Detection and removal of contaminating hydroxylamines from the spin trap DEPMPO, and re-evaluation of its use to indicate nitrone radical cation formation and S(N)1 reactions.
A previous report that the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) allows DEPMPO radical cation formation to be detected via the production of a carbon-centred radical adduct (assigned as the cis-hydroxyethyl species, formed by an intramolecular process) is shown to be incorrect. Rather, this and other paramagnetic species arise from the facile oxidation of trace hydroxylamine impurities present in commercial DEPMPO samples. As a result, techniques for the detection and elimination of such hydroxylamine impurities from DEPMPO solutions were developed and are described; these should prove to be of general use in EPR spin trapping experiments.
Jackson
Simon K
SK
Department of Medical Microbiology, University of Wales College of Medicine, Cardiff, Wales, UK.
Liu
Ke Jian
KJ
Liu
Miao
M
Timmins
Graham S
GS
D002412:Cations / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006898:Hydroxylamines / Q000032:analysis* / Q000302:isolation & purification*; D009589:Nitrogen Oxides / Q000737:chemistry*; D013113:Spin Labels; D019097:Spin Trapping; D013997:Time Factors
D002412:Cations; D003497:Cyclic N-Oxides; D006898:Hydroxylamines; D009589:Nitrogen Oxides; D013113:Spin Labels; C015388:nitrones; C098505:5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide