DEVELOPMENT OF AN ASSAY FOR HISTAMINE USING AUTOMATED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

Previous studies have measured histamine by derivatization with o-phth aldialdehyde (OPA) and mercaptoethanol (ME), followed by reversed-phas e HPLC separation and electrochemical detection. The derivatization pr oduct, however, was very unstable. In the present study, inclusion of less polar solvents (e.g., acetonitrile or tetrahydrofuran) in the OPA /ME derivatization reaction produced an OPA/ME-histamine product that was stable for many hours. Changes of the HPLC mobile phase (increasin g its ionic strength and pH and including triethylamine) dramatically improved the chromatography and reduced the histamine detection limit to < 0.1 pmol. The modified assay was suitable for batchwise manual de rivatization of histamine samples followed by their automated analysis by HPLC with an automatic injector.