Diffusion kinetics of a prior developed automated dialysis system are investigated via in situ NMR spectroscopy for an optimization of conventional and advanced polymer purification. Using a polymeric solution, mixed with the respective monomer, several parameters like starting concentration, solvent volume, and solvent exchange by flow or complete one-time exchange are varied, resulting in a significant decrease of purification time for the automated setup. With an increased solvent flow (from 0.9 to 5.5 mL/min), 5.4 h and 2000 mL of solvent are required to decrease the monomer concentration to the detection limit. Without solvent flow, which corresponds to conventional dialysis, only 9 h and 250 mL of solvent are required for the same result, which is a time- and solvent-saving development for common purification of polymers.