Deuterated histamine

The reference standards of putrescine, cadaverine hydrochloride, spermidine hydrochloride, spermine, agmatine sulfate salt, N-acetyl-putrescine hydrochloride, N-acetyl-spermine trihydrochloride, N-acetyl-spermidine dihydrochloride, L-ornithine hydrochloride, lysine, L-arginine, S-adenosyl-1-methionine, aminobutyric acid, deuterated histamine, heptafluorobutyric acid (HFBA), and methanol LC/MS grade were purchased from Sigma-Aldrich (St. Louis, MO, USA). Water for LCMS was purchased from Fisher Scientific (Fair Lawn, NJ, USA).

The reference standards of putrescine, cadaverine hydrochloride, spermidine hydrochloride, spermine, agmatine sulphate salt, N-acetyl-putrescine hydrochloride, N-acetylspermine trihydrochloride, N-acetylspermidine dihydrochloride, l-ornithine hydrochloride, lysine, l-arginine, aminobutyric acid, deuterated histamine, heptafluorobutyric acid (HFBA) and methanol were purchased from Sigma-Aldrich (St. Louis, MO, USA) for analytical type analysis. Water for LCMS was purchased from Fisher Scientific (Fair Lawn, NJ, USA).
Liquid chromatography–high-resolution mass spectrometry (LC-HRMS) analysis was performed using an UPLC Ultimate 3000 (Thermo Fisher-Dionex San Jose, CA, USA) system equipped with a HESI-II electrospray source to a Q-Exactive-Orbitrap™-based mass spectrometer (all from Thermo Scientific, San Jose, CA, USA). Chromatographic separation was carried out on the C18 column of the Gemini C18 (Phenomenex, Torrance, CA, USA), 100 mm × 2 mm, particle size 3 µm, the column was held at 37 °C. Chromatographic separation was achieved with gradient elution using a mobile phase composed of 0.05% heptafluorobutyric acid (HFBA) in water (A) and 0.05% HFBA in methanol (B).