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Trimpin S, Inutan ED, Pagnotti VS, Karki S, Marshall DD, Hoang K, Wang B, Lietz CB, Richards AL, Yenchick FS, Lee C, Lu IC, Fenner M, Madarshahian S, Saylor S, Chubatyi ND, Zimmerman T, Moreno-Pedraza A, Wang T, Adeniji-Adele A, Meher AK, Madagedara H, Owczarzak Z, Musavi A, Hendrickson TL, Peacock PM, Tomsho JW, Larsen BS, Prokai L, Shulaev V, Pophristic M, McEwen CN. Direct sub-atmospheric pressure ionization mass spectrometry: Evaporation/sublimation-driven ionization is amazing, fundamentally, and practically. J Mass Spectrom 2024; 59:e5018. [PMID: 38736378 DOI: 10.1002/jms.5018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/08/2023] [Accepted: 03/04/2024] [Indexed: 05/14/2024]
Abstract
This paper covers direct sub-atmospheric pressure ionization mass spectrometry (MS). The discovery, applications, and mechanistic aspects of novel ionization processes for use in MS that are not based on the high-energy input from voltage, laser, and/or high temperature but on sublimation/evaporation within a region linking a higher to lower pressure and modulated by heat and collisions, are discussed, including how this new reality has guided a series of discoveries, instrument developments, and commercialization. A research focus, inter alia, is on how best to understand, improve, and use these novel ionization processes, which convert volatile and nonvolatile compounds from solids (sublimation) or liquids (evaporation) into gas-phase ions for analysis by MS providing reproducible, accurate, sensitive, and prompt results. Our perception on how these unprecedented versus traditional ionization processes/methods relate to each other, how they can be made to coexist on the same mass spectrometer, and an outlook on new and expanded applications (e.g., clinical, portable, fast, safe, and autonomous) is presented, and is based on ST's Opening lecture presentation at the Nordic Mass spectrometry Conference, Geilo, Norway, January 2023. Focus will be on matrix-assisted ionization (MAI) and solvent-assisted ionization (SAI) MS covering the period from 2010 to 2023; a potential paradigm shift in the making.
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Affiliation(s)
- Sarah Trimpin
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
- MSTM, LLC, Newark, Delaware, USA
| | - Ellen D Inutan
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
- MSTM, LLC, Newark, Delaware, USA
- Mindanao State University-Iligan Institute of Technology, Iligan City, Philippines
| | - Vincent S Pagnotti
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Santosh Karki
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
- MSTM, LLC, Newark, Delaware, USA
| | - Darrell D Marshall
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
- MSTM, LLC, Newark, Delaware, USA
| | - Khoa Hoang
- MSTM, LLC, Newark, Delaware, USA
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Beixi Wang
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | | | - Alicia L Richards
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | - Frank S Yenchick
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | - Chuping Lee
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | - I-Chung Lu
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
- Department of Chemistry, National Chung Hsing University, Taichung, Taiwan
| | - Madeleine Fenner
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Sara Madarshahian
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Sarah Saylor
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Nicolas D Chubatyi
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Teresa Zimmerman
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | | | - Tongwen Wang
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Adetoun Adeniji-Adele
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Anil K Meher
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
- MSTM, LLC, Newark, Delaware, USA
| | - Hasini Madagedara
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | - Zachary Owczarzak
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | - Ahmed Musavi
- Department of Chemistry, Wayne State University, Detroit, Michigan, USA
| | | | | | - John W Tomsho
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | | | - Laszlo Prokai
- Department of Pharmacology and Neuroscience, The University of North Texas Health Science Center at Forth Worth, Fort Worth, Texas, USA
| | - Vladimir Shulaev
- Department of Biological Sciences, The University of North Texas, Denton, Texas, USA
| | - Milan Pophristic
- MSTM, LLC, Newark, Delaware, USA
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
| | - Charles N McEwen
- MSTM, LLC, Newark, Delaware, USA
- Department of Chemistry & Biochemistry, Saint Joseph's University, Philadelphia, Pennsylvania, USA
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Bouza M, Ahlmann N, García-Reyes JF, Franzke J. Solvent-Assisted Laser Desorption Flexible Microtube Plasma Mass Spectrometry for Direct Analysis of Dried Samples on Paper. Anal Chem 2023; 95:18370-18378. [PMID: 37902451 PMCID: PMC10733904 DOI: 10.1021/acs.analchem.3c03009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/11/2023] [Accepted: 10/20/2023] [Indexed: 10/31/2023]
Abstract
The present study investigated the potential for solvent-assisted laser desorption coupled with flexible microtube plasma ionization mass spectrometry (SALD-FμTP-MS) as a rapid analytical technique for direct analysis of surface-deposited samples. Paper was used as the demonstrative substrate, and an infrared hand-held laser was employed for sample desorption, aiming to explore cost-effective sampling and analysis methods. SALD-FμTP-MS offers several advantages, particularly for biofluid analysis, including affordability, the ability to analyze low sample volumes (<10 μL), expanded chemical coverage, sample and substrate stability, and in situ analysis and high throughput potential. The optimization process involved exploring the use of viscous solvents with high boiling points as liquid matrices. This approach aimed to enhance desorption and ionization efficiencies. Ethylene glycol (EG) was identified as a suitable solvent, which not only improved sensitivity but also ensured substrate stability during analysis. Furthermore, the addition of cosolvents such as acetonitrile/water (1:1) and ethyl acetate further enhanced sensitivity and reproducibility for a standard solution containing amphetamine, imazalil, and cholesterol. Optimized conditions for reproducible and sensitive analysis were determined as 1000 ms of laser exposure time using a 1 μL solvent mixture of 60% EG and 40% acetonitrile (ACN)/water (1:1). A mixture of 60% EG and 40% ACN/water (1:1) resulted in signal enhancements and relative standard deviations of 12, 20, and 13% for the evaluated standards, respectively. The applicability of SALD-FμTP-MS was further evaluated by successfully analyzing food, water, and biological samples, highlighting the potential of SALD-FμTP-MS analysis, particularly for thermolabile and polarity diverse compounds.
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Affiliation(s)
- Marcos Bouza
- Analytical
Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
| | - Norman Ahlmann
- ISAS—Leibniz
Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
| | - Juan F. García-Reyes
- Analytical
Chemistry Research Group, Department of Physical and Analytical Chemistry, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain
| | - Joachim Franzke
- ISAS—Leibniz
Institut für Analytische Wissenschaften, Bunsen-Kirchhoff-Str. 11, 44139 Dortmund, Germany
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Trimpin S, Marshall DD, Karki S, Madarshahian S, Hoang K, Meher AK, Pophristic M, Richards AL, Lietz CB, Fischer JL, Elia EA, Wang B, Pagnotti VS, Lutomski CA, El-Baba TJ, Lu IC, Wager-Miller J, Mackie K, McEwen CN, Inutan ED. An overview of biological applications and fundamentals of new inlet and vacuum ionization technologies. Rapid Commun Mass Spectrom 2021; 35 Suppl 1:e8829. [PMID: 32402102 DOI: 10.1002/rcm.8829] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 05/01/2020] [Accepted: 05/10/2020] [Indexed: 06/11/2023]
Abstract
RATIONALE The developments of new ionization technologies based on processes previously unknown to mass spectrometry (MS) have gained significant momentum. Herein we address the importance of understanding these unique ionization processes, demonstrate the new capabilities currently unmet by other methods, and outline their considerable analytical potential. METHODS The inlet and vacuum ionization methods of solvent-assisted ionization (SAI), matrix-assisted ionization (MAI), and laserspray ionization can be used with commercial and dedicated ion sources producing ions from atmospheric or vacuum conditions for analyses of a variety of materials including drugs, lipids, and proteins introduced from well plates, pipet tips and plate surfaces with and without a laser using solid or solvent matrices. Mass spectrometers from various vendors are employed. RESULTS Results are presented highlighting strengths relative to ionization methods of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization. We demonstrate the utility of multi-ionization platforms encompassing MAI, SAI, and ESI and enabling detection of what otherwise is missed, especially when directly analyzing mixtures. Unmatched robustness is achieved with dedicated vacuum MAI sources with mechanical introduction of the sample to the sub-atmospheric pressure (vacuum MAI). Simplicity and use of a wide array of matrices are attained using a conduit (inlet ionization), preferably heated, with sample introduction from atmospheric pressure. Tissue, whole blood, urine (including mouse, chicken, and human origin), bacteria strains and chemical on-probe reactions are analyzed directly and, especially in the case of vacuum ionization, without concern of carryover or instrument contamination. CONCLUSIONS Examples are provided highlighting the exceptional analytical capabilities associated with the novel ionization processes in MS that reduce operational complexity while increasing speed and robustness, achieving mass spectra with low background for improved sensitivity, suggesting the potential of this simple ionization technology to drive MS into areas currently underserved, such as clinical and medical applications.
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Affiliation(s)
- Sarah Trimpin
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
- MS™, LLC, Newark, DE, 19711, USA
| | - Darrell D Marshall
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
- MS™, LLC, Newark, DE, 19711, USA
| | - Santosh Karki
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
- MS™, LLC, Newark, DE, 19711, USA
| | | | - Khoa Hoang
- MS™, LLC, Newark, DE, 19711, USA
- University of the Sciences, Philadelphia, PA, 19104, USA
| | - Anil K Meher
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
- MS™, LLC, Newark, DE, 19711, USA
| | - Milan Pophristic
- MS™, LLC, Newark, DE, 19711, USA
- University of the Sciences, Philadelphia, PA, 19104, USA
| | - Alicia L Richards
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | | | - Joshua L Fischer
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Efstathios A Elia
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Beixi Wang
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | | | - Corinne A Lutomski
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Tarick J El-Baba
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - I-Chung Lu
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - James Wager-Miller
- Gill Center for Biomolecular Science and Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
| | - Ken Mackie
- Gill Center for Biomolecular Science and Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405, USA
| | - Charles N McEwen
- MS™, LLC, Newark, DE, 19711, USA
- University of the Sciences, Philadelphia, PA, 19104, USA
| | - Ellen D Inutan
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
- MS™, LLC, Newark, DE, 19711, USA
- Mindanao State University Iligan Institute of Technology, Iligan City, 9200, Philippines
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Karki S, Meher AK, Inutan ED, Pophristic M, Marshall DD, Rackers K, Trimpin S, McEwen CN. Development of a robotics platform for automated multi-ionization mass spectrometry. Rapid Commun Mass Spectrom 2021; 35 Suppl 1:e8449. [PMID: 30950108 DOI: 10.1002/rcm.8449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/02/2019] [Accepted: 03/26/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE Successful coupling of a multi-ionization automated platform with commercially available mass spectrometers provides improved coverage of compounds in complex mixtures through implementation of new and traditional ionization methods. The versatility of the automated platform is demonstrated through coupling with mass spectrometers from two different vendors. Standards and complex biological samples were acquired using electrospray ionization (ESI), solvent-assisted ionization (SAI) and matrix-assisted ionization (MAI). METHODS The MS™ prototype automated platform samples from 96- or 384-well plates as well as surfaces. The platform interfaces with Thermo Fisher Scientific mass spectrometers by replacement of the IonMax source, and on Waters mass spectrometers with additional minor source inlet modifications. The sample is transferred to the ionization region using a fused-silica or metal capillary which is cleaned between acquisitions using solvents. For ESI and SAI, typically 1 μL of sample solution is drawn into the capillary tube and for ESI slowly dispensed near the inlet of the mass spectrometer with voltage placed on the delivering syringe barrel to which the tubing is attached, while for SAI the sample delivery tubing inserts into the inlet without the need for high voltage. For MAI, typically, 0.2 μL of matrix solution is drawn into the syringe before drawing 0.1 μL of the sample solution and dispensing to dry before insertion into the inlet. RESULTS A comparison study of a mixture of angiotensin I, verapamil, crystal violet, and atrazine representative of peptides, drugs, dyes, and herbicides using SAI, MAI, and ESI shows large differences in ionization efficiency of the various components. Solutions of a mixture of erythromycin and azithromycin in wells of a 384-microtiter well plate were mass analyzed at the rate of ca 1 min per sample using MAI and ESI. In addition, we report the analysis of bacterial extracts using automated MAI and ESI methods. Finally, the ability to perform surface analysis with the automated platform is also demonstrated by directly analyzing dyes separated on a thin-layer chromatography (TLC) plate and compounds extracted from the surface of a beef liver tissue section. CONCLUSIONS The prototype multi-ionization automated platform offers solid matrix introduction used with MAI, as well as solution introduction using either ESI or SAI. The combination of ionization methods extends the types of compounds which are efficiently ionized and is especially valuable with complex mixtures as demonstrated for bacterial extracts. While coupling of the automated multi-ionization platform to Thermo and Waters mass spectrometers is demonstrated, it should be possible to interface it with most commercial mass spectrometers.
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Affiliation(s)
- Santosh Karki
- Department of Chemistry, Wayne State University, Detroit, MI, USA
- MSTM, LLC, Newark, DE, USA
| | - Anil K Meher
- Department of Chemistry, Wayne State University, Detroit, MI, USA
- MSTM, LLC, Newark, DE, USA
| | - Ellen D Inutan
- Department of Chemistry, Wayne State University, Detroit, MI, USA
- MSTM, LLC, Newark, DE, USA
| | - Milan Pophristic
- MSTM, LLC, Newark, DE, USA
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA, USA
| | | | | | - Sarah Trimpin
- Department of Chemistry, Wayne State University, Detroit, MI, USA
- MSTM, LLC, Newark, DE, USA
- Cardiovascular Research Institute, Wayne State University, Detroit, MI, USA
| | - Charles N McEwen
- MSTM, LLC, Newark, DE, USA
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, PA, USA
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Apsokardu MJ, Kerecman DE, Johnston MV. Ion formation in droplet-assisted ionization. Rapid Commun Mass Spectrom 2021; 35 Suppl 1:e8227. [PMID: 29971846 DOI: 10.1002/rcm.8227] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/31/2018] [Accepted: 06/25/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE In droplet-assisted ionization (DAI), intact molecular ions are generated from molecules in aerosol droplets by passing the droplets through a temperature-controlled capillary inlet. Ion formation is explored through the effects of analyte mass flow, droplet solvent composition, and capillary temperature on ion signal intensity. METHODS A Waters SYNAPT G2-S is adapted for DAI by reconfiguring the inlet with a temperature-controlled capillary. Droplets are generated by atomization of a solution containing analyte and then sampled through the inlet. If desired, solvent can be removed from the droplets prior to analysis by sending the aerosol through a series of diffusion dryers. Size distributions of the dried aerosols allow the mass flow of analyte into the inlet to be determined. RESULTS Analyte signal intensities are orders of magnitude higher from droplets containing a protic solvent (water) than an aprotic solvent (acetonitrile). The highest signal intensities for DAI are obtained with inlet temperatures above 500°C, though the optimum temperature is analyte dependent. At elevated temperatures, droplets are thought to undergo rapid solvent evaporation and bursting to produce ions. The lowest signal intensities are generally obtained in the 100-350°C range, where slow solvent evaporation is thought to inhibit ion formation. As the temperature decreases from 100°C down to 25°C, the signal intensity increases significantly. When 3-nitrobenzonitrile, a common matrix for solid-state matrix-assisted ionization (MAI), is added to droplets consisting of 50/50 v/v water and acetonitrile, the matrix enhances ion formation to produce a signal intensity comparable to DAI in 100% water. CONCLUSIONS The results are consistent with other inlet ionization techniques, suggesting that similar ion formation mechanisms are operative. Optimized ion yields (the combined effects of ionization probability and ion transmission) for DAI are currently in the 10-5 to 10-6 range, which is sufficient for many aerosol applications.
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Affiliation(s)
- Michael J Apsokardu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Devan E Kerecman
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Murray V Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
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Trimpin S. Novel ionization processes for use in mass spectrometry: 'Squeezing' nonvolatile analyte ions from crystals and droplets. Rapid Commun Mass Spectrom 2019; 33 Suppl 3:96-120. [PMID: 30138957 DOI: 10.1002/rcm.8269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/29/2018] [Accepted: 08/15/2018] [Indexed: 05/25/2023]
Abstract
Together with my group and collaborators, I have been fortunate to have had a key role in the discovery of new ionization processes that we developed into new flexible, sensitive, rapid, reliable, and robust ionization technologies and methods for use in mass spectrometry (MS). Our current research is focused on how best to understand, improve, and use these novel ionization processes which convert volatile and nonvolatile compounds from solids or liquids into gas-phase ions for analysis by MS using e.g. mass-selected fragmentation and ion mobility spectrometry to provide reproducible, accurate, and improved mass and drift time resolution. In my view, the apex was the discovery of vacuum matrix-assisted ionization (vMAI) in 2012 on an intermediate pressure matrix-assisted laser desorption/ionization (MALDI) source without the use of a laser, high voltages, or any other added energy. Only exposure of the matrix:analyte to the sub-atmospheric pressure of the mass spectrometer was necessary to initiate ionization. These findings were initially rejected by three different scientific journals, with comments related to 'how can this work?', 'where do the charges come from?', and 'it is not analytically useful'. Meanwhile, we and others have demonstrated analytical utility without a complete understanding of the mechanism. In reality, MALDI and electrospray ionization are widely used in science and their mechanisms are still controversially discussed despite use and optimization of now 30 years. This Perspective covers the applications and mechanistic aspects of the novel ionization processes for use in MS that guided us in instrument developments, and provides our perspective on how they relate to traditional ionization processes.
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Affiliation(s)
- Sarah Trimpin
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
- Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, MI, 48201, USA
- MSTM, LLC, Newark, DE, 19711, USA
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Trimpin S, Pophristic M, Adeniji-Adele A, Tomsho JW, McEwen CN. Vacuum Matrix-Assisted Ionization Source Offering Simplicity, Sensitivity, and Exceptional Robustness in Mass Spectrometry. Anal Chem 2018; 90:11188-11192. [DOI: 10.1021/acs.analchem.8b03378] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Sarah Trimpin
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
- Cardiovascular Research Institute, School of Medicine, Wayne State University, Detroit, Michigan 48202, United States
- MSTM LLC, Newark, Delaware 19711, United States
| | | | - Adetoun Adeniji-Adele
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, United States
| | - John W. Tomsho
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, United States
| | - Charles N. McEwen
- MSTM LLC, Newark, Delaware 19711, United States
- Department of Chemistry & Biochemistry, University of the Sciences, Philadelphia, Pennsylvania 19104, United States
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Abstract
We developed a technique to monitor spatially confined surface reactions with mass spectrometry under ambient conditions, without the need for voltage or organic solvents. Fused-silica capillaries immersed in an aqueous solution, positioned in close proximity to each other and the functionalized surface, created a laminar flow junction with a resulting reaction volume of ∼5 pL. The setup was operated with a syringe pump, delivering reagents to the surface through a fused-silica capillary. The other fused-silica capillary was connected to a Venturi easy ambient sonic-spray ionization source, sampling the resulting analytes at a slightly higher flow rate compared to the feeding capillary. The combined effects of the inflow and outflow maintains a chemical microenvironment, where the rate of advective transport overcomes diffusion. We show proof-of-concept where acetylcholinesterase was immobilized on an organosiloxane polymer through electrostatic interactions. The hydrolysis of acetylcholine by acetylcholinesterase into choline was monitored in real-time for a range of acetylcholine concentrations, fused-silica capillary geometries, and operating flow rates. Higher reaction rates and conversion yields were observed with increasing acetylcholine concentrations, as would be expected.
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Affiliation(s)
- Erik T Jansson
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Department of Chemistry-BMC, Uppsala University , SE-75124 Uppsala, Sweden
| | - Maria T Dulay
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Richard N Zare
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
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Porcari AM, Fernandes GD, Barrera-Arellano D, Eberlin MN, Alberici RM. Food quality and authenticity screening via easy ambient sonic-spray ionization mass spectrometry. Analyst 2016; 141:1172-84. [PMID: 26820190 DOI: 10.1039/c5an01415h] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This review is the first to summarize a decade of studies testing the use of easy ambient sonic-spray ionization mass spectrometry (EASI-MS) and its several sister techniques, Venturi (V-EASI), thermal imprinting (TI-EASI) and Spartan (S-EASI) mass spectrometry in food quality control and authentication. Since minimal or no sample preparation is required, such ambient desorption/ionization techniques have been shown to provide direct, fast and selective fingerprinting characterization at the molecular level based on the pools of the most typical components. They have also been found to be applicable on intact, undisturbed samples or on simple solvent extracts. Fundamentals of EASI-MS and its sister techniques, including mechanisms, devices, parameters and strategies, as well as the many applications reported for food analysis, are summarized and discussed.
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Affiliation(s)
- Andreia M Porcari
- ThoMSon Mass Spectrometry Laboratory, Institute of Chemistry, University of Campinas, UNICAMP, 13083-970 Campinas, SP, Brazil.
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Abstract
The systematic study of the temperature and pressure dependence of matrix-assisted ionization (MAI) led us to the discovery of the seemingly impossible, initially explained by some reviewers as either sleight of hand or the misinterpretation by an overzealous young scientist of results reported many years before and having little utility. The “magic” that we were attempting to report was that with matrix assistance, molecules, at least as large as bovine serum albumin (66 kDa), are lifted into the gas phase as multiply charged ions simply by exposure of the matrix:analyte sample to the vacuum of a mass spectrometer. Applied heat, a laser, or voltages are not necessary to achieve charge states and ion abundances only previously observed with electrospray ionization (ESI). The fundamentals of how solid phase volatile or nonvolatile compounds are converted to gas-phase ions without added energy currently involves speculation providing a great opportunity to rethink mechanistic understanding of ionization processes used in mass spectrometry. Improved understanding of the mechanism(s) of these processes and their connection to ESI and matrix-assisted laser desorption/ionization may provide opportunities to further develop new ionization strategies for traditional and yet unforeseen applications of mass spectrometry. This Critical Insights article covers developments leading to the discovery of a seemingly magic ionization process that is simple to use, fast, sensitive, robust, and can be directly applied to surface characterization using portable or high performance mass spectrometers.
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Affiliation(s)
- Sarah Trimpin
- />Department of Chemistry, Wayne State University, Detroit, MI 48202 USA
- />Cardiovascular Research Institute, Wayne State University School of Medicine, Detroit, MI 48201 USA
- />MSTM, LLC, Newark, DE 19711 USA
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Santos JM, Vendramini PH, Schwab NV, Eberlin MN, de Morais DR. A dopant for improved sensitivity in easy ambient sonic-spray ionization mass spectrometry. J Mass Spectrom 2016; 51:53-61. [PMID: 26757072 DOI: 10.1002/jms.3726] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 10/19/2015] [Accepted: 10/27/2015] [Indexed: 06/05/2023]
Abstract
Recently, 3-nitrobenzonitrile (3-NBN) has been used to improve sensitivity of sonic-spray ionization mass spectrometry. Easy ambient sonic-spray ionization (EASI) is one of the simplest, gentlest and most used spray-based desorption/ionization ambient techniques, but limited sensitivity has been commonly taken as its major drawback. Herein we investigate the use of 3-NBN as a dopant in EASI-MS for improved sensitivity. Using a few typical EASI samples as test cases, the presence of 10 ppm (µg ml(-1) ) of 3-NBN in the spray solvent showed two to fourfold gains in EASI-MS sensitivity as measured both by total ion current and S/N ratios, accompanied with significant reductions in chemical noise. Sensitivity for DESI using 3-NBN as a dopant also improved and dopant DESI versus dopant EASI sensitivities were compared. The use of solvent dopants seems therefore to be a promising strategy to improve sensitivity for spray-based ambient MS techniques. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Jandyson M Santos
- ThoMSon Mass Spectrometry Laboratory, University of Campinas-UNICAMP, Institute of Chemistry, Campinas, São Paulo, 13083-970, Brazil
| | - Pedro H Vendramini
- ThoMSon Mass Spectrometry Laboratory, University of Campinas-UNICAMP, Institute of Chemistry, Campinas, São Paulo, 13083-970, Brazil
| | - Nicolas V Schwab
- ThoMSon Mass Spectrometry Laboratory, University of Campinas-UNICAMP, Institute of Chemistry, Campinas, São Paulo, 13083-970, Brazil
| | - Marcos N Eberlin
- ThoMSon Mass Spectrometry Laboratory, University of Campinas-UNICAMP, Institute of Chemistry, Campinas, São Paulo, 13083-970, Brazil
| | - Damila R de Morais
- ThoMSon Mass Spectrometry Laboratory, University of Campinas-UNICAMP, Institute of Chemistry, Campinas, São Paulo, 13083-970, Brazil
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Yu C, Qian X, Chen Y, Yu Q, Ni K, Wang X. Microfluidic self-aspiration sonic-spray ionization chip with single and dual ionization channels for mass spectrometry. RSC Adv 2016. [DOI: 10.1039/c6ra07959h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In consideration of the miniaturization, integration, and universal disadvantages of microfluidic chip-based ionization coupled with mass spectrometry, this study proposed a novel microfluidic self-aspiration sonic-spray ionization chip.
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Affiliation(s)
- Cilong Yu
- Division of Advanced Manufacturing
- Graduate School at Shenzhen
- Tsinghua University
- Shenzhen
- China
| | - Xiang Qian
- Division of Advanced Manufacturing
- Graduate School at Shenzhen
- Tsinghua University
- Shenzhen
- China
| | - Yan Chen
- Shenzhen Institutes of Advanced Technology
- Chinese Academy of Sciences
- Shenzhen 518055
- China
| | - Quan Yu
- Division of Advanced Manufacturing
- Graduate School at Shenzhen
- Tsinghua University
- Shenzhen
- China
| | - Kai Ni
- Division of Advanced Manufacturing
- Graduate School at Shenzhen
- Tsinghua University
- Shenzhen
- China
| | - Xiaohao Wang
- Division of Advanced Manufacturing
- Graduate School at Shenzhen
- Tsinghua University
- Shenzhen
- China
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Yu C, Qian X, Chen Y, Yu Q, Ni K, Wang X. Three-Dimensional Electro-Sonic Flow Focusing Ionization Microfluidic Chip for Mass Spectrometry. Micromachines 2015; 6:1890-902. [DOI: 10.3390/mi6121463] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Ambient ionization MS has become very popular in analytical science and has now evolved as an effective analytical tool in metabolomics, biological tissue imaging, protein and small molecule drug analysis, where biological samples are probed in a rapid and direct fashion with minimal sample preparation at ambient conditions. However, certain inherent challenges continue to hinder the vibrant prospects of these methods for in situ analyses or to replace conventional methods in bioanalysis. This review provides an introduction to the field and its application in bioanalysis, with an emphasis on the most recent developments and applications. Furthermore, ongoing challenges or limitations related to quantitation, sensitivity, selectivity, instrumentation and mass range of these ambient methods will also be discussed.
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