The analytical group at Boehringer Ingelheim, Fremont, USA needed a robust assay to measure the biological activity of an antibody fragment (Fab) molecule for in-process testing as well as stability and lot release testing in their Quality Control (QC) department. The developed Fab activity assay is accurate and robust, with intermediate and intramediate precision less than 10%. Drug activity measurement using the Octet® system has become a critical parameter for their product evaluation and has resulted in increased Fab drug…