Regulatory standards and clinical administration require thorough documentation of quality attributes pertaining to drug product identity, purity, potency, stability, and safety. However, the high complexity of C>s poses a considerable challenge for impurity and product characterization strategies. Unlike traditional biologics, which are typically manufactured by expressing one recombinant protein in a single cell line, advanced therapies contain highly heterogeneous protein mixtures from multiple sources and organisms. Traditional biologics also have well-defined manufacturing processes supported by established analytical methods, whereas the manufacturing processes for cell & gene therapies are often still in development. Improved analytical tools, such as mass spectrometry (LC-MS), ensure process consistency and quality and meet regulatory requirements for product release and characterization.