Current work indicates that trivalent lanthanides will consistently sorb to a rotating disk mercury film electrode in bulk aqueous solution thus allowing the user to pre-concentrate trivalent lanthanides for further separation. However, the mechanism of sorption to the mercury film is largely unknown, making it difficult if not impossible to predict a priori the conditions under which pre-concentration is optimized. In the present study, we explore some of the electrochemical factors affecting this pre-concentration process to optimize the technique for use in a wide variety of aqueous media. Trivalent neodymium (Nd(III)) is used as a model for the trivalent f-element cations. The factors investigated include pH of solution, rotation rate of the electrode, concentration of mercury, potential application waveforms, order of deposition, and time dependency.