Electrochemical Push–Pull Scanner with Mass Spectrometry Detection

This manuscript presents a push–pull electrochemical scanner able to image reactivity of initially dry surfaces by scanning electrochemical microscopy (SECM) and to probe molecules present or generated at the surface by mass spectrometry (MS). The proof-of-concept is demonstrated by coupling SECM with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for imaging latent human fingerprints, which had been in contact with picric acid used here as a model explosive. The push–pull electrochemical scanner has also been coupled with electrospray ionization mass spectrometry (ESI-MS) to assay the activity of surface spotted enzymes. These experimental studies are complemented by 3D finite element simulations solving Navier–Stokes and diffusion–convection differential equations to optimize the coupling between SECM imaging and mass spectrometry detection.