The utility of multiplexed quantitation using isobaric tags (ITRAQ or TMT) has been well documented in the literature. Today such protein quantitation approach has become a first choice method in many proteomics laboratories due to its proven protocol and productivity to facilitate comparative study of up to 10 experiments. On a high resolution mass spectrometer, the quantitative data are obtained from the cyclic targeted MSMS process (data-dependent acquisition) which releases the associated reporter tags for the detected peptides. In most complex sample situation, isolations of target peptides during DDA have been challenged with co-isolation of other peptides within a 2-Da or 3-Da selection window. This invariably leads to unresolvable error in quatitation. A novel approach based on the new hybrid Orbitrap platform (Orbitrap Fusion) offers significant improvement in accuracy and sensitivity in complex labelled quantitation scenarios. This method involves a triple-stage HRMS measurements (MS3) using ion-trap based CID followed by HCD to generate the corresponding reporter tag ions.