A
mass spectrometer is configured with individual multipole
ion guides, configured in an
assembly in alignment along a common centerline wherein at least a portion of at least one multipole
ion guide mounted in the
assembly resides in a vacuum region with higher background pressure, and the other portion resides in a vacuum region with lower background pressure. Said multipole
ion guides are operated in
mass to charge selection and ion fragmentation
modes, in either a high or low pressure region, said region being selected according to the optimum pressure or pressure gradient for the function performed. The
diameter, lengths and applied frequencies and phases on these contiguous ion guides may be the same or may differ. A variety of MS and MS / MSn analysis functions can be achieved using a series of contiguous multipole ion guides operating in either higher background vacuum pressures, or along pressure gradients in the region where the pressure drops from high to low pressure, or in low pressure regions. Individual sets of RF, + / −DC and resonant frequency waveform
voltage supplies provide potentials to the rods of each multipole ion guide allowing the operation of ion transmission,
ion trapping,
mass to charge selection and ion fragmentation functions independently in each ion guide. The presence of background pressure maintained sufficiently high to cause ion to neutral gas collisions along a portion of each multiple ion guide linear
assembly allows the conducting of Collisional Induced Dissociation (CID) fragmentation of ions by axially accelerating ions from one multipole ion guide into an adjacent ion guide. Alternatively ions can be fragmented in one or more multipole ion guides using resonant frequency excitation CID. A multiple multipole ion guide assembly can be configured as the primary
mass analyzer in single or triple
quadrupole mass analyzers with or without mass selective axial ejection. Alternatively, the multiple multipole ion guide linear assembly can be configured as part of a
hybrid Time-Of-Flight, Magnetic Sector,
Ion Trap or
Fourier Transform mass analyzer.