Atmospheric Pressure Corona Discharge Ionization of n-Heptane (I). Formation of Molecular Ion M+•, and Dehydrogenated Ions [M−2H]+• and [M−nH]⁺ (n=1, 3, 5)

The formation of M + , [M-2H] + , and [M-nH] + (n=1, 3, 5) ions has been reported by using atmospheric pressure corona discharge (APCD) of n-heptane.The M + and [M-H] + ions can be produced by high-electric field tunnel ionization (HEFTI) and hydride abstraction reactions, respectively.It has been proposed that the [M-2H] + , Mass Spectrometry Advance Publication result of collisional interactions between the M + ion and the air components such as N2, O2, and Ar, or to the result of the HEF-induced cracking reaction leading to the alkyl fragments.