Threshold fluences for production of positive and negative ions in matrix-assisted laser desorption/ionisation using liquid and solid matrices

Abstract

Dependences of positive and negative analyte-ion and matrix-ion signals upon pulse energy (at 266 nm) have been measured in matrix-assisted laser desorption/ionization (MALDI), for a liquid matrix (3-nitrobenzyl alcohol) and for a solid matrix (sin-apinic acid). The analyte was the protein bovine insulin. The results suggest that the threshold fluences for the formation of positive and of negative ions are the same as each other, for a given matrix. The threshold fluences are lower in the case of the liquid matrix as compared to the solid matrix.