Ion–molecule reactions of fragment ions derived from protonated allyl methyl ether

Abstract

Unusual behaviour has been noted for allyl methyl ether (1) chemically ionized in a high-pressure ion source. Tandem mass spectrometry indicates the formation of methylcyclopentadienyl and methoxy-1-propenylcarbenium ions (d, m/z 81 and e, m/z 85). The origin of these unexpected ions has been elucidated using conventional and Fourier transform ion cyclotron resonance experiments: primary fragment ions derived from protonated 1 (allyl ions a and methoxymethyl cations b) generate collision complexes with neutral 1, giving rise to the ions d and e. respectively, after methanol elimination.

Fragment‐molecule adduct formation from oxime carbamates during negative‐ion chemical ionization mass spectrometry

“…Positive-ion chemical ionization (PCI) spectra using methane as a reagent gas can exhibit adduct ions in the form of protonated molecular ions [M+Hl+, reagent adducts [M+291+, and proton-bound dimers [H+(M)2]+ ( 1). Several recent papers have described fragment-molecule reactions, in PCI conditions, that lead to adduct formation (2)(3)(4). For example, several heterocyclic drugs were found to add fragment ions ranging from m/z 57 to m/z 91, producing adducts with m/z greater than the molecular weight of the parent molecule The experiments were conducted on an Extrel 400-1 quadrupole MS equipped with solids probe, desorption chemical ionization (DCI), Waters high performance liquid chromatograph (LC), and particle beam (Thermabeamm) LC/MS interface for sample introduction.…”