1
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Affiliation(s)
- Thomas Herl
- Institute of Analytical Chemistry, Chemo- and BiosensorsUniversity of Regensburg Universitätsstraße 31 93053 Regensburg Germany
| | - Frank‐Michael Matysik
- Institute of Analytical Chemistry, Chemo- and BiosensorsUniversity of Regensburg Universitätsstraße 31 93053 Regensburg Germany
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2
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Fangmeyer J, Scheeren SG, Schmid R, Karst U. Fast Online Separation and Identification of Electrochemically Generated Isomeric Oxidation Products by Trapped Ion Mobility–Mass Spectrometry. Anal Chem 2019; 92:1205-1210. [DOI: 10.1021/acs.analchem.9b04337] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jens Fangmeyer
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 30, 48149 Münster, Germany
| | - Simon G. Scheeren
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 30, 48149 Münster, Germany
| | - Robin Schmid
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 30, 48149 Münster, Germany
| | - Uwe Karst
- Westfälische Wilhelms-Universität Münster, Institut für Anorganische und Analytische Chemie, Corrensstraße 30, 48149 Münster, Germany
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3
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Liu W, Shiue YL, Lin YR, Lin HYH, Liang SS. A Derivative Method with Free Radical Oxidation to Predict Resveratrol Metabolites by Tandem Mass Spectrometry. CURR ANAL CHEM 2015; 11:300-306. [PMID: 27594817 PMCID: PMC5003074 DOI: 10.2174/1573411011666150515233817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 05/12/2015] [Accepted: 05/14/2015] [Indexed: 11/24/2022]
Abstract
In this study, we demonstrated an oxidative method with free radical to generate 3,5,4′-trihydroxy-trans-stilbene (trans-resveratrol) metabolites and detect sequentially by an autosampler coupling with liquid chromatography electrospray ionization tandem mass spectrometer (LC-ESI–MS/MS). In this oxidative method, the free radical initiator, ammonium persulfate (APS), was placed in a sample bottle containing resveratrol to produce oxidative derivatives, and the reaction progress was tracked by autosampler sequencing. Resveratrol, a natural product with purported cancer preventative qualities, produces metabolites including dihydroresveratrol, 3,4′-dihydroxy-trans-stilbene, lunularin, resveratrol monosulfate, and dihydroresveratrol monosulfate by free radical oxidation. Using APS free radical, the concentrations of resveratrol derivatives differ as a function of time. Besides simple, convenient and time- and labor saving, the advantages of free radical oxidative method of its in situ generation of oxidative derivatives followed by LC-ESI–MS/MS can be utilized to evaluate different metabolites in various conditions.
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Affiliation(s)
- Wangta Liu
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung,Taiwan
| | - Yow-Ling Shiue
- Institute of
Biomedical Science, National Sun Yat-Sen University, Kaohsiung,Taiwan
| | - Yi-Reng Lin
- Department of Biotechnology, Fooyin University, Kaohsiung,Taiwan
| | - Hugo You-Hsien Lin
- Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung,Taiwan;; Division of Nephrology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; 6Department of
Internal Medicine, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan; 7Center for Resources, Research and Development, Kaohsiung Medical University, Kaohsiung,Taiwan
| | - Shih-Shin Liang
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung,Taiwan;; Institute of
Biomedical Science, National Sun Yat-Sen University, Kaohsiung,Taiwan
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4
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Oberacher H, Erb R, Plattner S, Chervet JP. Mechanistic aspects of nucleic-acid oxidation studied with electrochemistry-mass spectrometry. Trends Analyt Chem 2015. [DOI: 10.1016/j.trac.2014.12.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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5
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van den Brink FTG, Büter L, Odijk M, Olthuis W, Karst U, van den Berg A. Mass Spectrometric Detection of Short-Lived Drug Metabolites Generated in an Electrochemical Microfluidic Chip. Anal Chem 2015; 87:1527-35. [DOI: 10.1021/ac503384e] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Floris T. G. van den Brink
- BIOS
− Lab on a Chip group, MESA+ Institute for Nanotechnology and
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Lars Büter
- Institute
of Inorganic and Analytical Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany
- NRW
Graduate School of Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Mathieu Odijk
- BIOS
− Lab on a Chip group, MESA+ Institute for Nanotechnology and
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Wouter Olthuis
- BIOS
− Lab on a Chip group, MESA+ Institute for Nanotechnology and
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Uwe Karst
- Institute
of Inorganic and Analytical Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany
- NRW
Graduate School of Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Albert van den Berg
- BIOS
− Lab on a Chip group, MESA+ Institute for Nanotechnology and
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
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6
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Oberacher H, Pitterl F, Erb R, Plattner S. Mass spectrometric methods for monitoring redox processes in electrochemical cells. MASS SPECTROMETRY REVIEWS 2015; 34:64-92. [PMID: 24338642 PMCID: PMC4286209 DOI: 10.1002/mas.21409] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/24/2013] [Accepted: 08/12/2013] [Indexed: 06/03/2023]
Abstract
Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation-reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common.
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Affiliation(s)
- Herbert Oberacher
- Institute of Legal Medicine and Core Facility Metabolomics, Innsbruck Medical UniversityInnsbruck, Austria
| | - Florian Pitterl
- Institute of Legal Medicine and Core Facility Metabolomics, Innsbruck Medical UniversityInnsbruck, Austria
| | - Robert Erb
- Institute of Legal Medicine and Core Facility Metabolomics, Innsbruck Medical UniversityInnsbruck, Austria
| | - Sabine Plattner
- Institute of Legal Medicine and Core Facility Metabolomics, Innsbruck Medical UniversityInnsbruck, Austria
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7
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Simulation of oxidative stress of guanosine and 8-oxo-7,8-dihydroguanosine by electrochemically assisted injection–capillary electrophoresis–mass spectrometry. Anal Bioanal Chem 2013; 406:687-94. [DOI: 10.1007/s00216-013-7500-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 11/26/2022]
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8
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Online monitoring oxidative products and metabolites of nicotine by free radicals generation with Fenton reaction in tandem mass spectrometry. ScientificWorldJournal 2013; 2013:189162. [PMID: 23983622 PMCID: PMC3745948 DOI: 10.1155/2013/189162] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 05/22/2013] [Indexed: 12/21/2022] Open
Abstract
In general, over 70% absorbed nicotine is metabolized to cotinine and trans-3′-hydroxycotinine by cytochrome oxidase P450, and nicotine is also a major addictive and the psychoactive component in cigarettes. As a xenobiotic metabolism, hydrophobic compounds are usually converted into more hydrophilic products through enzyme systems such as cytochrome oxidase P450, sulfotransferases, and UDP-glucuronosyltransferases to deliver drug metabolites out of the cell during the drug metabolic process. In this study, an electrodeless electrochemical oxidation (EEO) reaction via Fenton reaction by producing free radical to react with nicotine to immediately monitor the oxidative products and metabolic derivatives of nicotine by tandem mass spectrometer (MS) is done. Fenton reaction generates free radicals via ferrous ion (Fe2+) and hydrogen peroxide (H2O2) to oxidize DNA and to degrade proteins in cells. In the EEO method, the oxidative products of nicotine including cotinine, cotinine-N-oxide, trans-3′-hydroxycotinine, nornicotine, norcotinine, 4-oxo-4-(3-pyridyl)-butanoic acid, 4-hydroxy-4-(3-pyridyl)-butanoic acid, and nicotine-N′-oxide were detected by tandem mass spectrometer to simulate the changes of nicotine and its derivatives in a time-dependent manner.
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9
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Chen L, Hofmann D, Klumpp E, Xiang X, Chen Y, Küppers S. Bottom-up approach for the reaction of xenobiotics and their metabolites with model substances for natural organic matter by electrochemistry-mass spectrometry (EC-MS). CHEMOSPHERE 2012; 89:1376-1383. [PMID: 22819944 DOI: 10.1016/j.chemosphere.2012.05.105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/19/2012] [Accepted: 05/23/2012] [Indexed: 06/01/2023]
Abstract
Risk assessment of xenobiotics requires a comprehensive understanding of their transformation in the environment. As most of the transformation processes usually involve a redox reaction or a hydrolysis as the first steps of the transformation, we applied an approach that uses an electrochemical cell to investigate model "redox" reactions in aqueous solutions for environmental processes. We investigated the degradation of a variety of xenobiotics from polar to nonpolar and analyzed their degradation products by on-line coupling of electrochemistry with mass spectrometry (EC-MS). Furthermore, we evaluated possible binding reactions with regard to the generation of non-extractable residues with some model substances (catechol, phthalic acid, γ-L-Glutamyl-L-cysteinyl-glycine (GSH) and L-histidine) deduced from a natural organic matter (NOM) structure model and identified possible binding-sites. Whereas typically investigations in soil/water-systems have been applied, we used to our knowledge for the first time a bottom-up approach, starting from the chemicals of interest and different model substances for natural organic matter to evaluate chemical binding mechanisms (or processes) in the EC-MS under redox conditions. Under oxidative conditions, bindings of the xenobiotics with catechol, GSH and histidine were found, but no reactions with the model compound phthalic acid were observed. In general, no chemical binding has yet been found under reductive conditions. In some cases (i.e. benzo[a]anthracene) the oxidation product only underwent a binding reaction, whereas the xenobiotic itself did not undergo any reactions. EC-MS is a promising fast and simple screening method to investigate the environmental behavior of xenobiotics and to evaluate the potential risks of newly synthesized substances.
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Affiliation(s)
- Lei Chen
- College of Environmental & Resource Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China
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10
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Jahn S, Karst U. Electrochemistry coupled to (liquid chromatography/) mass spectrometry—Current state and future perspectives. J Chromatogr A 2012; 1259:16-49. [DOI: 10.1016/j.chroma.2012.05.066] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/09/2012] [Accepted: 05/19/2012] [Indexed: 02/04/2023]
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11
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Investigation of the biotransformation pathway of verapamil using electrochemistry/liquid chromatography/mass spectrometry – A comparative study with liver cell microsomes. J Chromatogr A 2011; 1218:9210-20. [DOI: 10.1016/j.chroma.2011.10.052] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 10/06/2011] [Accepted: 10/20/2011] [Indexed: 11/21/2022]
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12
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Pitterl F, Chervet JP, Oberacher H. Electrochemical simulation of oxidation processes involving nucleic acids monitored with electrospray ionization-mass spectrometry. Anal Bioanal Chem 2010; 397:1203-15. [PMID: 20393841 DOI: 10.1007/s00216-010-3674-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 03/18/2010] [Accepted: 03/21/2010] [Indexed: 02/03/2023]
Abstract
Oxidation is commonly involved in the alteration of nucleic acids giving rise to diverse effects including mutation, cell death, malignancy, and aging. We demonstrate that electrochemistry represents an efficient and fast method to mimic oxidative modification of nucleic acids occurring in biological systems. Oxidation reactions were performed in a thin-layer cell employing a conductive diamond electrode as the working electrode and were monitored with electrospray ionization-mass spectrometry. Mass voltammograms were acquired for guanosine, adenosine, cytidine, and uridine. The observed oxidation potentials increased in the order guanosine << adenosine < cytidine < uridine. Oxidation products of guanosine were characterized using high-resolution (tandem) mass spectrometry performed with a quadrupole-quadrupole time-of-flight instrument. On the basis of these experiments, it was concluded that the initial electrode reaction involves a one-electron, one-proton step to give a free radical. The primary oxidation product represents the starting point for a number of follow-up reactions, including guanosine dimerization as well as further oxidation to 8-hydroxyguanosine. Similar results were obtained for guanosine monophosphate and the corresponding dinucleotide. Furthermore, the guanosine radical was identified as an important intermediate for the formation of a covalent adduct with acetaminophen. This observation sheds new light on the mechanism of adduct formation as it demonstrates that oxidative activation of both the nucleobase and the adduct-forming agent is necessary to observe a detectable amount of adduct species.
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Affiliation(s)
- Florian Pitterl
- Institute of Legal Medicine, Innsbruck Medical University, Muellerstrasse 44, 6020 Innsbruck, Austria
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13
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Baumann A, Lohmann W, Jahn S, Karst U. On-Line Electrochemistry/Electrospray Ionization Mass Spectrometry (EC/ESI-MS) for the Generation and Identification of Nucleotide Oxidation Products. ELECTROANAL 2010. [DOI: 10.1002/elan.200900358] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Odijk M, Baumann A, Lohmann W, van den Brink FTG, Olthuis W, Karst U, van den Berg A. A microfluidic chip for electrochemical conversions in drug metabolism studies. LAB ON A CHIP 2009; 9:1687-1693. [PMID: 19495451 DOI: 10.1039/b822962g] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have designed a microfluidic microreactor chip for electrochemical conversion of analytes, containing a palladium reference electrode and platinum working and counter electrodes. The counter electrode is placed in a separate side-channel on chip to prevent unwanted side-products appearing in the measured spectrograms. Using this chip, cyclic voltammograms are measured in volumes of 9.6 nL. Furthermore the conversion efficiency of ferricyanide is characterized using UV/vis-spectroscopy. We have obtained an on-line conversion of 97% using a flow rate of 1 microL/min. We have used the microreactor chip to study the electrochemical metabolism pathway of amodiaquine using electrochemistry (EC)-liquid chromatography (LC)-mass spectrometry (MS). We have compared our results with measurements obtained with commercially available electrochemical flow-through cells. Using our chip it was possible to obtain similar results. Therefore, we have fabricated an electrochemical cell on-chip which is used successfully in EC-UV/vis and EC-LC-MS experiments.
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Affiliation(s)
- M Odijk
- BIOS - the Lab-on-a-Chip group, MESA+ Institute of Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands.
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15
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Baumann A, Lohmann W, Schubert B, Oberacher H, Karst U. Metabolic studies of tetrazepam based on electrochemical simulation in comparison to in vivo and in vitro methods. J Chromatogr A 2009; 1216:3192-8. [PMID: 19233363 DOI: 10.1016/j.chroma.2009.02.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 01/28/2009] [Accepted: 02/03/2009] [Indexed: 11/19/2022]
Abstract
During the last 2 years, the knowledge on the metabolic pathway of tetrazepam, a muscle relaxant drug, was expanded by the fact that diazepam was identified as a degradation product of tetrazepam. The present study demonstrates that this metabolic conversion, recently discovered by in vivo studies, can also be predicted on the basis of a purely instrumental method, consisting of an electrochemical cell (EC) coupled to online liquid chromatography (LC) and mass spectrometry (MS). By implementing a new electrochemical cell type into the EC-LC-MS set-up and by an enhanced oxidation potential range up to 2V, one limitation of the electrochemical metabolism simulation, the hydroxylation of alkanes and alkenes, has been overcome. Instead of commonly used flow-through cell with a porous glassy carbon working electrode, a wall-jet cell with exchangeable electrode material was used for this study. Thereby, the entire metabolic pathway of tetrazepam, in particular including the hydroxylation of the tetrazepam cyclohexenyl moiety, was simulated. The electrochemical results were not only compared to microsomal incubations, but also to in vivo experiments, by analysing urine samples from a patient after tetrazepam delivery. For structure elucidation of the detected metabolites, MS/MS experiments were performed. The comparison of electrochemistry to in vitro as well as to in vivo experiments underlines the high potential of electrochemistry as a fast screening tool in the prediction of metabolic transformations in drug development.
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Affiliation(s)
- Anne Baumann
- University of Münster, Institute of Inorganic and Analytical Chemistry, Münster, Germany
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16
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Lohmann W, Dötzer R, Gütter G, Van Leeuwen SM, Karst U. On-line electrochemistry/liquid chromatography/mass spectrometry for the simulation of pesticide metabolism. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:138-145. [PMID: 18842426 DOI: 10.1016/j.jasms.2008.09.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/01/2008] [Accepted: 09/01/2008] [Indexed: 05/26/2023]
Abstract
On-line electrochemistry/liquid chromatography/mass spectrometry (EC/LC/MS) was employed to mimic the oxidative metabolism of the fungicide boscalid. High-resolution mass spectrometry and MS/MS experiments were used to identify its electrochemical oxidation products. Furthermore, the introduction of a second electrochemical cell with reductive conditions provided important additional information on the oxidation products. With this equipment, hydroxylation, dehydrogenation, formation of a covalent ammonia adduct, and dimerization were detected after initial one-electron oxidation of boscalid to a radical cation. On-line reaction with glutathione yielded different isomeric covalent glutathione adducts. The results of the electrochemical oxidation are in good accordance with previously reported in vivo experiments, showing that EC/LC/MS is a useful tool for studying biotransformation reactions of various groups of xenobiotics.
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Affiliation(s)
- Wiebke Lohmann
- Westfälische Wilhelms-Universität Münster, Institute of Inorganic and Analytical Chemistry, Münster, Germany
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17
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Lohmann W, Meermann B, Möller I, Scheffer A, Karst U. Quantification of Electrochemically Generated Iodine-Containing Metabolites Using Inductively Coupled Plasma Mass Spectrometry. Anal Chem 2008; 80:9769-75. [DOI: 10.1021/ac801878k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wiebke Lohmann
- Institut für Anorganische and Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
| | - Björn Meermann
- Institut für Anorganische and Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
| | - Ines Möller
- Institut für Anorganische and Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
| | - Andy Scheffer
- Institut für Anorganische and Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
| | - Uwe Karst
- Institut für Anorganische and Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
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18
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Amaro S, Planas AM, Chamorro A. Uric acid administration in patients with acute stroke: a novel approach to neuroprotection. Expert Rev Neurother 2008; 8:259-70. [PMID: 18271711 DOI: 10.1586/14737175.8.2.259] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Uric acid (UA) is the end product of purine catabolism in humans and is a powerful antioxidant whose generation is increased under ischemic conditions. However, both clinical and experimental studies reveal a gradual exhaustion of the antioxidant capacity after transient cerebral ischemia, and the magnitude of this consumption seems to be correlated with the extent of brain tissue injury, growth of the infarction, severity of neurological impairment in the acute phase, and long-term functional outcome. Growing evidence supports the neuroprotective effect of UA administration after brain ischemia. In experimental conditions, the administration of UA is neuroprotective both in mechanical models of brain ischemia (transient or permanent intraluminal occlusion of the middle cerebral artery) and in thromboembolic models of autologous clot injection. The administration of UA is feasible and safe in healthy volunteers. In acute stroke patients treated with recombinant tissue plasminogen activator (rt-PA), co-administration of UA has proven to reduce lipid peroxidation and to prevent the fall in UA blood levels that occur very early after stroke onset. Currently, a multicentric Phase III clinical trial is testing whether the administration of UA increases the clinical benefits of rt-PA, which represents the only approved therapy in patients with acute ischemic stroke. This review summarizes the available information justifying such a novel therapeutic approach in this devastating clinical condition.
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Affiliation(s)
- Sergio Amaro
- Stroke Unit, Department of Neurological Sciences, Hospital Clínic Barcelona. 170 Villarroel, 08036, Barcelona, Spain.
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19
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Thevis M, Lohmann W, Schrader Y, Kohler M, Bornatsch W, Karst U, Schänzer W. Use of an electrochemically synthesised metabolite of a selective androgen receptor modulator for mass spectrometry-based sports drug testing. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2008; 14:163-170. [PMID: 18708696 DOI: 10.1255/ejms.924] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The elucidation of the metabolism of new therapeutics is a major task for pharmaceutical companies and of great interest for drug testing laboratories. The latter in particular need to determine the presence or absence of drugs or their metabolic products in urine to test for a misuse of these compounds. Commonly, in vitro or animal models are used to mimic the human metabolism and produce potential targets in amounts allowing for method development. An alternative route based on electrochemical reactions of drugs was reported to allow for the generation of selected metabolites. The utility of this approach for doping control purposes was demonstrated with a novel class of anabolic agents termed selective androgen receptor modulators (SARMs). An arylpropionamide- derived drug candidate was subjected to electrochemical "metabolism" and a major phase-I- metabolite, resulting from the elimination of a substituted phenol residue as identified in in vitro experiments, was generated and characterised using liquid chromatography/nuclear magnetic resonance spectroscopy and high resolution/high accuracy mass spectrometry. The metabolite was included in routine doping control procedures based on liquid chromatography/tandem mass spectrometry and has served as a reference compound for 5000 doping control specimens.
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Affiliation(s)
- Mario Thevis
- Center for Preventive Doping Research-Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
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20
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Lohmann W, Karst U. Biomimetic modeling of oxidative drug metabolism. Anal Bioanal Chem 2007; 391:79-96. [DOI: 10.1007/s00216-007-1794-x] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 12/03/2007] [Accepted: 12/04/2007] [Indexed: 10/22/2022]
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21
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Affiliation(s)
- K H Schram
- College of Pharmacy, University of Arizona, Tucson
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22
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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]
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23
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Abstract
Humans excrete uric acid as the final breakdown product of unwanted purine nucleotides. Urate scavenges potential harmful radicals in our body. However, in conjunction with genetic or environmental (especially dietary) factors, urate may cause gout, nephrolitiasis, hypertension, and vascular disease. Blood levels of urate are maintained by the balance between generation and excretion. Excretion requires specialized transporters located in renal proximal tubule cells, intestinal epithelial cells, and vascular smooth muscle cells. The recently identified human urate transporters URAT1, MRP4, OAT1, and OAT3 are thought to play central roles in homeostasis and may prove interesting targets for future drug development.
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Affiliation(s)
- Matthias A Hediger
- Membrane Biology Program and Renal Division, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
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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]
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25
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Bökman CF, Zettersten C, Sjöberg PJR, Nyholm L. A Setup for the Coupling of a Thin-Layer Electrochemical Flow Cell to Electrospray Mass Spectrometry. Anal Chem 2004; 76:2017-24. [PMID: 15053666 DOI: 10.1021/ac030388r] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel setup for the coupling of a commercially available thin-layer cell to electrospray mass spectrometry (ESI-MS) which allows the electrochemical reactions at the counter electrode to be straightforwardly separated from the flow into the mass spectrometer has been developed. In this way, interferences from reaction products formed at the counter electrode can be minimized. This reduces the risk of changes in the mass spectra as a result of electrochemical reactions in the solution. The described setup also enables the working electrode to be positioned close to the electrospray (ESI) emitter without the need for a grounding point or a long transfer line between the electrochemical cell and the electrospray emitter. By decoupling the electrochemical reactions in the flow cell and those in the electrospray emitter, improved facilities for studies of electrochemical reactions are obtained through a better control of the potential of the working electrode. The setup has been used to study the oxidation of a drug (Olsalazine), which previously has been found to involve chemical follow-up reactions. It is also demonstrated that uncharged thiols can be detected in ESI-MS after spontaneous adsorption on a gold working electrode, followed by oxidative desorption to yield sulfinates or sulfonates. This adsorption and potential-controlled desorption has been used for the preconcentration of micromolar concentrations of 1-hexanethiol as well as for desalting of solutions containing micromolar concentrations of thiols. The results indicate that the present on-line coupling of an electrochemical cell to ESI-MS provides promising possibilities for sample preconcentration, matrix exchange (including desalting), and ionization of neutral compounds, such as thiols.
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Affiliation(s)
- C Fredrik Bökman
- Department of Analytical Chemistry, Uppsala University, P.O. Box 599, SE-751 24 Uppsala, Sweden
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26
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Hayen H, Karst U. Strategies for the liquid chromatographic-mass spectrometric analysis of non-polar compounds. J Chromatogr A 2003; 1000:549-65. [PMID: 12877188 DOI: 10.1016/s0021-9673(03)00505-3] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Electrospray ionization and atmospheric pressure chemical ionization (APCI) have evolved recently as very useful tools for the liquid chromatographic-mass spectrometric (LC-MS) analysis of polar substances. Non-polar compounds, however, are difficult to analyze with these atmospheric pressure ionization techniques due to their soft ionization mechanism. Recently, new approaches have been introduced which are likely to overcome this obstacle, at least partly. On-line electrochemical conversion of the analytes to more polar reaction products, atmospheric pressure photoionization, atmospheric pressure electron capture negativeion-MS and coordination ionspray-MS are four techniques which are presented in detail compared and discussed critically with respect to their current status and future perspectives. Particular focus is directed from a chemical viewpoint on the substance groups which are accessible by each of the new approaches.
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Affiliation(s)
- Heiko Hayen
- University of Twente, Department of Chemical Analysis, MESA Research Institute, P.O. Box 217, 7500 AE Enschede, Netherlands
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27
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Abstract
The drug development bottlenecks of attrition and development time are being addressed by acquiring a profile of the candidate's physicochemical and physiological properties during early discovery phases. This information assists selection and optimization of pharmaceutical properties in parallel with activity. High throughput methods to measure the properties: solubility, permeability, lipophilicity, pKa, stability and integrity are described and compared in this article. The underlying discovery requirements, needs and application strategies are discussed.
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Affiliation(s)
- E H Kerns
- Wyeth-Ayerst Research, Princeton, New Jersey 08543-8000, USA.
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28
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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]
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29
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Regino MCS, Brajter-Toth A. Real Time Characterization of Catalysis by On-Line Electrochemistry/Mass Spectrometry. Investigation of Quinone Electrocatalysis of Amine Oxidation. ELECTROANAL 1999. [DOI: 10.1002/(sici)1521-4109(199905)11:5<374::aid-elan374>3.0.co;2-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Hambitzer G, Heitbaum J, Stassen I. Electrochemical Thermospray Mass Spectrometry Instrumentation for Coupling Electrochemistry to Mass Spectrometry. Anal Chem 1998; 70:838-42. [DOI: 10.1021/ac970753c] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Günther Hambitzer
- Fraunhofer-Institut für Chemische Technologie, Postfach 1240, D-76318 Pfinztal, Germany
| | | | - Ingo Stassen
- Fraunhofer-Institut für Chemische Technologie, Postfach 1240, D-76318 Pfinztal, Germany
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31
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Hendricks JH, Lyapustina SA, de Clercq HL, Snodgrass JT, Bowen KH. Dipole bound, nucleic acid base anions studied via negative ion photoelectron spectroscopy. J Chem Phys 1996. [DOI: 10.1063/1.471482] [Citation(s) in RCA: 234] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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O'Neill RD, Lowry JP. On the significance of brain extracellular uric acid detected with in-vivo monitoring techniques: a review. Behav Brain Res 1995; 71:33-49. [PMID: 8747173 DOI: 10.1016/0166-4328(95)00035-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The concentration of uric acid [UA] in the extracellular fluid (ECF) estimated with in-vivo voltammetry and microdialysis data is compared for probes of different diameters from the day of implantation (acute) to several days (chronic) or even months after surgery. For small probes (diameter < 160 microns) the acute [UA] of ca. 5 microM decreased significantly to ca. 1 microM under chronic conditions. For larger probes (e.g., 320-microns diameter) the acute [UA] was also ca. 5 microM, but this value significantly increased to ca. 50 microM under chronic conditions. Associated with this difference in [UA], there were parallel differences in the extent of gliosis around the probes. These findings are discussed in terms of possible sources of extracellular UA and their implications for in-vivo monitoring techniques in behaving animals.
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Affiliation(s)
- R D O'Neill
- Department of Chemistry, University College Dublin, Belfield, Ireland.
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33
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Lowry JP, O'Neill RD. Partial characterization in vitro of glucose oxidase-modified poly(phenylenediamine)-coated electrodes for neurochemical analysis in vivo. ELECTROANAL 1994. [DOI: 10.1002/elan.1140060504] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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34
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Zhu SM, Brajter-Toth A. Liquid chromatographic determination of 6-thiopurine metabolites formed in vitro in electrochemical and enzymatic oxidative activation. Anal Chim Acta 1990. [DOI: 10.1016/s0003-2670(00)83933-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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35
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Volk KJ, Yost RA, Brajter-Toth A. On-line mass spectrometric investigation of the peroxidase-catalysed oxidation of uric acid. J Pharm Biomed Anal 1990; 8:205-15. [PMID: 2094419 DOI: 10.1016/0731-7085(90)80028-n] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The enzymatic and electrochemical oxidation pathways of uric acid were determined on-line with thermospray-tandem mass spectrometry. Products and intermediates formed as a result of electrooxidation were monitored as the electrode potential was varied. Electrochemical results served as a model for the enzymatic studies. In fact, electrochemical studies were essential for elucidating the structures of intermediates because of the high conversion efficiencies in electrooxidation. Products and intermediates formed as a result of enzymatic oxidation of uric acid were monitored as the reaction time was varied. When the enzymatic oxidation of uric acid with peroxidase and H2O2 was studied, the same intermediates and products were observed as in the electrochemical oxidation. The tandem mass spectrometric results provide convincing evidence that the primary intermediate produced during both the enzymatic and electrochemical oxidation of uric acid has a quinonoid diimine structure. The primary intermediate can follow three distinct reaction pathways to produce the identified final products. The final enzymatic and electrochemical oxidation products observed in these studies were urea, CO2, alloxan, alloxan monohydrate, allantoin, 5-hydroxyhydantoin-5-carboxamide and parabanic acid.
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Affiliation(s)
- K J Volk
- Department of Chemistry, University of Florida, Gainesville 32611
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36
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37
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Tomer KB, Parker CE. Biochemical applications of liquid chromatography-mass spectrometry. JOURNAL OF CHROMATOGRAPHY 1989; 492:189-221. [PMID: 2670991 DOI: 10.1016/s0378-4347(00)84469-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The current state-of-the-art liquid chromatography-mass spectrometry (LC-MS) is reviewed with particular attention to biomedical applications. The most common LC-MS interface designs are described and compared. These interfaces include transport, direct liquid introduction, thermospray, atmospheric pressure ionization, monodisperse aerosol generation, open-tubular LC and continuous-flow fast atom bombardment. The relative sensitivities of the techniques are compared as much as possible, as well as their tendencies to induce thermal decomposition of the sample. Applications of these various interface types to a variety of biomedically important compound classes, including peptides, nucleotides, steroids, lipids, carbohydrates, xenobiotic metabolites and drugs, are also reviewed.
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Affiliation(s)
- K B Tomer
- Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
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38
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Getek TA, Korfmacher WA, McRae TA, Hinson JA. Utility of solution electrochemistry mass spectrometry for investigating the formation and detection of biologically important conjugates of acetaminophen. J Chromatogr A 1989; 474:245-56. [PMID: 2768396 DOI: 10.1016/s0021-9673(01)93919-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
On-line formation and detection of glutathione and cysteine conjugates of acetaminophen were accomplished by the interfacing of a coulometric electrochemical cell with a thermospray mass spectrometer in a flow-injection experiment using a liquid chromatographic pump. Formation of the conjugates occurred only after acetaminophen was oxidized electrochemically by a two-electron transfer to N-acetyl-p-benzoquinoneimine and reacted in a mixing tee with either glutathione or cysteine. The newly formed conjugate was detected by thermospray mass spectrometry by observing the [M + H]+ ion for the acetaminophen-glutathione conjugate at m/z 457, or the [M + H]+ ion for the acetaminophen cysteine conjugate at m/z 271. Both the glutathione and cysteine conjugates produced a common fragment ion at m/z 184. The on-line reaction of glutathione and electrochemically generated N-acetyl-p-benzoquinoneimine was monitored at varying pH. At pH 8.5 the ion intensity for the acetaminophen-glutathione conjugate was greater than at lower pH, indicating that lower proton concentration enhanced the reaction of glutathione with N-acetyl-p-benzoquinoneimine. This on-line electrochemical-thermospray mass spectrometric method demonstrated that acetaminophen conjugates may be formed and detected in the time frame of 1 s.
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Affiliation(s)
- T A Getek
- National Center for Toxicological Research, Jefferson, AR 72079
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39
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Volk KJ, Yost RA, Brajter-Toth A. Characterization of solution-phase and gas-phase reactions in on-line electrochemistry-thermospray tandem mass spectrometry. J Chromatogr A 1989; 474:231-43. [PMID: 2768395 DOI: 10.1016/s0021-9673(01)93918-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Electrochemistry was used on-line with high-performance liquid chromatography-thermospray tandem mass spectrometry to provide insight into the solution-phase decomposition reactions of electrochemically generated oxidation products. Products formed during electrooxidation were monitored as the electrode potential was varied. The solution reactions which follow the initial electron transfer at the electrode are affected by the vaporizer tip temperature of the thermospray probe and the composition of the thermospray buffer. Either hydrolysis or ammonolysis reactions of the initial electrochemical oxidation products can occur with pH 7 ammonium acetate buffer. Both the electrochemically generated and the synthesized disulfide of 6-thiopurine decompose under thermospray conditions to produce 6-thiopurine and purine-6-sulfinate. Solution-phase studies indicate that nucleophilic and electrophilic substitution reactions with purine-6-sulfinate result in the formation of purine, adenine, and hypoxanthine. Products were identified and characterized by tandem mass spectrometry. This work shows the first example of high-performance liquid chromatography used on-line with electrochemistry to separate stable oxidation products prior to analysis by thermospray tandem mass spectrometry. In addition, solution-phase and gas-phase studies with methylamine show that the site of the nucleophilic and electrophilic reactions is probably inside the thermospray probe. Most importantly, these results also show that the on-line combination of electrochemistry with thermospray tandem mass spectrometry provides valuable information about redox and associated chemical reactions of biological molecules such as the structures of intermediates or products as well as providing insight into reaction pathways.
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Affiliation(s)
- K J Volk
- Department of Chemistry, University of Florida, Gainesville 32611
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Subramanian P, Nguyen N, Dryhurst G, Hutzenlaub W, Pfleiderer W. Confirmation of 5-hydroxy-7-methyl-Δ4,9-isouric acid as an intermediate in the electrochemical oxidation of 7-methyluric acid. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0022-0728(89)85104-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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