Assay |
Purpose |
Field flow fractionation multiangle light scattering (FFF-MALS) |
Determine particle number and aggregation state |
Atomic force microscopy (AFM) |
Determine particle number and aggregation state |
Transmission electron microscopy (TEM) |
Determine particle number |
Size exclusion chromatography multi - angle light scattering (SEC-MALS) |
Determine particle number and aggregation state |
TCID, FFA, plaque, or other assays |
Determine proportion of defective particles based on the difference between total particles and infectious particles |
Polymerase chain reaction (PCR) |
Determine proportion of nucleic acid containing particles |
Density gradient centrifugation |
Determine proportion of defective particles based on relative densities of particle populations |
Analytical ultracentrifugation (AUC) |
Determine proportion of defective and aggregated particles based on hydrodynamic properties of particle populations |
Capillary electrophoresis (CE) |
Determine proportion of defective and aggregated particles based on particle mass and charge |
Reversed-phase HPLC (RPHPLC) |
Determine proportion of defective and aggregated particles based on hydrophobic interaction properties |
Ion-exchange chromatography (IEC) |
Determine proportion of defective and aggregated particles based on charge state of the particles |
Size exclusion chromatography (SEC) |
Determine proportion of defective and aggregated particles based on hydrodynamic sieving properties of particle populations |
SDS-PAGE (or equivalent) |
Determine composition of proteins contained in preparation based on polypeptide chain sizes |
Western blot |
Determine composition of immunoreactive proteins contained in preparation |
Process residuals (BSA, benzonase, polysorbate, etc.) |
Quantify process-related impurities |