Journal of the American Society for Mass Spectrometry最新文献

{"title":"Mass Spectrometric Exploration of Biclonal Gammopathy: Insights from a Diagnostic Laboratory.","authors":"Deepalakshmi D Putchen, Ankitha K Puthiyaveettil, Prajwal Ammalli, Champakalakshmi Adinarayana, Sujay Ramaprasad","doi":"10.1021/jasms.5c00215","DOIUrl":"https://doi.org/10.1021/jasms.5c00215","url":null,"abstract":"<p><p>Biclonal gammopathy is observed in approximately 1% of myeloma cases. Most current understanding of this condition is derived from incidental or anecdotal findings based on serum protein electrophoresis (SPEP) and immunofixation electrophoresis (IFE). The widespread use of therapeutic monoclonal antibodies (tmAbs), such as daratumumab, has introduced additional complexity, as these agents may appear as monoclonal bands on IFE, potentially interfering with accurate diagnosis. This study utilizes the enhanced sensitivity and molecular specificity of liquid chromatography-triple quadrupole mass spectrometry (LC-TQMS) to characterize biclonal patterns in patient sera. Over a 3.3-year period (January 2022 to April 2025), 124 cases initially reported as biclonal by IFE were reviewed, of which 85 samples were selected for LC-TQMS analysis following immunoglobulin enrichment using camelid antibodies targeting immunoglobulin isotypes and light chains. Released light chains, following reduction, were separated by liquid chromatography, and their molecular masses determined by TQMS. Among the isotype combinations, IgG-IgA was the most frequent (34.3%), followed by IgG-IgG (31.4%), while IgG-IgM and IgM-IgM combinations were each observed in 2.9% of cases. Regarding light chain patterns, κ-λ combinations were observed in 40% of cases, λ-λ in 25.7%, and κ-κ in only 5.7%, the latter likely reflecting tmAb interference. LC-TQMS analysis revealed biclonal patterns in 31.8%, monoclonal patterns in 52.9%, and tmAb interference in 9.4%. LC-TQMS demonstrated robust capability in resolving biclonality, including cases with or without coexistent free light chains, and in distinguishing analytical artifacts due to tmAb or conformational changes in immunoglobulin light chains that may mimic biclonal patterns on IFE. These findings underscore the importance of incorporating treatment history into IFE interpretation and support the implementation of LC-TQMS as an orthogonal method for resolving complex gammopathy profiles. A workflow is proposed to aid in accurate interpretation of biclonal cases.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145063152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Site-Specific Hydrogen Deuterium Exchange Difference Mass Spectrometry Measurements for Ligand Binding","authors":"Joseph Anacleto,&nbsp;, ,&nbsp;Suzanne Ackloo,&nbsp;, ,&nbsp;Cheryl Arrowsmith,&nbsp;, ,&nbsp;Esther Wolf,&nbsp;, ,&nbsp;Yves Leblanc,&nbsp;, ,&nbsp;Cristina Lento,&nbsp;, and ,&nbsp;Derek J. Wilson*,&nbsp;","doi":"10.1021/jasms.5c00229","DOIUrl":"10.1021/jasms.5c00229","url":null,"abstract":"<p >Conventional bottom-up HDX-MS experiments are highly suitable for use in drug development; however, a major limitation of this approach is that it generally provides only peptide-level structural resolution. Site specific (<i>i.e</i>., single amino acid-resolved) HDX-MS measurements have been achieved using ECD/ETD, but the low efficiency of these fragmentation techniques, combined with poor ion transmission associated with ‘detuning’ the instrument to fully prevent deuterium scrambling, results in sensitivity losses that make ligand binding measurements impractical in a ‘real-world’ (<i>e.g</i>., drug development) context. Here we apply a recently developed method for zero scrambling, high efficiency ECD in the challenging context of ligand binding differential HDX experiments, demonstrating a wealth of additional information that can be acquired when HDX-MS analyses are conducted at the amino acid level.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2315–2318"},"PeriodicalIF":2.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/jasms.5c00229","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145063088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection of Gas-Phase Formaldehyde via C2H5O+ Produced by VUV Illumination and Enhanced by Doping Propionaldehyde","authors":"Zhiyang Wei,&nbsp;, ,&nbsp;Lixin Shan,&nbsp;, ,&nbsp;Yongze Gao,&nbsp;, ,&nbsp;Zhiyuan Luo,&nbsp;, ,&nbsp;Shiyu Cheng,&nbsp;, and ,&nbsp;Jinian Shu*,&nbsp;","doi":"10.1021/jasms.5c00181","DOIUrl":"10.1021/jasms.5c00181","url":null,"abstract":"<p >Formaldehyde (CH₂O) is one of the main indoor organic pollutants due to its carcinogenicity and teratogenicity. However, CH₂O has been an undetectable species for common VUV lamp-based photoionization mass spectrometry (PI-MS) due to its high ionization energy. In this article, we report a mass spectrometric technique developed for detecting gas-phase CH₂O by monitoring C₂H₅O⁺ (<i>m</i>/<i>z</i> 45) formed in VUV illumination and enhanced by doping propionaldehyde. The unique mass peak at <i>m</i>/<i>z</i> 45 was observed by VUV illuminating ppm-level CH₂O in ∼1300 Pa of nitrogen or synthetic air. The <i>m</i>/<i>z</i> 45 ion was assigned to be C₂H₅O⁺ via verification with a high-resolution mass spectrometric measurement and a deuteron transfer experiment. The formation process of the C₂H₅O⁺ ion observed in the experiment is similar to that of C₂H₅O⁺ formed in the combustion of hydrocarbons, discussed in the paper. Doping propionaldehyde in the carrier gas remarkably enhanced the signal intensity of C₂H₅O⁺ by nearly 13 times. The detection sensitivities of CH₂O via C₂H₅O⁺ reached 46.0 counts ppb^–1, and the LOD of the method was 4.3 ppb, enhanced by doping propionaldehyde. The influence of the humidity on the detection could be alleviated with desiccants, and the recovery with CaCl₂·2H₂O as the desiccant was achieved at 30% of the dry condition under 100% RH. This experiment demonstrated that the <i>m</i>/<i>z</i> 45 ions can be used as the characteristic ion for detecting CH₂O.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2181–2188"},"PeriodicalIF":2.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145068857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insight into Desorption Mechanisms in a Helium Low-Temperature Plasma Ionization Source Using Computational Simulations","authors":"Odhisea Gazeli*,&nbsp;, ,&nbsp;Constantinos Lazarou,&nbsp;, ,&nbsp;Marcos Bouza,&nbsp;, ,&nbsp;David Moreno-González,&nbsp;, ,&nbsp;Charalambos Anastassiou,&nbsp;, ,&nbsp;Joachim Franzke,&nbsp;, ,&nbsp;Juan F. García-Reyes*,&nbsp;, and ,&nbsp;George E. Georghiou,&nbsp;","doi":"10.1021/jasms.5c00171","DOIUrl":"10.1021/jasms.5c00171","url":null,"abstract":"<p >Understanding desorption mechanisms is essential for the optimization of analytical techniques that enable the direct sampling and ionization of condensed-phase samples without preparation. The low-temperature plasma (LTP) ionization source, first described by Harper (Harper; et al. <cite><i>Anal. Chem.</i></cite> <span>2008</span>, <em>80</em>, 9097–9104) and based on the dielectric barrier discharge principle, is among the more representative and replicated plasma-based ambient desorption/ionization tools for mass spectrometry (MS), although there are a wide array of designs and configurations. However, the fundamental desorption mechanisms directly associated with LTP and other related plasma-based sources remain unclear. In this study, we utilized plasma simulations using COMSOL Multiphysics to understand analyte release from solid samples placed on glass and exposed to the plasma of a simplified helium LTP configuration. Our simulations revealed that the accumulation of surface charge on the sample–substrate that is caused by the plasma results in localized electric fields strong enough to likely aid in disruption of analyte–substrate interactions and facilitate desorption. Importantly, our model estimates that electrons in plasma have energies of approximately 2.5 eV, suggesting this simulated energy level is an indicator for desorption efficiency. Our findings provide new insight into the complex interplay between plasma-induced phenomena and desorption processes.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2151–2163"},"PeriodicalIF":2.7,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/jasms.5c00171","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145038908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cysteine Reactivity Profiling Illuminates Monoclonal Antibody Disulfide Bond Reduction Mechanisms in Biopharmaceutical Process Intermediates","authors":"Taku Tsukidate,&nbsp;, ,&nbsp;Zhenshu Wang,&nbsp;, ,&nbsp;Andrew Hsieh,&nbsp;, ,&nbsp;Patricia Rose,&nbsp;, and ,&nbsp;Xuanwen Li*,&nbsp;","doi":"10.1021/jasms.5c00204","DOIUrl":"10.1021/jasms.5c00204","url":null,"abstract":"<p >Monoclonal antibodies (mAbs) are crucial biotherapeutics in the face of increasing global demand, but their production can be impacted by the reduction of disulfide bonds. This study presents a chemical proteomics workflow aimed at elucidating the mechanisms underlying disulfide bond reduction in mAbs produced from Chinese hamster ovary (CHO) cells. We employed iodoacetamide-desthiobiotin (IA-DTB) and the parallel accumulation and serial fragmentation combined with data-independent acquisition (diaPASEF) methodology for cysteine reactivity profiling and successfully quantified approximately 4,500 cysteine-containing peptides from harvested cell culture fluids (HCCF). Our findings reveal that various protein disulfide oxidoreductases were active in reducing HCCF, offering critical insights into the redox environment affecting mAb stability. Notably, we quantified specific cysteine residues in enzymes such as glutaredoxin and thioredoxin domain–containing protein 12, suggesting potential links between their activity and disulfide bond dynamics. This workflow not only complements conventional abundance proteomics but also enhances our understanding of functional enzyme states in bioprocessing. Ultimately, our approach provides a promising strategy for assessing enzymes contributing to disulfide bond reduction, paving the way for improved manufacturing processes of mAbs.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2222–2229"},"PeriodicalIF":2.7,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145051557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SLIM Ion Mobility-Based Analysis of Low Molecular Weight Explosives","authors":"Heidi M. Sabatini,&nbsp; and ,&nbsp;Christopher D. Chouinard*,&nbsp;","doi":"10.1021/jasms.5c00268","DOIUrl":"10.1021/jasms.5c00268","url":null,"abstract":"<p >The detection and differentiation of explosive compounds remain critical components of security applications and forensic work due to the potential complexity of samples and presence of isomeric compounds. Standalone ion mobility spectrometry (IMS) has been used in security screening for decades, useful for its ability to rapidly separate gas-phase ions based on differences in their size, shape, and charge. More recently developed high-resolution ion mobility-mass spectrometry (HRIM-MS) methods incorporate higher resolving power with accurate mass measurements to provide improved isomer separations and identification of unknowns. This work utilizes a novel Structures for Lossless Ion Manipulations (SLIM) ion mobility platform featuring a rounded turn design, which enhances the transmission of low-mass explosive compounds using helium buffer gas. Using negative mode atmospheric pressure chemical ionization (APCI), we demonstrate separation of isomeric nitroaromatic compounds such as 2,4- vs 2,6-dinitrotoluene (2,4-/2,6-DNT) and 2-amino-4,6- vs 4-amino-2,6-DNT. The rounded turn SLIM design significantly improved ion transmission efficiency over the traditional 90° turn system, especially for these low <i>m</i>/<i>z</i> analytes. With this, we demonstrate the ability of SLIM HRIM-MS to combine mobility separations, accurate mass, and isotopic patterns for improved separation and identification of isomeric explosives.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2022–2025"},"PeriodicalIF":2.7,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145032382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nontargeted Screening of Fingermark Residue Using Comprehensive Two-Dimensional Gas Chromatography–Time-of-Flight Mass Spectrometry for Future Use in Forensic Applications","authors":"Emma L. Macturk,&nbsp; and ,&nbsp;Katelynn A. Perrault Uptmor*,&nbsp;","doi":"10.1021/jasms.5c00258","DOIUrl":"10.1021/jasms.5c00258","url":null,"abstract":"<p >Fingerprints are routinely used as evidence in forensic investigations. Fingermarks, any mark left by a donor whether a complete print or not, include sweat and oil excreted by the donor. The chemical components of fingermarks are typically analyzed by gas chromatography–mass spectrometry (GC-MS). Complexity from the number of endogenous and exogenous components associated with fingermarks tends to cause challenging coelutions in resulting chromatograms. In these scenarios, nontargeted analysis can provide substantial benefits over traditional targeted methods that exist in the literature. In this proof-of-concept study, a nontargeted method for analyzing fingermarks was developed and optimized using comprehensive two-dimensional gas chromatography (GC×GC-TOFMS). Two different methods for extracting fingermarks off a microscope slide were evaluated for reproducibility and the quantity of extracted analytes, and a cotton swab collection with solvent extraction was chosen. Instrumental parameters were experimentally optimized to produce a final workflow. The optimized extraction and instrument methods together identified 70 fingermark analytes. Exogenous components within the deposited residue were resolved from endogenous fingermark compounds and used to differentiate donors based on personal care products used by the donor. The extra chromatographic space from GC×GC-TOFMS analysis was beneficial for resolving cosmetic compounds from endogenous fingermark compounds, some of which have been shown to coelute in GC-MS studies previously. The potential for a nontargeted screening of fingermarks for exogenous compounds in a forensic setting is demonstrated as an analysis of trace evidence.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2299–2309"},"PeriodicalIF":2.7,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/jasms.5c00258","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Charge Reduction on Sequence Coverage of Proteins by 193 nm Ultraviolet Photodissociation","authors":"Sean D. Dunham,&nbsp;, ,&nbsp;Mohamed I. Gadallah,&nbsp;, and ,&nbsp;Jennifer S. Brodbelt*,&nbsp;","doi":"10.1021/jasms.5c00230","DOIUrl":"10.1021/jasms.5c00230","url":null,"abstract":"<p >An ongoing goal of top-down mass spectrometry is to increase the performance for larger proteins. Using higher energy activation methods, like 193 nm ultraviolet photodissociation (UVPD), offers the potential to cause more extensive fragmentation of large proteins and thereby yield greater sequence coverage. Obtaining high sequence coverage requires confident identification and assignment of fragment ions, and this process is hampered by spectral congestion and low signal-to-noise ratio (S/N) of the fragment ions. Here we explore the use of charge reduction methods to produce lower charge states of large proteins to increase ion accumulation and generate lower charge states of fragment ions, ones that are naturally dispersed in the <i>m</i>/<i>z</i> domain to alleviate spectral congestion. UVPD of low charge states of enolase (47 kDa) and PRN-1 (63 kDa) resulted in sequence coverages as high as 47% (24+ charge state of enolase) and 23% (32+ of PRN-1) in comparison to 17% (55+ charge state of enolase) and 9% (55+ charge state of PRN-1) obtained for standard high charge states. Proton transfer charge reduction (PTCR) reactions were performed to further disperse fragment ions in the <i>m</i>/<i>z</i> domain and enhance identification. When employing PTCR after UVPD, sequence coverage was maximized for the highest charge states for enolase (55+, 67%) and PRN-1 (55+, 34%), confirming that charge reduction of fragment ions had a more notable impact on outcomes than charge reduction of precursor ions. Sequence coverages were increased further by combining results from electron transfer higher energy collision dissociation (EThcD) and UVPD (85% coverage for enolase and 52% coverage for PRN-1), bolstering the use of complementary MS/MS methods to yield greater dividends for top-down analysis of larger proteins.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2253–2266"},"PeriodicalIF":2.7,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complementary Separation of Novel Synthetic Opioids","authors":"Andrew R. Forero,&nbsp;, ,&nbsp;Samuel A. Miller,&nbsp;, ,&nbsp;Lilian Valadares Tose,&nbsp;, ,&nbsp;Matthew Willetts,&nbsp;, ,&nbsp;Mark E. Ridgeway,&nbsp;, ,&nbsp;Melvin A. Park,&nbsp;, ,&nbsp;Elisa N. Shoff,&nbsp;, and ,&nbsp;Francisco Fernandez-Lima*,&nbsp;","doi":"10.1021/jasms.5c00203","DOIUrl":"10.1021/jasms.5c00203","url":null,"abstract":"<p >The escalating prevalence and diversity of fentanyl analogues poses an immediate concern for the global community. Fentanyl and its analogues are the primary contributors to both fatal and nonfatal overdoses in the United States. The most recent instances of fentanyl-related overdoses have been attributed to the illicit production of fentanyl, characterized by its exceptionally potent nature. In this study, we present a high-throughput mass spectrometry based method for effective screening of fentanyl analogues with focus on the isomeric separation using commercially available platforms combining liquid chromatography, trapped ion mobility spectrometry, and tandem mass spectrometry (LC-TIMS-q-TOF MS/MS). The proposed analysis allows for effective separation and identification of 250 synthetic opioids based on the isotopic pattern, retention time, mobility profile, and MS/MS pattern. Our approach capitalizes on the advancements incorporating parallel accumulation in the mobility trap followed by sequential fragmentation (PASEF) using collision-induced dissociation on the liquid chromatography time scale. While a single chromatography band is commonly observed for single isomeric analogues, a dual mobility band profile attributed to two protonation sites is commonly observed for most fentanyl analogues. Reference mobility values are reported from single standards with 0.2% RSD collected at high resolution (R_IMS ≈ 80–120). The added mobility separation resulted in the separation of isomeric compounds without compromising the sensitivity of the LC-q-TOF MS/MS analysis; that is, a good linear dynamic and (R² &gt; 0.98) and low limits of detection (LOD) in the 0.08–4 ng/mL range were observed for all synthetic analogues (∼100 analogues can be observed with LOD &lt; 1 ng/mL).</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2206–2212"},"PeriodicalIF":2.7,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced Charge-Sensitive Amplifier Performance Leads to Substantially Reduced CD-MS Measurement Times for Charge State Resolution","authors":"Raj A Parikh,&nbsp;, ,&nbsp;Andrew W. Alexander,&nbsp;, and ,&nbsp;Martin F Jarrold*,&nbsp;","doi":"10.1021/jasms.5c00236","DOIUrl":"10.1021/jasms.5c00236","url":null,"abstract":"<p >In charge detection mass spectrometry (CD-MS) ions are trapped in an electrostatic linear ion trap (ELIT) where they oscillate back and forth through a conducting cylinder. The oscillating ions induce a periodic charge separation that is detected by a charge sensitive amplifier (CSA) connected to the cylinder. The resulting time domain signal is analyzed using short-time Fourier transforms to give the mass-to-charge ratio and charge for each ion, which are then multiplied to give the mass. For ions to be assigned to the correct integer charge states with a low error rate, the charge should be measured with a precision of &lt;0.2 e (elementary charges). Electrical noise reduces the precision of the charge measurement. However, the effect of the noise can be ameliorated by signal averaging, and the measurement time can, in principle, be increased to achieve a precision of &lt;0.2 e. Previously, through optimized ELIT design and improvements to the CSA, the measurement time (with a cryogenically cooled input JFET) required to achieve a charge precision of &lt;0.2 e was reduced by a factor of 2, from 3 s to 1.5 s. In this study, further improvements in JFET selection, capacitance matching, and cryogenic cooling has allowed us to further reduce the electrical noise so that the target precision of &lt;0.2 e can now be achieved for mAb MSQC4 in 600–700 ms with the input JFET cryogenically cooled, and in 900–1000 ms with the input JFET at room temperature. This performance upgrade cuts the overall time for high-resolution charge measurements by more than another factor of 2. For a measurement time of 100 ms, the charge RMSD is 0.51 e with cryogenic cooling. The results presented here further cements CD-MS with an ELIT as the fastest and most accurate approach to single ion MS measurements.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 10","pages":"2290–2298"},"PeriodicalIF":2.7,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}