Characterization of the radical product formed from the reaction of nitricoxide with the spin trap 3,5-dibromo-4-nitrosobenzene sulfonate

Previously, 3,5-dibromo-4-nitrosobenzene sulfonate (DBNBS) has been used in combination with electron paramagnetic resonance (EPR) spectrometry to tra p nitric oxide (NO.). The reaction between DBNBS and NO. yields a radical p roduct which gives rise to an EPR signal consisting of three lines with an A(N) = 0.96 mT, hut the structure of this product is unknown. A two-stage h igh-performance liquid chromatography fractionation was performed to isolat e the radical product from the other components in the DBNBS/NO. reaction m ixture. The fractions containing the radical product were identified by the presence of the three-line EPR signal, and then these fractions were analy zed by negative ion fast atom bombardment-mass spectrometry (FAB-MS). Colle ctively, the FAB-MS data suggested that the radical product is the monosodi um electrostatic complex with the dianion, bis(2,6-dibromo-4-sulfophenyl) n itroxyl. Analysis of the Gaussian and Lorentzian linewidths of the EPR sign al suggested that bis(2,6-dibromo-4-sulfophenyl) nitroxyl molecules may gro up together to form micelles. Further studies also indicated that significa nt amounts of nitrogen and nitrate were produced during the reaction betwee n DBNBS and NO.. A reaction scheme consistent with these results is present ed. (C) 2001 Academic Press.