QUANTITATIVE DETECTION OF REDUCED, RADICAL AND OXIDIZED FORMS OF ALPHA-(4-PYRIDYL-1-OXIDE)-N-TERT-BUTYLNITRONE RADICAL ADDUCT USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

Reduced, radical and oxidized forms of alpha-(4-pyridyl-1-oxide)-N-ter t.-butylnitrone (4-POBN)-phenyl radical adduct were detected as separa ted peaks on the HPLC elution profile using either a high-performance liquid chromatography-ultraviolet absorption detector-electrochemical detector (HPLC-UV-ED) technique or a high-performance liquid chromatog raphy-electrochemical detector-ultraviolet absorption (HPLC-ED-UV) tec hnique. In the HPLC-ED-UV, the Coulochem ED electrode is placed betwee n an injector and an HPLC column, and used as a reactor which oxidizes the reduced form of the 4-POBN-phenyl radical adduct to the correspon ding radical and oxidized forms, respectively. Thus, the reduced, radi cal and oxidized forms of the 4-POBN-phenyl radical adduct are clearly identified. Furthermore, the concentration of the reduced and radical forms of the 4-POBN-phenyl radical adduct is quantitatively determine d by the Coulochem ED. It is possible to determine the concentration o f the respective forms of the 4-POBN-phenyl radical adduct because Cou lochem ED oxidizes all of the radical and reduced forms which flow thr ough the electrode.