Comparability of In-line and At-line Variable Pathlength Technology for Concentration Monitoring

This white paper presents a study on the comparability of two Variable Pathlength Technology (VPT) systems, the FlowVPX and the SoloVPE PLUS, for real-time concentration monitoring in tangential flow filtration (TFF) processes. The objective is to evaluate the performance of these systems using monoclonal antibodies and antibody-drug conjugates across a range of concentrations. The FlowVPX System utilizes UV spectrophotometry to measure concentration directly during operation, minimizing interferences from buffer and scatter corrections. The study involved a series of experiments comparing in-line measurements from the FlowVPX with off-line measurements from the SoloVPE PLUS, assessing the impact of various method modifications, including scatter correction settings. Results indicated that both systems were comparable in accuracy, with percent differences remaining within acceptable limits for typical UF/DF processes. The findings underscore the advantages of real-time monitoring in enhancing process understanding and potentially improving yield by reducing reliance on off-line sampling methods.