Thermo Fisher recently released an additional channel for TMT, which means you can now combine up to 11 different samples as one for better sample comparability and more complete data! It is now possible to use “isotopologue” encoding to split the 131 (last) channel into 131-N and 131-C to get from TMT-10plex to TMT-11plex.
For people unfamiliar with how TMT works, fragmentation of a TMT-6plex labelled precursor releases 6 reporter ions ranging from 126 to 131 Da, which can then be relatively quantified. TMT-10plex expanded the repertoire of TMT-6plex by splitting the 4 middle peaks into 4 pairs of 2 very closely related “N” and “C” peaks: because the mass shift (changes to nuclear binding energy) of adding a neutron to a nucleus is not simply like adding the mass of one neutron, but also depends on the general nuclear context and how the extra neutron affects total nuclear stability, there is a subtle difference between the 15N-14N and 13C-12C delta masses: (13.003355 – 12.000000) – (15.000109 – 14.003074) = 0.00632 Da. Amazingly, modern Orbitrap mass spectrometers can resolve these incredibly close peaks!
Now TMT-11plex applies this same peak splitting to the last of the original TMT-6plex reporter peaks.