Development and Optimization of an Electrospray Diverter for Reduced Background Signal in Ambient Ionization Sources

A common issue in pulsed ambient ionization sources is the presence of background ions, which can cause ionization suppression and negatively influence downstream statistical analysis. Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is an ionization technique commonly used for mass spectrometry imaging and high throughput screening, both of which highly benefit from reduced background signals. An electrospray diverter was developed to act as an ion shutter, preventing ions from entering the mass spectrometer when a sample related signal was not present. After timing optimization for both liquid based screening and tissue imaging, reductions in background signal up to 4-fold were observed, as well as increases in sample related signal up to 11-fold. In all cases, a relative increase in the sample related signal was observed, and no negative impacts on sample related data were detected.