[Determination of nitrotyrosine with catalytic spectrophotometry combining the substitution of nitroxyl by iodide].

The nitroxyl of nitrotyrosine can be substituted quantitatively by iodide when the nitroxyl is reduced to amino and then diazotized to diazonium. The iodide can be determined by catalytic spectrophotometric method with iodide-nitrous acid-arsenious acid system. Thus, a new catalytic spectrophotometric method combining the substitution of nitroxyl by iodide for the determination of nitrotyrosine has been established. The limit of detection is 0.002 mumol.L-1 and the linear range is 0.005-0.25 mumol.L-1. The method has been used for the determination of nitrotyrosine in the products of the reaction of tyrosine with peroxynitrite and the results are satisfactory.