The venerable solution-depletion method is perhaps the most unambiguous method of measuring solute adsorption from solution to solid particles, requiring neither complex instrumentation nor associated interpretive theory. We describe herein an SDS-gel electrophoresis implementation of the solution--depletion method for measuring protein adsorption and protein-adsorption kinetics. Silanized-glass particles with different surface chemistry/energy and hydrophobic sepharose-based chromatographic media are used as example adsorbents. Electrophoretic separation enables quantification of adsorption competition among multiple proteins in solution for the same adsorbent surface, demonstrated herein by adsorption--competition kinetics from binary solution.