Use of Capillary Electrophoresis to Determine the Dilute Protein Concentration in Formulations Containing Interfering Excipients

Abstract

Excipients like human serum albumin (HSA) or surfactants are often added to prevent non-specific adsorption of proteins to surfaces. An enzyme-linked immunosorbent assay (ELISA) has been routinely used to quantify proteins when such excipients interfere with conventional biochemical assays, e. g., UV and HPLC, and make the accurate determination of low protein concentrations and purity difficult. Although the ELISA is a very sensitive assay, the results have large experimental errors contributed by the complicating nature of the assay. In addition, ELISA does not provide information about the qualitative degradation profile of protein, e. g., aggregation, cleavage, and deamidation. As an alternative to the ELISA a novel capillary electrophoresis (CE) method has been developed to determine both the purity and quantity of Infergen® (Interferon alfacon-1) formulated with interfering excipients like HSA. Results obtained from the CE method were consistent with the results from ELISA but the CE assay provided more reproducible and precise results. The optimized CE method was successfully applied to the formulation development by determining the recovery of diluted Infergen® in various formulations.KeywordsRelative Standard DeviationHuman Serum AlbuminCapillary ElectrophoresisSurface AdsorptionMigration TimeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.