IMPROVED MASS ACCURACY IN MATRIX-ASSISTED LASER DESORPTION IONIZATIONTIME-OF-FLIGHT MASS-SPECTROMETRY OF PEPTIDES/

One problem of matrix-assisted laser desorption ionization coupled to time-of-flight mass spectrometry is the moderate mass accuracy that ty pically can be obtained in routine applications. Here we report improv ed mass accuracy for peptides, even when low amounts and complex pepti de mixtures are used. A new procedure for preparing matrix surfaces is used, and there is no need to mix the matrix with the sample or to ad d internal standards. Examples are shown with a mass accuracy better t han 50 ppm in a peptide mixture. Peptide mapping as well as sequencing by creating ''ragged ends'' or ''ladder sequencing'' should benefit e specially from the improved mass accuracy.