Different behavior of 3-nitrotyrosine and tyrosine toward perfluorinated reagents suitable for one-step preparation of volatile derivatives

In view to develop a gas-chromatographic (GC) determination of the 3-nitrotyrosine (NY)/tyrosine (Y) ratio as a marker of nitro-oxidative stress, different reagents were tested with the objective of obtaining a single volatile fluorinated product for each amino acid by a one-step derivatization procedure. The heptafluorobutyric anhydride (HFBA) /heptafluorobutanol (HFBOH) mixture proved unsuccessful for NY and Y simultaneous analysis. The reaction with different chloroformates [isobutyl chlorofomate (iBuCF) and ethyl chloroformate (EtCF)] in the presence of different perfluorinated alcohols such as trifluoroethanol (TFEOH) and HFBOH was investigated. Combination EtCF/fluorinated alcohols yielded derivatives of NY and Y as single peaks suitable to the GC determination of the NY/Y ratio. The different behaviour of two amino acids in the used reaction mixtures and the parameters influencing the results were discussed