Proteins, monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) are powerful therapeutic agents. Because of their high molecular complexity, however, biopharmaceuticals may be quite sensitive to changes in the manufacturing processes that can lead to considerable micro-heterogeneity. As a result, a panel of separation techniques based on both liquid chromatography and electrophoresis has been used for their characterization and comparability studies. In terms of detection, mass spectrometry (MS) plays a pivotal role in the structural elucidation of biopharmaceuticals, because it offers an additional degree of separation by mass/charge ratio, greatly facilitating the characterization of variants. This two-part web seminar will discuss possibilities and limitations of chromatographic techniques and mass spectrometry detection for the physico-chemical characterization of biopharmaceutical compounds. Part II will focus on mass spectrometry techniques for the physico-chemical characterization of mAbs and related compounds. Classical MS analysis comprising intact mAb mass measurements, LC-MS analyses in reducing conditions or after deglycosylation treatment, and peptide mapping will be presented. The focus will be on enzymatic treatments that generate mAb fragments of smaller size that are more readily analyzable by MS techniques. In this presentation, some new trends in MS including native MS and ion mobility?MS (IM-MS) approaches will be also discussed. Finally, the benefits of high resolution native MS analysis will be explained.