Abstract: Nitric oxide has many biological functions, but nitric oxide generated in biological systems can not be trapped by the nitroso spin traps. DETC iron complex can be used to trap nitric oxide generated in biological tissues, but there are some difficulties in analysis of the ESR spectroscopy. The g-values and hyperfine splitting structure of the ESR signals appeared in the DETC Fe trapped nitric oxide system are analysed and the methods for solving the difficulties are suggested.

Key words: Nitric oxide free radicals, ESR spectroscopy analysis, Biological tissue