Solvent effects on the ion internal energy in ESI were first evidenced with water/glycerol mixtures giving higher internal energies than water/methanol . showed that the internal energy of ions produced by a ESI source with a quadrupole-TOF hybrid mass spectrometer had been calculated by using five different benzhydrilpyridinium ions diluted in dichloromethane or methanol. The survival yield analysis led to internal energy distribution with maxima at 2.06 ± 0.13 eV in dichloromethane and 1.88 ± 0.11 eV in methanol, suggesting that the solvent effect had a small but significant influence.