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Wen L, Yoshinaga K, Imasaka T, Imasaka T. Trace analysis of nitrated polycyclic aromatic hydrocarbons based on two-color femtosecond laser ionization mass spectrometry. Talanta 2023; 265:124807. [PMID: 37327661 DOI: 10.1016/j.talanta.2023.124807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/10/2023] [Accepted: 06/09/2023] [Indexed: 06/18/2023]
Abstract
Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are suspected to be highly carcinogenic and mutagenic compounds that are present in the environment. Gas chromatography combined with mass spectrometry (GC-MS) is the most frequently used technique for trace analysis. The electron ionization techniques that are currently used in MS, however, typically do not result in the formation of a molecular ion, thus making the determination of these compounds more difficult. In this study, we report on the use of a compact highly-repetitive (low-pulse-energy) ultraviolet (UV) femtosecond laser as the ionization source in combination with a miniature time-of-flight mass analyzer and a time-correlated ion counting system. The UV laser pulses emitted at 343, 257, and 206 nm were produced by harmonic generations of a femtosecond Yb laser emitting at 1030 nm and were utilized for single-color multiphoton ionization. A combination of the 343-nm and 257-nm pulses was further employed to achieve two-color two-photon ionization. This technique was found to be more useful for sensitive detection and also resulted in the formation of a molecular ion. A pump-and-probe technique using these pulses was examined in a proof-of-concept study to measure the femtosecond lifetimes of the nitro-PAHs separated by GC, providing additional information for use in the characterization of the analyte. The developed technique was applied in the analysis of an authentic sample, an organic solvent extract from diesel exhaust particulates. The nitro-PAHs contained in a standard reference material (SRM1975) were determined on a two-dimensional GC-MS display, suggesting that this technique would be useful for the practical trace analysis of nitro-PAHs in environmental samples.
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Affiliation(s)
- Lu Wen
- Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540: 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Katsunori Yoshinaga
- Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540: 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Totaro Imasaka
- Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan; Hikari Giken, Co., 2-10-30, Sakurazaka, Chuou-ku, Fukuoka, 810-0024, Japan
| | - Tomoko Imasaka
- Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540: 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
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Yoshinaga K, Hao NV, Imasaka T, Imasaka T. Miniature time-of-flight mass analyzer for use in combination with a compact highly-repetitive femtosecond laser ionization source. Anal Chim Acta 2022; 1203:339673. [DOI: 10.1016/j.aca.2022.339673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/01/2022] [Accepted: 03/01/2022] [Indexed: 11/24/2022]
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Wen L, Jin F, Imasaka T, Imasaka T. Esterification of perfluorinated carboxylic acids with bromomethyl aromatic compounds for gas chromatography combined with laser ionization mass spectrometry. J Chromatogr A 2021; 1656:462546. [PMID: 34547552 DOI: 10.1016/j.chroma.2021.462546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/02/2021] [Accepted: 09/05/2021] [Indexed: 10/20/2022]
Abstract
Perfluorinated carboxylic acids (PFCAs) were derivatized with two types of aromatic compounds that contained a bromomethyl group, i.e., 2-(bromomethyl)naphthalene (BMN) and benzyl bromide (BB). The conditions for derivatization were optimized in terms of reaction temperature and time and the concentration of derivatizing reagent. Using these optimal conditions, the PFCAs-MN and PFCAs-B derivatives were measured by gas chromatography (GC) combined with mass spectrometry using an ultraviolet femtosecond laser (267 nm) as the ionization source. The efficiency of derivatization for PFCAs-B was higher than that for PFCAs-MN because of the smaller size of the chromophore (benzene). The ionization efficiency of PFCAs-MN, however, was better than PFCAs-B, since a larger sized chromophore (naphthalene) and then a larger molar absorptivity was preferable for resonance-enhanced two-photon ionization. Due to superior GC separation, BB was successfully used as the derivatizing agent for the trace analysis of PFCAs, with detection limits of 6.0, 8.4, and 9.5 ng/mL for perfluoroheptanoic, perfluorooctanoic, and perfluorononanoic acids, respectively. The other bromomethyl aromatic compounds were evaluated for use as a derivatization reagent in future studies.
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Affiliation(s)
- Lu Wen
- Department of Environmental Design, Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540, Japan: 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Fengdan Jin
- Department of Environmental Design, Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540, Japan: 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; Present address: Yanshan University, Qinhuangdao, Hebei 066004, China
| | - Totaro Imasaka
- Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; Hikari Giken, Co., 2-10-30, Sakurazaka, Chuou-ku, Fukuoka 810-0024, Japan
| | - Tomoko Imasaka
- Department of Environmental Design, Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540, Japan: 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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McPherson SL, Shusterman JM, López Peña HA, Ampadu Boateng D, Tibbetts KM. Quantitative Analysis of Nitrotoluene Isomer Mixtures Using Femtosecond Time-Resolved Mass Spectrometry. Anal Chem 2021; 93:11268-11274. [PMID: 34347440 DOI: 10.1021/acs.analchem.1c02245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Discrimination of isomers in a mixture is a subject of ongoing interest in biology, pharmacology, and forensics. We demonstrate that femtosecond time-resolved mass spectrometry (FTRMS) effectively quantifies mixtures of ortho-, para-, and meta-nitrotoluenes, the first two of which are common explosive degradation products. The key advantage of the FTRMS approach to mixture quantification lies in the ability of the pump-probe laser control scheme to capture distinct fragmentation dynamics of each nitrotoluene cation isomer on femtosecond timescales, thereby allowing for discrimination of the isomers using only the signal of the parent molecular ion at m/z 137. Upon measurement of reference dynamics of each individual isomer, the molar fractions of binary and ternary mixtures can be predicted to within ∼5 and ∼7% accuracy, respectively.
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Affiliation(s)
- Shane L McPherson
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Jacob M Shusterman
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Hugo A López Peña
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Derrick Ampadu Boateng
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Katharine Moore Tibbetts
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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Imasaka T, Imasaka T. Femtosecond ionization mass spectrometry for chromatographic detection. J Chromatogr A 2021; 1642:462023. [PMID: 33714081 DOI: 10.1016/j.chroma.2021.462023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 11/17/2022]
Abstract
Mass spectrometry is now in widespread use for the detection of the analytes separated by chromatography. Electron ionization is the most frequently used method in mass spectrometry. However, this ionization technique sometimes suffers from extensive fragmentation of analytes, which makes identification difficult. A photoionization technique has been developed for suppressing this fragmentation and for subsequently observing a molecular ion. A variety of lasers have been employed for the sensitive and selective ionization of organic compounds. A femtosecond laser has a high peak power and is preferential for efficient ionization as well as for suppressing fragmentation, providing valuable information concerning molecular weight and chemical structure as well. In this review, we report on applications of femtosecond ionization mass spectrometry combined with gas chromatography.
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Affiliation(s)
- Totaro Imasaka
- Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; Hikari Giken, Co., 2-10-30, Sakurazaka, Chuou-ku, Fukuoka 810-0024, Japan
| | - Tomoko Imasaka
- Department of Environmental Design, Faculty of Design, Kyushu University, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540, Japan.
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Sugiyama T, Iwata M, Ueyama T, Uchimura T. Characteristic Signal Behaviors for Water-in-Oil and Oil-in-Water Emulsions Measured by Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry. ACS OMEGA 2020; 5:31289-31294. [PMID: 33324839 PMCID: PMC7726925 DOI: 10.1021/acsomega.0c04734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/13/2020] [Indexed: 06/12/2023]
Abstract
Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) was used to study the characteristic signal behaviors obtained from two types of emulsions: water-in-oil (W/O) and oil-in-water (O/W). All emulsions were prepared using phase inversion emulsification, i.e., a solution for an aqueous phase was added dropwise to an oil phase with constant stirring to obtain an emulsion. Toluene served as a detection component. When using REMPI-TOFMS to measure an emulsion, a time profile for the target component can be constructed by plotting peak areas for the corresponding component on a series of mass spectra. In the case of a W/O emulsion at a water volume fraction (f w) of 0.005, the concentration of toluene was instantaneously decreased due to the existence of water droplets, and therefore, several negative spikes were detected on the time profile while establishing a baseline. In the case of a W/O emulsion at f w = 0.3, negative peaks consisting of several plots appeared on the time profile because of the formation of aggregates of water droplets while the emulsion was flowed through a capillary column for sample introduction. An O/W emulsion at f w = 0.995 was analyzed following phase inversion, and positive peaks were detected due to the aggregates of many oil droplets. In this manner, the direct mass analysis of emulsions before and after phase inversion was achieved, and the resultant signal inversion was confirmed via REMPI-TOFMS.
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Uchimura T. Laser Mass Spectrometry. ANAL SCI 2020; 36:285-286. [PMID: 32161224 DOI: 10.2116/analsci.highlights2003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Affiliation(s)
- Tomohiro Uchimura
- Department of Materials Science and Engineering, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507, Japan
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Madunil SL, Imasaka T, Imasaka T. Resonant and non-resonant femtosecond ionization mass spectrometry of organochlorine pesticides. Analyst 2020; 145:777-783. [DOI: 10.1039/c9an01861a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The ionization mechanism was studied based on resonance-enhanced two-photon ionization and non-resonant two- and three-photon ionizations.
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Affiliation(s)
| | - Totaro Imasaka
- Division of International Strategy
- Center of Future Chemistry
- Kyushu University
- Fukuoka 819-0395
- Japan
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Moore Tibbetts K. Coherent Vibrational and Dissociation Dynamics of Polyatomic Radical Cations. Chemistry 2019; 25:8431-8439. [DOI: 10.1002/chem.201900363] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Indexed: 01/26/2023]
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