Separation of L-DOPA and four metabolites in plasma using a porous graphitic carbon column in capillary liquid chromatography

Porous graphitic carbon has been successfully used for the separation of L-DOPA and four metabolites (dopamine, 3,4-dihydroxy-phenyl-acetic acid, homovanillic acid and 3-O-methyl-L-DOPA) and with a volatile mobile phase of relatively high percentage organic modifier (methanol-ammonium formate pH 2.9, 60∶40, v/v). The substances were analysed in plasma. Ultrafiltration was used to remove the proteins from the sample and a coupled column system to enrich and perform on-line sample clean up. Both precolumn and separation column of i. d. 0.2 mm were packed with porous graphitic carbon.