Liquid chromatographic assay for cerebrospinal fluid serotonin

A novel liquid chromatographic method was developed for accurate and precise routine quantification of serotonin in human cerebrospinal fluid. Serotonin is derivatized with an amine-specific reagent leaving its hydroxy group free for electrochemical detection and making it lipophilic enough for efficient extraction into organic solvents. The method is reproducible, linear and free of interferences by endogenous amines other than serotonin. The limit of sensitivity is 100 fmol/ml CSF or 20 parts per trillion. Serotonin concentrations in lumbar cerebrospinal fluid from drug free, depressed patients were in the low nanomolar range.