A Three-point Calibration Procedure for Matrix-assisted Laser Desorption/Ionization Mass Spectrometry Utilizing Multiply Charged Ions and Their Mean Initial Velocities

This paper reports the results obtained by using a new calibration procedure for linear time-of-flight matrix-assisted laser desorption/ionization mass spectrometry (MALDI). The procedure takes into account the usual MALDI spectra structure by considering the multiply charged molecular ions and the mean initial velocities as a self calibrating property. The mean velocities for all molecular ions are taken to be the same and the procedure is based on the solution of a number of equations (at least three) which relate time-of-flight to mass. Three times better accuracy was obtained in comparison with the normal internal calibration procedure.