Since the FDA approved the first monoclonal based therapy in 1985, mAbs have had significant clinical success and have been used to provide effective treatment for a range of diseases. During development and quality control, you may use a range of analytical technologies to characterize biotherapeutic drugs in terms of their structural integrity and activity. This presentation includes some examples on the use of Biacore™ surface plasmon resonance (SPR) systems for active concentration measurement, target binding, and describe how you can use these assays for assessment of drug potency (EC50) and stability.