Ultra High Resolution Linear Ion Trap Orbitrap Mass Spectrometer (Orbitrap Elite) Facilitates Top Down LC MS/MS and Versatile Peptide Fragmentation Modes

TLDR

The combination of a linear ion trap with an Orbitrap analyzer has become a standard platform for protein and proteome characterization. This work introduces the Orbitrap Elite, a novel instrument that improves three key performance areas. It incorporates redesigned ion‑transfer optics that block line of sight for robustness, a compact high‑field Orbitrap analyzer, and a survey scan paired with selected‑ion monitoring and HCD microscans for top‑down experiments. The Elite delivers >12 Hz tandem‑MS speed, 240 000 resolving power at m/z 400, cycle times of only a few seconds, a 30 % boost in protein identifications in bottom‑up workflows, and routinely captures complementary dissociation data for all fragmented peptides.

Abstract

Although only a few years old, the combination of a linear ion trap with an Orbitrap analyzer has become one of the standard mass spectrometers to characterize proteins and proteomes. Here we describe a novel version of this instrument family, the Orbitrap Elite, which is improved in three main areas. The ion transfer optics has an ion path that blocks the line of sight to achieve more robust operation. The tandem MS acquisition speed of the dual cell linear ion trap now exceeds 12 Hz. Most importantly, the resolving power of the Orbitrap analyzer has been increased twofold for the same transient length by employing a compact, high-field Orbitrap analyzer that almost doubles the observed frequencies. An enhanced Fourier Transform algorithm-incorporating phase information-further doubles the resolving power to 240,000 at m/z 400 for a 768 ms transient. For top-down experiments, we combine a survey scan with a selected ion monitoring scan of the charge state of the protein to be fragmented and with several HCD microscans. Despite the 120,000 resolving power for SIM and HCD scans, the total cycle time is within several seconds and therefore suitable for liquid chromatography tandem MS. For bottom-up proteomics, we combined survey scans at 240,000 resolving power with data-dependent collision-induced dissociation of the 20 most abundant precursors in a total cycle time of 2.5 s-increasing protein identifications in complex mixtures by about 30%. The speed of the Orbitrap Elite furthermore allows scan modes in which complementary dissociation mechanisms are routinely obtained of all fragmented peptides.