on 05-01-201210:48 AM - edited on 11-09-202101:18 AM by usermigration2
Michalski A, Damoc E, Lange O, Denisov E, Nolting D, Müller M, Viner R, Schwartz J, Remes P, Belford M, Dunyach JJ, Cox J, Horning S, Mann M, Makarov A. Mol Cell Proteomics. 2012 Mar;11(3):O111.013698. 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 which blocks the line of sight to achieve more robust operation. The MS/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 two fold for the same transient length by employing a compact, high-field Orbitrap analyzer that almost doubles the observed frequencies. An enhanced Fourier Transform (eFT) 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 LC MS/MS. For bottom-up proteomics, we combined survey scans at 240,000 resolving power with data-dependent CID of the 20 most abundant precursors in a total cycle time of 2.5 s increasing protein identifications in complex mixtures by about 30 percent. The speed of the Orbitrap Elite furthermore allows scan modes in which complementary dissociation modes are routinely obtained of all fragmented peptides.