Reference values of neuroactive amino acids in the cerebrospinal fluid by high-performance liquid chromatography with electrochemical and fluorescence detection.

Sampling and HPLC analysis procedures for CSF amino acid determinations were evaluated. In order to increase sensitivity, a precolumn derivatization of amino acids by o-phthalaldehyde-mercaptoethanoi reagent was used. By using fluorimetric and electrochemical detection in series, positive peak identification can be obtained in a single chromatographic run. It is recommended to analyze freshly collected CSF. Amino acids are stable for short periods over a wide range of temperature, but storage at -80°C is recommended. The CSF samples for the calculation of the reference values were taken from 40 healthy subjects, hospitalized for lumbar disk herniation, placed on the same diet and kept drug-free for at least 1 week. The mean values (μmol/l) and the ranges (in parentheses) were: 0.27 (0.09-0.63), 0.62 (0.18-1.15), 5.32 (3.05-11.50), 6.16 (2.90-13.30), 0.16 (0.03-0.22) for aspartic acid, glutamic acid, glycine, taurine and γ-aminobutyric acid respectively.