Simple and sensitive procedure for the assay of serotonin and catecholamines in brain by high-performance liquid chromatography using fluorescence detection

A simple, rapid and specific method for the determination of serotonin and catecholamines in brain is described. After tissue homogenisation, catecholamines are isolated by adsorption onto alumina and elution with perchloric acid. Serotonin is isolated by extraction into n-heptanol and back-extraction into acid. High-performance liquid chromatography of the acid extracts is performed with a C₁₈ reversed-phase column and simple mobile phases. Detection is by the intrinsic fluorescence of the amines on excitation at 200 nm. Detection limits are 100 pg for norepinephrine, 300 pg for dopamine and 20 pg for serotonin. The results are found to correlate well with a catechol O-methyl transferase radioenzymatic assay for catecholamines and a ninhydrin derivatisation procedure for serotonin.