A method for the fluorometric assay of histamine in tissues.

A sensitive and specific fluorometric method for the estimation of histamine in tissues is described. The method involves extraction of histamine into butanol from alkalinized perchloric acid tissue extracts, return to an aqueous phase, and condensation with o -phthalaldehyde to form a highly fluorescent product which is estimated in a spectrofluorometer. Concentrations of histamine as low as 0.005 µg/ml can be assayed. Low levels of histamine (0.2-0.4 µg/g) occur in brain. Gross dissection of brain showed no marked localization of brain histamine.