Rapid Communications in Mass Spectrometry最新文献

{"title":"Profiling Hydrolysis Rates of αS1-Casein to αS1-I-Casein During Cheese Ripening by Intact-Protein Liquid Chromatography–High Resolution Mass Spectrometry","authors":"Sebastiaan Dolman,&nbsp;Marjolein van der Eijk,&nbsp;Loes Bevers,&nbsp;Kees Muijlwijk,&nbsp;Mee Loke Lim,&nbsp;Margriet Hendriks,&nbsp;Nicolas Abello,&nbsp;Rob van der Hoeven","doi":"10.1002/rcm.70153","DOIUrl":"https://doi.org/10.1002/rcm.70153","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>The proteolytic behavior of chymosins during cheese ripening impacts cheese texture, flavor, and quality. Especially, the specific hydrolysis of αS1-casein to αS1-I-casein is relevant for early cheese texture development, and this activity varies between chymosin variants. Accurate profiling of αS1-casein and αS1-I-casein during cheese ripening is crucial for understanding these differences between chymosins and the impact on cheese quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Intact-protein liquid chromatography–high-resolution mass spectrometry (LC-HRMS) was employed to monitor the hydrolysis of αS1-casein to αS1-I-casein during mozzarella cheese ripening. Cheese samples, produced with both bovine and camel chymosin variants, were collected at multiple ripening stages. Protein extraction, separation, and quantification were performed using optimized LC-HRMS protocols to assess hydrolysis kinetics and phosphorylation variants.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>LC-HRMS analysis revealed that the tested bovine chymosins displayed significantly higher rates of αS1-casein hydrolysis to αS1-I-casein compared to camel chymosins throughout mozzarella cheese ripening. Distinct phosphorylation variants were confidently detected and quantified. Kinetic profiles demonstrated consistent proteolytic activity differences between coagulants.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>LC-HRMS allows tracking of αS1-casein hydrolysis kinetics throughout mozzarella cheese ripening. This approach not only highlights the pronounced and faster proteolytic activity of bovine chymosins compared to camel chymosins, resulting in more rapid αS1-I-casein formation, but also facilitates the monitoring of phosphorylation variants present in the cheese. These findings emphasize the enzyme-specific effects on cheese texture and quality, demonstrating the importance of advanced protein analysis for comprehensively understanding cheese production and maturation processes.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 21","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.70153","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148700013","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":"Dopant-Assisted APCI for Enhanced Sugar Analysis: Overcoming Ionization Bottlenecks","authors":"Nathan Traullé,&nbsp;Théo Voellinger,&nbsp;Jasmine Hertzog,&nbsp;Sébastien Schramm,&nbsp;Vincent Carré,&nbsp;Frédéric Aubriet","doi":"10.1002/rcm.70152","DOIUrl":"https://doi.org/10.1002/rcm.70152","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>The investigation of lignocellulosic biomass by atmospheric-pressure chemical ionization (APCI) mass spectrometry (MS) has revealed significant issues for carbohydrate ionization, particularly during biomass pyrolysis analyses. Unequal ionization of carbohydrates and significant fragmentation have been reported. The introduction of suitable dopants into the ion source shows promise for limiting fragmentation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>To investigate these ionization disturbances, both direct infusion (DI) and modified direct insertion probe (DIP) APCI coupled with a Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were employed. Solvents with increasing proton affinity (PA) were used to assess solvent PA influence in DI-APCI ionization processes. The DIP system was modified to enable the introduction of an inert gas stream passing through a dopant-rich atmosphere prior to entering the ion source.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>A significant PA difference between the solvent and the analyte promotes carbohydrate dissociation after their ionization. Experiments without solvent and with deuterated compounds showed that carbohydrate ionization and dissociation may be self-induced by water formed during carbohydrate dehydration. The introduction of ammonia in the ion source promoted the [M + NH₄]⁺ adduct formation, reducing ionization-induced dissociation and increasing the intensity of the carbohydrate signal by at least one order of magnitude in DI-APCI. The method was successfully applied to both standards and cellulose pyrolysis samples.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The dopant-assisted APCI (dAPCI) approach appears highly promising for the rapid assessment of biomass fast pyrolysis, particularly when highly oxygenated compounds are key markers. Careful selection of dopants and solvents is essential in carbohydrate analysis to preserve analyte structural integrity during ionization.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 21","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148700039","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":"Identification of Impurities in Norvancomycin Hydrochloride Drug Substance Using UHPLC-QTOF-MS","authors":"Yanni Liu,&nbsp;Jinqi Zheng,&nbsp;Jia Sun,&nbsp;Mingjuan Zhao,&nbsp;Abdelghani Mahmoudi,&nbsp;Peixi Zhu,&nbsp;Erwin Adams","doi":"10.1002/rcm.70157","DOIUrl":"10.1002/rcm.70157","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Norvancomycin (NVCM) hydrochloride belongs to a group of glycopeptide antibiotics and exhibits strong effects against Gram-positive cocci and bacilli. The safety of patients' lives is directly related to the quality of drugs. The impurities play often an important role in this process. This study aimed to investigate the impurity profile of NVCM hydrochloride.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>To identify the impurities, a simple and sensitive ultrahigh performance liquid chromatography quadrupole–time-of-flight mass spectrometry (UHPLC-QTOF-MS) method was developed. An ACQUITY UPLC BEH C18 column (2.1 × 100 mm, 1.7 μm) was used. The flow rate was set at 0.2 mL/min. Mobile phase (A) consisted of 10 mmol/L ammonium formate (pH 9.0) and mobile phase (B) was methanol. Gradient elution was performed as follows: 0–5 min, 15% B; 5–25 min, 15% B to 20% B; 25–40 min, 20% B to 70% B. Stress degradation experiments were conducted to check the specificity of the method.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Thirteen impurities and two degradation products were characterized using UHPLC-QTOF-MS.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Based on MS/MS spectral data and exact mass measurements, the chemical structures of the impurities were elucidated. This study provided a reference method for the quality control of NVCM hydrochloride.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148700222","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":"Study on Diphenylamine Oxidation by Ozone Using Atmospheric Pressure Chemical Ionization Mass Spectrometry","authors":"Eunji Chae,&nbsp;Chae Eun Son,&nbsp;Sung-Seen Choi","doi":"10.1002/rcm.70154","DOIUrl":"10.1002/rcm.70154","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Diphenylamine (DPAH) derivatives, widely used as antioxidants, interact with oxygen molecules (or ozone) to form radicals at the amine group. Although the antioxidation mechanism involves radical processes, separating these radicals using chromatography is challenging.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Rapid oxidation of DPAH was achieved through ozonation in an acetone solution, and the oxidation products, including radical and neutral species, were analyzed using direct APCI-MS. The analysis was performed using a single quadrupole mass spectrometer in both positive- and negative-ion modes. The types and yields of the oxidation products were analyzed according to the ozonation time. Energy differences based on the oxidation product size were compared to explain their favorability for formation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The major oxidation products included (DPA^• + <i>n</i>O) and (DPA^• + <i>n</i>O − H). They were detected as [DPA^• + <i>n</i>O + H]⁺ and [DPA^• + <i>n</i>O]⁺ in the positive-ion mode, respectively, and observed as [DPA^• + <i>n</i>O − H]⁻ and [DPA^• + <i>n</i>O − 2H]⁻ in the negative-ion mode, respectively. The abundance of oxidized DPAH products increased significantly until (DPA^• + 2O) and (DPA^• + 2O − H) and then notably decreased as the number of oxygen atoms increased.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>No significant differences in energies were observed for the consecutive addition of oxygen atoms to (DPA^• + <i>n</i>O) and (DPA^• + <i>n</i>O − H) with <i>n</i> = 1–6. Steric hindrance significantly influenced the number of oxygen atoms adducted to DPAH. The reasonable maximum number of oxygen atoms adducted to DPAH is five, considering thermodynamic favorability and steric hindrance.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13440329/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148676513","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":"Systematic Optimization of an SLE-DAPTAD LC–MS/MS Workflow for Simultaneous Quantification of Low-Abundance Vitamin D3 Metabolites in Plasma","authors":"Marzieh Amirmostofian,&nbsp;Michael D. Wiese,&nbsp;Paul H. Anderson,&nbsp;Peter Hoffmann","doi":"10.1002/rcm.70158","DOIUrl":"10.1002/rcm.70158","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis of vitamin D₃ metabolites is analytically challenging because these compounds are structurally similar, strongly matrix-associated, and have poor ionization efficiency. These limitations are particularly important for low-abundance metabolites such as 1,25(OH)₂D₃. This study systematically compared extraction and derivatization strategies to develop a simplified workflow for simultaneous quantification of 25(OH)D₃, 3-epi-25(OH)D₃, 1,25(OH)₂D₃, and 24,25(OH)₂D₃ in plasma.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Five sample-preparation approaches—simple protein precipitation, liquid–liquid extraction, salting-out assisted liquid–liquid extraction, solid-phase extraction, and supported liquid extraction—were evaluated under comparable conditions. Two derivatization reagents, 4-(4′-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione (DAPTAD) and 2-fluoro-1-methylpyridinium-<i>p</i>-toluenesulfonate (FMP-TS), were compared. The selected workflow was validated according to bioanalytical method validation criteria.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Supported liquid extraction using ethyl acetate/methyl tert-butyl ether (1:1, v/v) provided the best overall balance of signal intensity, reproducibility, simplicity, and suitability for high-throughput processing. DAPTAD derivatization produced a substantially higher MS response than FMP-TS and was selected for the final method. The optimized SLE-DAPTAD LC–MS/MS workflow showed good linearity (<i>r</i>² &gt; 0.99), acceptable accuracy and precision, recovery of 72.5%–104%, and limits of quantification of 0.08 ng/mL for 3-epi-25(OH)D₃, 1,25(OH)₂D₃, and 24,25(OH)₂D₃, and 0.88 ng/mL for 25(OH)D₃.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The optimized SLE-DAPTAD LC–MS/MS workflow provides a simple, sensitive, and automation-compatible approach for simultaneous quantification of four vitamin D₃ metabolites in plasma. The method is positioned as an analytical workflow for method development and low-volume plasma analysis, rather than as a fully standardized routine diagnostic assay for endogenous 1,25(OH)₂D₃ measurement.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13441545/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148676422","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":"Multiparameter Simulation for the Optimization of Ion Transmission Efficiency Through Mass Spectrometry Inlet Capillary","authors":"Di Wang,&nbsp;Chenlu Wang,&nbsp;Junhui Li,&nbsp;Jiancheng Yu,&nbsp;Keqi Tang","doi":"10.1002/rcm.70155","DOIUrl":"10.1002/rcm.70155","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>According to the mass spectrometry (MS) design principles, the ions generated in an atmospheric pressure ion source must pass through a narrow-bore capillary in order to maintain the needed system vacuum pressure. The ion transmission efficiency through the inlet capillary is one of the key factors directly influencing the analytical performance of MS. Its design and operating parameters, including inner diameter, length, temperature, and those related to the ion source operation, can alter ion diffusion losses, gas flow dynamics, and space-charge effects both around and inside the inlet capillary, thereby influencing ion sampling efficiency and transmission efficiency to the mass analyzer.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A comprehensive simulation of ion transmission efficiency through an MS inlet capillary has been performed in this study by adjusting the important design and operating parameters.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The simulation results show that the ion transmission efficiency through the inlet capillary is positively correlated with the inner diameter of the capillary and negatively correlated with the length of the capillary. Specifically, under the conditions of a capillary diameter of 0.8 mm and a temperature of 573.15 K, the ion transmission efficiency through a 10-cm-long capillary can reach 90%. The efficiency decreases with a reduction in the inner diameter or an increase in the length. When the temperature exceeds 573.15 K, the flow field inside the capillary transits from laminar to turbulent flow, leading to a sharp decline in ion transmission efficiency. For every 100-K increase in temperature beyond this point, the ion transmission efficiency decreases by 10%–20%.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The main results from this study have provided crucial design guidelines, emphasizing the use of larger diameters, moderate lengths, and strict temperature control below the turbulent transition threshold to maximize ion transmission and overall instrument sensitivity for MS instruments.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148663063","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":"Integrated 1D-LC-HRMS and Heart-Cutting 2D-LC–MS for Impurity Profiling and Chiral Separation of Mitiglinide Drug Substance","authors":"Chenxi Wang,&nbsp;Shiwen Zhou,&nbsp;Wanhao Sun,&nbsp;Yuanjiang Pan,&nbsp;Hongru Feng","doi":"10.1002/rcm.70144","DOIUrl":"https://doi.org/10.1002/rcm.70144","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>The comprehensive quality control of chiral pharmaceuticals like mitiglinide necessitates simultaneous assessment of chemical impurities and enantiomeric purity, yet conventional workflows address these separately, leading to inefficiency. This study develops a comprehensive analytical strategy to overcome this challenge for the anti-diabetic drug mitiglinide.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>For chiral analysis, an online heart-cutting two-dimensional liquid chromatography–high-resolution mass spectrometry (2D-LC-HRMS) method was developed. First, impurity profiling of mitiglinide was accomplished using a one-dimensional reversed-phase LC-HRMS (1D-LC-HRMS) method. Subsequently, the 2D-LC-HRMS system achieved enantiomer separation by online coupling of a C18 column (first dimension) with a polysaccharide-based chiral column (second dimension), with the separated analytes detected by an Orbitrap mass spectrometer.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>1D-LC-HRMS identified five major impurities, structurally characterizing four, with the main component accounting for only 49.12% of the total integrated peak area (relative abundance by EIC peak area normalization, not absolute purity). The 2D-LC-HRMS method achieved effective enantiomer separation. A consistent third minor chromatographic peak was observed across six replicate analyses, which is tentatively assigned as a potential diastereomeric impurity based on stereochemical interpretation of the chromatographic behavior; confirmatory evidence is required for definitive identification.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This work successfully establishes a comprehensive strategy that efficiently consolidates impurity profiling and chiral purity assessment for mitiglinide. It provides a reliable, more informative approach for the quality control of complex chiral pharmaceuticals.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148647645","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":"A Dual GC–MS and LC–MS/MS Analytical Strategy for Evaluating Free Chlorine Toxicity in Aqueous Samples","authors":"Avital Shifrovitch,&nbsp;Adi Tzadok,&nbsp;Moran Madmon,&nbsp;Avi Weissberg","doi":"10.1002/rcm.70151","DOIUrl":"https://doi.org/10.1002/rcm.70151","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Chlorine gas is a highly toxic industrial chemical that poses a significant risk in accidental releases and deliberate terrorist attacks. Reliable analytical methods for the determination of chlorine in aqueous samples are therefore required for forensic and environmental investigations. This study aimed to develop a rapid and selective mass spectrometry-based method for chlorine determination following derivatization.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Chlorine in aqueous samples was derivatized with methyl 2-(3,4,5-trimethoxyphenyl)acetate (MTMPA) at 50°C for 15 min, yielding methyl 2-(2-chloro-3,4,5-trimethoxyphenyl)acetate (Cl-MTMPA). The derivatization product was analyzed by gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–tandem mass spectrometry (LC–MS/MS). While LC–MS/MS analysis was performed directly, GC–MS analysis required an additional liquid–liquid extraction step. Reaction conditions were optimized to maximize derivatization efficiency.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The derivatization reaction provided a high yield of Cl-MTMPA under the optimized conditions. GC–MS and LC–MS/MS analyses produced a common major fragment ion at <i>m/z</i> 215.0. Further structural confirmation by liquid chromatography–high-resolution tandem mass spectrometry (LC-HRMS/MS) revealed a characteristic product ion at <i>m/z</i> 215.0473 generated from the precursor ion at <i>m/z</i> 275.0681. Calibration curves covering acute toxicologically relevant chlorine concentrations (5–200 mg/L) showed excellent linearity, with correlation coefficients (<i>R</i>²) exceeding 0.99.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>A rapid and selective derivatization-based method was developed in which the resulting chlorine derivative is readily analyzed by both GC–MS and LC–MS/MS. The method affords reliable analyte identification through characteristic fragmentation and excellent quantitative performance, making it suitable for forensic toxicology and environmental investigations involving chlorine exposure.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/rcm.70151","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617309","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":"Implementation of Nonisobaric TMT Analogs for Accurate Precursor-Level Quantification by plexDIA","authors":"Ting-Yu Wei,&nbsp;Joao A. Paulo","doi":"10.1002/rcm.70146","DOIUrl":"https://doi.org/10.1002/rcm.70146","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>Multiplexed quantitative proteomics enables simultaneous analysis of multiple biological samples, increasing throughput while reducing instrument time and sample requirements. However, integrating sample multiplexing with data-independent acquisition (DIA) remains challenging. We present a TMTpro plexDIA strategy leveraging MS1-level mass differences between nonisobaric TMTpro reagent variants to enable multiplexed quantification without compromising DIA sensitivity.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Three <i>Saccharomyces cerevisiae</i> deletion strains (<i>Δmet6</i>, <i>Δpfk2</i>, and <i>Δura2</i>) were labeled with TMTproZero (light), TMTpro16 (standard), and super-heavy TMTpro (heavy), mixed in three permutations, and analyzed by narrow-window DIA (2 <i>m</i>/<i>z</i> isolation, 300 scan events) on an Orbitrap Astral mass spectrometer. Database searching was performed using FragPipe/MSFragger with plex-DIA quantification enabled.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Over 2000 protein groups and over 20 000 precursors were identified per channel per mixture, with closely matched identification rates across all three channels. All nine expected deletion patterns were correctly identified, with channel-specific depletion reproduced consistently across precursor charge states (2+, 3+, and 4+).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>TMTpro plex-DIA enables accurate, multiplexed quantitative proteomics through MS1-level mass separation of the nonisobaric TMTpro isotopologs. The characteristic deletion patterns observed for each knockout strain serve as intrinsic molecular barcodes, validating sample identity and demonstrating the broad utility of plex-DIA for high-throughput, multiplexed proteomics applications.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617021","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":"LC-HRMS-Based Metabolic Profiling of the REV-ERB Agonist SR9009 in Camel Liver Homogenate and Cunninghamella elegans for Anti-Doping Analysis","authors":"Ansar Babu Palathinkal,&nbsp;S. Farook Basha,&nbsp;Saraswathy Laya,&nbsp;Jahfar Nalakath,&nbsp;O. K. Praseen,&nbsp;Marina Joseph,&nbsp;Shantymol V. Jose","doi":"10.1002/rcm.70149","DOIUrl":"https://doi.org/10.1002/rcm.70149","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Rationale</h3>\u0000 \u0000 <p>SR9009 is a synthetic REV-ERB agonist with potential performance-enhancing properties and is included on the World Anti-Doping Agency (WADA) Prohibited List for human sport. Its potential misuse has also raised concerns in animal sports, particularly equine and camel racing. Although SR9009 metabolism has been investigated in human and equine models, its metabolic fate in racing camels (<i>Camelus dromedarius</i>) remains unclear. Characterizing its biotransformation pathways and identifying suitable biomarkers are essential for developing reliable anti-doping screening strategies for camel racing.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>An in vitro metabolic study was conducted using camel liver homogenate and the fungal model <i>Cunninghamella elegans</i>. Metabolites were characterized using liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Putative structural elucidation was achieved through accurate mass measurements of precursor and product ions. Diagnostic fragmentation pathways were established using collision-induced dissociation (CID) tandem mass spectrometry (MS/MS), enabling the systematic identification of metabolic modifications based on characteristic fragment ions and neutral losses.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Seventeen Phase I metabolites of SR9009 were identified. Major biotransformation pathways included N-dealkylation, mono-hydroxylation, di-hydroxylation, and combinations thereof. The N-dealkylated metabolite was the predominant metabolite detected in both camel liver homogenate and <i>Cunninghamella elegans</i>, indicating its suitability as a primary analytical target for anti-doping screening. No Phase II metabolites were detected under the experimental conditions employed. Putative structural assignments were supported by characteristic high-resolution tandem mass spectral fragmentation patterns.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study provides the first comprehensive metabolic profile of SR9009 in a camel-specific in vitro model. The identification of 17 Phase I metabolites, particularly the predominant N-dealkylated derivative, provides valuable analytical targets for doping control. These findings establish a metabolic foundation for future in vivo studies to determine pharmacokinetics and detection windows in racing camels.</p>\u0000 </section>\u0000 </div>","PeriodicalId":225,"journal":{"name":"Rapid Communications in Mass Spectrometry","volume":"40 20","pages":""},"PeriodicalIF":1.8,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617035","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}