Determination of urinary excretion of histamine and 1-methylhistamine by liquid chromatography

Urinary histamine (Him) and 1-methylhistamine (MH) were determined by liquid chromatography (LC) using on-column derivatization coupled with a column-switching technique. An intact urine sample without any purification was applicable to the LC system because all steps for purification and fluorescence derivatization were fully automated. It was observed that the concentrations of Him and MH increased after hydrolysis of the urine, suggesting the presence of conjugated Him and MH. The level of total/free Him in urine was significantly higher in cancer patients than in normal subjects. Further, a significant correlation between Him and MH was observed in the hydrolysed urine of both normal subjects and cancer patients.