Abstract Mass spectrometry imaging (MSI) is an analytical technique that enables the simultaneous detection and localization of hundreds to thousands of molecules across a tissue surface. The addition of ammonium fluoride to the electrospray or to tissue samples has been shown to increase the signal of lipids in both nano-DESI-MSI and MALDI-MSI, respectively. Herein, this strategy is applied to infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) which demonstrated signal enhancement for both lipids and N -linked glycans using 70 µM and 350 µM NH 4 F in 50% ACN with 1 mM acetic acid as the ESI solvent, respectively. Up to a 93-fold increase in signal was observed for these biomolecules without any change in sample preparation or to the mass spectrometer parameters, including detecting lipids not seen with the control ESI solvent. On average, lipids were enhanced by eightfold, and the glycan signal increased by 1.2-fold. The enhancement factor for lipids was significantly impacted by lipid class, while glycan enhancement was affected by charge state and the observed adduct. Graphical Abstract
Eisenberg et al. (Tue,) studied this question.