Updated project metadata. We investigated if additional peptide purification by traveling wave ion mobility separation (TWIMS) can reduce precursor contamination using a mixture of S. cerevisiae and HeLa proteomes. In accordance with previous reports on FAIMS-Orbitrap instruments, we find that TWIMS provides a remarkable improvement (on average 2.85 times) in signal to noise ratio for sequence ions. We also report, that TWIMS reduces reporter ions contamination by around one third (to 14 - 15% contamination) and even further (to 6-9%) when combined with narrowed quadrupole isolation window.