of the study made the direct comparison of the two different ¹⁸O scales possible. Our results demonstrate a small discrepancy in the presently recommended relation between the two oxygen isotope delta scales.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 19","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10093","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144300341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A High-Precision Analytical Technique for Dissolved N2 Isotopes in Aquatic Systems: Biogeochemical Applications and Determination of Solubility Equilibrium Isotope Effects","authors":"Katelyn McPaul,&nbsp;Scott D. Wankel,&nbsp;Alan M. Seltzer","doi":"10.1002/rcm.10094","DOIUrl":"10.1002/rcm.10094","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Rationale&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The isotopic composition of dissolved dinitrogen gas (δ&lt;sup&gt;15&lt;/sup&gt;N-N&lt;sub&gt;2&lt;/sub&gt;) in water can offer a powerful constraint on the sources and pathways of nitrogen cycling in aquatic systems. However, because of the large presence of atmosphere-derived dissolved N&lt;sub&gt;2&lt;/sub&gt; in these systems, high-precision (on the order of 0.001‰) measurements of N&lt;sub&gt;2&lt;/sub&gt; isotopes paired with inert gas measurements are required to disentangle atmospheric and biogeochemical signals. Additionally, the solubility equilibrium isotope fractionation of N&lt;sub&gt;2&lt;/sub&gt; and its temperature and salinity dependence are underconstrained at this level of precision.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;We introduce a new technique for sample collection, processing, and dynamic dual-inlet mass spectrometry allowing for high-precision measurement of δ&lt;sup&gt;15&lt;/sup&gt;N-N&lt;sub&gt;2&lt;/sub&gt; and δ(N&lt;sub&gt;2&lt;/sub&gt;/Ar) with simultaneous measurement of δ(&lt;sup&gt;40&lt;/sup&gt;Ar/&lt;sup&gt;36&lt;/sup&gt;Ar) and δ(Kr/N&lt;sub&gt;2&lt;/sub&gt;) in water. We evaluate the reproducibility of this technique and employ it to redetermine the solubility equilibrium isotope effects for dissolved N&lt;sub&gt;2&lt;/sub&gt; across a range of temperatures and salinities.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Our technique achieves measurement reproducibility (1σ) for δ&lt;sup&gt;15&lt;/sup&gt;N-N&lt;sub&gt;2&lt;/sub&gt; (0.006‰) and δ(N&lt;sub&gt;2&lt;/sub&gt;/Ar) (0.41‰) suitable for tracing biogeochemical nitrogen cycling in aquatic environments. Through a series of air–water equilibration experiments, we find a N&lt;sub&gt;2&lt;/sub&gt; solubility equilibrium isotope effect (ε = α/1000 − 1, where α = (&lt;sup&gt;29&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;/&lt;sup&gt;28&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;dissolved&lt;/sub&gt;/(&lt;sup&gt;29&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;/&lt;sup&gt;28&lt;/sup&gt;N&lt;sub&gt;2&lt;/sub&gt;)&lt;sub&gt;gas&lt;/sub&gt;) in water of ε(‰) = 0.753 − 0.004•&lt;i&gt;T&lt;/i&gt; where &lt;i&gt;T&lt;/i&gt; is the temperature (°C), with uncertainties on the order of 0.001‰ over the temperature range of ~2°C–23°C and salinity range of ~0–30 psu. We find no apparent dependence of ε on salinity.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Our new method allows for high-precision measurements of the isotopic composition of dissolved N&lt;sub&gt;2&lt;/sub&gt; and Ar, and dissolved N&lt;sub&gt;2&lt;/sub&gt;/Ar and Kr/N&lt;sub&gt;2&lt;/sub&gt; ratios, within the same sample. Pairing measurements of N&lt;sub&gt;2&lt;/sub&gt; with inert gases facilitates the quantification of excess N&lt;sub&gt;2&lt;/sub&gt; from biogeochemical sources and its isotopic composition. This method allows for a wide range of applications in marine, coastal, and freshwater environments to characterize and quantitatively constrai","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 19","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10094","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144300342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparing Dual Water Equilibration Methods for Hydrogen Stable Isotope Analysis of Plant Carbohydrates and Proteinaceous Animal Samples","authors":"Daniel B. Nelson,&nbsp;Ansgar Kahmen,&nbsp;Jochem Baan,&nbsp;Selina Hugger,&nbsp;Cristina Mercoli,&nbsp;Meisha Holloway-Phillips","doi":"10.1002/rcm.10091","DOIUrl":"10.1002/rcm.10091","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>The hydrogen stable isotope composition (<i>δ</i> ²H) of organic samples carries information about processes including hydrology, climate, ecology, and plant metabolism. Numerous methods exist to control for hydrogen in organic samples that can isotopically exchange with ambient water or vapor.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We compared two established dual water steam equilibration approaches to control for exchangeable hydrogen in isotopic analysis: hot vacuum equilibration using the Uniprep autosampler and hot atmospheric pressure equilibration under varying equilibration temperatures and times. We evaluated how the extent of hydrogen isotope exchange and calculated exchange-corrected hydrogen stable isotope values varied among methods and sample types.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>More exchange could be achieved with atmospheric pressure methods compared to the Uniprep, and we confirmed that this was not a drying artifact. When direct comparisons were possible, atmospheric pressure methods yielded <i>δ</i> ²H values that agreed better with values from chemical derivatization, while Uniprep values agreed better with values provided for purchased reference materials based on room temperature equilibrations. Best long-term precision was achieved with fitted rather than prescribed isotope fractionation factors for equilibration.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Different equilibration methods can give reproducible yet distinct results. This is due to varying degrees to which different methods access non–carbon-bound hydrogen that is difficult to liberate from interior hydrogen bonds in complex biological structures such as cellulose or keratins. The optimal method depends on the application.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 19","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144299578","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Characterization of Pragia fontium Lipid A by MALDI Mass Spectrometry","authors":"Linda K. Nartey,&nbsp;Abanoub Mikhael,&nbsp;Hyojik Yang,&nbsp;David Šmajs,&nbsp;Robert K. Ernst,&nbsp;Helena Pětrošová,&nbsp;David R. Goodlett","doi":"10.1002/rcm.10087","DOIUrl":"10.1002/rcm.10087","url":null,"abstract":"","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 18","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144273168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}