Separation of free amino acids in human plasma by capillary electrophoresis with laser induced fluorescence: potential for emergency diagnosis of inborn errors of metabolism

Free amino acids (AAs) in human plasma are derivatized with 3-(4-carboxyben zoyl)quinoline -2-carboxaldehyde (CBQCA) and analyzed by capillary electrop horesis (CE) with laser induced fluorescence (LIF) detection. The labeling procedure is significantly improved over results reported previously. Deriv atization can be completed in 40 min, with concentrations as low as 4x10(-8 ) M successfully labeled in favourable cases. Twenty-nine AAs (including 2 internal standards) are identified and can be reproducibly separated in 70 min. Migration time RSD values for 23 of these AAs were calculated and foun d in the range from 0.5 to 4%. The rapid derivatization procedure and the r esolution obtained in the separation are sufficient for a semi-quantitative , emergency diagnosis of several inborn errors of metabolism (IEM). Amino a cid profiles for both normal donor plasma samples and plasma samples of pat ients suffering from phenylketonuria, tyrosinemia, maple syrup urinary dise ase, hyperornithinemia. and citrullinemia are studied. (C) 2001 Elsevier Sc ience B.V. All rights reserved.