Studies of Dopamine Oxidation Process by Atmospheric Pressure Glow Discharge Mass Spectrometry

Dongli Dai; Yueqin Zhu; Zhenli Zhu; Rong Qian; Shangjun Zhuo; Anqi Liu; Xian Li; Wei Li; Qiao Chen

doi:10.3390/molecules28093844

Molecules (May 2023)

Studies of Dopamine Oxidation Process by Atmospheric Pressure Glow Discharge Mass Spectrometry

Dongli Dai,
Yueqin Zhu,
Zhenli Zhu,
Rong Qian,
Shangjun Zhuo,
Anqi Liu,
Xian Li,
Wei Li,
Qiao Chen

Affiliations

Dongli Dai: National Center for Inorganic Mass Spectrometry in Shanghai, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Yueqin Zhu: National Center for Inorganic Mass Spectrometry in Shanghai, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Zhenli Zhu: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
Rong Qian: National Center for Inorganic Mass Spectrometry in Shanghai, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Shangjun Zhuo: National Center for Inorganic Mass Spectrometry in Shanghai, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Anqi Liu: National Center for Inorganic Mass Spectrometry in Shanghai, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Xian Li: National Center for Inorganic Mass Spectrometry in Shanghai, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China
Wei Li: School of Material and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China
Qiao Chen: Department of Chemistry, School of Life Sciences, University of Sussex, Brighton BN1 9QJ, UK

DOI: https://doi.org/10.3390/molecules28093844
Journal volume & issue: Vol. 28, no. 9
p. 3844

Abstract

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An atmospheric pressure glow discharge ionisation source was constructed and utilized to study the dopamine (DA) oxidation process coupling with mass spectrometry. During the DA oxidation process catalysed by polyphenol oxidase (PPO), six cationic intermediates were directly detected by the atmospheric pressure glow discharge mass spectrometry (APGD-MS). Combined with tandem mass spectrometry, the structures of the dopamine o-semiquinone radical (DASQ) and leukodopaminochrome radical (LDAC●) intermediates and structures of the isomers of dopaminochrome (DAC) and 5,6-dihydroxyindole (DHI) were further characterised with the introduction of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) and deuterium oxide (D2O) to APGD-MS. Meanwhile, UV–Vis studies confirmed the important role of PPO in catalyzing the DA oxidation reaction. Based on APGD-MS studies, a possible mechanism could be proposed for DA oxidation catalysed by PPO. Furthermore, APGD-MS could provide possibilities for the effective detection and characterisation of short-lived intermediates, even in complicated systems.

Published in Molecules

ISSN: 1420-3049 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Chemistry: Organic chemistry
Website: http://www.mdpi.com/journal/molecules

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