Despite the increasing popularity of data-independent acquisition workflows, data-dependent acquisition (DDA) is still the prevalent method of LC-MS based proteomics. DDA is the basis of isobaric mass tagging technique, a powerful MS2 quantification strategy that allows co-analysis of up to 10 proteomics samples. A well-documented limitation of DDA, however, is precursor co-selection, whereby a target peptide is co-isolated with other ions for fragmentation. Here, 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. We discuss challenges associated with applying TWIMS purification to isobaric mass tagging experiments, including correlation between ion m/z and drift time, which means that co-selected peptides are expected to have similar mobility. We also demonstrate that labelling results in peptides having more uniform m/z and drift time distributions than observed for unlabelled peptides.