The Thermo Scientific LTQ Velos mass spectrometer incorporates a revolutionary dualpressure linear ion trap design. Prior to the LTQ Velos™ dual-pressure design, ion traps were operated at a single pressure that was a compromise between the optimum pressures for ion manipulation (trapping, isolating, fragmenting) and detection (mass analysis). The unique dual-pressure linear ion trap technology features two discrete pressure regions (cells) that allow the decoupling of ion manipulation and detection. A high-pressure cell (HPC) is used for trapping injected ions, isolating precursor ions, and fragmenting precursor ions. A low-pressure cell (LPC) is used for scanning ions out to the detectors, i.e. mass analysis.