An Improved Protocol for the Analysis of Alcohols by Direct Analysis in Real Time Mass Spectrometry

Authors: J. Michael Nilles, Theresa Connell, H. Dupont Durst, James A. Laramée
American Laboratory 2009, Jun, 18, 41, 25-27

 

It was previously reported1 that when Direct Analysis in Real Time (DART®™) (JEOL USA, Inc., Peabody, MA) mass spectrometry was applied to the analysis of very pure alcohols, their mass spectra were unexpectedly complicated. The plethora of peaks was found to be a DART®-induced artifact that resulted from the open-air nature of the technique. This problem was solved by converting the alcohol into its corresponding carbamate via an N-hydro-C-alkoxy-addition reaction (reaction 1) with phenyl isocyanate:

ROH + C6H5NCO ? RO?C(O)NHC6H5 (1)

Although this reaction conveniently allows alcohols to be DART®’ed, the reaction time ranges from 1 to 16 hr. This obviously led the authors to test the hypothesis that shorter reaction times can be achieved by using activated phenyl isocyanates with proper ring substitution. It is now timely to report these results.