ION-MOLECULE REACTIONS OF OXYGENATED CHEMICAL-IONIZATION REAGENTS WITH VINCAMINE

The ion-molecule reactions of ions from acetone, dimethyl ether, 2-met hoxyethanol, and vinyl methyl ether with vincamine were investigated. Reactions with dimethyl ether result in [M + 13](+) and [M + 45](+) pr oducts, reactions with 2-methoxyethanol produce [M + 13](+) and [M + 8 9](+) ions, and reactions with acetone or vinyl methyl ether ions gene rate predominantly [M + 43](+) ions. Collision-activated dissociation and deuterium labeling experiments allowed speculation about the produ ct structures and mechanisms of dissociation. The methylene substituti on process was shown to occur at the hydroxyl oxygen and the phenyl ri ng of vincamine for dimethyl. ether reactions, but the methylene subst itution process was not favored at the hydroxyl oxygen for the 2-metho xyethanol reactions, instead favored at the 12 phenyl position. The re action site is Likely different for the 2-methoxyethanol ion due to it s capability for secondary hydrogen-bonding interactions. For the [M 45](+) and [M + 89](+) ions, evidence suggests that charge-remote fra gmentation processes occur from these products. In general, the use of dimethyl ether ions or 2-methoxyethanol ions for ion-molecule reactio ns prove highly diagnostic for the characterization of vincamine; both molecular weight and structural information are obtained. Limits of d etection for vincamine with dimethyl ether chemical ionization via thi s technique on a benchtop ion trap gas chromatography-tandem mass spec trometer are in the upper parts per trillion range.