FIRST SYNTHESIS OF C-PHENYL N-TERT-BUTYL [N-15]NITRONE (PBN-N-15) FORTHE EPR SPIN-TRAPPING METHODOLOGY

As compared to normal PBN, about fifty percent increase of electron pa ramagnetic resonance (EPR) spin trapping sensitivity has been gained b y using a new 100% N-15-enriched spin trap, C-phenyl N-tert-butyl[N-15 ]nitrone (PBN-N-15). PBN-N-15 has been prepared by a convenient four-s tep route using ammonium-N-15 chloride as the starting material. This synthetic method produces 2-methyl-2-[N-15]nitropropane which is usefu l for the synthesis of many other PBN-N-15 type spin traps for the pur pose of increasing spin trapping sensitivity. EPR spin trapping with P BN-N-15 in benzene and in phosphate buffer has been investigated. The N-15 hyperfine splitting constant (N-15-hfsc) is larger than N-14-hfsc by 40%. The larger N-15-hfsc gives more opportunity to identify diffe rent radical addends within the same system.