Oxidation of Ferrocene Derivatives in Desorption/Ionization on Porous Silicon

Abstract

In matrix-assisted laser desorption/ionization (MALDI), the true molecular structures of some analytes are not represented by the observed ions due to a redox reaction. In earlier reports, electron transfer from analyte to chemical matrix has been proposed for the oxidation of ferrocene derivatives in MALDI. To address such a redox phenomenon in laser desorption/ionization processes, two ferrocene derivatives, FcCH₂CH₂Fc and FcCH₂NMe₂ [Fc:(C₅H₅)Fe(C₅H₄)], were analyzed by a matrix-free method, desorption/ionization on porous silicon (DIOS). The oxidized species, Fc⁺CH₂NMe₂ and FcCH₂CH₂Fc⁺, were detected in the DIOS mass spectra. The results suggested that electron transfer from the analytes to the sample target occurs during the ionization process.