TuO-04
ACCURATE MASS MEASUREMENTS USING MALDI-TOF WITH DELAYED EXTRACTION
Arnold M. Falick, Edward Takach, Dale Patterson, Peter Juhasz, Wade Hines, Marvin Vestal & Stephen Martin
PerSeptive Biosystems, Inc., 400 Old Connecticut Path, Framingham, MA, USA
Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF)
mass spectrometry has become an essential tool for the analysis of biopolymers. The sensitivity and mass range of this technique are unsurpassed, but mass measurement accuracy and resolution have been limiting factors. The introduction of delayed extraction (DE) in MALDI-TOF instruments has led to a large improvement in achievable resolving power and a concomitant increase in mass measurement accuracy. The ability tomeasure mass accurately provides opportunities for compositional analysis ofpeptides and other analytes. For example, with sufficient mass measurement accuracy, it is possible to distinguish Lys from Gln (mass difference = 0.036 Da) in a peptide. In some cases it is also possible to determine the elemental composition of small molecules or peptide adducts, and in data base searching strategies, a smaller mass window greatly decreases the number of possible candidates.
Results will be presented demonstrating mass measurement accuracy of
10 ppm or better, using MALDI-TOF instruments in the reflector mode and
internal mass standards. A mixture of known peptides extending over the mass range from 900 to 4000 Da is used to demonstrate accuracy, reproducibility and linearity. Additional examples of accurate mass determinations of peptides and smaller molecules will be presented.