At-line mid infrared spectroscopy for monitoring downstream processing unit operations

Abstract At-line mid infrared spectroscopy (FT-MIR) was used for monitoring monoclonal antibody (mAb) titer, host cell protein levels and antibody aggregate amount in samples, originating from different downstream processing unit operations, performed during technical laboratory scale development runs. Antibody aggregate quantification was possible down to 1% [w/w], while host cell protein levels could be monitored down to 700 ng ml −1 . Antibody titer could be determined with high accuracy for samples >0.7 g L −1 , with the possibility to further increase sensitivity when using samples with highly similar matrix. Comparing these results to relevant levels during downstream processing, the most promising applicability of FT-MIR is within target protein (mAb) monitoring, while HCP monitoring following intermediate and polishing chromatography steps is currently not a well-suited application. FT-MIR for aggregate monitoring is more suitable for steps resulting in higher aggregate levels such as pH stress and shear stress- related purification steps. Additionally, FT-MIR might be considered for monitoring of samples with higher HCP and aggregate amount profiles, which can occur during initial purification steps and when using alternative purification methods such as precipitation.