Detection of the Short-Lived Radical Cation Intermediate in the Electrooxidation of N,N-Dimethylaniline by Mass Spectrometry

The N,N-dimethylaniline (DMA) radical cation DMA^.+, a long-sought transient intermediate, was detected by mass spectrometry (MS) during the electrochemical oxidation of DMA. This was accomplished by coupling desorption electrospray ionization (DESI) MS with a waterwheel working electrode setup to sample the surface of the working electrode during electrochemical analysis. This study clearly shows that DESI-based electrochemical MS is capable of capturing electrochemically generated intermediates with half-lives on the order of microseconds, which is 4–5 orders of magnitude faster than previously reported electrochemical mass spectrometry techniques.