Electrospray droplet impact/secondary ion mass spectrometry (EDI/SIMS) using NaF and AgF as cationization matrices

In our previous paper, it was suggested that metal fluorides may be useful as cationization matrices in Electrospray droplet impact/SIMS. In this work, NaF and AgF were used as the cationization matrices for cyclodextrin (CD), polyethylene glycol (PEG), polystyrene (PS), garlic juice, and sliced raw rice. EDI mass spectra were measured without and with the use of matrices. Enhancement of ion abundances of [M + Na]⁺ for CD and PEG with NaF matrix and that of [M + Ag]⁺ for PS with AgF matrix were observed. However, the addition of matrices was not effective for the cationization of garlic juice and sliced raw rice samples. This may be due to the Coulombic repulsion of the reagent ions of Na⁺ or Ag⁺ with the preformed K⁺ adducts of oligosaccharides already present in the samples. Copyright © 2015 John Wiley & Sons, Ltd.