In-beam electron impact mass spectrometry of aliphatic alcohols

The characteristics of the in-beam electron impact mass spectra of six isomers of undecanol as well as several 1-alkanols have been examined. In addition to the characteristic ions observed in the conventional electron impact spectra, the 2M+1]⁺, 2M+1-H₂O]⁺, 2M+1-2H₂O]⁺, 2M-R or R′]⁺, 2M-H₂O? R or R′]⁺, 2M? 2H₂O? R or R′]⁺ and M+1? H₂O]⁺ peaks are common in the in-beam electron impact mass spectra of the undecanol isomers of structure RCH(OH)R′. Deuterium labelling experiments have shown that the extra proton in the protonated dimer ions, 2M+1]⁺, originates from the hydroxy group. The processes which produce the important peaks in the high m/e regions are discussed.