title: Quantitative electron paramagnetic resonance and spectrophotometric determination of the free radical 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy.
abstract: The first quantitative estimation of the stable free radical 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPOL) simultaneously performed by electron paramagnetic resonance (EPR) and visible spectrophotometric titration is reported. The obtained molar absorptivity of TEMPOL 13.2 +/- 0.1 l(-1) m(-1) cm(-1) at 22,900 cm(-1) may be used as the future criterium about the purity of the EPR active substance. The studied compound may be considered as the second (after 1,1-diphenyl-2-pikrilhydrazil) material calibrated as the primary standard for quantitative EPR spectrometry.
authors.affiliation: Institute of Catalysis, Bulgarian Academy of Sciences, Sofia. ndyepr@bas.bg
authors.forename: N D
authors.initials: ND
authors.lastname: Yordanov
authors.forename: K
authors.initials: K
authors.lastname: Ranguelova
mesh_terms: D003497:Cyclic N-Oxides / Q000032:analysis* / Q000592:standards; D004578:Electron Spin Resonance Spectroscopy / Q000592:standards*; D005609:Free Radicals / Q000737:chemistry; D012015:Reference Standards; D013053:Spectrophotometry; D013113:Spin Labels
chemical_list: D003497:Cyclic N-Oxides; D005609:Free Radicals; D013113:Spin Labels; C001803:tempol