Analysis of Nα-methylhistamine by gas chromatography–mass spectrometry

A gas chromatography–electron capture mass spectrometry assay has been developed for the histamine H3 receptor agonist, Nα-methylhistamine (Nα-MH). The assay is linear from 50 pg–10 ng, with a limit of detection of 50 pg/ml for gastric juice and plasma, and 50 pg/sample for bacteria (107–108 CFU) and gastric tissue (5–10 mg wet weight). The limits of quantification are 100 pg/ml for gastric juice (%RSD=1.4) and plasma (%RSD=9.4), and 100 pg/sample for bacteria (%RSD=3.9) and tissue (%RSD=5.8). Nα-MH was not present in human plasma, but low levels (1.4 ng/ml and 0.4 ng/ml) were detected in two samples of human gastric juice obtained from patients infected with Helicobacter pylori.