High resolution mass spectrometry (HRMS)

We use a custom-built nano-electrospray ionization (ESI) source that is switchable to a nano-desorption electrospray (nano-DESI) source, modeled after the nano-DESI design that was developed in the lab of Alexander Laskin. These ESI-based ion sources are coupled to an LTQ-Orbitrap analyzer (mass resolving power up to 100,000 m/d(m)) to perform high-resolution mass spectrometry (HRMS) analysis of aerosol filter extracts and of analytes on surfaces (nano-DESI). We perform data processing and mass assignments using custom tools written in Matlab based on a heuristic filtering protocol described by the lab of Oliver Fiehn combined with Kendrick mass defect analysis.