Rapid Communications in Mass Spectrometry最新文献

{"title":"Selective Solid Phase Extraction Using a Mixed-Mode Cation Exchange Cartridge Facilitates the Mass Spectrometry Analysis on Dissolved Organic Nitrogen","authors":"Yuanyuan Dong,&nbsp;Wenrui Yao,&nbsp;Yulin Qi,&nbsp;Yufu Han,&nbsp;Chao Ma,&nbsp;Dietrich A. Volmer","doi":"10.1002/rcm.10037","DOIUrl":"https://doi.org/10.1002/rcm.10037","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Dissolved organic nitrogen (DON) is a crucial component in environment, which acts as the largest reservoir of nitrogen and plays a significant role in the nitrogen cycling, pollutant transport, and substrate utilization among various environmental systems. DON exhibits a relatively low concentration in environment, which presents a great challenge for DON detection, and an efficient separation and enrichment lab protocol is required to fully understand its structural and compositional characteristics. However, there is no standard method to extract DON from complex environmental samples efficiently.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The DON was extracted utilizing solid-phase extraction (SPE), with a one-step elution by the Bond Elut PPL cartridge and the Waters HLB cartridge, and a three-step elution by the Waters MCX cartridge. UV-Vis, fluorescence, mass spectrometry (MS), and gas chromatography-nitrogen chemiluminescence detector (GC-NCD) techniques were utilized to investigate and compare the characteristics of DON from the three different SPE strategies.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Combined the fluorescence and MS results, it is found that the stepwise extraction using the MCX cartridge exhibits the best recovery of DON for both standard and environmental samples, and its performance is less affected by the chemical interferences such as surfactants during MS analysis. Furthermore, the MCX fraction exhibits the highest number of DON molecular formulas with a low O/C ratio and a high H/C ratio in environmental samples, and such a fraction also shows an enrichment of nitrosamine-type substances.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This work establishes an efficient MCX-SPE protocol to extract and analyze DON, which can be applied to environmental samples straightforward. The presented work provides a theoretical support for the analysis of DON, which facilitates a comprehensive understanding of the chemical composition and environmental effect of nitrogen-containing substances.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10037","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143801826","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":"Integrated Element Doping and Standard-Sample Bracketing for Enhanced Fe–Zn Isotope Precision in MC-ICPMS","authors":"Dong-Yong Li,&nbsp;Long Chen,&nbsp;Hai-Ou Gu,&nbsp;Guo-Chao Sun,&nbsp;Jiang-Hong Deng,&nbsp;Sheng-Yao Yu,&nbsp;Yan-Yan Zhao,&nbsp;Yang Zhang,&nbsp;Nan Wang,&nbsp;Xiao-Qiang Guo,&nbsp;Zhi-Shun Zhang,&nbsp;Kai-Xin Feng,&nbsp;Rong-Bin Zhang,&nbsp;San-Zhong Li","doi":"10.1002/rcm.10041","DOIUrl":"https://doi.org/10.1002/rcm.10041","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Standard-sample bracketing (SSB) and element doping are widely used for correcting instrumental mass bias in Fe–Zn isotope analysis using multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). However, the combined effects of analyte concentration and spike-analyte ratios on measurement accuracy remain underexplored.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We developed an improved Fe–Zn isotope analysis method that combines SSB with element doping to mitigate concentration effects. By systematically evaluating Ni/Fe and Cu/Zn ratios (0.1–2.1) and analyte concentrations ranging from 0.1 to 2.0 times the concentration of the bracketing standards, we assessed their influence on isotope precision and accuracy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Our findings indicate that, when low-concentration isotopes are accurately quantified, variations in Ni/Fe and Cu/Zn ratios exert minimal influence on measurement precision. Compared to conventional SSB, the combined approach reduces concentration matching constraints by 30%–50%, broadening the acceptable Fe and Zn concentration ranges. Validation using 10 geological reference materials, including 6 from the United States Geological Survey and 4 from the Geological Survey of Japan, confirmed its reliability, with isotopic values aligning with published data within analytical uncertainty.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The combined approach enhances measurement precision and applicability to diverse geological samples, offering a robust method for Fe–Zn isotope studies.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143793460","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":"APCI-Multistage Mass Spectrometry Following Liquid Chromatography for Selected 4-Desmethyl-Sterols and Their Deuterium-Labelled Analogues Unveils Characteristic Fragmentation Routes for Cholesterol and Phytosterols Identification","authors":"V. Cinquepalmi,&nbsp;I. Losito,&nbsp;A. Castellaneta,&nbsp;C. D. Calvano,&nbsp;T. R. I. Cataldi","doi":"10.1002/rcm.10039","DOIUrl":"https://doi.org/10.1002/rcm.10039","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Several phytosterols (PSs), well known for their role in plant physiology and their health benefits, represent a subset of the family of 4-desmethyl-sterols. They exhibit remarkable structural variability due to differences in the number and position of C=C bonds in their tetracyclic backbone and side chain composition. When analysed using tandem mass spectrometry (MS/MS), PSs often produce complex and potentially informative spectra, as in the case of electron ionization. However, these spectra have been only partially interpreted so far. Here, a systematic interpretation of the fragmentation of PSs, specifically free sterols, was pursued through a synergic use of high- and low-resolution multistage mass spectrometry (MSⁿ, <i>n</i> = 2–4).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The study focused on protonated and dehydrated forms of standard 4-desmethyl-sterols ([M + H-H₂O]⁺), generated via atmospheric pressure chemical ionization (APCI) following reversed-phase liquid chromatography (RPLC). Deuterium-labelled versions of cholesterol and stigmasterol, appropriately labelled on their side chains, were examined alongside their natural counterparts and other key PS standards, including β-sitosterol, campesterol, brassicasterol, Δ⁵-avenasterol (isofucosterol) and its isomer Δ⁷-avenasterol.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The use of isotopically labelled standards allowed the identification of diagnostic, low <i>m/z</i>, product ions associated with the side chain, demonstrating that the positive charge can localize not only at the C3 position (associated with the hydroxyl group) but also on the side chain itself (C24/C25). Furthermore, all remaining peak signals in the tandem MS spectra of PSs were successfully elucidated with the help of MS³/MS⁴ measurements, unveiling complex fragmentation pathways involving both the steroidal backbone and the side chain and indicating C17 as an additional potential site for positive charge localization.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The findings described in the paper offer a strong basis for identifying critical structural features of PSs, thus opening interesting perspectives for the identification of minor PSs, often isomeric with more common ones, that can be detected in vegetal matrices.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784304","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":"Optimisation of Heated Electrospray Ionisation Parameters to Minimise In-Source Generated Impurities in the Analysis of Oligonucleotide Therapeutics","authors":"Mollie A. Glenister,&nbsp;Ulrik Mistarz,&nbsp;Ken Cook,&nbsp;James L. Stephenson,&nbsp;Mark J. Dickman","doi":"10.1002/rcm.10033","DOIUrl":"https://doi.org/10.1002/rcm.10033","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Oligonucleotides have emerged as an important new class of therapeutic. Due to their structural complexity, this presents significant challenges for the development of analytical methods to characterise and determine their impurity profile. In this study, we introduce a sensitive ion-pair reverse phase method interfaced with mass spectrometry for analysis of antisense oligonucleotides and small interfering RNAs.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Liquid chromatography–mass spectrometry analysis of antisense oligonucleotides and small interfering RNAs was performed using hexylamine: hexafluoro-2-propanol mobiles phases. LC-MS analysis was performed in both negative and positive ion mode. Electrospray ionisation source conditions including collision energy and temperature were optimised to minimise in-source generated impurities and alkylamine adducts in the analysis of oligonucleotide therapeutics.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The results show that under low or no in-source collision energy the presence of hexylamine adducts are observed and are predominantly on the lowest charge states present. As the in-source collision energy is increased, a reduction of hexylamine adducts is observed in conjunction with an increase in nucleobase loss in the gas phase, therefore generating in-source impurities. In comparison to tributylammonium acetate, increased MS sensitivity, higher charge states and effective removal of hexylamine adducts using mild source conditions was achieved.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Optimisation of the mild source conditions in conjunction with high pH mobile phases was combined with high-resolution accurate mass spectrometry analysis and automated deconvolution workflows to develop a simplified and streamlined approach for characterising oligonucleotide therapeutics and their related impurities.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143770096","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":"Analysis of Volatile Organic Compounds Differences of Black and White Pepper by HS-GC-IMS and HS-SPME-GC-MS","authors":"Xue Chen,&nbsp;Jiaxin Yin,&nbsp;Yang Zhang,&nbsp;Jiaxuan Chen,&nbsp;Songtao Bie,&nbsp;Xinbo Song,&nbsp;Zheng Li,&nbsp;Liping Kang,&nbsp;Heshui Yu","doi":"10.1002/rcm.10036","DOIUrl":"https://doi.org/10.1002/rcm.10036","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>As a medicinal and edible herb, <i>Piper nigrum L</i>. is abundant in volatile organic compounds (VOCs), and its essential oil has antibacterial properties. Notably, the aromatic profiles of black pepper (BP) and white pepper (WP) are markedly distinct. Consequently, it is essential to comprehensively characterize the VOCs of BP and WP, and analyze the differences in their VOCs and antibacterial efficacy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>This study analyzed the VOCs of BP and WP using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The fingerprint of HS-GC-IMS was established. Random forest analysis, orthogonal partial least squares discriminant analysis and heatmap were used to analyze differences in BP and WP. Furthermore, the antibacterial efficacy of volatile oils derived from BP and WP was assessed using the antibacterial zone diameter method.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>A total of 108 and 123 VOCs were identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. The results of multivariate statistical analysis showed that the VOCs of BP and WP are significantly different. In contrast, WP has a milder smell than BP, while BP has a more pungent odor. Eight differential markers were selected. Both BP and WP had inhibitory effects on <i>Staphylococcus aureus</i> and <i>Candida albicans</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>This study helps to decipher the flavor differences between BP and WP, and provides a material basis for their quality control and pharmacodynamics. It is beneficial to enhance its utilization within the domains of nutrition and traditional Chinese medicine.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143769985","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":"Rapid Determination of 15 Herbicides in Blood and Soil by Direct Analysis in Real Time-Tandem Mass Spectrometry","authors":"Zhou Yuan,&nbsp;Zhang Ying,&nbsp;Hou Xiaolong,&nbsp;Xue Chenyu,&nbsp;Zhang Wenfang,&nbsp;Qiao Jing,&nbsp;Liu Hua,&nbsp;Zhang Wenjin,&nbsp;Guo Yizhu","doi":"10.1002/rcm.10023","DOIUrl":"https://doi.org/10.1002/rcm.10023","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>The rampant abuse of herbicides in agricultural practices has resulted in frequent incidents of both unintended and deliberate poisoning, posing dual threats to ecosystems and human health. This underscores an urgent need for efficient herbicide detection methods.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A direct analysis in real time coupled with tandem mass spectrometry (DART-MS/MS) method was developed for the simultaneous detection of 15 herbicides in blood and soil. Systematic optimization of mass spectrometric parameters established optimal detection conditions in multiple reaction monitoring (MRM) mode, with the ion source temperature set at 450°C. Following liquid-liquid extraction of blood or soil samples, the processed supernatant was analyzed directly.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The method demonstrated excellent linearity (R^² ≥ 0.99) across a wide concentration range. Sensitivity was validated with limits of detection (LODs) of 1–20 ng/mL in blood and 1–10 ng/g in soil, and limits of quantification (LOQs) of 1–50 ng/mL in blood and 1–20 ng/g in soil. Satisfactory recovery rates and controlled matrix effects met toxicological requirements. In 2024, the method was successfully applied to four real cases of herbicide poisoning.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study established the first DART-MS/MS method for simultaneous analysis of 15 herbicides in biological (blood) and environmental (soil) matrices. The complete analytical workflow required only 20 minutes from sample preparation to detection, significantly advancing forensic applications of DART-MS/MSwhile providing a reliable technical solution for herbicide screening in forensic investigations.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749549","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":"Comprehensive Two-Dimensional Gas Chromatography–Mass Spectrometry for the Analysis of Atmospheric Particulate Matter","authors":"Jingying Ma,&nbsp;Yufu Han,&nbsp;Jinfeng Ge,&nbsp;Ling Wen,&nbsp;Chao Ma,&nbsp;Yulin Qi,&nbsp;Dietrich A. Volmer","doi":"10.1002/rcm.10034","DOIUrl":"https://doi.org/10.1002/rcm.10034","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Atmospheric particulate matter (PM) is a complex mixture with a wide range of sources, but only a limited proportion can be identified by existing analytical techniques. Comprehensive two-dimensional gas chromatography–mass spectrometry (GC × GC-MS) couples the advantages on high resolution, sensitivity, and peak capacity on gas chromatography, together with the high mass accuracy and acquisition frequency of time-of-flight mass spectrometry (TOFMS). GC × GC-MS has been gradually applied on the analysis of environmental organic pollutants.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Aims</h3>\u0000 \u0000 <p>This review introduces the principles of GC × GC together with MS and discusses its application on organic compounds in atmospheric PM in the last two decades, so as to provide an outlook on the future trends of GC × GC-MS in this research frontiers.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>The review synthesizes findings on the application of GC × GC-MS for analyzing organic pollutants in PM, covering its operational principles and the coupling with TOFMS to enhance mass accuracy and acquisition speed.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>GC × GC-MS has significantly improved the identification of PM-associated organic compounds by offering superior separation, peak capacity, and detection sensitivity. The technique has enabled the discovery of previously unresolvable compounds and enhanced source apportionment of PM.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Discussion</h3>\u0000 \u0000 <p>Despite its analytical advantages, the widespread application of GC × GC-MS in atmospheric studies is hindered by challenges such as complex data processing, instrument cost, and standardization issues.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>GC × GC-MS offers superior separation and identification of complex pollutants, making it invaluable for environmental analysis and applications. Emerging technologies, such as machine learning, will enhance its analytical capabilities and broaden its future applications.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143741042","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":"Evaluation of Matrix Effects in SIMS Using Gaussian Process Regression: The Case of Olivine Mg Isotope Microanalysis","authors":"Keita Itano,&nbsp;Kohei Fukuda,&nbsp;Noriko T. Kita,&nbsp;Kenta Ueki,&nbsp;Tatsu Kuwatani,&nbsp;Shotaro Akaho","doi":"10.1002/rcm.10038","DOIUrl":"https://doi.org/10.1002/rcm.10038","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Matrix effects by secondary ion mass spectrometry (SIMS) are empirically corrected by calibration using matrix-matched reference materials. However, conventional parametric regression cannot estimate the prediction uncertainty to account for the difference in compositions of new data and reference materials. Applying Gaussian process regression (GPR), a nonparametric probabilistic method, enables the correction for matrix effect while providing quantitative prediction uncertainty.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We developed GPR models for estimating instrumental mass fractionation (IMF). Magnesium isotope dataset of 17 olivine reference materials was used as training data, and the developed model was applied to another data set of extraterrestrial olivines.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The GPR model using FeO/MgO, CaO/MgO, Cr₂O₃/MgO, and MnO/MgO achieved the higher prediction accuracy of IMF (<i>R</i>² = 0.98) than a previous study. We found that minor elements in olivine, such as Ca, Cr, and Mn, independently affected the matrix effect. We also demonstrated the effectiveness of this method for extraterrestrial materials.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>We concluded that GPR is a powerful approach for correcting the SIMS matrix effect, especially when minor elements impact the matrix effect. This approach can be applied to other trace element and isotope analyses of solid-solution minerals.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 13","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.10038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143741170","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":"Discovering Novel Short- and Medium-Chain Esters of Hydroxy Fatty Acids in Human Fecal Samples Using Untargeted Liquid Chromatography/Mass Spectrometry","authors":"Jayashankar Jayaprakash,&nbsp;Divyavani Gowda,&nbsp;Rachana M. Gangadhara,&nbsp;Shalini Jain,&nbsp;Hariom Yadav,&nbsp;Siddabasave Gowda B. Gowda,&nbsp;Shu-Ping Hui","doi":"10.1002/rcm.10032","DOIUrl":"https://doi.org/10.1002/rcm.10032","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Exploring novel metabolites produced by host gut microbiome communication is crucial for understanding their roles in various disease pathologies. We previously uncovered a novel class of lipids, short-chain fatty acid esters of hydroxy fatty acids (SFAHFAs), in mouse fecal samples and demonstrated their promising physiological functions in mammals. However, the discovery of SFAHFAs in human samples remains unexplored.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>This study aimed to analyze the SFAHFAs and their structural analogs in human fecal samples using liquid chromatography/mass spectrometry.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We identified 26 isomeric lipid species, including SFAHFAs and novel medium-chain fatty acid esters of hydroxy fatty acids (MFAHFAs). The detected SFAHFAs and MFAHFAs were characterized by accurate mass measurements using MSⁿ analysis. The results were validated by matching the mass spectral fragmentation and retention time with authentic standards. Two new MFAHFAs, enanthic acid and caprylic acid esters of long-chain hydroxy fatty acids (C24 and C26), were detected and characterized for the first time in human fecal samples. Among the 26 isomeric lipid species, SFAHFA 2:0/24:0 or 4:0/22:0 and SFAHFA 2:0/24:1 were most abundant among the saturated and unsaturated SFAHFAs, respectively.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study offers the first insights into detecting and characterizing novel gut microbial lipids in human fecal samples. Further investigations are essential to recognize the metabolism and function of these lipids in the human gut.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143707451","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":"Rapid Determination of Isotopic Purity of Stable Isotope (D, 15N, or 13C)-Labeled Organic Compounds by Electrospray Ionization-High-Resolution Mass Spectrometry","authors":"Chenlong Liang,&nbsp;Lin Ling,&nbsp;Hao-Yang Wang","doi":"10.1002/rcm.10031","DOIUrl":"https://doi.org/10.1002/rcm.10031","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Stable isotope-labeled organic compounds, containing D, ¹⁵N, or ¹³C, have widespread applications in chemistry, biology, environmental science, and agriculture. However, the isotopic purity calculations for these labeled organic compounds are usually complicated, especially in mixed isotopes-labeled scenarios. Herein, the electrospray ionization-high-resolution mass spectrometry (ESI-HRMS) was applied to determine the isotopic purity for stable isotope-labeled organic compounds, containing D, ¹⁵N, or ¹³C.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The representative isotopolog ion with its specific molecular formula was proposed to represent various labeled states. The isotopic purity was calculated using the corrected intensities of representative isotopolog ions by removing the natural isotopic contributions from preceding peaks. A unified equation has been proposed for the calculation of isotopic purity for various labeled situations including D, ¹⁵N, or ¹³C.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Several case studies were presented and our calculated isotopic purities were all consistent with the isotopic purities provided in the certificate. In-source CID method was applied for the labeled compound (molecular weight &gt; 400 u), when the maximum resolution setting was insufficient to differentiate isobaric isotopolog ions.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Finally, a workflow with a Python calculation program was summarized for determinations of the isotopic purity for mono isotope-labeled or mixed isotopes-labeled organic compounds, involving D, ¹⁵N, or ¹³C, by using ESI-HRMS to assign the representative isotopolog ions with accurate mass and excluding the isobar interference.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"39 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143698942","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}