5-Hydroxytryptophol in human cerebrospinal fluid: quantitative determination by gas chromatography-mass spectrometry using a deuterated internal standard.

Procedures for the quantification of 5-hydroxyindole-3-ethanol, or 5-hydroxy-tryptophol (5-HTOL), in human cerebrospinal fluid are described. 5-HTOL was determined as its di-pentafluorpropionyl derivative. Deuterium labelled 5-hydroxyindole-3-ethanol-a,a,b,b-d4 (5-HTOL-d4) was used as internal standard. Mass fragmentography was performed by double ion monitoring each for 5-HTOL and 5-HTOL-d4 and their ratios were determined for specificity. Assay sensitivities of 0.15 ng/ml were achieved using 2.0 ml of cerebrospinal fluid. Free 5-HTOL concentrations in human cerebrospinal fluid were determined to be 0.73 +/- 0.44 ng/ml (mean +/- S.D.) (range 0.33-2.11 ng/ml) from 15 patients with various neurological disorders, and 0.85 +/- 0.30 ng/ml (range 0.48-1.32 ng/ml) from 9 subjects who complained of low back pain but did not show signs of neurological illnesses.