Distribution profiles of nitroxide spin probes in human skin—a combined study using spatially resolved electron spin resonance spectroscopy and mass spectrometry

• Published in: Analytical and bioanalytical chemistry Vol. 401; no. 3; pp. 901 - 907
• Main Authors: Hochkirch, U., Herrmann, W., Stößer, R., Linscheid, M., Borchert, H.-H.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2011; Springer
• Subjects: Analytical Chemistry; Antioxidants - chemistry; Biochemistry; Biological materials; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Cyclic N-Oxides - chemistry; Cyclic N-Oxides - metabolism; Electron paramagnetic resonance; Electron spin resonance; Electron Spin Resonance Spectroscopy; Exact sciences and technology; Female; Food Science; Human; Humans; Investigations; Laboratory Medicine; Mass Spectrometry; Mathematical analysis; Monitoring/Environmental Analysis; Nitrogen Oxides - chemistry; Nitrogen Oxides - metabolism; Original Paper; Radicals; Skin; Skin - chemistry; Skin - metabolism; Spectrometric and optical methods; Spectroscopy; Spin Labels; Nitroxide radicals; Human skin; Hydroxylamine; Electron spin resonance spectroscopy; AP-MALDI mass spectrometry; Spatial resolution; Chemical analysis; Atmospheric pressure; EPR spectrometry; Product; Matrix assisted laser desorption ionization; Probe; Biological material; Free radical; Ion trap; Reduction; Detection limit; Human; Use; Biological compound; Spatial distribution; Distribution; Analytical method; Skin; Detection; Mass spectrometry
• ISSN: 1618-2642; 1618-2650; 1618-2650
• DOI: 10.1007/s00216-011-5150-9

Electron spin resonance spectroscopy and mass spectrometry are two analytical methods that are very rarely used in combination. In this paper, we will show that the methods complement one another in the example of the distribution of stable nitroxide radicals in human skin, including the spatial resolution of these distribution processes. There are many ESR investigations dealing with this subject, but unfortunately, they are all limited to the detection of paramagnetic species. The combination with MS allows the successful examination of the distribution profile of the main biotransformation product of the nitroxide radicals, the respective “ESR-silent” hydroxylamines. In order to maintain the biological state of the sample material as far as possible, atmospheric pressure matrix-assisted laser desorption/ionization with ion trap detection has been used for the mass spectrometric investigations. The results validate the former findings of the strong reduction of stable free radicals by biological material; moreover, the diamagnetic species formed during these processes have been identified. Figure Comparison of the ESR and MS results concerning the distribution of the nitroxide radical CAT-1 and CAT-1-H in a human skin biopsy