Analytical Protein A affinity columns have been routinely used to monitor the titer of mAb and other Fc containing constructs such as fusion proteins and bi-specific antibodies in cell culture. In addition, ProA columns have been deployed for online 2D purification in front of SEC to enable the direct size variant analysis of mAbs in cell culture by either connecting the two columns via switching valves or in series without switching valves. Here, we present a direct-connect 2D ProA-SEC method that makes use of a recently developed high efficiency, low volume ProA column.