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Smith BL, Hankinson T, Maher S. Portable Instrumentation for Ambient Ionization and Miniature Mass Spectrometers. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2024; 17:69-102. [PMID: 38640067 DOI: 10.1146/annurev-anchem-061522-040824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/21/2024]
Abstract
We critically evaluate the current status of portable mass spectrometry (pMS), particularly where this aligns with ambient ionization. Assessing the field of pMS can be quite subjective, especially in relation to the portable aspects of design, deployment, and operation. In this review, we discuss what it means to be portable and introduce a set of criteria by which pMS and ambient ionization sources can be assessed. Moreover, we consider the recent literature in terms of the most popular and significant advances in portable instrumentation for ambient ionization and miniature mass spectrometers. Finally, emerging trends and exciting future prospects are discussed and some recommendations are offered.
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Affiliation(s)
- Barry L Smith
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom;
| | - Thomas Hankinson
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom;
| | - Simon Maher
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom;
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2
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Fan J, Ma W, Yu Y, Li Y, Nie Z. Recent advances in entirely hand-held ionization sources for mass spectrometry. Anal Bioanal Chem 2024; 416:2057-2063. [PMID: 37930374 DOI: 10.1007/s00216-023-05022-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/07/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023]
Abstract
Ambient ionization mass spectrometry (AIMS) has been developing explosively since its first debut. The ionization process was hence able to be achieved under atmospheric pressure, facilitating on-site field analysis in a variety of areas, such as clinical diagnosis, metabolic phenotyping, and surface analysis. As part of the ambitious goal of making MS a general device that can be used in everyday life, lots of efforts have been paid to miniaturize the ionization source. This review discusses avant-garde sources that could be entirely hand-held without any accessories. The structure and applications of the devices are described in detail as well. They could be expediently used in real-time and on-site analysis, presenting a great future potential for the routinizing of MS.
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Affiliation(s)
- Jinghan Fan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wenbo Ma
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan, 750021, China
| | - Yile Yu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuze Li
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan, 750021, China.
| | - Zongxiu Nie
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- State Key Laboratory of High-Efficiency Utilization of Coal and Green Chemical Engineering, College of Chemistry and Chemical Engineering, Ningxia University, Yinchuan, 750021, China.
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Yue H, He F, Zhao Z, Duan Y. Plasma-based ambient mass spectrometry: Recent progress and applications. MASS SPECTROMETRY REVIEWS 2023; 42:95-130. [PMID: 34128567 DOI: 10.1002/mas.21712] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/28/2020] [Accepted: 06/02/2020] [Indexed: 06/12/2023]
Abstract
Ambient mass spectrometry (AMS) has grown as a group of advanced analytical techniques that allow for the direct sampling and ionization of the analytes in different statuses from their native environment without or with minimum sample pretreatments. As a significant category of AMS, plasma-based AMS has gained a lot of attention due to its features that allow rapid, real-time, high-throughput, in vivo, and in situ analysis in various fields, including bioanalysis, pharmaceuticals, forensics, food safety, and mass spectrometry imaging. Tens of new methods have been developed since the introduction of the first plasma-based AMS technique direct analysis in real-time. This review first provides a comprehensive overview of the established plasma-based AMS techniques from their ion source configurations, mechanisms, and developments. Then, the progress of the representative applications in various scientific fields in the past 4 years (January 2017 to January 2021) has been summarized. Finally, we discuss the current challenges and propose the future directions of plasma-based AMS from our perspective.
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Affiliation(s)
- Hanlu Yue
- College of Life Sciences, Sichuan University, Chengdu, China
| | - Feiyao He
- College of Life Sciences, Sichuan University, Chengdu, China
| | - Zhongjun Zhao
- School of Chemical Engineering, Sichuan University, Chengdu, China
| | - Yixiang Duan
- College of Life Sciences, Sichuan University, Chengdu, China
- School of Manufacturing Science and Engineering, Sichuan University, Chengdu, China
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Wang J, Pursell ME, DeVor A, Awoyemi O, Valentine SJ, Li P. Portable mass spectrometry system: instrumentation, applications, and path to 'omics analysis. Proteomics 2022; 22:e2200112. [PMID: 36349734 PMCID: PMC10278091 DOI: 10.1002/pmic.202200112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 11/11/2022]
Abstract
Mass spectrometry (MS) is an information rich analytical technique and plays a key role in various 'omics studies. Standard mass spectrometers are bulky and operate at high vacuum, which hinder their adoption by the broader community and utility in field applications. Developing portable mass spectrometers can significantly expand the application scope and user groups of MS analysis. This review discusses the basics and recent advancements in the development of key components of portable mass spectrometers including ionization source, mass analyzer, detector, and vacuum system. Further, major areas where portable mass spectrometers are applied are also discussed. Finally, a perspective on the further development of portable mass spectrometers including the potential benefits for 'omics analysis is provided.
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Affiliation(s)
- Jing Wang
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Madison E. Pursell
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Amanda DeVor
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Olanrewaju Awoyemi
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Stephen J. Valentine
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Peng Li
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
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Evans-Nguyen K, Stelmack AR, Clowser PC, Holtz JM, Mulligan CC. FIELDABLE MASS SPECTROMETRY FOR FORENSIC SCIENCE, HOMELAND SECURITY, AND DEFENSE APPLICATIONS. MASS SPECTROMETRY REVIEWS 2021; 40:628-646. [PMID: 32722885 DOI: 10.1002/mas.21646] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 02/24/2020] [Indexed: 05/26/2023]
Abstract
Mass spectrometry is commonly used in forensic chemistry laboratories for sensitive, definitive analysis. There have been significant efforts to bring mass spectrometry analysis on-site through the development of ruggedized, fieldable instruments. Testing samples in the field is of particular interest in forensic science, homeland security, and defense applications. In forensic chemistry, testing seized drugs in the field can significantly improve efficiencies in processing of related criminal cases. The screening of passengers and luggage at transportation hubs is a critical need for homeland security for which mass spectrometry is well suited to provide definitive answers with low false positive rates. Mass spectrometry can yield reliable data for military personnel testing sites for potential chemical weapons release. To meet the needs of the forensic and security communities fieldable mass spectrometers based on membrane inlet systems and hybrid gas chromatography systems have been developed and commercialized. More recently developed ambient ionization mass spectrometry methods can eliminate the time, equipment, and expertise associated with sample preparation, and so are especially appealing for on-site analysis. We describe the development of fieldable mass spectrometry systems, with emphasis on commercially available systems that have been deployed for on-site analysis of seized drugs, chemical warfare agents, explosives, and other analytes of interest to the forensic and security communities. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Kenyon Evans-Nguyen
- Department of Chemistry, Biochemistry and Physics, University of Tampa, Tampa, FL
| | | | | | - Jessica M Holtz
- Department of Chemistry, Illinois State University, Normal, IL
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Charoensumran P, Rauytanapanit M, Sricharoen N, Smith BL, Wongravee K, Maher S, Praneenararat T. Rapid geographical indication of peppercorn seeds using corona discharge mass spectrometry. Sci Rep 2021; 11:16089. [PMID: 34373549 PMCID: PMC8352875 DOI: 10.1038/s41598-021-95462-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/27/2021] [Indexed: 11/08/2022] Open
Abstract
With increasing demands for more rapid and practical analyses, various techniques of ambient ionization mass spectrometry have gained significant interest due to the speed of analysis and abundance of information provided. Herein, an ambient ionization technique that utilizes corona discharge was applied, for the first time, to analyze and categorize whole seeds of black and white peppers from different origins. This setup requires no solvent application nor gas flow, thus resulting in a very simple and rapid analysis that can be applied directly to the sample without any prior workup or preparation. Combined with robust data pre-processing and subsequent chemometric analyses, this analytical method was capable of indicating the geographical origin of each pepper source with up to 98% accuracies in all sub-studies. The simplicity and speed of this approach open up the exciting opportunity for onsite analysis without the need for a highly trained operator. Furthermore, this methodology can be applied to a variety of spices and herbs, whose geographical indication or similar intellectual properties are economically important, hence it is capable of creating tremendous impact in the food and agricultural industries.
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Affiliation(s)
- Preeyarad Charoensumran
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand
- The Chemical Approaches for Food Applications Research Group, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand
| | - Monrawat Rauytanapanit
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand
- The Chemical Approaches for Food Applications Research Group, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand
| | - Nontawat Sricharoen
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand
- Center of Excellence in Bioactive Resources for Innovative Clinical Applications, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Barry L Smith
- Department of Electrical Engineering & Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
| | - Kanet Wongravee
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand.
- Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand.
| | - Simon Maher
- Department of Electrical Engineering & Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
| | - Thanit Praneenararat
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand.
- The Chemical Approaches for Food Applications Research Group, Faculty of Science, Chulalongkorn University, Phayathai Rd., Pathumwan, Bangkok, 10330, Thailand.
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Meisenbichler C, Kluibenschedl F, Müller T. A 3-in-1 Hand-Held Ambient Mass Spectrometry Interface for Identification and 2D Localization of Chemicals on Surfaces. Anal Chem 2020; 92:14314-14318. [PMID: 33063994 PMCID: PMC7643069 DOI: 10.1021/acs.analchem.0c02615] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
![]()
Desorption electrospray ionization
(DESI), easy ambient sonic-spray
ionization (EASI) and low-temperature plasma (LTP) ionization are
powerful ambient ionization techniques for mass spectrometry. However,
every single method has its limitation in terms of polarity and molecular
weight of analyte molecules. After the miniaturization of every possible
component of the different ion sources, we finally were able to embed
two emitters and an ion transfer tubing into a small, hand-held device.
The pen-like interface is connected to the mass spectrometer and a
separate control unit via a bundle of flexible tubing and cables.
The novel device allows the user to ionize an extended range of chemicals
by simple switching between DESI, voltage-free EASI, or LTP ionization
as well as to freely move the interface over a surface of interest.
A mini camera, which is mounted on the tip of the pen, magnifies the
desorption area and enables a simple positioning of the pen. The interface
was successfully tested using different types of chemicals, pharmaceuticals,
and real life samples. Moreover, the combination of optical data from
the camera module and chemical data obtained by mass analysis facilitates
a novel type of imaging mass spectrometry, which we name “interactive
mass spectrometry imaging (IMSI)”.
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Affiliation(s)
- Christina Meisenbichler
- Institute of Organic Chemistry, Leopold-Franzens University Innsbruck, 6020 Innsbruck, Austria
| | - Florian Kluibenschedl
- Institute of Organic Chemistry, Leopold-Franzens University Innsbruck, 6020 Innsbruck, Austria
| | - Thomas Müller
- Institute of Organic Chemistry, Leopold-Franzens University Innsbruck, 6020 Innsbruck, Austria
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8
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Desorption atmospheric pressure chemical ionization: A review. Anal Chim Acta 2020; 1130:146-154. [DOI: 10.1016/j.aca.2020.05.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 05/29/2020] [Accepted: 05/30/2020] [Indexed: 01/27/2023]
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Jjunju FPM, Damon DE, Romero-Perez D, Young IS, Ward RJ, Marshall A, Maher S, Badu-Tawiah AK. Analysis of non-conjugated steroids in water using paper spray mass spectrometry. Sci Rep 2020; 10:10698. [PMID: 32612114 PMCID: PMC7329809 DOI: 10.1038/s41598-020-67484-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 06/01/2020] [Indexed: 11/09/2022] Open
Abstract
A novel strategy for the direct analysis of non-conjugated steroids in water using paper spray mass spectrometry (PS-MS) has been developed. PS-MS was used in the identification and quantification of non-conjugated (free) steroids in fish tank water samples. Data shown herein indicates that individual amounts of free steroids can be detected in aqua as low as; 0.17 ng/µL, 0.039 ng/µL, 0.43 ng/µL, 0.0076 ng/µL for aldosterone, corticosterone, cortisol, and β-estrone, respectively, and with an average relative standard deviation of ca. < 10% in the positive ion mode using PS-MS/MS. Direct detection of free steroids in a raw water mixture, from aquaculture, without prior sample preparation is demonstrated. The presence of free steroids released in fish water samples was confirmed via tandem mass spectrometry using collision-induced dissociation. This approach shows promise for rapid and direct water quality monitoring to provide a holistic assessment of non-conjugated steroids in aqua.
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Affiliation(s)
- Fred P M Jjunju
- Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
| | - Deidre E Damon
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - David Romero-Perez
- Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
| | - Iain S Young
- Institute of Integrative Biology, Biosciences Building, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Ryan J Ward
- Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
| | - Alan Marshall
- Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK
| | - Simon Maher
- Department of Electrical Engineering and Electronics, University of Liverpool, Brownlow Hill, Liverpool, L69 3GJ, UK.
| | - Abraham K Badu-Tawiah
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA.
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Smith BL, Boisdon C, Young IS, Praneenararat T, Vilaivan T, Maher S. Flexible Drift Tube for High Resolution Ion Mobility Spectrometry (Flex-DT-IMS). Anal Chem 2020; 92:9104-9112. [PMID: 32479060 PMCID: PMC7467419 DOI: 10.1021/acs.analchem.0c01357] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
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This paper describes,
in detail, the development of a novel, low-cost,
and flexible drift tube (DT) along with an associated ion mobility
spectrometer system. The DT is constructed from a flexible printed
circuit board (PCB), with a bespoke “dog-leg” track
design, that can be rolled up for ease of assembly. This approach
incorporates a shielding layer, as part of the flexible PCB design,
and represents the minimum dimensional footprint conceivable for a
DT. The low thermal mass of the polyimide substrate and overlapping
electrodes, as afforded by the dog-leg design, allow for efficient
heat management and high field linearity within the tube–achieved
from a single PCB. This is further enhanced by a novel double-glazing
configuration which provides a simple and effective means for gas
management, minimizing thermal variation within the assembly. Herein,
we provide a full experimental characterization of the flexible DT
ion mobility spectrometer (Flex-DT-IMS) with corresponding electrodynamic
(Simion 8.1) and fluid dynamic (SolidWorks) simulations. The Flex-DT-IMS
is shown to have a resolution >80 and a detection limit of low
nanograms
for the analysis of common explosives (RDX, PETN, HMX, and TNT).
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Affiliation(s)
- Barry L Smith
- Department of Electrical Engineering & Electronics, University of Liverpool, Liverpool L69 3GJ, U.K
| | - Cedric Boisdon
- Department of Electrical Engineering & Electronics, University of Liverpool, Liverpool L69 3GJ, U.K
| | - Iain S Young
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 3BX, U.K
| | - Thanit Praneenararat
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Tirayut Vilaivan
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Simon Maher
- Department of Electrical Engineering & Electronics, University of Liverpool, Liverpool L69 3GJ, U.K
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Potential of Recent Ambient Ionization Techniques for Future Food Contaminant Analysis Using (Trans)Portable Mass Spectrometry. FOOD ANAL METHOD 2019. [DOI: 10.1007/s12161-019-01666-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
AbstractIn food analysis, a trend towards on-site testing of quality and safety parameters is emerging. So far, on-site testing has been mainly explored by miniaturized optical spectroscopy and ligand-binding assay approaches such as lateral flow immunoassays and biosensors. However, for the analysis of multiple parameters at regulatory levels, mass spectrometry (MS) is the method of choice in food testing laboratories. Thanks to recent developments in ambient ionization and upcoming miniaturization of mass analyzers, (trans)portable mass spectrometry may be added to the toolkit for on-site testing and eventually compete with multiplex immunoassays in mixture analysis. In this study, we preliminary evaluated a selection of recent ambient ionization techniques for their potential in simplified testing of selected food contaminants such as pesticides, veterinary drugs, and natural toxins, aiming for a minimum in sample preparation while maintaining acceptable sensitivity and robustness. Matrix-assisted inlet ionization (MAI), handheld desorption atmospheric pressure chemical ionization (DAPCI), transmission-mode direct analysis in real time (TM-DART), and coated blade spray (CBS) were coupled to both benchtop Orbitrap and compact quadrupole single-stage mass analyzers, while CBS was also briefly studied on a benchtop triple-quadrupole MS. From the results, it can be concluded that for solid and liquid sample transmission configurations provide the highest sensitivity while upon addition of a stationary phase, such as in CBS, even low μg/L levels in urine samples can be achieved provided the additional selectivity of tandem mass spectrometry is exploited.
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Smith BL, Hughes DM, Badu-Tawiah AK, Eccles R, Goodall I, Maher S. Rapid Scotch Whisky Analysis and Authentication using Desorption Atmospheric Pressure Chemical Ionisation Mass Spectrometry. Sci Rep 2019; 9:7994. [PMID: 31142757 PMCID: PMC6541643 DOI: 10.1038/s41598-019-44456-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 05/13/2019] [Indexed: 01/17/2023] Open
Abstract
Whisky, as a high value product, is often adulterated, with adverse economic effects for both producers and consumers as well as potential public health impacts. Here we report the use of DAPCI-MS to analyse and chemically profile both genuine and counterfeit whisky samples employing a novel 'direct from the bottle' methodology with zero sample pre-treatment, zero solvent requirement and almost no sample usage. 25 samples have been analysed from a collection of blended Scotch whisky (n = 15) and known counterfeit whisky products (n = 10). Principal component analysis has been applied to dimensionally reduce the data and discriminate between sample groups. Additional chemometric modelling, a partial least squares regression, has correctly classified samples with 92% success rate. DAPCI-MS shows promise for simple, fast and accurate counterfeit detection with potential for generic aroma profiling and process quality monitoring applications.
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Affiliation(s)
- Barry L Smith
- Department of Electrical Engineering & Electronics, University of Liverpool, Liverpool, UK
| | - David M Hughes
- Department of Biostatistics, University of Liverpool, Liverpool, UK
| | | | - Rebecca Eccles
- The Scotch Whisky Research Institute, The Robertson Trust Building, Edinburgh, UK
| | - Ian Goodall
- The Scotch Whisky Research Institute, The Robertson Trust Building, Edinburgh, UK
| | - Simon Maher
- Department of Electrical Engineering & Electronics, University of Liverpool, Liverpool, UK.
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In-Situ Analysis of Essential Fragrant Oils Using a Portable Mass Spectrometer. Int J Anal Chem 2019; 2019:1780190. [PMID: 31057619 PMCID: PMC6463677 DOI: 10.1155/2019/1780190] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/16/2019] [Accepted: 03/05/2019] [Indexed: 12/13/2022] Open
Abstract
A portable mass spectrometer was coupled to a direct inlet membrane (DIM) probe and applied to the direct analysis of active fragrant compounds (3-methylbutyl acetate, 2-methyl-3-furanthiol, methyl butanoate, and ethyl methyl sulfide) in real time. These fragrant active compounds are commonly used in the formulation of flavours and fragrances. Results obtained show that the portable mass spectrometer with a direct membrane inlet can be used to detect traces of the active fragrant compounds in complex mixtures such as essential fragrant oils and this represents a novel in-situ analysis methodology. Limits of detection (LOD) in the sub-ppb range (< 2.5 pg) are demonstrated. Standard samples in the gaseous phase presented very good linearity with RSD % at 5 to 7 for the selected active fragrant compounds (i.e., isoamyl acetate, 2-methyl-3-furanthiol, methyl butanoate, and methyl ethyl sulphide). The rise and fall times of the DIM probe are in the ranges from 15 to 31 seconds and 23 to 41 seconds, respectively, for the standard model compounds analysed. The identities of the fragrance active compounds in essential oil samples (i.e., banana, tangerine, papaya, and blueberry muffin) were first identified by comparison with a standard fragrance compounds mixture using their major fragment peaks, the NIST standard reference library, and gas chromatography mass spectrometry (GC-MS) analysis. No sample preparation is required for analysis using a portable mass spectrometer coupled to a DIM probe, so the cycle time from ambient air sampling to the acquisition of the results is at least 65 seconds.
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Bristow R, Young I, Pemberton A, Williams J, Maher S. An extensive review of the extraction techniques and detection methods for the taste and odour compound geosmin (trans-1, 10-dimethyl-trans-9-decalol) in water. Trends Analyt Chem 2019. [DOI: 10.1016/j.trac.2018.10.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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15
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Zeng W, Manoj D, Sun H, Yi R, Huang X, Sun Y. One-pot synthesis of high-density Pd nanoflowers decorated 3D carbon nanotube-graphene network modified on printed electrode as portable electrochemical sensing platform for sensitive detection of nitroaromatic explosives. J Electroanal Chem (Lausanne) 2019. [DOI: 10.1016/j.jelechem.2018.12.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Antony Joseph MJ, McIntosh DG, Gibson JR, Taylor S. Effects of the source gap on transmission efficiency of a quadrupole mass spectrometer. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:677-685. [PMID: 29490121 PMCID: PMC5947150 DOI: 10.1002/rcm.8094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE Recent trends towards miniature and portable quadrupole mass spectrometry (QMS) entail challenges in instrumental sensitivity, which is influenced by 3D fringe field effects on ion transmission in the Quadrupole Mass Filter (QMF). The relationship of these effects with the gap from the ion source to the QMF entrance (source gap) is significant and little explored. We examine transmission characteristics experimentally and use the results to test the predictive accuracy of a recently developed 3D QMF simulation model. The model is then applied to directly investigate optimal transmission m/z ranges across multiple source gaps. METHODS A portable single filter quadrupole mass spectrometer is used to analyse transmission characteristics across a range of common gases. We use an experimental approach originally proposed by Ehlert, enhanced with a novel method for absolute calibration of the transmission curve. Custom QMF simulation software employs the boundary element method (BEM) to compute accurate 3D electric fields. This is used to study the effects of the source gap on transmission efficiency. RESULTS Experimental findings confirm a centrally peaked transmission curve; simulations correctly predict the optimal transmission location (in m/z) and percentage, and extend the experimental trend. We compare several methods for determining fringe field length, demonstrating how the size of the physical source gap influences both the length and the intensity of the fringe field at the QMF entrance. A complex relationship with ion transmission is revealed in which different source gaps promote optimal transmission at differing m/z ranges. CONCLUSIONS The presented results map the relationship between the source gap and transmission efficiency for the given instrument, using a simulation method transferrable to other setups. This is of importance to miniature and portable quadrupole mass spectrometers design for specific applications, for the first time enabling the source gap to be tailored for optimal transmission in the desired mass range.
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Affiliation(s)
- Mariya J. Antony Joseph
- Mass Spectrometry and Instrumentation Group, Department of Electrical Engineering and ElectronicsUniversity of LiverpoolBrownlow HillLiverpoolL69 3GJUK
| | - David G. McIntosh
- Mass Spectrometry and Instrumentation Group, Department of Electrical Engineering and ElectronicsUniversity of LiverpoolBrownlow HillLiverpoolL69 3GJUK
| | - J. Raymond Gibson
- Mass Spectrometry and Instrumentation Group, Department of Electrical Engineering and ElectronicsUniversity of LiverpoolBrownlow HillLiverpoolL69 3GJUK
| | - Stephen Taylor
- Mass Spectrometry and Instrumentation Group, Department of Electrical Engineering and ElectronicsUniversity of LiverpoolBrownlow HillLiverpoolL69 3GJUK
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17
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Abstract
Ambient mass spectrometry has evolved rapidly over the past decade, yielding a plethora of platforms and demonstrating scientific advancements across a range of fields from biological imaging to rapid quality control. These techniques have enabled real-time detection of target analytes in an open environment with no sample preparation and can be coupled to any mass analyzer with an atmospheric pressure interface; capabilities of clear interest to the defense, customs and border control, transportation security, and forensic science communities. This review aims to showcase and critically discuss advances in ambient mass spectrometry for the trace detection of explosives.
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Affiliation(s)
- Thomas P Forbes
- National Institute of Standards and Technology, Materials Measurement Science Division, Gaithersburg, MD, USA.
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18
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Tsai CW, Tipple CA, Yost RA. Integration of paper spray ionization high-field asymmetric waveform ion mobility spectrometry for forensic applications. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:552-560. [PMID: 29380926 DOI: 10.1002/rcm.8068] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 11/30/2017] [Accepted: 01/20/2018] [Indexed: 05/28/2023]
Abstract
RATIONALE Paper spray ionization (PSI) is an attractive ambient ionization source for mass spectrometry (MS) since it allows the combination of surface sampling and ionization. The minimal sample preparation inherent in this approach greatly reduces the time needed for analysis. However, the ions generated from interfering compounds in the sample and the paper substrate may interfere with the analyte ions. Therefore, the integration of PSI with high-field asymmetric ion mobility spectrometry (FAIMS) is of significant interest since it should reduce the background ions entering the mass analyzer without complicating the analysis or increasing analysis time. Here we demonstrate the integration of PSI with FAIMS/MS and its potential for analysis of samples of forensic interest. METHODS In this work, the parameters that can influence the integration, including sampling and ionization by paper spray, the FAIMS separation of analytes from each other and background interferences, and the length of time that a usable signal can be observed for explosives on paper, were evaluated with the integrated system. RESULTS In the negative ion analysis of 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), amounts as low as 1 ng on paper were readily observed. The successful positive ion separation of a set of illicit drugs including heroin, methamphetamine, and cocaine was also achieved. In addition, the positive ion analysis of the chemical warfare agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP) was evaluated. CONCLUSIONS The integration of PSI-FAIMS/MS was demonstrated for the analyses of explosives in negative ion mode and for illicit drugs and CW simulants in positive mode. Paper background ions that could interfere with these analyses were separated by FAIMS. The compensation voltage of an ion obtained by FAIMS provided an additional identification parameter to be combined with the mass spectrum for each analyte.
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Affiliation(s)
- Chia-Wei Tsai
- Department of Chemistry, University of Florida, Gainesville, FL, USA
- Counterterrorism and Forensic Science Research Unit, Visiting Scientist Program, Federal Bureau of Investigation Laboratory Division, Quantico, VA, USA
| | - Christopher A Tipple
- Counterterrorism and Forensic Science Research Unit, Federal Bureau of Investigation Laboratory Division, Quantico, VA, USA
| | - Richard A Yost
- Department of Chemistry, University of Florida, Gainesville, FL, USA
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19
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Rahman MM, Jiang T, Tang Y, Xu W. A simple desorption atmospheric pressure chemical ionization method for enhanced non-volatile sample analysis. Anal Chim Acta 2018; 1002:62-69. [DOI: 10.1016/j.aca.2017.11.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/04/2017] [Accepted: 11/14/2017] [Indexed: 02/06/2023]
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20
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Boggess A, Crump S, Gregory C, Young J, Kessinger G. Analytical method for nitroaromatic explosives in radiologically contaminated soil for ISO/IEC 17025 accreditation. Forensic Chem 2018. [DOI: 10.1016/j.forc.2017.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Jagerdeo E, Wriston A. Rapid analysis of forensic-related samples using two ambient ionization techniques coupled to high-resolution mass spectrometers. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:782-790. [PMID: 28263006 DOI: 10.1002/rcm.7844] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/22/2017] [Accepted: 02/23/2017] [Indexed: 05/05/2023]
Abstract
RATIONALE This paper highlights the versatility of interfacing two ambient ionization techniques, Laser Diode Thermal Desorption (LDTD) and Atmospheric Solids Analysis Probe (ASAP), to high-resolution mass spectrometers and demonstrate the method's capability to rapidly generate high-quality data from multiple sample types with minimal, if any, sample preparation. METHODS For ASAP-MS analysis of solid and liquid samples, the material was transferred to a capillary surface before being introduced into the mass spectrometer. For LDTD-MS analysis, samples were solvent extracted, spotted in a 96-well plate, and the solvent was evaporated before being introduced into the mass spectrometer. All analyses were performed using Atmospheric Pressure Chemical Ionization in positive mode. RESULTS Seven consumer "Spice" packets were combined and analyzed by both ASAP and LDTD, which identified 11 synthetic cannabinoids/cathinones by full MS and MS/MS experiments. To further show the usefulness of these techniques, black tar heroin was analyzed, which resulted in the identification of heroin and its impurities (monoacetylmorphine, papaverine, and noscapine). These experiments were performed on the LTQ-Orbitrap to demonstrate the ability to perform both parallel and serial MS and MSn experiments. CONCLUSIONS Interfacing LDTD and ASAP to high-resolution mass spectrometers allows for expeditious analysis of a wide range of samples, with minimal or no sample preparation. Both allow for rapid full scan, MS/MS, and/or MSn experiments from a single sample introduction. Published in 2017. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Eshwar Jagerdeo
- Federal Bureau of Investigation Laboratory, Quantico, VA, 22135, USA
| | - Amanda Wriston
- Federal Bureau of Investigation Laboratory, Quantico, VA, 22135, USA
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22
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Rapid identification and desorption mechanisms of nitrogen-based explosives by ambient micro-fabricated glow discharge plasma desorption/ionization (MFGDP) mass spectrometry. Talanta 2017; 167:75-85. [DOI: 10.1016/j.talanta.2017.02.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 02/04/2017] [Indexed: 01/22/2023]
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23
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Affiliation(s)
- Patricia M Peacock
- First State IR, LLC , 118 Susan Drive, Hockessin, Delaware 19707, United States
| | - Wen-Jing Zhang
- Department of Chemistry, Wayne State University , 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Sarah Trimpin
- Department of Chemistry, Wayne State University , 5101 Cass Avenue, Detroit, Michigan 48202, United States
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24
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Direct Analysis and Quantification of Metaldehyde in Water using Reactive Paper Spray Mass Spectrometry. Sci Rep 2016; 6:35643. [PMID: 27767044 PMCID: PMC5073298 DOI: 10.1038/srep35643] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 09/30/2016] [Indexed: 12/22/2022] Open
Abstract
Metaldehyde is extensively used worldwide as a contact and systemic molluscicide for controlling slugs and snails in a wide range of agricultural and horticultural crops. Contamination of surface waters due to run-off, coupled with its moderate solubility in water, has led to increased concentration of the pesticide in the environment. In this study, for the first time, rapid analysis (<~1 minute) of metaldehyde residues in water is demonstrated using paper spray mass spectrometry (PS-MS). The observed precursor molecular ions of metaldehyde were confirmed from tandem mass spectrometry (MS/MS) experiments by studying the fragmentation patterns produced via collision-induced dissociation. The signal intensity ratios of the most abundant MS/MS transitions for metaldehyde (177 → 149 for protonated ion) and atrazine (221 → 179) were found to be linear in the range 0.01 to 5 ng/mL. Metaldehyde residues were detectable in environmental water samples at low concentration (LOD < 0.1 ng/mL using reactive PS-MS), with a relative standard deviation <10% and an R2 value >0.99, without any pre-concentration/separation steps. This result is of particular importance for environmental monitoring and water quality analysis providing a potential means of rapid screening to ensure safe drinking water.
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25
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Giannoukos S, Brkić B, Taylor S, Marshall A, Verbeck GF. Chemical Sniffing Instrumentation for Security Applications. Chem Rev 2016; 116:8146-72. [PMID: 27388215 DOI: 10.1021/acs.chemrev.6b00065] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Border control for homeland security faces major challenges worldwide due to chemical threats from national and/or international terrorism as well as organized crime. A wide range of technologies and systems with threat detection and monitoring capabilities has emerged to identify the chemical footprint associated with these illegal activities. This review paper investigates artificial sniffing technologies used as chemical sensors for point-of-use chemical analysis, especially during border security applications. This article presents an overview of (a) the existing available technologies reported in the scientific literature for threat screening, (b) commercially available, portable (hand-held and stand-off) chemical detection systems, and (c) their underlying functional and operational principles. Emphasis is given to technologies that have been developed for in-field security operations, but laboratory developed techniques are also summarized as emerging technologies. The chemical analytes of interest in this review are (a) volatile organic compounds (VOCs) associated with security applications (e.g., illegal, hazardous, and terrorist events), (b) chemical "signatures" associated with human presence, and
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Affiliation(s)
- Stamatios Giannoukos
- Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool, L69 3GJ, U.K
| | - Boris Brkić
- Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool, L69 3GJ, U.K.,Q-Technologies Ltd., 100 Childwall Road, Liverpool, L15 6UX, U.K
| | - Stephen Taylor
- Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool, L69 3GJ, U.K.,Q-Technologies Ltd., 100 Childwall Road, Liverpool, L15 6UX, U.K
| | - Alan Marshall
- Department of Electrical Engineering and Electronics, University of Liverpool , Liverpool, L69 3GJ, U.K
| | - Guido F Verbeck
- Department of Chemistry, University of North Texas , Denton, Texas 76201, United States
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26
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Zhang H, Lu H, Huang H, Liu J, Fang X, Yuan BF, Feng YQ, Chen H. Quantification of 1-hydroxypyrene in undiluted human urine samples using magnetic solid-phase extraction coupled with internal extractive electrospray ionization mass spectrometry. Anal Chim Acta 2016; 926:72-8. [DOI: 10.1016/j.aca.2016.04.033] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 04/11/2016] [Accepted: 04/16/2016] [Indexed: 02/07/2023]
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27
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Affiliation(s)
- Dalton T. Snyder
- Department of Chemistry and Center for Analytical Instrumentation
Development, Purdue University, W. Lafayette, IN 47907
| | - Christopher J. Pulliam
- Department of Chemistry and Center for Analytical Instrumentation
Development, Purdue University, W. Lafayette, IN 47907
| | - Zheng Ouyang
- Weldon School of Biomedical Engineering, Purdue University, W.
Lafayette, IN 47907
| | - R. Graham Cooks
- Department of Chemistry and Center for Analytical Instrumentation
Development, Purdue University, W. Lafayette, IN 47907
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28
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Jjunju FPM, Maher S, Damon DE, Barrett RM, Syed SU, Heeren RMA, Taylor S, Badu-Tawiah AK. Screening and Quantification of Aliphatic Primary Alkyl Corrosion Inhibitor Amines in Water Samples by Paper Spray Mass Spectrometry. Anal Chem 2016; 88:1391-400. [DOI: 10.1021/acs.analchem.5b03992] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Fred P. M. Jjunju
- Department
of Electrical Engineering and Electronics University of Liverpool, Brownlow
Hill, L69 3GJ, U.K
- Q-Technologies Ltd., 100 Childwall Road, Liverpool L15 6UX, U.K
| | - Simon Maher
- Department
of Electrical Engineering and Electronics University of Liverpool, Brownlow
Hill, L69 3GJ, U.K
| | - Deidre E. Damon
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Richard M. Barrett
- B & V Water Treatment, Lamport Drive, Heartlands Business Park Daventry, Northamptonshire NN11 8YH, U.K
| | - S. U. Syed
- M4I,
the Maastricht Multi Modal Molecular Imaging Institute, University of Maastricht Universiteitssingel, 50 6229, ER Maastricht, The Netherlands
| | - Ron M. A. Heeren
- M4I,
the Maastricht Multi Modal Molecular Imaging Institute, University of Maastricht Universiteitssingel, 50 6229, ER Maastricht, The Netherlands
| | - Stephen Taylor
- Department
of Electrical Engineering and Electronics University of Liverpool, Brownlow
Hill, L69 3GJ, U.K
- Q-Technologies Ltd., 100 Childwall Road, Liverpool L15 6UX, U.K
| | - Abraham K. Badu-Tawiah
- Department
of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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29
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Zhai Y, Jiang T, Huang G, Wei Y, Xu W. An aerodynamic assisted miniature mass spectrometer for enhanced volatile sample analysis. Analyst 2016; 141:5404-11. [DOI: 10.1039/c6an00956e] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Low ppb-level VOC detection sensitivity was achieved by integrating an in-vacuum plasma ionization source into the continuous atmospheric pressure interfaced miniature mass spectrometer.
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Affiliation(s)
- Yanbing Zhai
- School of Life Science
- Beijing Institute of Technology
- Beijing 100081
- China
| | - Ting Jiang
- School of Life Science
- Beijing Institute of Technology
- Beijing 100081
- China
| | - Guangyan Huang
- State Key Laboratory Explosion Science and Technology
- Beijing Institute of Technology
- Beijing 100081
- China
| | - Yongzheng Wei
- First School of Clinic Medicine
- Guangzhou University of Chinese Medicine
- Guangzhou 510006
- China
| | - Wei Xu
- School of Life Science
- Beijing Institute of Technology
- Beijing 100081
- China
- State Key Laboratory Explosion Science and Technology
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30
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Spencer SE, Santiago BG, Glish GL. Miniature Flow-Through Low-Temperature Plasma Ionization Source for Ambient Ionization of Gases and Aerosols. Anal Chem 2015; 87:11887-92. [PMID: 26531160 DOI: 10.1021/acs.analchem.5b03447] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The design and operation of an inexpensive, miniature low-temperature plasma ion source is detailed. The miniature low-temperature plasma ion source is operated in a "flow-through" configuration, wherein the gaseous or aerosolized analyte, caffeine or pyrolyzed ethyl cellulose, in a carrier gas is used as the plasma gas. In this flow-through configuration, the sensitivity for the caffeine standard and the pyrolysis products of ethyl cellulose is maintained or increased and the reproducibility of the ion source is increased. Changes in the relative intensity of ions from the aerosol produced by pyrolysis of ethyl cellulose are observed in the mass spectrum when the low-temperature plasma ion source is used in the flow-through configuration. Experiments suggest this change in relative intensity is likely due to differences in ionization efficiency rather than increased fragmentation of ethyl cellulose pyrolysis products during ionization. Flow-through low-temperature plasma ionization with the miniature ion source is shown to be a promising technique for the ionization of compounds in gases or aerosol particles.
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Affiliation(s)
- Sandra E Spencer
- University of North Carolina at Chapel Hill , Department of Chemistry, Chapel Hill, North Carolina 27599-3290, United States
| | - Brandon G Santiago
- University of North Carolina at Chapel Hill , Department of Chemistry, Chapel Hill, North Carolina 27599-3290, United States
| | - Gary L Glish
- University of North Carolina at Chapel Hill , Department of Chemistry, Chapel Hill, North Carolina 27599-3290, United States
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