Gas-phase reactions of laser-desorbed molecules with ions from electrospray

Gas-phase reactions of neutral molecules delivered by laser desorption with ions introduced via an electrospray interface have been observed. To maximize the production of neutrals while keeping laser ionization products negligible, the laser fluence has been adjusted only slightly above the ionization threshold fluence. The reactions have been performed in the entrance to an ion funnel operated at 3-4 mbar. Both the laser desorption assembly and the electrospray interface belong to an electrospray ionization to matrix-assisted laser desorption/ionization switchable combination ion source attached to a Fourier transform ion cyclotron resonance mass spectrometer. The reaction products of molecular species of 1-aza[6]-helicene, 1,8-dihydroxy-9-anthrone (dithranol) and 2-mercaptobenzothiazole with protonating reagent ions and silver cations from etectrospray were detected. The products were identified by their accurate mass, proton/deuterium isotopic exchange and by resolving the corresponding peaks of isotopolog ions.