The fragmentations of alkylamine ions C~nH~2~n~+~1NH~2^+ produced from 18 kinds of alkylamine salts by the electron impact ionization and protonated alkylamine C~nH~2~n~+~1NH~3^+ produced from them by the chemical ionization were examined using collision- induced dissociation. Major dissociation pathways of C~nH~2~n~+~1NH~3^+ include the loss of C~XH~2~X, C~XH~2~X~+~1, C~XH~2~X~+~2, and NH~3, accompanied with the formation of [C~yH~2~y~+~1]^+ and CH~3CH=NH~2^+. Major dissociation pathways of C~nH~2~n~+~1NH~2^+ include the loss of C~XH~2~X, C~XH~2~X~+~1, and NH~3, followed by the formation of [C~mH~2~m~-~1]^+, CH~2=NH~2^+ and CH~3CH=NH~2^+. With increasing the collision energy, the distribution of the product ions was changed because of competing between the charge-remote fragmemtation and charge-induced processes, such as [C~yH~2~y~+~1]^+ and [C~mH~2~m~-~1]^+. The charge-remote fragmentation of protonated alkylamines and the fragmentation of alkylamine ions can be explaned by using the radical mechanism and hydrogen abstraction of intramolecule, respectively.

Key words: ION-MOLECULE REACTION, CHEMICAL IONIZATION SOURCE MASS SPECTROMETRY, ELECTRON BOMBARDMENT, FRAGMENTAION REACTION, ALIPHATIC AMINES, PROTONATION, MASS SPECTROGRAPHY