Determination of histamine by chemical ionization mass spectrometry: application to human urine.

A determination of histamine in urine by selected ion monitoring, using (15N2)histamine as internal standard, is described. Three different ionization methods were used, chemical ionization with ammonia as reactant gas offering the highest sensitivity (detection limit 40 fmol of histamine on column). The 24 h urinary excretions of 10 normal adults ranged from 142-1100 nmol (mean 321 nmol). Patients with an anaphylactoid reaction and patients with mastocytosis showed above normal values.