Proteomics has become a key technology to understand and characterize protein expression , interactions and sequence modifications in modern biology . Quantitative bottom-up proteomics has dominated three different approaches depending on whether isotope labels are introduced and how they are introduced, in vivo metabolic labelling , in vitro labelling , and label-free . Some of the most prominent labelling methods are isotope labelling by amino acids in cell culture (SILAC), isobaric tags for relative and absolute quantification (iTRAQ), and tandem mass tags (TMT) . In quantitative label-free, no isotopes or labels are added to the sample and the samples are not multiplexed in the same runs. Additionally, the approach has not limited in the number of samples that can be analyzed making it ideal for largesample analyses in clinical screening or biomarker discovery experiments. A vast literature on label-free quantification (LFQ) methods, reviewed in 5, 7 and 8, 9 already exists.