QUADRUPOLE-DETECTION FT-ICR MASS-SPECTROMETRY

A new detection scheme for Fourier transform-ion cyclotron resonance (FT-ICR) studies is proposed and initial experimental results are presented. While in conventional FT-ICR the difference of the transient signals from two opposite electrodes yields a signal at the reduced cyclotron frequency v+, which depends on the applied trapping voltage and space charge, it is also possible to use the difference of the sum of these signals and the sum of a similar set of electrodes perpendicular to the first. In this way resonances are observed at the harmonic of the reduced cyclotron frequency, 2· ν+, as well as at (v+ + v-). The latter is interesting in respect of accurate mass measurements, since (v+ + v-) does not depend on the trapping voltage. © 1990.