Tandem ion trap design with enhanced mass analysis capabilities for large populations of ions.

A new arrangement consisting of two separate radio frequency (rf) quadrupole ion traps is used to analyze large populations of ions over a wide mass-to-charge (m/z) range. The setup consists of an "accumulation" trap that is maintained at a higher pressure than the second high-performance "analyzer" trap. The two traps are scanned simultaneously, with a mass difference between that determines the residence time and mass range of ions in the analytical trap. Initially, all ions are trapped in the accumulation trap and then mass-selectively ejected into the analyzer trap. As ions arrive in the analyzer trap, they cool through collisions with the buffer gas and then are mass selectively ejected toward the detector. This concurrent linked mass scanning reduces the total number of ions present in the analyzer trap during mass analysis, thereby reducing space charge effects and leading to improved resolution and mass accuracy of analytical spectra.