Reversed-phase liquid chromatography (RPLC) is traditionally employed as the method of choice in TDP, i.a. due to its reproducibility, separation capacity, and MS compability, though capillary zone electrophoresis (CZE) represents an alternative for online MS. In particular, the separation principle of CZE is based on differences in electrophoretic mobilities (charge-to-size ratio) and is considered largely "orthogonal" to RPLC, where separation is driven by the hydrophobicity of analyte molecules. For this reason, the combination of information generated by both techniques is anticipated to increase the number of identified proteins and proteoforms.