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Urban RD, Fischer TG, Charvat A, Wink K, Krafft B, Ohla S, Zeitler K, Abel B, Belder D. On-chip mass spectrometric analysis in non-polar solvents by liquid beam infrared matrix-assisted laser dispersion/ionization. Anal Bioanal Chem 2021; 413:1561-1570. [PMID: 33479818 PMCID: PMC7921053 DOI: 10.1007/s00216-020-03115-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/01/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022]
Abstract
By the on-chip integration of a droplet generator in front of an emitter tip, droplets of non-polar solvents are generated in a free jet of an aqueous matrix. When an IR laser irradiates this free liquid jet consisting of water as the continuous phase and the non-polar solvent as the dispersed droplet phase, the solutes in the droplets are ionized. This ionization at atmospheric pressure enables the mass spectrometric analysis of non-polar compounds with the aid of a surrounding aqueous matrix that absorbs IR light. This works both for non-polar solvents such as n-heptane and for water non-miscible solvents like chloroform. In a proof of concept study, this approach is applied to monitor a photooxidation of N-phenyl-1,2,3,4-tetrahydroisoquinoline. By using water as an infrared absorbing matrix, analytes, dissolved in non-polar solvents from reactions carried out on a microchip, can be desorbed and ionized for investigation by mass spectrometry.
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Affiliation(s)
- Raphael D Urban
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Tillmann G Fischer
- Institut für Organische Chemie, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany
| | - Ales Charvat
- Leibniz-Institut für Oberflächenmodifizierung e.V., Abteilung Funktionale Oberflächen, Permoserstr. 15, 04318, Leipzig, Germany
| | - Konstantin Wink
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Benjamin Krafft
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Stefan Ohla
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Kirsten Zeitler
- Institut für Organische Chemie, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany
| | - Bernd Abel
- Leibniz-Institut für Oberflächenmodifizierung e.V., Abteilung Funktionale Oberflächen, Permoserstr. 15, 04318, Leipzig, Germany
| | - Detlev Belder
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany.
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Lu Y, Pieterse CL, Robertson WD, Miller RJD. Soft Picosecond Infrared Laser Extraction of Highly Charged Proteins and Peptides from Bulk Liquid Water for Mass Spectrometry. Anal Chem 2018. [PMID: 29522677 DOI: 10.1021/acs.analchem.7b04306] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the soft laser extraction and production of highly charged peptide and protein ions for mass spectrometry directly from bulk liquid water at atmospheric pressure and room temperature, using picosecond infrared laser ablation. Stable ion signal from singly charged small molecules, as well as highly charged biomolecular ions, from aqueous solutions at low laser pulse fluence (∼0.3 J cm-2) is demonstrated. Sampling via single picosecond laser pulses is shown to extract less than 27 pL of volume from the sample, producing highly charged peptide and protein ions for mass spectrometry detection. The ablation and ion generation is demonstrated to be soft in nature, producing natively folded proteins ions under sample conditions described for native mass spectrometry. The method provides laser-based sampling flexibility, precision and control with highly charged ion production directly from water at low and near neutral pH. This approach does not require an additional ionization device or high voltage applied directly to the sample.
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Affiliation(s)
- Yinfei Lu
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149 , Hamburg 22761 , Germany
| | - Cornelius L Pieterse
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149 , Hamburg 22761 , Germany
| | - Wesley D Robertson
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149 , Hamburg 22761 , Germany
| | - R J Dwayne Miller
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149 , Hamburg 22761 , Germany
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Iguchi Y, Hazama H, Awazu K. Continuous flow reduced-pressure infrared laser desorption/ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:1845-1850. [PMID: 28850755 DOI: 10.1002/rcm.7970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 08/04/2017] [Accepted: 08/19/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Continuous flow ionization methods using infrared (IR) lasers have several favorable characteristics, including ionization without any additional matrices and tolerance to contaminants such as detergents and buffer salts. However, poor sensitivity due to low ion-transfer efficiency from the sample plate to the inlet capillary of the mass spectrometer under atmospheric pressure remains a serious problem. METHODS We developed a new continuous flow IR laser desorption/ionization (IR-LDI) method using a frit plate and wavelength-tunable mid-IR laser with an optical parametric oscillator. Continuous flow samples were directly injected into the ion source without any additional matrices. The ion source was covered with a decompression chamber, and could vary the pressure of the ion source from 21 to 101 kPa. RESULTS Reduction of the pressure of the IR-LDI source from 101 to 71 kPa increased the signal intensity for the [M + H]+ ion of angiotensin II by 1.8-fold. On the other hand, the ion signal intensity was reduced at pressures lower than 71 kPa. It became clear that reducing pressure was more effective when ionization occurred with lower laser pulse energy and lower ion source temperature. In addition, signal intensities for the [M + 2H]2+ and [M + 3H]3+ ions of insulin were also increased, by 1.4-fold and 1.1-fold, respectively, upon reduction of the pressure to 91 and 81 kPa. CONCLUSIONS Although many studies have described IR-LDI using a differential pumping mass spectrometer, the optimal pressure of the ion source has never been investigated. We found that a slight reduction in pressure enhances sensitivity. This knowledge may be applicable to a number of ambient ionization methods using IR lasers.
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Affiliation(s)
- Yasunari Iguchi
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hisanao Hazama
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kunio Awazu
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
- Global Center for Medical Engineering and Informatics, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Ingram AJ, Boeser CL, Zare RN. Going beyond electrospray: mass spectrometric studies of chemical reactions in and on liquids. Chem Sci 2016; 7:39-55. [PMID: 28757996 PMCID: PMC5508663 DOI: 10.1039/c5sc02740c] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/01/2015] [Indexed: 12/16/2022] Open
Abstract
There has been a burst in the number and variety of available ionization techniques to use mass spectrometry to monitor chemical reactions in and on liquids. Chemists have gained the capability to access chemistry at unprecedented timescales, and monitor reactions and detect intermediates under almost any set of conditions. Herein, recently developed ionization techniques that facilitate mechanistic studies of chemical processes are reviewed. This is followed by a discussion of our perspective on the judicious application of these and similar techniques in order to study reaction mechanisms.
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Affiliation(s)
- Andrew J Ingram
- Department of Chemistry , Stanford University , Stanford , CA 94305 , USA .
| | | | - Richard N Zare
- Department of Chemistry , Stanford University , Stanford , CA 94305 , USA .
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Li L, Schug KA. Continuous-flow extractive desorption electrospray ionization coupled to normal phase separations and for direct lipid analysis from cell extracts. J Sep Sci 2014; 37:2357-63. [DOI: 10.1002/jssc.201400361] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 06/01/2014] [Accepted: 06/02/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Li Li
- Department of Chemistry and Biochemistry; The University of Texas at Arlington; Arlington TX USA
| | - Kevin A. Schug
- Department of Chemistry and Biochemistry; The University of Texas at Arlington; Arlington TX USA
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Park SG, Murray KK. Ambient laser ablation sampling for capillary electrophoresis mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:1673-1680. [PMID: 23821560 DOI: 10.1002/rcm.6618] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/06/2013] [Accepted: 05/06/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE Ambient laser ablation with mass spectrometric detection is a powerful method for direct analysis of biological samples in their native environment. Capillary electrophoresis (CE) can separate complex mixtures of biological molecules prior to mass spectrometry (MS) analysis and an ambient sampling interface for CE/MS will allow the detection of minor components. METHODS An infrared (IR) laser ablated and transferred sample materials under ambient conditions for direct loading onto the CE separation column. Samples were deposited on a transparent target and ablated in transmission geometry using a pulsed mid-IR laser. The ablated materials were captured in the exposed sampling solvent and then loaded into a capillary by electrokinetic injection for separation and analysis by electrospray ionization (ESI)-MS. RESULTS The system was tested using mixtures of peptide and protein standards. It is estimated that tens of fmol of material was transferred from the ablation target for injection into the CE system and the theoretical plate number was between 1000 and 3000. CONCLUSIONS A novel interface for ambient sampling to CE/MS was developed. The interface is generally applicable and has potential utility for mass spectrometry imaging as well as the loading of microfluidic devices from untreated ambient samples.
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Affiliation(s)
- Sung-Gun Park
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
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Park SG, Murray KK. Infrared laser ablation sample transfer for on-line liquid chromatography electrospray ionization mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2012; 47:1322-1326. [PMID: 23019163 DOI: 10.1002/jms.3096] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have demonstrated an on-line laser ablation sampling system and coupling of the system to liquid chromatography (LC) using an infrared (IR) laser to ablate and transfer materials into a flowing solvent stream. With this approach, samples are deposited on a microscope slide mounted on a translation stage and ablated in transmission geometry using a pulsed mid-IR laser. The ablated material is captured in an exposed flowing solvent stream that carries the ablated material to the electrospray source. Post-ablation separation is accomplished using a capillary column downstream of the capture zone. The performance of the system was assessed using peptide and protein mixtures ablated from the target and analyzed with and without LC separation.
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Affiliation(s)
- Sung-Gun Park
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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Yao ZP. Characterization of proteins by ambient mass spectrometry. MASS SPECTROMETRY REVIEWS 2012; 31:437-47. [PMID: 21898526 DOI: 10.1002/mas.20346] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 06/07/2011] [Accepted: 06/19/2011] [Indexed: 05/16/2023]
Abstract
Proteins play important roles in living systems and are topics of many fundamental and applied research projects. With the introduction of electrospray ionization and matrix-assisted laser desorption/ionization for analysis of biomacromolecules in the late 1980s, mass spectrometry has become an important tool for characterization of proteins. Characterization of proteins in raw samples by these mass spectrometric techniques, however, usually requires extensive sample pretreatment. Ambient ionization techniques are new mass spectrometric techniques that allow direct analysis of samples with no or little sample preparation. Can these techniques facilitate or even eliminate sample preparation for mass spectrometric analysis of proteins? Apart from sample preparation, do these techniques offer any new features for characterization of proteins as compared with conventional ESI or MALDI? Recent advances in characterization of proteins by ambient mass spectrometry are summarized and commented in this article.
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Affiliation(s)
- Zhong-Ping Yao
- State Key Laboratory for Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, China.
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Harris GA, Galhena AS, Fernández FM. Ambient sampling/ionization mass spectrometry: applications and current trends. Anal Chem 2011; 83:4508-38. [PMID: 21495690 DOI: 10.1021/ac200918u] [Citation(s) in RCA: 366] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Glenn A Harris
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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