DIFFERENCE MEASUREMENTS AND SHAPED WAVE-FORMS APPLIED TO HADAMARD-TRANSFORM FT ICR/

This tutorial paper is focused on the application of the Hadamard tran sform to FT/ICR mass spectrometry. The use of Hadamard schemes in comb ination with ''difference measurements'' and ''shaped waveforms'' beco mes a simple and reliable measurement technique. Collision-induced dis sociation spectra can be recorded without any ejection of ions and wit h a simultaneous gain in signal-to-noise ratio. For the measurement of ion/molecule reaction the required ejections are reduced to a minimum . Precise criteria concerning the selective ejection or activation of ions are defined and the use of optimally shaped waveforms is stressed in order to shorten the pulse length, when high front-end resolution is needed.