Automated assay of gamma-aminobutyric acid in human cerebrospinal fluid.

We describe an automated amino acid analyzer with fluorescence detection (o-phthalaldehyde) which permits sensitive and rapid determinations of gamma aminobutyric acid in human cerebrospinal fluid. Concentrations as low as 50 nmol/liter can be accurately determined in 100 mul samples at the rate of one sample per hour. Concentrations in untreated cerebrospinal fluid increase rapidly after sampling by lumbar puncture. The concentration in immediately deproteinized samples from 38 patients with intervertebral disc disorders was 220 +/- 81 nmol/liter (mean +/- SD).