Multi-modal Mass Spectromety Approach to Characterize Clozapine and Metabolites by Combining Imaging Modalities and Absolute Quantitation

Introduction
In pharmaceutical research, mass spectrometry-based techniques provide a variety of information to enable new drug development. In this work, we performed a multi-modal approach to fully characterize a model drug, clozapine, and its major metabolite by combining mass spectrometric modalities: matrix assisted laser desorption mass spectrometry (MALDI-MS) imaging, laser ablation electrospray ionization mass spectrometry (LAESI-MS) imaging, and LC-MS workflows. The spatial localization of the drug and metabolite from the imaging modalities was combined with absolute quantitation by LC-MS to gain a more complete evaluation of clozapine metabolism and biodistribution within tissues.