Building Orthogonal Analytics Techniques for Molecule Characterization

Sponsored by Waters Corporation

Relying on multiple orthogonal analytical techniques to fully characterize a bioconjugate can create operational bottlenecks if routine and characterization are not clearly defined. Zhengqi Zhang, Associate Principal Scientist at Merck & Co., describes how his team addresses this by using standardized, routine methods—such as hydrophobic interaction chromatography ultra-violet (HIC-UV) for drug-to-antibody ratio (DAR), size exclusion chromatography (SEC) for high-molecular-weight species, capillary sodium dodecyl sulfate (CSDS) for size variants, and imaged capillary isoelectric focusing (icIEF) for charge variants—for release and in-process testing. Decisions about which method to use are based on throughput needs and regulatory risk, with high-resolution mass spectrometry (MS) methods such as SEC-MS, HIC-MS, and RPM reserved for extended characterization, investigations, or regulatory filings. Lance Cadang, Scientist, Synthetic Molecule Analytical Chemistry at Genentech adds that his team builds multi-attribute capability into methods from the start, while reserving techniques such as multiangle light scattering (MALS), analytical ultracentrifugation (AUC), and MS for cross-checking high-molecular-weight species at later development stages. Both speakers describe MALS used alongside SEC to estimate the size of material underneath a chromatographic peak, while AUC is generally reserved for later-stage confirmation.