Juergen O. Metzger et.al.: Electrospray ionization and atmospheric pressure ionization mass spectrometry of stable organic radicals

Author(s): Juergen O. Metzger, Jens Griep-Raming

Title: Electrospray ionization and atmospheric pressure ionization mass spectrometry of stable organic radicals

Date of Upload: 1999

Article: Eur. J. Mass Spectrom. 5, 157 - 163 (1999), Department of Chemistry, University of Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg, Germany;

Keywords: electrospray ionization, atmospheric pressure chemical ionization, stable radicals, ESI-MS, mass spectrometry, reactive intermediate, reaction, solution

Abstract:
The ionization behavior of stable radicals (1–8) was studied under electrospray ionization (ESI) and atmospheric pressure ionization (APCI) conditions. With APCI, using methanol + water as the solvent, most radicals were protonated to give the radical cation [M + 1], whereas TEMPO (5) was detected as the M+ ion and galvinoxyl (1) gave the [M + 2]+ ion. Using benzene as the solvent, all radicals (1–8) were efficiently oxidized to give M+ as the base peak. Under ESI conditions using methanol + water with 1% acetic acid, stable radicals (5–7) gave [M + 1] , (2–4) M+ , whereas (1) and (8) showed the [M + 2]+ ion as the base peak. Using the ESI source as a controlled-current electrolytic cell, radicals (2–8) were efficiently oxidized to give M+ ions. Radical (1) was detected as the [M + 2]+ ion. Detection limits for the radicals (1–8) were between 3 x 10-9 mol L-1 and 5 x 10-7 mol L-1 using APCI or ESI in the full-scan mode. In most cases detection limits were lower using the tandem mass spectrometry (MS/MS) full-scan mode.

URL: http://www.chemie.uni-oldenburg.de/oc/metzger/publikationen/pdf/82.pdf (text/plain)


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