Recently, the biotech industry has embarked on an effort to adopt a Quality by Design (QbD) approach in developing manufacturing processes that can robustly deliver biopharmaceutical products with desired quality attributes.The first, and perhaps the most critical, step in the QbD approach is to identify the critical quality attributes (CQAs) for a biopharmaceutical product.CQAs cannot be confidently determined without a thorough understanding of the relationship between the structure and function a molecule.