Effects of heavy-atom substituents on matrices used for matrix-assisted laser desorption-Ionization mass spectrometry.

The data reported show that heavy-atom substitution on matrices that are used for matrix-assisted laser desorption-ionization mass spectrometry enhance [M + H](+) ion yields of both Leu-enkephalin and vitamin B12. Heavy-atom substitution alters the excited state relaxation dynamics of the matrices as indicated by measured decreases in the measured luminescence (fluorescence and/or phosphorescence) observed for heavy atoms that contain matrices relative to the nonheavy-atom-substituted matrices. The results presented are consistent with the direct involvement of an electronically excited state of the matrix in the formation of analyte [M + H](+) ions.