LIQUID-CHROMATOGRAPHIC ASSAY OF DITYROSINE IN HUMAN CEREBROSPINAL-FLUID

A micro-scale method for separation and measurement of dityrosine in h uman cerebrospinal fluid (CSF) is described utilizing liquid-liquid ex traction and ion-paired, reversed-phase high-performance liquid chroma tography with fluorimetric detection. A mobile phase containing 1-hept anesulfonic acid linearly increased in methanol from 0 to 100% over 30 min allows the resolution of dityrosine from other fluorescent compou nds with excitation at 285 nm and emission at 410 nm. As little as 0.1 5 mi CSF sample can be utilized with a detection limit of 60 pg dityro sine on the column. This method facilitates the use of CSF dityrosine as a measure of free radical mediated protein damage in the central ne rvous system. (C) 1997 Elsevier Science B.V.