A simple and novel sample preparation approach for effective characterization of antibody low molecular weight impurities by CE-SDS method

Product and process related impurities of biopharmaceuticals have serious implications on product safety and efficacy in clinical use. Low molecular weight (LMW) impurities are generated during process and stability studies are routinely analyzed using non-reducing capillary electrophoresis with SDS during different stages of product development and release. The current sample processing methodology with heat denaturation is known to induce fragmentation and interfere with the LMW impurity analysis. In this study, we compared different sample processing buffers with different compositions and pH and finally found a solution to the problem of sample artifacts generated during heat denaturation step of sample processing which interferes with the LMW impurity analysis by CE-SDS method. We compared three sample buffers (100 mM Tris-Cl, 25mM Citrate and 25mM citrate with Urea) in for their ability to maintain product integrity during sample processing at different pH and temperatures in the non-reducing CE-SDS analysis. This study suggests that, the sample processing with 25mM citrate with 8M Urea sample processing buffer does not require heat denaturation at higher temperatures and hence is the most appropriate buffer for sample processing in the LMW impurity analysis. The 25mM Citrate + 8M Urea buffer has shown better drug product stability and integrity compared to other buffers.

Hence, we recommend the 25mM Citrate buffer with 8M Urea for sample processing in LMW impurity analysis by CE-SDS method.