Fast Online Separation and Identification of Electrochemically Generated Isomeric Oxidation Products by Trapped Ion Mobility–Mass Spectrometry

Trapped ion mobility spectrometry (TIMS) is presented as a new and rapid method to distinguish between electrochemically generated isomeric oxidation products. Separation was performed online directly after generation and ionization of the analytes, thus providing the opportunity to detect even short-lived and reactive transformation products. The same setup enables structure elucidation based on TIMS aligned fragmentation experiments. Due to the high resolution, TIMS was able to distinguish between two isomeric transformation products of the model compound metoprolol, which only differ in the position of the hydroxylation taking place in the benzylic and aromatic positions, respectively. Using this method, the analysis time is at least five times shorter compared to conventional chroma­tography approaches. Consequently, TIMS may arise as a powerful tool in electrochemical metabolism studies.