Figure 2.

Detection of n-propyl heptafluorobutyryl derivatives of ortho-tyrosine (a), meta-tyrosine (b), and o,o’-dityrosine (c) in monkey thoracic aortic tissue by selected ion monitoring negative-ion electron capture GC/MS. Tissue samples were delipidated, hydrolyzed with acid, and subjected to solid-phase extraction on a C-18 column. Isolated oxidized amino acids were derivatized and analyzed by GC/MS. Note co-elution of the major ion expected for (a) ortho-tyrosine (m/z 595) with that of ortho-[¹³C₆]tyrosine (m/z 601), (b) meta-tyrosine (m/z 417) with that of meta-[¹³C₆]tyrosine (m/z 423), and (c) o,o’-dityrosine (m/z 1208) with that of o,o’-[¹³C₁₂]dityrosine (m/z 1220).