Hi everyone, An old method for determining the zeta potential of a particle involves measuring the time it takes for the particles to move a certain distance towards the electrode in an electrophoresis bath. One can find the zeta potential using the Smoluchowski equation: μ = εr ε0ζ/η What I don't quite understand is whether the equation compensates for size of the particle or not. I assume larger, heavier particles would migrate toward the electrode slower. This would mean the zeta potential calculated via the formula would look lower than it actually is. Is there some factor I'm missing or is the effect simply too small to matter in most cases? Thanks!