The field ion mass spectra of unbranched and branched amines with carbon numbers from C2 to C10 are discussed. Both thin platinum wires and tips have been used for production of the ionizing high fields. Some general rules are derived from the mass spectra which are consistent with the theoretical model used for interpretation of field ion mass spectra. The results lead to an extension of the model to polar molecules, regarding the influence of orientation of the molecules on the field ion mass spectra.