The first observation of organic dications formed by multiple electron loss in electrospray mass spectra is reported. The dications of β-carotene, canthaxanthine, cobalt(II) octaethylporphyrin, and nicke(II) octaethylporphyrin were created in solution via chemical electrontransfer reactions and detected in the gas phase by electrospray ionization mass spectrometry (ES-MS) using a flow-injection experiment. The analytes were injected into a flowing solvent-oxidant stream (10 μL/min) composed of dried methylene chloride containing ≈ 0.1% by volume trifluoroacetic acid and 0.1% by volume antimony pentafluoride (SbF5). The dications created in this oxidizing solvent system were preserved for detection by rapidly transferring them from the reactive solvent-oxidant system to the gas phase, where, in the absence of the solvent system, they were "long-lived" and amenable to mass analysis. This work demonstrates means to produce ions novel to ES-MS and means to detect and study by ES-MS species that are short-lived in solution. In addition, this work shows that electrospray ionization can potentially be used to generate gas-phase dications for mass spectrometric study that are difficult to produce directly from gas-phase neutrals by other ionization techniques (e.g., M2+ from β-carotene). © 1994 American Society for Mass Spectrometry.
Van Berkel, G. J., Asano, K. G., & McLuckey, S. A. (1994). Observation of gas-phase molecular dications formed from neutral organics in solution via qemical electron-transfer reactions by using electrospray Ionization Mass Spectrometry. Journal of the American Society for Mass Spectrometry, 5(7), 689–692. https://doi.org/10.1016/1044-0305(94)85009-7