Oxidation of ferrocene derivatives in desorption/ionization on porous silicon

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, FcCH(2)CH(2)Fc and FcCH(2)NMe(2) [Fc:(C5H5)Fe(C5H4)], were analyzed by a matrix-free method, desorption/ionization on porous silicon (DIOS). The oxidized species, Fc(+)CH(2)NMe(2) and FcCH(2)CH(2)Fc(+), 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.