Analytical Sciences

Oxidation of Ferrocene Derivatives in Desorption/Ionization on Porous Silicon

Shoji OKUNO,* Kunihiko OKA,** and Ryuichi ARAKAWA**

*Japan Science and Technology Agency, Innovation Plaza Osaka, Wada Project Laboratory, 3-1-10 Technostage, Izumi, Osaka 594-1144, Japan
**Department of Applied Chemistry, Kansai University, 3-3-35 Yamatecho, Suita, Osaka 564-8680, Japan

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.

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