1
|
Liu CY, Chen Y, Hu J. Identification of the Electrogenerated Hidden Nitrenium Ions by In Situ Mass Spectrometry. Anal Chem 2024; 96:3354-3361. [PMID: 38295431 DOI: 10.1021/acs.analchem.3c04315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
The identification of the electrogenerated reactive intermediates is essential for an in-depth understanding of the electroredox processes. Although various short-lived intermediates are well characterized by coupling electrochemistry with mass spectrometry (EC/MS), many electrogenerated transient species (τ < 1 μs) are still rarely captured by the currently available EC/MS approaches. Here, we present a low-delay coupling device, which was constructed by decorating a microelectrode into the front tip of a microsized ion emitter. For the first time, the in situ detection of a previously hidden intermediate, i.e., the transient nitrenium ion of carbazole (τ = 333 ns), was achieved. The electrochemical generation of indole nitrenium ion, whose half-life is estimated to be shorter compared to the carbazole nitrenium ion due to less resonance stabilization, was also confirmed by direct observation. This clog-free microelectrode/ion emitter is cheap and easy to fabricate and offers a general and powerful approach to monitoring the fast reactions of electrogenerated reactive intermediates. We believe that our integrated EC/MS approach holds substantial potential for broad applicability, particularly in probing the intricate and ultrafast electroredox processes occurring at the electrode-solution interface.
Collapse
Affiliation(s)
- Chun-Yan Liu
- School of Pharmacy, Nanjing Medical University, Nanjing 211166, P. R. China
| | - Yun Chen
- School of Pharmacy, Nanjing Medical University, Nanjing 211166, P. R. China
| | - Jun Hu
- School of Pharmacy, Nanjing Medical University, Nanjing 211166, P. R. China
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi 214122, P. R. China
| |
Collapse
|
2
|
Bai J, Bao M, Wang S, Wen T, Li Y, Zhang J, Mei T, Guo Y. Insights into electrogenerated intermediates and rapid screening of electrochemical reactions by surface-modified carbon fiber paper redox spray ionization mass spectrometry. Anal Chim Acta 2023; 1279:341794. [PMID: 37827687 DOI: 10.1016/j.aca.2023.341794] [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: 06/06/2023] [Revised: 08/29/2023] [Accepted: 09/06/2023] [Indexed: 10/14/2023]
Abstract
The combination of electrochemistry and mass spectrometry is a powerful analytical tool for studying redox reaction mechanisms and identifying products or intermediates. However, the previously reported devices all require bespoke fabrication and are too complicated to be assembled and used by others. Crucially, the long ion transport distance and small spray volumes make it difficult to capture the short-lived intermediates. We present a practical mass spectrometric method in which surface-modified carbon fiber paper is innovatively applied to detect electrogenerated intermediates. Treating carbon fiber paper with dilute nitric acid removes its surface impurities, enhancing the capability of electro-redox. Electrospray ionization and redox reaction occur simultaneously on the tip of the paper. Transient electro-redox species generate and transfer into gas phase as soon as the appearance of spray. Rapid transport of quantities of electrogenerated ions to the mass spectrometer inlet makes it possible for mass spectrometric identification on the millisecond scale. The short-lived radical cations and iminium ions were successfully captured, reflecting the starting step of the cross-dehydrogenation coupling reaction. The real-time oxidation and online functionalization reactions of tertiary amines were achieved using this device without additional oxidants and electrolytes. In this way we could achieve in-depth mechanistic understanding and rapid screening of serial reactions.
Collapse
Affiliation(s)
- Jiahui Bai
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Mingmai Bao
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Shanshan Wang
- College of Science, Chang'an University, Xi'an, 710064, China
| | - Tianlun Wen
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Yuling Li
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Jing Zhang
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
| | - Tiansheng Mei
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
| | - Yinlong Guo
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
| |
Collapse
|
3
|
Xi XJ, Hu J, Chen HY, Xu JJ. Rapid identification of the short-lived intermediates in alternating-current electrolysis by mass spectrometry. Chem Commun (Camb) 2022; 58:10233-10236. [PMID: 36004520 DOI: 10.1039/d2cc04363g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, we report the rapid mass spectrometric identification of the short-lived intermediates generated under AC electrolysis via combining bipolar electrochemistry with nanoelectrospray ionization in a hybrid ultramicroelectrode/ion emitter. The key reactive intermediates involved in the C-O/O-H cross-metathesis between 4-alkoxy anilines and alcohols were successfully captured and identified for the first time, providing direct evidence for the previously proposed mechanism.
Collapse
Affiliation(s)
- Xiao-Jun Xi
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
| | - Jun Hu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
| |
Collapse
|
4
|
Ma Y, Cui L, Li M, Cao J, Zheng L, Wei Z. Product Identification and Mechanism Exploration of Organic Electrosynthesis Using on-line Electrochemistry-Mass Spectrometry. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.116459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
5
|
Hu J, Zhang N, Zhang P, Chen Y, Xia X, Chen H, Xu J. Coupling a Wireless Bipolar Ultramicroelectrode with Nano‐electrospray Ionization Mass Spectrometry: Insights into the Ultrafast Initial Step of Electrochemical Reactions. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202008577] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jun Hu
- School of Pharmacy Nanjing Medical University Nanjing 211166 China
| | - Nan Zhang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Pan‐Ke Zhang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Yun Chen
- School of Pharmacy Nanjing Medical University Nanjing 211166 China
| | - Xing‐Hua Xia
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Hong‐Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Jing‐Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| |
Collapse
|
6
|
Hu J, Zhang N, Zhang P, Chen Y, Xia X, Chen H, Xu J. Coupling a Wireless Bipolar Ultramicroelectrode with Nano‐electrospray Ionization Mass Spectrometry: Insights into the Ultrafast Initial Step of Electrochemical Reactions. Angew Chem Int Ed Engl 2020; 59:18244-18248. [DOI: 10.1002/anie.202008577] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/01/2020] [Indexed: 12/29/2022]
Affiliation(s)
- Jun Hu
- School of Pharmacy Nanjing Medical University Nanjing 211166 China
| | - Nan Zhang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Pan‐Ke Zhang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Yun Chen
- School of Pharmacy Nanjing Medical University Nanjing 211166 China
| | - Xing‐Hua Xia
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Hong‐Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| | - Jing‐Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences School of Chemistry and Chemical Engineering Nanjing University Nanjing 210023 China
| |
Collapse
|
7
|
Liquid-inlet online electrochemical mass spectrometry for the in operando monitoring of direct ethanol fuel cells. Electrochem commun 2018. [DOI: 10.1016/j.elecom.2017.12.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
8
|
Portychová L, Schug KA. Instrumentation and applications of electrochemistry coupled to mass spectrometry for studying xenobiotic metabolism: A review. Anal Chim Acta 2017; 993:1-21. [PMID: 29078951 DOI: 10.1016/j.aca.2017.08.050] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 08/21/2017] [Accepted: 08/26/2017] [Indexed: 01/03/2023]
Abstract
The knowledge of metabolic pathways and biotransformation of xenobiotics, artificial substances foreign to the entire biological system, is crucial for elucidation of degradation routes of potentially toxic substances. Nowadays, there are many methods to simulate xenobiotic metabolism in the human body in vitro. In this review, the metabolism of various substances in the human body is described, followed by a summary of methods used for prediction of metabolic pathways and biotransformation. Above all, focus is placed on the coupling of electrochemistry to mass spectrometry, which is still a relatively new technique. This promising tool can mimic both oxidative phase I and conjugative phase II metabolism. Different experimental arrangements, with or without a separation step, and various applications of this technique are illustrated and critically reviewed.
Collapse
Affiliation(s)
- Lenka Portychová
- Research Institute for Organic Synthesis, Inc., 533 54 Rybitví, Czech Republic; Department of Analytical Chemistry, Palacký University, 771 46 Olomouc, Czech Republic
| | - Kevin A Schug
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA.
| |
Collapse
|
9
|
Odijk M, Olthuis W, van den Berg A, Qiao L, Girault H. Improved Conversion Rates in Drug Screening Applications Using Miniaturized Electrochemical Cells with Frit Channels. Anal Chem 2012; 84:9176-83. [DOI: 10.1021/ac301888g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Mathieu Odijk
- BIOS Lab-on-a-Chip Group, MESA+ Institute
for Nanotechnology, University of Twente, Enschede, The Netherlands
| | - Wouter Olthuis
- BIOS Lab-on-a-Chip Group, MESA+ Institute
for Nanotechnology, University of Twente, Enschede, The Netherlands
| | - A. van den Berg
- BIOS Lab-on-a-Chip Group, MESA+ Institute
for Nanotechnology, University of Twente, Enschede, The Netherlands
| | - Liang Qiao
- Laboratory of Physical and Analytical
Chemistry, EPFL, Lausanne,
Switzerland
| | - Hubert Girault
- Laboratory of Physical and Analytical
Chemistry, EPFL, Lausanne,
Switzerland
| |
Collapse
|
10
|
Gun J, Bharathi S, Gutkin V, Rizkov D, Voloshenko A, Shelkov R, Sladkevich S, Kyi N, Rona M, Wolanov Y, Rizkov D, Koch M, Mizrahi S, Pridkhochenko PV, Modestov A, Lev O. Highlights in Coupled Electrochemical Flow Cell-Mass Spectrometry, EC/MS. Isr J Chem 2010. [DOI: 10.1002/ijch.201000035] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
11
|
Zettersten C, Lomoth R, Hammarström L, Sjöberg PJ, Nyholm L. The influence of the thin-layer flow cell design on the mass spectra when coupling electrochemistry to electrospray ionisation mass spectrometry. J Electroanal Chem (Lausanne) 2006. [DOI: 10.1016/j.jelechem.2006.02.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
12
|
Guo T, Li L, Cammarata V, Illies A. Electrochemical/electrospray mass spectrometric studies of I- and SCN- at gold and platinum electrodes: direct detection of (SCN)3-. J Phys Chem B 2005; 109:7821-5. [PMID: 16851910 DOI: 10.1021/jp047439o] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Results on the electrochemistry of I- and SCN- at gold and platinum electrodes using an electrochemical cell coupled to an electrospray mass spectrometer are reported. We demonstrate that our apparatus is capable of these very challenging electrochemical/electrospray experiments and that B(C6H5)4- is a suitable internal standard for negative-ion studies in acetonitrile. With I- at a platinum electrode, we observe well-behaved oxidation to I3-. Experiments on I- at gold electrodes are more complex, showing AuI2- as well as I3-. The AuI2- mass spectrometric ion intensity varies in a complex way throughout the applied electrochemical voltage range studied; we propose that this variation involves the adsorption of I- on the gold electrode surface. In experiments on SCN- from (C4H9)4NSCN at gold electrodes, we observe Au(SCN)2-. Finally, at platinum electrodes, we directly observe (SCN)3-, a species analogous to I3- and (CN)3- that has been previously postulated but unverified. This important finding was confirmed by the isotope pattern and demonstrates the stability of the anion.
Collapse
Affiliation(s)
- Tan Guo
- Department of Chemistry and Biochemistry, Auburn University, Alabama 36849-5312, USA
| | | | | | | |
Collapse
|
13
|
Sparrenberger RC, Cross CK, Conte ED. A Solid-Phase Microextraction Device for the Analysis of Electrochemical Reaction Products by Gas Chromatography/Mass Spectrometry. Anal Chem 2004; 76:6156-9. [PMID: 15481967 DOI: 10.1021/ac0490090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Presented is a solid-phase microextraction syringe-electrode assembly that may be used to identify electrode reaction products. After an electrochemical experiment, the electrode within this syringe-electrode assembly can be introduced into the injection port of a gas chromatograph. Electrochemical reaction products can be analyzed, provided they adhere to the electrode surface and are amenable to gas chromatographic/mass spectrometric analysis. We highlight the potential usefulness of this device using well-known electrochemical reaction of quinones.
Collapse
Affiliation(s)
- Robert C Sparrenberger
- Department of Chemistry, Western Kentucky University, Bowling Green, Kentucky 42101, USA
| | | | | |
Collapse
|
14
|
On-line electrochemical–mass spectrometry study of the mechanism of oxidation of N,N-dimethyl-p-phenylenediamine in aqueous electrolytes. J Electroanal Chem (Lausanne) 2004. [DOI: 10.1016/j.jelechem.2003.09.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
15
|
Van Berkel GJ, Asano KG, Granger MC. Controlling Analyte Electrochemistry in an Electrospray Ion Source with a Three-Electrode Emitter Cell. Anal Chem 2004; 76:1493-9. [PMID: 14987108 DOI: 10.1021/ac035240m] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The inherent electrochemistry occurring at the emitter electrode of an electrospray ion source was effectively controlled by incorporating a three-electrode controlled-potential electrochemical cell into the controlled-current electrospray emitter circuit. Two different basic cell designs were investigated to accomplish this control, namely, a planar flow-by working electrode and a porous flow-through working electrode design, each operated with a potentiostat floated at the electrospray high voltage. Control of the analyte electrochemistry was tested using the indole alkaloid reserpine, which is often used to test the specifications of electrospray mass spectrometry instrumentation. Reserpine was relatively easy to oxidize (E(p) = 0.73 V vs Ag/AgCl) in the acidic electrospray medium (acetonitrile/water 1:1 v/v, 5.0 mM ammonium acetate, 0.75 vol % acetic acid) and was oxidized when the conventional electrospray emitter was used at low solution flow rate. With the proper cell auxiliary electrode configuration and adjustment of the working electrode potential, it was found that reserpine oxidation could be "turned off" at flow rates as low as 2.5 microL/min as well as at flow rates as high as 30-40 microL/min. Just as important, it was also possible to "turn on" essentially 100% oxidation of reserpine in this flow rate range. The area of the auxiliary electrode along with flow rate, which affect mass transport of analytes to this electrode, were found to be critical in controlling the electrochemical reactions in the emitter cell. Such control over analyte electrochemical reactions in the emitter has been difficult or impossible to achieve with a conventional electrospray emitter. This control is paramount in obtaining experimental results free from electrochemically generated artifacts of the analyte or in exploiting electrochemical reactions involving the analyte to analytical advantage.
Collapse
Affiliation(s)
- Gary J Van Berkel
- Organic and Biological Mass Spectrometry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6131, USA.
| | | | | |
Collapse
|
16
|
Trojanowicz M, Szewczynska M, Wcislo M. Electroanalytical Flow Measurements-Recent Advances. ELECTROANAL 2003. [DOI: 10.1002/elan.200390041] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
17
|
Modestov AD, Srebnik S, Lev O, Gun J. Scanning capillary microscopy/mass spectrometry for mapping spatial electrochemical activity of electrodes. Anal Chem 2001; 73:4229-40. [PMID: 11569814 DOI: 10.1021/ac001369+] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new technique for microscopic imaging of electrochemically active surfaces is introduced. The technique combines concepts of probe microscopy and advances in mass spectrometry. The technique is based on a miniature electrochemical flow cell scanner. A liquid feed stream containing a redox component is introduced to the vicinity of the examined location through the annulus of a coaxial capillary set. The incoming reagent interacts with the target location, and the generated product stream is transferred through the inner capillary to an electrospray mass spectrometer, ESI-MS. Thus, a multicomponent, potential-dependent image of the products' distribution versus the location on the electrode is generated. The use of the technique is demonstrated by scanning the electrochemical heterogeneity of model electrodes.
Collapse
Affiliation(s)
- A D Modestov
- Division of Environmental Sciences, Fredy and Nadine Herrmann School of Applied Science, The Hebrew University of Jerusalem, Israel
| | | | | | | |
Collapse
|
18
|
Anderson JL, Coury LA, Leddy J. Dynamic electrochemistry: methodology and application. Anal Chem 2000; 72:4497-520. [PMID: 11008788 DOI: 10.1021/ac0007837] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J L Anderson
- Department of Chemistry, University of Georgia, Athens 30602-2556, USA
| | | | | |
Collapse
|
19
|
On-line investigation of the generation of nonaqueous intermediate radical cations by electrochemistry/mass spectrometry. Anal Chem 2000; 72:2533-40. [PMID: 10857631 DOI: 10.1021/ac9912348] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Anodic oxidation of triphenylamine (TPA) in acetonitrile was investigated by electrochemistry (EC) combined online with mass spectrometry (MS) through a particle beam (PB) interface, EC/PB/MS. Electrooxidation of TPA generates a TPA*+ radical cation (m/z 245) which dimerizes to tetraphenylbenzidine (TPB, MW 488). TPB is readily oxidized to TPB*+ (m/z 488) and TPB2+ (m/z 244) at the oxidation potential of TPA. In EC/PB/MS, direct monitoring of the oxidation of TPB to TPB*+ radical cation as a function of the electrode potential was achieved via selective ion monitoring of the ion peak at m/z 488. By using the relative intensity ratio of ions at m/z 244 (TPB2+) to 245 (TPA*+), the formation of TPB2+ as a function of the electrode potential was also monitored. EC/PB/MS showed a maximum rate of formation of TPB*+ at +1.2 Vvs Pd, while TPB2+ is generated at a maximum rate at +1.6 V vs Pd. The effect of spectral interference from the electron impact ionization of TPA, on EC/PB/MS results, is also discussed. Finally, a significant signal enhancement is observed in the presence of tetrabutylammonium perchlorate (TBAP) and is reported for the first time. Compatibility of coupling of EC with MS via PB interface for EC/MS studies in nonaqueous solvents is demonstrated. The observation of significant signal enhancement in the presence of TBAP may facilitate other applications of LC/MS.
Collapse
|
20
|
Deng H, Berkel GJV. A Thin-Layer Electrochemical Flow Cell Coupled On-Line with Electrospray-Mass Spectrometry for the Study of Biological Redox Reactions. ELECTROANAL 1999. [DOI: 10.1002/(sici)1521-4109(199908)11:12<857::aid-elan857>3.0.co;2-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|