Efficient extraction and mass spectrometric assay of serotonin in biological fluids

A gas chromatographic mass spectrometric assay for serotonin (5-hydroxytryptamine) has been developed. Serotonin is acylated in homogenized biological media, efficiently extracted into ethyl acetate, and further derivatized with pentafluoropropionic anhydride. Mass spectral characterization of derivatized serotonin using electron and positive or negative chemical ionization indicates that electron ionization mass spectrometry is useful for serotonin assay in most biological fluids and tissues, but that electron capture negative chemical ionization is required for samples containing less than 1-2 ng (cerebrospinal fluid). An assay limit of 10 pg per sample has been established. Examples of applications for the assay of serotonin in human platelets, rat spinal cord, and monkey cerebrospinal fluid are presented.