Mass measurement accuracy of matrix‐assisted laser desorbed biomolecules: A Fourier‐transform ion cyclotron resonance mass spectrometry study

The use of binary matrices and internal calibrants to improve the mass measurement accuracy in matrix‐assisted laser desorption ionization (MALDI) with Fourier‐transform ion cyclotron resonance (FTICR) mass spectro‐metry is described. Binary matrices enhance the analyte ion yield and enable a complete MALDI‐FTICR mass spectrum to be obtained from a single laser shot. The advantage of single‐laser‐shot data acquisition is that it eliminates line‐broadening due to shot‐to‐shot frequency variations. It is shown that unresolved product ions, mainly due to loss of H 2 O and/or NH 3 , shift the centroid of an unresolved multi‐component peak. A mass measurement accuracy of 12 ppm was obtained for the bovine insulin [M+H] + ion using melittin as an internal calibrant.