During production of therapeutic antibodies, harvest titer is measured to monitor product mass loaded onto the protein A capture column. This prevents both column underloading (underusing expensive resin) and overloading (wasting product as flow-through (FT)) while allowing for column yield calculations. Batch production yields a single homogenous harvest pool, thus only one titer measurement (along with volume loaded) is sufficient to determine the mass loaded. During continuous production, however, cell-free harvest (permeate) continuously exits a perfusion reactor and loads a…