High-performance liquid chromatographic determination of histamine N-methyltransferase activity.

A method for the determination of histamine N-methyltransferase (HMT) activity by high-performance liquid chromatography based on post-column derivatization with omicron-phthalaldehyde is described. The determination involves the separation of the substrate, histamine, from its product. N tau-methylhistamine, using a weak cation exchanger, followed by on-line derivatization of these imidazoleamines with omicron-phthalaldehyde and their detection and quantitation with a fluorimetric detector. This assay method is suitable for the measurement of HMT activity during enzyme purification.