If you're looking for a detailed answer, I'd recommend to provide some more details on the question you have..
At first instance, it doesn't sound very logical (i.e. impossible) that a molecule gets protonated by an electron, it could become positively charged upon losing an electron.
But again, could you provide some more details, please? This will help getting it answered eventually.
It looks like you are talking about electron ionization source (so I guess coupled to GC. In that case, the impact of electron will excitate the molecule giving, as a result, the loss of 1 electron from the neutral molecule and quite often abundant fragemtnation.
For more information, jsut look for mechanism of ionization in electron ionazation source.
Protonated by an additional electron in mass spectroscopy ??? I would then be awarded the Nobel Prize.
Either get a molecule an electron, it's negatively charged or it loses an electron, it's positively charged.
EI-ionization (GC-MS), it loses one electron, and then to the positive radical.
Also e.g. at ESI ionization it usually gets an H (proton) and becomes a positive ion [M + H] + or it loses an H (proton) and becomes a negative ion [M-H] -!
I propose again read all about mass spectroscopy before.