Electromagnetophoretic Dynamic Force Measurement of Particle-Wall Interaction in Solution; Effects of pH and Metal Ions

The electromagnetophoretic buoyancy exerted on a carboxylated polystyrene particle in an electrolyte solution was utilized for the measurements of the desorption force of the particles from the carboxylated capillary wall. The effects of the pH and the presence of Cu2+, Ni2+, Fe3+ or Al3+ on the desorption dynamics were examined. The observed histogram of the desorption events of the particles as a function of the pulling force was analyzed by the Bell mechanism, which could be used to evaluate the spontaneous desorption rate constant of the particle in the absence of the external force and the critical distance for the breaking of the interaction. The feasibility of the present method as a simple dynamic force measurement technique of chemical interaction was demonstrated.